Anatomy Midterm 2

Blood Vessels

• Arteries: blood away from the heart

• Veins: blood toward the heart

• Capillaries: where blood interacts with tissues

  • between arteries and veins

Arteries

• Lumen: hollow space inside the artery

• Tunica intima: innermost layer of the artery that actually touches blood (really thin)

  • Endothelium: simple squamous epithelium to prevent blood from clotting

  • Subendothelial layer: loose connective tissue that provides structural support to endothelium

• Internal elastic lamina: elastic connective tissue that is able to stretch when the blood volume increases and shrink when the blood volume decreases

• Tunica media: thick layer of smooth muscle that can constrict to reduce the size of the artery and increase pressure OR relax and cause vasodilation

  • Able to change the size of the lumen

  • Thicker in arteries than veins

• External elastic lamina: elastic connective tissue that is able to stretch when the blood volume increases and shrink when the blood volume decreases

• Tunica externa: loose connective tissue that is superficial, contains arteries, veins, and nerves needed

  • Provides hollow space so that each artery has its own blood supply and nerves

    • Nerves control contractions and provide energy for the smooth muscle of the tunica media to do its job

• How to classify arteries:

  • The composition of their walls and how big they are

  • Thick walls, prevent them from collapsing when there is no blood (circular in histology)

• Elastic arteries:

  • largest arteries

  • ex/ aorta

  • closest to the heart to carry large amounts of high pressure blood (highest pressure)

  • dampens pulsatile flow from the heart, makes the pressure more consistent for other blood vessels that can’t handle high amounts of pressure

    • There are rapid changes of blood pressure in arteries; if a capillary were to undergo a rapid change, it would pop

  • During systole (ventricles pumping), high pressure

  • During diastole (ventricles relaxing), lower pressure

• Aortic dissection: over time, damage to the tunica intima → blood does dissection (forces its way through the walls and cuts through as it goes) → generating a large structure known as the ‘false lumen’

  • Caused by uncontrolled high blood pressure

    • Endothelium and connective tissue cannot manage high blood pressure → start to break down → blood sneaks in between tunica intima and tunica media → expands → creates space where blood and fluid collect

    • As blood continues to go into the false lumen, dissection grows into an aneurysm (a big bulge on the side of the artery)

  • If an aneurysm continues to get bigger, it can pinch the blood flow going through the actual lumen of the aorta and prevent blood flow to tissues → tissue death

  • If the false lumen gets really large, it can overstretch all of the walls of the aorta → aorta wall rupture → 100% chance of death

  • Symptoms: fatigue, abnormal pulse in chest

    • Difficult to detect

    • IF detected early, can be repaired

      • If survive → lots of complications

• Aortic dissection repair:

  • Procedure:

    1. Know there is a dissection, see a massive aneurysm

    2. Go into the heart and find the area before and after the aneurysm and insert a large graft/stent (made of carbon or kevlar mesh) as a bypass to get past the location where the aneurysm has occurred

  • Problem:

    • lots of small branches

    • graft cuts off smaller arteries that are important → blood vessels that provide oxygen to the spinal cord get cut, damaged, or don’t receive blood → non-traumatic spinal cord injury

    • nerves don’t recover well from large anoxic injuries → doesn’t heal

    • ex/ can no longer walk

  • Usually patients with the risk of rupture are admitted to the hospital where their blood pressure is managed with meds (kept low to prevent rupture) so that the procedure can be done in the coming weeks and not as an emergency procedure

  • Risk of clotting forever because of stent → anticoagulants forever

  • Risk of leaks if high pressure → BP meds forever

• Muscular arteries:

  • Slightly smaller than elastic arteries (midsize)

    • Contain blood flow to organs and limbs (like the stomach)

    • VERY thick tunica media → control how much blood flow enters each tissue

  • Vasoconstriction of unnecessary arteries to have more blood flow in other areas

• Arterioles

  • Smallest arteries leading into capillary beds

  • Control blood flow into capillary beds through vasoconstriction and vasodilation

  • Same layers but smaller

    • Less smooth muscle in tunica media

  • Ex/ cold → skin turns blue to prevent heat loss (move blood flow to other organs)

Capillaries

• prone to leak and burst

• Function: get things in blood OUT, get things out of blood IN

• Want: thin walls and potential for leakiness (but not overly leaky)

• Can handle 1 RBC at a time, very fragile and small

• Structure:

  • Endothelial cells on the inside (simple squamous epithelium)

  • Intercellular cleft: between endothelial cells, doors open/close to increase or prevent leakiness

  • Basement membrane (outside layer)

• During inflammation →want capillaries to be more leaky

  • Infection in tissues → sinus, kidneys, skin, etc.

    • WBCs in blood, need to get them out

    • Make capillaries more leaky to send WBCs to tissue

  • Problem: more fluid leakage → swelling

• Do NOT want to see RBCs leaking out of capillaries (bleeding)

  • capillaries can be selective in what they leak out (fluid, plasma, H₂O)

• Pulmonary Edema:

  • Cause: heart failure → affects lungs

    • DCM- left ventricle struggles to pump and receive blood

      • Blood comes back to the heart faster than it can pump it out (congestion, backup)

      • Leads to increased pressure of blood in the lungs

        • Capillaries leakier than normal

          • Fluid leaks into the alveoli (where gas exchange occurs) → drowning, collection of fluid in the lungs (coming from overly leaky capillaries)

  • Treatment:

    • give a lot of diuretics

      • get more fluid out of blood (plasma) and pee it out →less volume → less pressure in capillaries → leak less →reduce pulmonary edema

Veins

• Lumen: hollow space inside the vein

• Valve: blood inside the veins has very little pressure (sometimes blood doesn’t flow because the pressure is less than gravity)

  • Prevent blood flow backwards by closing

  • Ex/ in legs

• Tunica intima: innermost layer

  • Made up of endothelium (simple squamous epithelium) and the subendothelial layer (loose connective tissue)

• Tunica media: don’t need a lot of smooth muscle because less pressure

• Tunica externa: loose connective tissue → contains veins, arteries, and nerves needed to provide nutrients to tunica media

• Walls significantly thinner than arteries

• No need for stretchiness because slow blood flow and no massive pressure change → no need for internal and external elastic lamina

• Histology - oddly shaped because of the thin tunica media and the lack of blood

• Verricose veins:

  • caused by age, usually a cosmetic issue unless severe

  • Caused by: valves malfunction

    • Valves don’t properly close and blood moves backwards → blood pools in the veins & veins get stretched out and stay that way

      • Damage neighboring valves, gets bigger, twisted swollen vein (blood DOES flow out, but very slowly)

    • Close to the surface of the skin, so it shows

  • Treatment:

    • close the vein off

      • not problematic because some other veins can pick up the blood that used to go through that vein

    • burn the vein closed → no blood flow → shrinks within a few weeks

• Veins

  • large vessels carrying large volumes (same rate it is pumped) of low pressure blood, bigger volume of blood

  • contain valves to prevent backflow, thin walls

  • run close to skeletal muscles to assist with blood flow back to the heart (contract muscle → squeeze vein → push blood back to the heart)

  • ex/ vena cava, brachian vein, femoral vein

• Venule

  • function: receive blood from capillary beds

  • small vessels that exit capillary beds and merge to form veins

  • small vessels with thin walls

  • fragile, easily damaged, and blood flow restricted

  • bruise: trauma to a venule

Lungs

• they heal but they don’t respond well to surgery/transplant

• lobes -

  • superior, middle, and inferior lobes on right side

  • superior, inferior lobes on left side

  • fissures separate the lobes

• gas exchange occurs in the lungs

  • Alveolus: tiny sacs in the lungs where gas exchange occurs

  • alveolus surrounded by blood capillary

  • O₂ in alveolus goes into the blood, CO₂ from blood capillary goes out of the blood, into the alveolus → exhaled

  • Alveolar sac: collection of different alveoli stuck together

  • Capillary network: around each alveolus

• trachea: air from the mouth, down the throat, to the lungs

• lungs rub against ribs & heart → friction

• layers:

  • visceral pleura: innermost

  • left pleural cavity/sac: space between visceral and parietal pleura

  • parietal pleura: outer layer

  • pleura - serous membrane with simple squamous epithelium adjacent to dense irregular connective tissue

    • makes serous fluid

    • 1 continuous layer folded in on itself to form parietal and visceral pleura

Alveolus

• Type II cells: secrete surfactant

• Type I cells: structure of alveolar wall

  • simple squamous epithelium

  • O₂ and CO₂ diffuse → capillary

• Macrophage: resident/alveolar WBC

  • If you breathe something bad in, resident macrophages kill/eat it

• Fused basal lamina - shared basement membrane, easier for O₂ and CO₂ to diffuse into or out of blood

  • Epithelium is always next to a basement membrane (connective tissue)

• Alveolar pores: to conserve space in the sac, holes instead of airways to bring more air in

• Surfactant

  • surface tension: molecular attraction between water molecules

  • inside alveoli, there is water and vapor, should always be wet

    • allows cells to move (expand - breathe in, contract - breathe out)

  • water molecules in alveoli are attracted to each other

    • surface tension is strong → resists alveolar expansion

    • surfactant breaks apart surface tension

      • it is a detergent

        • reduces the attraction of water molecules

  • diseases of the lungs affect surfactant → loss of function

• Blood flow and gas exchange

  • concentration gradients facilitate gas exchange

    • O₂ in alveoli diffuse into O₂-poor blood

    • CO₂-rich blood diffuse into CO₂-poor alveoli

Pneumonia and ARDS

• Pneumonia: a symptom, not a disease

  • fluid in the alveoli increases to the point of standing water, alveoli full of water

  • can’t get air inside the alveoli → no gas exchange

  • can’t get to capillaries → can’t diffuse

  • have a LOT of alveoli, even with pneumonia, the majority of the alveoli are not full of fluid

• Pulmonary edema/pneumonia

  • caused by infections

  • capillaries leak WBCs and fluid (leads to pneumonia)

    • necessary

    • normally, the body gets rid of fluid

    • if infection is very strong, send more WBCs (and more fluid) → pneumonia

• ARDS: acute respiratory distress syndrome

  • very intense pneumonia

    • usually pneumonia is only in few spots of lungs

    • however, ARDS is when pneumonia is everywhere in the lungs and fast

      • lungs are completely underwater in 24-48 hrs

  • very fatal (death ~50% of the time)

  • triggers: infection, autoimmune, allergy, etc.

  • body’s immune system thinks you will die, dilates all capillaries that go to the lungs (to save you (not)) → fluid rushes in, drown

    • ex/ COVID-19 triggered cytokine storm (signalling used to regulate capillary leakiness)

      • Body released storm of cytokines → very leaky capillaries → underwater lungs → death

  • capillaries are leaky to move WBCs into the lungs

    • break down bacteria and viruses in the fluid

    • pump out stuff that does targeted killing of bacteria and viruses but also makes the environment toxic → type I and II alveolar cells also die

      • walls become fragile → stop making surfactant →alveoli can’t expand even if air is pumped in

    • WBCs create fibrin inside alveolar walls and fluid → turn water-like fluid into jello-consistency

      • harder to cough out

      • TRY to prevent this

        • ex/ covid is longer if ARDS

        • should get antivirals ASAP to prevent ARDS

  • options after this point: mechanical ventilation

    • fluid in alveolus → alveolar collapse → need to reopen alveoli with high pressure from ventilator

    • ARDS doesn’t progress to all parts of the lungs at the same rate

      • repositioning in ‘prone’ can cause you to use other parts of the lungs where ARDS has not yet progressed and to reopen some alveoli

    • ventilation perfusion matching: controls how blood floes into lungs → goes into area with O₂

      • prone position → encourages surfactant and pulls blood into regions with surfactant

    • lungs are permanently damaged and scarred

      • damage cannot be reversed

      • common for ARDS to require a lung transplant

    • the lungs are fragile → on a ventilator, physicians prescribe high amounts of pressure → alveoli pop and never recover (aka barotrauma)

    • BEST CASE: some lung damage, continue living as normal

• COVID-19

  • hypoxemia caused by blood vessels, not lungs

    • vessels had receptors that COVID binded to

      • endothelium was damaged by infection, inflammation, etc. → blood clots made

  • microvascular capillary clotting: blood clots in capillary beds going to alveoli → no blood in the capillary for O₂ to bind to → shortness of breath, hypoxemia, lungs still healthy

  • cytokine storm → ARDS

    • cytokine storm - possibly caused by genetics

    • antivirals given to people at risk to prevent ARDS (50/50 mortality)

Respiration

• At rest - not breathing/moving air in and out

  • Intrapleural pressure: pressure within pleural cavity (space filled with serous fluid that surrounds the lungs)

    • 756 mmHg

• Inspiration/inhalation - air in

  • 758 mmHg (lower than atm - 760 mmHg, so air flows in)

  • diaphragm between thoracic and abdominal cavity contracts and pulls thoracic cavity down, makes more room in the thoracic cavity →less pressure on the lungs → air comes in

• Expiration/exhalation - air out

  • 763 mmHg (higher than atm - 760 mmHg, so air flows out)

  • diaphragm relax → put thoracic cavity back up, smaller → increased pressure → air pushed out of the lungs

• Pressure gradients move air in and out

• Breathing in - active, muscles contract

• Breathing out - passive, muscles relax

• Intrapleural pressure reduces friction when lungs open and close so that lungs aren’t rubbing against other structures

  • Intrapleural pressure must be less than the pressure of alveoli at ALL times

    • Why?

      • To keep alveoli open

      • If there is pressure exerted on alveoli by an external force, the alveoli will collapse

    • By surrounding the lungs with an area of lower pressure (intrapleural pressure), alveoli are encouraged to stay open

• Experiment: Put balloon inside vacuum chamber

  • Pressure of air inside balloon constant

  • Vacuum chamber (pressure of outside chamber decreasing) → causes balloon to expand dramatically

  • Air inside alveolus is set pressure that changes when we breathe but pressure around it must be lower than the pressure inside the alveolus so that the alveolus can remain inflated

• Do you want the pressure in the intrapleural space to stay lower than the alveoli at ALL times or just SOME of the times?

  • ALL times

• Diaphragm: big, dome-shaped muscle at the bottom of the thoracic cavity but at the top of the abdominal cavity

  • At rest, this is the only muscle involved in breathing

  • Contract the diaphragm → air pushes in

  • Relax the diaphragm → air pushes out

• Accessory muscles of respiration

  • Usually used when doing exercise (taking large, labored breaths)

  • Muscles of inspiration

  • Muscles of expiration

    • Letting the diaphragm relax is not going to push air out fast enough so must contract muscles to push out air faster

    • Majority of muscles relied on are the abs

• Diaphragm

  • Under both volitional control (controlled) and autonomic control (sleep)

  • Lots of different mechanisms that help you determine when it is the right time to breathe

    • Problems can happen when you breathe too little and when you breathe too much

    • Sensors in brain, blood vessels, muscles, and the lungs tell you → breathe faster or slower

      • is there too little/much O₂ in my blood? → increase or decrease respiratory rate

      • Is the pH of my blood too high/low?→ increase or decrease respiratory rate

      • ex/ too little O₂ to tissues →tissues die →speed up breathing

• Pathology

  • Pleural Effusion: Due to infection, immune issue, trauma, etc. → more fluid in pleural cavity (sometimes even blood)

    • Pressure in pleural cavity increases → squishes balloon of lungs → alveoli collapse →less available space for gas exchange

    • X-RAY: lung where pleural effusion was would be visibly smaller than a healthy lung

      • know something is squishing the lung

    • TREAT:

      1. put in a chest tube→ drain the fluid in the cavity

      2. What is causing this?

         • Infection

         • Treat the infection →this issue will go away on its own

    • If effusion is bad enough → more issues

      • can completely compress the lung to the point where one or both lungs can’t experience significant gas exchange

    • Pleural cavity is lined by epithelium which has a basement membrane around it (which contains blood vessels) → blood vessels provide nutrition and oxygen for epithelium that can produce serous fluid

      • Capillaries and lymphatic vessels have the job of reabsorbing excess fluid from tissue spaces

        • HOPEFULLY, over time, lymphatic vessels and blood vessels can absorb the excess fluid

  • Pneumothorax: something is causing a puncture either in the walls of the chest or in the alveoli themselves, which is allowing atmospheric air to enter the pleural cavity

    • NEED there to be certain times when intrapleural pressure is less than atmospheric pressure (inspiration); however, with pneumothorax, during inspiration and at rest, pressure inside pleural cavity due to atm air is higher than it should be → lung collapse

      • Atalectasis: alveolar collapse or lung collapse

    • pneumo - air

    • thorax - chest

    • TREAT:

      • short term, if severe:

        • set up chest tube in cavity, vacuum suction to draw air out of thoracic space (pleural cavity) and generate a lower pressure → allow lung to re-expand

        • Emergent chest tube placement

      • if not severe:

        • find leak, plug it

        • ex/chest wound→sew it up and make sure air doesn’t leak → reduce pressure →allow lung to expand

  • Hemothorax: blood within pleural cavity

Airways

Organization

• Upper respiratory tract

  • Nasal cavity

  • Pharynx

  • Larynx

• Lower respiratory tract

  • Trachea

  • Primary bronchi

  • Lungs

Respiratory Mucosa

• Most airways lined with the same kind of tissue - special kind of epithelial layer: respiratory mucosa

• Respiratory Mucosa: pseudostratified columnar epithelium

• 2 kinds of cells

  • Ciliated cells

    • have cilia on top, works to move something around on the surface of a cell

    • cilia moves mucus around (mucus generated by goblet cells)

  • Goblet cells

    • unicellular, mucus-secreting glands (exocrine glands)

    • mucus produced lines the surface of the epithelium (lines nose, trachea, bronchi, all the way down except smaller branches because we don’t want mucus down there)

• Why do we have this mucus?

  • we breathe in air, dirt, viruses, etc.

    • body wants to prevent bad stuff from reaching alveoli

      • mucus is there to coat all of the airways so that the particles we breathe in get trapped in the mucus, then the cilia move the mucus away from alveoli so that you don’t suffocate or drown→move mucus out of lungs

  • mucus also wet, we need alveoli to be wet and the air we breathe in isn’t always moist

    • as air is breathed in, picks up some moisture from mucus →when it gets to the alveoli, there is not a large difference between how moist the air is and how moist alveoli walls are, so alveoli do not dry out

    • when air is breathed out, want to keep moisture, so mucus does a good job of trapping some of the moisture → moisture not lost from body with each breath

• When respiratory epithelium is inflamed: Rhinitis

  • usually in the upper airways and in the nose and sinuses (sinusitis)

  • Why?

    • Infection or response to something inhaled (ex/ allergy) →mucosal epithelium inflamed →body starts pumping more blood, oxygen, nutrition to these cells →cells do their jobs faster

      • ex/ goblet cell does job faster→secretes more mucus

      • ex/ciliated cell does job faster →cilia move faster→move more mucus out of lungs and out of body→ mucus leaves body faster than it can dry → runny nose

    • defense mechanism

      • if body is encountering something bad (infection) & wants to prevent spread, starts secreting more mucus and moving it out →move infection out of body more quickly

  • TREAT:

    • drugs - pseudoephedrine (Sudafed) (stimulant)

      • vasoconstrictor

        • inflammation → blood vessels dilate to provide more oxygen and nutrition at the level of the inflamed tissue

      • vasoconstriction drug →less energy delivered to inflamed cells→ less inflammation because can’t produce as much mucus → no runny nose

      • PROBLEM: vasoconstrictor works everywhere, not just nose

        • if you already have hypertension→ increases blood pressure more

Nasal Cavity

• Anterior nares/external nares: nose holes, openings that air goes in/out of

• Vestibule: area inside nose but outside skull

• Enter skull → covered in respiratory mucosa

  • Add moisture to air breathed in, makes sure it is homeostatic temp and moisture before going to lungs

  • Catches particles in mucus

  • Adaptation: Increase surface area of respiratory mucosa to add moisture and catch particles by - turbinates/conchae (large bony projections/folds that stick out into nasal cavity covered with respiratory epithelium)

    • air comes in and bounces off surfaces →gets hotter and more moist

• Adaptation to increase surface area: sinuses (enclosed cavities of respiratory epithelium trapped within bones of skull) →air flows in and gets hot and moist → lungs

  • Frontals

  • Ethmoids

  • Sphenoids

  • Maxillary

• Problem: sinuses are large but passageways of air through the sinuses is small

  • tiny little passageway opening into a large sinus

  • inflammation of respiratory epithelium →secreting more mucus & tissue/individual cells swell up → block passageways that come in and out of sinuses

    • if air can’t get out of sinus, mucus produced also can’t get out

      • over time, as inflammation progresses & still pumping out a lot of mucus but passageways blocked, mucus gets stuck →increase in pressure until pain (sinus headache, clogging of sinuses, pressure buildup from mucus)

  • TREAT:

    • Sudafed - cause inflammation to go down → vasoconstriction reduces inflammation of epithelium →epithelium relaxes & shrinks → open up passageways again →mucus falls out and leaves

      • prevent addiction

    • Sinus plasty or sinoplasty: find narrow passageways that lead into sinuses and expand them by removing bone & epithelium → hoping epithelium scars and more doesn’t grow in its place

    • Balloon sinoplasty: take balloon and insert it into part with narrow passageway & expand it and hope it crushes neighboring bone and opens up the passageway

• Olfactory mucosa: makes it so that you can smell stuff

  • Pseudostratified columnar epithelium

    • Goblet cells

    • Nerve endings - olfactory receptor cells (neurons that project down through the layer of epithelium and have olfactory hairs on the end

      • Olfactory hairs hang out in the mucus & bind to chemical particles in the air you breathe in → trigger neurologic response where once these hairs bind to what you are breathing → signal gets transferred up to the nerve → signal goes through olfactory tract where it is perceived → brain knows what you are smelling and can tell if it smells good (interprets signal)

      • Epithelium between olfactory receptor cells: supporting cells (sustentocytes)

        • Supporting cells: provide nutritional support to these neurons to help make sure that they are well regulated, that they have enough O₂ to do their jobs, and to keep them protected in a relatively harsh environment of the inside of your nose

• COVID loss of smell caused by die off of supporting cells → no nutrition for neurons

  • new research shows covid also infiltrated nervous system → probably infected the actual neuron itself

Pharynx

• back of the mouth: pharynx

  • point where you have connection between your nose, mouth, and throat

• nasopharanx behind nose

• oropharanx behind mouth

• hypopharynx/laryngopharanx behind larynx

• Olfactory nerve: comes down right above nasal cavity and ends at olfactory bulb

  • Branches of olfactory nerve penetrate down through the skull and into the olfactory mucosa (on the roof of the nasal cavity)

Tonsils

• in the pharynx

• palatine tonsil - the ones we usually focus on

• lingual tonsil, palatine tonsil, pharyngeal tonsil

• now: using antihistamines, antivirals, antibiotics rather than doing a tonsilectomy

  • because tonsils have immune function

Larynx

• larynx: voicebox and gateway to the trachea, surrounded by cartilage

  • big, hollow tube with hyaline cartilage (rigid, strong, keeps things the same shape, resists forces)

• epiglottis: to get past laryngopharanx

  • food goes posterior → esophagus

  • air goes anterior → trachea

Cartilages

• Epiglottis: door

  • swallow → epiglottis closes and shuts off access to voice box, larynx, trachea to prevent food from going to lungs

• Arytenoid cartilage: attached to muscles and vocal fold/chord (tone, pitch, sound, volume)

  • moves, unlike other cartilages

  • glottis: space between vocal chords

    • air goes through the glottis

    • glottis changes in size

      • breathing → more open

      • talking → muscles pull chords together so that they vibrate → glottis gets smaller

  • when arytenoid cartilage moves, vocal chords follow

• Cricoid cartilage: forms complete ring around the lower portion of the larynx

  • strong

• Thyroid cartilage: Adam’s Apple

  • anterior surface of larynx

  • moves up/down when you swallow

Thyroid

• Trachea: macroscopic tube (1” diameter)

• Annular ligaments: pink rings, allow trachea to move

• Tracheal cartilage: cartilage rings with ligaments in between

  • prevent things from collapsing (rigid hyaline cartilage)

  • only cover from the front, spine protects it from the back

• Trachealis muscle: constrict and relax airway

  • ex/ asthma, can spasm → get tighter

Bronchi

• Carina: area of split of trachea

• Primary/main bronchi →lobar/secondary bronchi → segmental/tertiary bronchi

• Lobar bronchi → smaller branches (30-40 divisions)

  • each time the bronchus splits, it gives off 2 branches that are much smaller than it was

• Terminal bronchioles → Respiratory bronchioles → Alveolar sacs & alveoli

  • terminal bronchioles: smallest airway in the body that doesn’t directly have alveoli attached to it

  • respiratory bronchioles: alveoli are attached to it

  • alveolar sacs & alveoli: smallest part of airways

• Asthma: rapid onset inflammation in the respiratory mucosa

  • Respiratory mucosa is in all airways except the smallest 3

  • Inflamed respiratory mucosa → muscle contraction & cells get bigger → airways get smaller

  • People with chronic asthma have an enlarged epithelium and increased mucus production

  • Untreated asthma → scar tissue

  • Asthma is more complex than bronchospasm

    • can’t treat all symptoms of asthma with an inhaler

      • Inhaler treats bronchospasm component of asthma

    • anti-inflammatory drugs, drugs that help to break up excess mucus, or reduce mucus secretion (steroidal anti-inflammatories)

    • 2 inhalers: 1 rescue inhaler (albuterol or ventolin) + 1 maintenance inhaler (inhaled corticosteroid → reduce chronic inflammation in patient’s airways with asthma, ex/ Q-var)

• Respiratory bronchioles

  • terminal bronchi (no alveoli) → respiratory bronchi (alveoli)

Valsalva Maneuver

• external G-force (centrifugal force) because of inertia and gravity →affects flow of blood

• sharp turn → blood in the brain goes to the rest of the body

  • no blood in the brain → sleep

  • no blood in the brain for a long time → die

• Valsalva Maneuver: close glottis so air can’t get in or out, tighten abs

  • increase pressure in thoracic cavity

    • push on lungs, heart, abdominal cavity

    • squishing vein, not arteries, in thoracic cavity (superior and inferior vena cava that return blood to the heart)

  • keeps blood in the brain for a longer time (usually bad, but good for pilots) and maintain pressure → stay conscious

Digestive System

Upper Digestive Tract

• Oral cavity: mouth

  • Gingivae: stratified squamous epithelium

  • Vestibule

  • Oral Mucosa:

    • ~40 layers of stratified squamous epithelium: to handle the stress of the mouth

    • large basement membrane of connective tissue

  • Teeth

    • Enamel: prevents microorganisms in mouth from entering teeth

    • Crown: part of the tooth exposed in the mouth

    • Dentin: works like compact bone, has osteons, canals, etc.

    • Pulp cavity: hollow space at the center of the tooth, contains blood vessels and nerves

      • the nutrition that keeps the tooth alive comes from here

    • Neck: region covered by the gums but outside the bone

    • Root: where bones comes together

    • Root canal: hollow tube that allows blood vessels and nerves to enter tooth from the jaw

      • the way that nutrition gets to tooth

  • Teeth Organization (Medial to Lateral; ~32 teeth)

    • Central Incisor & Lateral Incisor

      • 4 on top, 4 on bottom

      • big, flat teeth with single surface (chopping surface) to cut pieces off of food and to bite

    • Cuspid (canine)

      • 2 on top, 2 on bottom

      • 1 sharp point

      • hold onto prey (large) → evolution to smaller because not grabbing onto animals with our teeth

    • First premolar (bicuspid) & Second premolar (bicuspid)

      • 4 on top, 4 on bottom

      • 2 sharp points, flat surface between them

      • grate and grind food

    • First molar & Second Molar & Third Molar

      • 6 on top, 6 on bottom

      • break food into smaller bits

    • Third Molar

      • Wisdom teeth

        • usually removed because of crowding → causing pain

        • Why? Theories:

          1. dentistry is relatively new; 150 years ago, people didn’t brush their teeth → common for ancestors to lose teeth, especially when young → extra set that come in when teen (3rd molar is backup if tooth lost in childhood)

          2. aesthetic → attractive evolutionarily (smaller jaws)

             1. 3rd molar doesn’t fit anymore

  • Muscles of Mastication

    • Temporalis: closer of jaw

    • Masseter: closer of jaw

    • Lateral pterygoid: protrude jaw, move jaw side to side

    • Medial pterygoid: protrude jaw, move jaw side to side

  • Salivary glands

    • Saliva: wettend mouth, makes food stick together, easier to chew

      • plays a role in mechanical and chemical digestion

      • Amylase: digestive enzyme in saliva that breaks down complex carbs and starches into simple sugars that are easier to absorb

    • Parotid gland: by the ear

    • Submandibular gland

    • Sublingual gland: below tongue, when speaking and spit

    • Chewing - mechanical digeston prepares food for the stomach

  • Tongue and taste buds

    • Papillae: bumps on the tongue; surface structures that protect the taste buds

      • surrounded by deep groove where taste buds exist

    • Taste buds: nerve endings close to tongue

    • Gustatory epithelial cells & gustatory hairs: bind to food and stimulate the neuron to brain where the taste is perceived

      • Tastebuds and hairs under the surface for their protection

      • Taste pore: the only way for dood to access the taste bud and bind to gustatory hairs

    • Stratified squamous epithelium of tongue: heals fastest, lots of layers, hard to damage reproductive/dividing cells

  • it is TRUE that there are parts of the tongue are more sensitive to certain tastes BUT they are not exclusive

    • all taste buds can taste each taste, but it is just more sensitive in certain areas

  • Palate, Uvula, Pharynx

    • Palate: roof of the mouth, separates oral and nasal cavity

      • 2 parts: hard, soft

    • Uvula: exhibits characteristics of both the oral mucosa on the bottom and the respiratory mucosa on the top; dangles in the back of the throat

      • bottom - stratified squamous epithelium

      • top - pseudostratified columnar epithelium with cilia

    • Pharynx: tube that connects nose, mouth, and throat

• Esophagus

  • relies on muscle contractions (peristalsis) to move food down

  • down through the throat, past the thorax, down into the abdomen

  • sphincter: collection of smooth muscles that completely close off the tube

  • Upper esophageal sphincter: back of the throat

  • Lower esophageal sphincter/cardiac sphincter: where the stomach and the esophagus meet

  • esophagus and the heart are touching→ when people have reflux, they think it is a heart attack

  • Histology

    • mucosa epithelium - stratified squamous epithelium

    • lamina propria - connective tissue

    • muscularis mucosa - smooth muscle layer that wraps around lamina propria

    • submucosa - blood vessels, nerves

    • muscularis externa - where peristalsis happens → closes off esophagus → thicker at the sphincter

    • adventitia/cirrosa: outer edge

• Stomach

  • inlet - esophagus

  • fundus: part of hollow organ farthest from the outlet

  • cardia: where food enters, adjacent to the esophagus

  • body: largest hollow portion of the stomach

  • antrum: narrowing portion of the stomach

  • pylorus: outlet

  • pyloric sphincter: valve that limits food flow from the stomach to the duodenum of the small intestine

    • walls thicker because threy move smooth muscle

• Stomach layers

  • Muscularis externa - move food around while digesting → mechanical digestion

  • Rugae of mucosa: wrinkles on inner surface of the stomach

    • designed to allow stretch

      • extra tissue is smushed together →eat a lot → flattens out and expands the stomach

• Layers of stomach wall (inner to outer)

  • Superficial

    • Surface epithelium: lining of the stomach (simple columnar epithelium), a lot of secretions of acids & enzymes that break down proteins but also break down the stomach because the stomach is made of protein

      • a lot of mucus-secreting cells and goblet cells

    • Muscularis Externa

  • Deeper

    • Gastric pits (wavy, not smooth surface)

    • Gasric glands

      • most of secretion cells exist here

      • Mucous neck cells: goblet cells that move out mucus through the pit to line the stomach

      • Parietal cells: secrete HCl

      • Chief cells: secrete pepsinogen (inactive form of pepsin)

  • Deeper

    • pepsinogen interacts with HCl to become pepsin

    • pepsin: aggressive, active enzyme that breaks down proteins and makes it easier to digest and absorb

      • pepsinogen until acidic environment (safer so that the stomach is not digested)

    • entero-endocrine cell: regulates activity of other cells

      • send signals to neighboring cells to turn them on or off

• Gastroesophageal Reflux Disease (GERD)

  • something in the stomach moves backwards into the esophagus (acids, enzumes, food)

  • chronic, on a regular basis, hard to manage

  • esophagus can’t protect its epithelial cells from acid

    • at the risk of damage, scarring, and perforation because of acid

  • 2 parts

    • leaky sphincter

    • too much acid in the stomach (oversecretion)

      • treated by medications (proton pump inhibitors) to reduce the production of acid

  • Procedure:

    • Fundoplication: procedure where fundus is stretched and wrapped around the esophagus

      • tight, more pressure, reinforce sphincter (less leakiness)

      • too tight → hard to swallow and move food down → reduced vomiting even when needed

      • permanent procedure

Lower Digestive Tract

• where absorption happens

• Small intestines

  • small diameter (same as the thumb) but long (>20 ft)

  • Organization

    • Duodenum

      • pyloric sphincter to duodenum

    • Jejunum

    • Ileum

      • enters large intestine

  • Function: absorption, increase surface area to get the most nutrition

    • Lacteal: lymphatic vessel that absorbs large fats from food through lymphatic system, processed, go back to blood

    • Circular folds: macroscopic folds in epithelial layer of walls of small intestine, increase surface area across same length

    • Blood capillary network: in each villus, carry nutrition absorbed to the rest of the body

    • Villi: velvet appearance (look like small fingers), increase surface area

    • Crypt lumen: on the surface of small intestine, deeper into the walls to increase surface area, intestinal crypt

    • Simple columnar epithelium also has microvilli on the surface to maximize absorption by increasing the surface area

    • Enterocyte: individual cells with microvilli that line the intestine

    • Goblet cells: secrete mucus

• Celiac Disease: immune response/allergy to gluten (protein in wheat)

  • disease of the small intestine

  • How to fix: don’t eat gluten

  • Diagnosis: only with biopsy

    • gluten allergy → inflammation

    • gluten sensitivity →mild reaction

  • Generates chronic inflammation if eat gluten with allergy (diarrhea, upset stomach, permanent damage to villi)

  • Villi knocked down and replaced with fibrin (less absorption of nutrition)

• Large Intestine - colon, large diameter (6-8 ft long)

  • dirtier environment than the small intestine

    • bacteria, etc.

  • Appendix: on the surface of the cecum

  • Cecum: large sac-like region that collects food

  • Ileum: where small intestine empties into the large intestine

  • Iliocecal valve: prevents bad environment from going to the small intestine (which could absorb bacteria or viruses) and prevent poop from going back

  • Ascending colon: goes up

  • Right colic (hepatic) flexure

  • Transverse colon

  • Left colic (splenic) flexure

  • Haustra: balloon, bubbly structures; folds to help with absorption by increasing surface area

    • farther apart than folds in small intestine

  • Descending colon: goes down

  • Sigmoid flexure

  • Sigmoid colon: looks like sigma

  • Rectum: last stop before poop leaves

  • Anus: where poop leaves the body

• Structure of Large Intestine

  • consistency of food moving through the intestine changes

    • paste in the small intestine → dry in the large intestine because the large intestine absorbs water and electrolytes (thicker, harder, more solid)

    • has the potential to damage walls (villi can’t handle it)

  • Colonocyte

    • like an enterocyte but the colon

      • take water, electrolytes and move into the bloodstream

  • Colonic crypt: protects goblet cells (more in the colon because mucus provides lubrication for dry poop and protects walls)

  • Smooth surface, nothing sticking up into the lumen

• Appendicitis

  • Appendix: likes to get inflamed

    • hollow pouch, can burst if inflamed

      • if burst, bad stuff in colon → abdominal cavity → blood →bloodstream →death

  • Appendix has a lot of immune cells

    • immune/lymphatic function

  • Sometimes, things get trapped in appendix, not moving for a long time → inflammation to try to move it out

    • when inflamed → appendix walls swell & appendix shuts off → whatever is trapped stays trapped → body sends WBCs → get bigger → swollen till it pops because no exit for excess fluid

  • Some success with antiinflammatories

  • Appendectomy done laparascopically (20-30 min procedure without anesthesia time)

• Pooping

  • Rectum - continence

    • Rectal valves; poop is going fast, so it is slowed down with turns to passively keep poop from escaping too quickly

    • Sphincters: very strong external and internal anal sphincters

  • External anal sphincter: skeletal musle, control poop (continence)

  • Internal anal sphincter: smooth muscle, autonomic control

    • Pressure builds up, sphincter releases, feel sense of urgency

• Spinal Cord Injury

  • Muscles and control of them are damaged → incontinence

  • Taught to trick body into going bathroom when they want to - bowel and bladder training program

Accessory Digestive Organs

• Liver

  • largest organ by mass

  • dense with a lot of unique and homogenous cells

  • on the right side of the body

  • right lobe and left lobe on anterior side

  • caudate lobe (superior) and quadrate lobe (inferior) on posterior side

  • gallbladder posterior and inferior to liver, near quadrate lobe

  • lobes separated by ligaments and fissures

• Hepatic Portal System

  • Liver: the first place absorbed food is procesed

  • Hepatic Vein: carries blood from the liver to the heart (not nutrient rich)

  • Hepatic Portal Vein: carries nutrient-rich blood from intestines to liver to drop off nutrients

• Structure of liver

  • Hepatic lobule: octagon structures made up of hepatocytes

    • Hepatocytes: liver cells that function in digestion, processing of blood from intestines

    • Bile canaliculi: bile capillaries

    • Portal triad

      • bile duct

      • portal venule

        • come into each lobule at point of portal triad

      • portal arteriole

    • Blood from portal venule and portal arteriole → sinusoids carry blood through the walls of the lobule & dump blood into the central vein → hepatic vein → heart

    • Sinusoids: let blood come into close contact with hepatocytes → mix of arteriole blood (with O₂) and venule blood (O₂ poor blood, but nutrient rich) good for hepatocytes

      • mix →hepatocytes do enzymatic activity → reduce toxicity in blood

      • ex/ alcohol

        • neurotoxin

        • hepatocytes secrete alcohol dehydrogenase into blood in the presence of high BAC, deactivate it (will not damage nervous system badly)

      • ex/ tylenol

        • body views tylenol as bad, liver works hard to deactivate it →inflammation of liver → hepatitis → liver failure

    • Store sugar in liver

      • Blood with sugar → sinusoids → absorbed into hepatocytes → stored for later use

      • Proteins stored and taken in by the liver → turned into more useful protein through protein synthesis and remodelling (done inside sinusoids and hepatocytes)

    • Hepatocytes:

      • mess with proteins

      • store sugar

      • work to detoxify blood

      • secrete bile

    • Bile: digestive enzyme that helps break down fats (needs to go from liver to intestines- goes through bile ducts)

      • Bile cannaliculi (bile capillaries) carry fluid bile into larger bile duct → leave liver → go down into intestines

  • Extrahepatic bile duct anatomy

    • right hepatic duct & low hepatic duct carry bile as it leaves the liver → common hepatic duct (merge L +R)

    • gallbladder: storage space for excess bile (if not used)

Cirrhosis

• high fat diet → fat stored in liver (hepatocytes) → get bigger (swell) →liver gets bigger → harder for blood to flow through, regulation, filtration → liver function decreases

• Cirrhosis: scarring of the liver

  • chronic inflammation

    • ex/ alcohol, hepatitis A, B, C

      • leads to inflammation →scarring

  • cirrhosis not reversible

• Ascites: massive accumulation of fluid inside abdominal cavity, secondary to cirrhosis

  • coming from blood that cannot flow through the liver anymore

  • weekly drain procedure

    • BP low, dehydrated, electrolyte balance bad, blood volume low

  • TREAT:

    • liver transplant

      • can survive outside the body for a while BUT prone to rejection

      • can do a part of the liver because it grows (can use a living donor)

        • If really severe, use whole liver from deceased patient

Gall Stones

• hardened pieces of bile

  • break down → send immune cells → inflammation → gallbladder must be removed

• Why?

  • possibly dietary component (not eating enough fats)

• If small stones leave and get trapped in bile duct, BAD THINGS (life-threatening)

Pancreas

• Organization

  • tucked under liver and stomach

  • Hepatopancreatic duct/ampulla (short duct)

  • Acinar cells: secrete enzymes to break down proteins to digest

  • Pancreatic islets: endocrine (release insulin and glucagon)

• Most people have 1 pancreatic duct

  • some people have accessory pancreatic duct

  • If gall stone stuck in duct, BAD (block flow and cause inflammation, block enzymes →pancreatitis)

Urinary System

Kidneys

• posterior to lower ribs to protect kidneys

• Retroperitoneal space:

  • retro: posterior

  • peritoneum: connective tissue that lines abdominal cavity

• surrounded by fat and connective tissue

• Structure of kidneys

  • Renal cortex: outer edge

  • Renal medulla: inner edge

  • Major calyx: tubes collecting urine

  • Papilla of pyramid: pointy part of pyramid

  • Renal pelvis: mini bladder, storage for urine within kidney until flowing into ureter

  • Minor calyx

  • Ureter

  • Renal Pyramid in renal medulla

  • Renal column

  • Renal hilum (dent)

    • Renal artery

    • Renal vein

    • Ureter

• Nephron

  • majority of nephrons in cortex (outer edge)

  • cortical nephron: majority exists in cortext

  • juxtamedullary nephron: 50% medulla, 50% cortex, larger loop of Henle

  • vasa recta: specialized peritubular capillaries that follow the loop

• Glomerular filtration:

  • afferent arteriole

  • glomerular capsule: tissue structure that surrounds capillaries

  • glomerulus: site of filtration (passive process where blood flows into glomerulus → glomerular capillaries (squiggles) → very leaky, selective filtration → only in glomerulus (passive)

  • efferent arteriole

  • proximal convoluted tubule

  • peritubular capillaries

  • loop of Henle

    • nephron loop

  • distal convoluted tubule

  • collecting tubule

  • bladder → out of body

• Reabsorption - from tubule back to blood capillaries

• Secretion - from blood capillaries to tubules

• 3 parts of tubules:

  • proximal tubule, distal tubule, loop of henle

    • reabsorption and secretion → controlled processes done between blood vessels and tubules

• JOB of the kidneys: make sure that there isn’t too much waste to help make sure that the volume of blood is balanced and that there is the right amount of electrolytes hanging out in your blood at any given time

  • ability of kindeys to filter blood (remove things you don’t need and keep stuff you do)

• Juxtaglomerular Apparatus

  • Afferent Arteriole → glomerular capillaries → efferent arteriole

    • distal convoluted tubule runs right next to afferent and efferent arterioles just before emptying into collecting duct

      • fluid going through is urine

  • Macula densa: detects quality of urine, senses how concentrated urine is (salts, water, etc.) & makes changes to future urine based on what it detects

  • Extraglomerular mesangial cells: like smooth muscle, pinch down on afferent arteriole and make it harder for blood to get into the glomerular capillaries →less blood → less filtration → less pee → good thing during dehydration

  • Granular cells: secrete renin hormone

    • in renin-angiotensin pathway

      • renin released → converted eventually to angiotensin → vasoconstricts → increase BP

      • renin released when BP is low (blood volume low)

  • Podocytes: work to restrict how much filtration occurs

    • capillaries leaky

    • podocytes wrap themselves around capillaries in glomerulus and can increase/decrease how leaky it is

    • areas of capillary covered by podocyte don’t leak, except in areas with filtration slits (which open/close for more/less filtration to occur)

• Urine is primarily composed of water and electrolytes

  • Has other substances that the body doesn’t like

  • kidneys take waste products and move them out of blood (ex/ urea is a neurotoxin, causes loss of control over muscles, hallucinations, etc.)

• Diabetes and kidneys

  • Early symptom →peeing a lot →why?

    • diabetes → abnormally elevated sugar in blood → inflammation of blood vessel walls → scarring, swelling, plaques forming, bad blood flow →high pressure in capillaries, leakier capillaries (glomerular capillaries) → pee a lot

  • Increased pressure in capillaries becomes chronic

    • pressure in kidneys → more fluid and large things leaking out of capillaries (RBCs, large proteins → damage to glomerulus)

    • makes capillaries damaged faster → scarred → closed off → blood can’t flow in anymore → glomerulus can’t balance blood, filter blood, regulate BP → die fast because of kidney failure

  • How to fix:

    • keep blood sugar levels lower

      • reduce inflammation, reduce leakiness, prevent irreversible damage

  • If not fixed asap,

    • transplant (easy because people have 2 kidneys)

      • dialysis (usually indefinite OR bridge transplant)

        • put blood through kidney → filter blood, adjust blood volume, etc., machine is like a big kidney, keep them alive, 4-6 hrs a day 3x a week (difficult)

    • continuous renal replacement therapy: 0 function kidneys, will die without a transplant

      • 22 hr/day dialysis

        • only off of dialysis when changing filtration

• Kidney stones: accumulation of waste products and electrolytes

  • ex/ urea sits → crystals → solid stones, ex/ calcium

  • usually stuck in ureters and urethra, can be made up of several things

  • when stone blocks ureter, becomes an issue

  • kidney swelling → high pressure → can’t function → blood can’t flow in → kidney could be inflamed, damaged, or die → blood can’t be filtered

  • Procedure:

    • Lithotrypsy: use electromagnetic radiation to shock stones to explode inside of you, pee it out (painfully)

• Ureters: connect kidneys to bladder

  • lumen, transitional epithelium (tissues that can stretch with large volumes of urine) makes up mucosa

• Bladder: holds urine

  • 2 ureteric orifices: holes where the uror empty into the bladder

  • opening to the urethra

  • triangle between ureteric origices and urethra: trigone

  • walls of bladder: really thick and have a lot of muscle in them (smooth muscle - detrusor muscle)

  • generating urination reflex is relaxation of sphincter and contraction of detrusor muscles

  • Internal urethral sphincter: smooth muscle (autonomic)

    • relaxation of this when bladder stretched → urgency to pee

  • External urethral sphincter: skeletal muscle (direct control)

  • Urogenital diaphragm/pelvic floor: skeletal muscle (direct control)

  • Continence: after spinal cord muscles spasm and stay there chronically → become tight → patients can’t pee → must use catheter and push up past spasmed muscles into the bladder to help drain the bladder on their own

  • transitional epithelium

• Urethra: connect bladder to outside world

  • transitional epithelium

  • not peeing → want muscularis (muscles in wall of urethra) to contract to prevent UTI

• UTI: bacterial/fungal/viral infection in urinary tract

  • why females higher rate of utis?

    • male penis is where urethra empties into the world

      • urethra in its own space → less UTIs

    • female urethra empties into shared space (vestibule) where the external urethral orifice is shared and closed off from the rest of the world by the labia (next to the vaginal orifice)

      • labia cover up both in vestibule

      • creates potential for cross-contamination → higher chance of UTIs