exam 4
Respiratory System
Functions: Absorbs O2 into blood, releases CO2, and other wastes from the body.
Houses the structures involved in speech.
Houses smell receptors (in nose)
Organs
Nose- inlet and outlet for air
nares= nostrils
Nasal cavity= space inside the nose (partitioned into left and right chambers by the “nasal septum”)
Nasal Conchae= ridges on the side walls of the nasal cavity.
Function to swirl inhaled air (generate air turbulence) to moisten, warm, and trap dust.
Lined with mucus membrane (mucus also traps dust and microbes from the inhaled air)
Functions as resonance chamber for speech (contribute to the sound of your voice)
Paranasal Sinuses aka “sinuses”
cavities/chambers surrounding the nasal cavity and attached to the nasal cavity via ducts
Lined with mucus membrane
They help resonate speech sounds and therefore contribute to the sound of our voice
Pharynx aka “the throat”
Lined with mucous membrane
Contains skeletal muscle
Houses tonsils, openings of eustachian tubes (aka “auditory tubes”)
Larynx aka “voice box”
Lined with mucus membrane
Epiglottis (flap of cartilage covered with mucus membrane at top of larynx). Folds down over the opening of the larynx during swallowing and blocks entry of food/drink
Thyroid cartilage is a shield of protective cartilage (on front part of larynx) also known as the “adam’s apple”
Vocal folds aka “vocal cords”. 2 ligaments with skeletal muscles attached, covered with mucus membrane. Exhalation of air across them vibrates them and generates speech sounds.
Speech Production
Pitch is controlled by loosening or tightening of the vocal cords
Volume is controlled by altering how much air is exhaled across the vocal cords
We then move our tongue, cheeks, and lips to enunciate the sounds into words
Nasal cavity and sinuses resonate the sound
Thicker and/or longer vocal cords give rise to a deeper voice
Thinner and/or shorter vocal cords give rise to higher pitch voice
➡Whispering= speaking without using vocal cords, only mouth is used (like whistling words)
Trachea-aka “windpipe”
5 inch long tube and has cartilage rings down its length
Lined with mucus membrane and lined with cilia that continuously flick mucus to the larynx
Lungs - Made up of bronchi, bronchioles, visceral pleura, and alveoli
Alveoli are microscopic air bulbs of the lungs (resemble tiny balloons). These are surrounded by pulmonary capillaries. They are the sites of gas exchange between the lung airways and blood. They have elastic connective tissue in their walls.
Alveolar Sacs- bundles of alveoli
3 Types of cells lining inside walls of alveoli
Type 1 Alveolar cells= flat epithelial cells arranged in a single layer (simple squamous epithelium)
Type 2 Alveolar cells= secrete a viscous, clear fluid that resembles liquid soap called “surfactant”. Surfactant coats the inside lining of the walls of alveoli to prevent it from collapsing (sticking shut)
Type 3 Alveolar Macrophages= Clear microbes and debris via phagocytosis
Infant Respiratory Distress Syndrome (IRDS)= Occurs when a baby is born and there’s not enough surfactant in their lungs
Bronchioles- tiny airways (<1 mm). Larger ones have cartilage rings, smallest ones lack cartilage rings.
Bronchocontriction is the contraction of smooth muscle in walls of bronchi and bronchioles which decreases airway diameter
Bronchodilation is the relaxation of smooth muscle in walls of bronchi and bronchioles which increases airway diameter
Bronchi are large airways (similar structure to trachea).
Primary Bronchi (2 of them), branch off the trachea and each is connected to a lung
Secondary Bronchi (5 of them), branch off primary bronchi and each of them is connected to a lobe of each lung.
Tertiary Bronchi (many of them and they branch off secondary bronchi)
Visceral Pleura - thin, slick, clear, and shiny membrane covering of the lungs.
Reduces friction between the lungs and the wall of the chest cavity
Parietal Pleura - Just like the visceral pleura but lining the chest cavity.
Respiration - Gas Exchange in the Body
3 Processes: Ventilation, External Respiration, and Internal Respiration
Ventilation= Gas exchange between the lungs and atmosphere
External Respiration= Gas exchange between the lungs (alveoli) and the blood
Internal Respiration= Gas exchange between the blood and tissues
Ventilation aka “breathing” 2 types of processes= Inspiration (inhalation) and Expiration (exhalation)
Inspiration= Breathing at rest (quiet breathing)
Diaphragm and the external intercostals contract which expands the chest cavity downward and outward. This causes the lungs to expand with the chest so the air pressure in the lungs drops and becomes less than the air pressure in the atmosphere. 500 mL of air gets sucked into the lungs.
Forced Inspiration (forced inhalation)= taking in a deep breath
Diaphragm, external intercostals contract along with other muscles including the sternocleidomastoids, pectoralis minors, and scalenes. This results in increased expansion of the chest and lungs. This causes air pressure in the lungs to drop significantly below the air pressure in the atmosphere. Up to 3,500 liters of air is sucked into the lungs.
Exhalation (Expiration)= when breathing at rest (quiet breathing)
Diaphragm and external intercostals relax so the force expanding chest and lungs subsides, the elastic connective in the walls of alveoli recoils and this causes the air pressure in the lungs to become greater than the atmospheric pressure (500mL of air is exhaled)
Exhalation at rest is a passive process (doesn’t require muscle contraction for it to occur)
Forced expiration (Exhalation)= forcibly blowing air out of lungs
Diaphragm and external intercostals relax and internal intercostals and abdominal muscles contract. This compresses the chest and lungs this causes the air pressure in the lungs to become much greater than the atmospheric pressure ( 1500mL of air can be exhaled)
Diseases that Affect Breathing
Asthma= disease characterized by acute episodes of bronchoconstriction and airway inflammation
Leads to decreased airway diameter and increased airway resistance (difficulty breathing)
Commonly triggered by allergies, exercise, breathing cold air, pollution, infection
COPD (chronic obstructive pulmonary disease)
2 forms (bronchitis,
Bronchitis= chronic airway inflammation. Caused by infection, smoking, breathing pollution,
Emphysema= caused by a loss of lung elasticity. Develops when elastic connective tissue in the lungs is destroyed and pleased with scar tissue. Also neighboring alveolar walls can be destroyed and they fuse. Commonly due to infection, specifically pneumonia, smoking, inhalation of pollution
Pneumonia = inflammation of alveoli
Typically caused by a respiratory infection spreading into alveoli. Alveoli fills with fluid and pus.
Control of Ventilation (breathing)
Conscious Control= we can mentally control the skeletal muscles involved in breathing.
Unconscious Control= the “respiratory center” is a region in the brain stem (located in the pons and medulla oblongata). It’s made up of neurons that are wired to the skeletal muscles involved in breathing. When we’re breathing at rest, the respiratory center triggers contraction of diaphragm and external intercostals for 2 seconds then relaxes for 3 seconds over and over.
Several reflexes are wired through the respiratory center to regulate breathing.
In the walls of the aorta and carotid arteries and also in the brain stem, there are receptors that monitor blood O2, CO2 and pH.
When there's decreased O2, increased CO2 and/or low pH it triggers hyperventilation. (Increased depth and increased frequency of breathing).
When there’s increased O2, decreased CO2 and/or increased pH it triggers hypoventilation (slow, shallow breathing)
Our proprioceptors (receptors in our skeletal muscles, tendons and joints) are wired to the respiratory center. When there’s increased body movement/exercise it triggers hyperventilation.
How O2 is Transported Through the Blood
1% of the O2 is dissolved in plasma, 99% is bound to hemoglobin
Factors that Influence Oxygen Hemoglobin Binding
Heat (high temperature causes oxygen to be released/detached from hemoglobin)
pH (low pH - acidity - causes oxygen to be released/detach from hemoglobin)
Co2 (high Co2 causes oxygen to be released/detach from hemoglobin)
When our tissues become more active (increased function), they produce more heat, acids, and CO2. This heat, acid, Co2, will enter the neighboring capillary blood and cause the hemoglobin to release its O2 and the O2 can then enter the tissue. The tissue can use the O2 to sustain its functioning. It’s activity/increased functioning.
How Co2 is Transported Through The Blood
About 7% of co2 is dissolved in plasma, 23% is bound to hemoglobin, about 70% is converted to HCO3 (bicarbonate)
When co2 levels increase in the blood (this occurs in the systemic capillary) this reaction occurs to form bicarbonate ( co2 +H2o -> H+ + HCO3- )
When Co2 levels decrease in the blood (this occurs in the pulmonary capillary blood) this reaction occurs to form CO2 ( H+ + Hco3- -> Co2 +H2o )
Carbon Monoxide (CO) Poisoning
CO is a colorless and odorless gas that’s produced when we burn organic material (plastic, wood, gasoline/fuel) is burned.
CO binds to hemoglobin more efficiently than oxygen does. It will bind to hemoglobin preferentially and cause a lack of oxygen in the blood and body (hypoxia). When carbon monoxide binds to hemoglobin it turns it bright red just like oxygen does.
Symptoms: Headache, dizziness, confusion, fatigue, nausea, loss of consciousness.
Breathing at High Altitude
When we’re at elevations over 5,000 ft above sea level, some of the hemoglobin in the blood passing through the lungs doesn’t get oxygenated. (less oxygen is absorbed into the blood than would be if breathing at lower altitude
Our body adapts to living at higher altitudes
Liver and kidneys secret more EPO which leads to increase RNC production (increase hematocrit)
Altitude Sickness: Form of mild hypoxia
Symptoms: headache, fatigue, nausea, dizziness
Digestive System
Carries out 3 basic functions:
Mechanical Digestion= physical breakdown and mixing of material in the digestive tract (chewing)
Also includes movement of material along the digestive tract (swallowing)
Chemical Digestion= chemical breakdown of food/drink/molecules into smaller molecules that can be absorbed. Carried out by digestive enzymes.
Absorption= Movement of food/drink/drug molecules across the wall of the digestive tract into the blood.
Digestive Tract= tube that extends from the mouth to the anus.
Its wall has 4 layers.
Mucosa= lines the inside wall of the tract
Stratified squamous epithelium in mouth, pharynx, esophagus and anus
Simple columnar epithelium in stomach, small/large intestine
Contains mucus secreting cells
Submucosa= areolar connective tissue
Where most of the tracts of blood vessels, lymphatic vessels, nerves, and bodies of digestive glands are found.
Muscularis Externa= muscular layer
Skeletal muscle in mouth, pharynx, upper esophagus and lower anus
Smooth muscle in the rest of the tract like lower esophagus, stomach, small/large intestine
2 layers of smooth muscle in the esophagus and intestines. Inner layer of circular muscle (contraction squeezes down on tract), outer longitudinal layer and contraction shortens the tube.
Peristalsis= coordinated contraction of these 2 layers to squeeze and move material down the esophagus and intestines.
3 layers of smooth muscles in the stomach.
Serosa= thin, slick, shiny membrane covering the esophagus (adventitia), stomach, and intestine (visceral peritoneum).
Mouth
Includes lips, cheeks, tongue, soft/hard palates
Mechanical Digestion= chewing aka “mastication”; mixes food and drink with saliva
Chewing forms a “bolus” which is a mix of food/drink/saliva that we swallow
Also involved in swallowing
Chemical Digestion= carried out by an enzyme in saliva called salivary amylase
Salivary amylase breaks down starch (also known as amylose) into glucose.
Saliva= about a liter produced/secreted per day by the salivary glands.
Made up of H2O, mucus, salivary amylase, HCO3 (bicarbonate), contains enzymes that break down specific types of bacteria.
H2O and mucus makes it easier to swallow and also dissolved food molecules so we can taste them
Bicarbonate neutralizes the ph of our food/drink
Absorption= only highly hydrophobic and small chemicals can be absorbed.
Ex: vitamin B12, nicotine, motion sickness meds and certain nausea meds.
Pharynx
Also known as the throat
Involved in swallowing (along with the mouth and esophagus)
Not much absorption or chemical digestion occurs in it.
Esophagus
Also known as the gullet
Like pharynx just involved in swallowing
Swallowing aka "deglatition"
The tongue pushes the bolus into the pharynx, soft palate folds up and helps block bolus from moving into nasopharynx.
Pharynx contracts and pushes the bolus into the esophagus. At the same time muscles connected to the larynx contract and the larynx is elevated and causes the epiglottis to fold over the opening of the larynx
Esophagus undergoes peristalsis and the bolus is squeezed down the length of the esophagus.
Cardiac sphincter (aka “lower esophageal sphincter” or “gastroesophageal” sphincter) relaxes and allows the bolus to enter the stomach.
Stomach
Lined with a thick layer of mucus (protects the mucosa from damage)
Contains gastric juice: 2-3 liters produced per day
Gastric juice is made up of hydrochloric acid (HCI), pepsin, and gastric lipase
Hydrochloric acid (HCI)= strong acid and makes gastric juice have a pH of 2.
The acidity denatures dietary proteins. This allows pepsin to break them down more efficiently. Also helps hills microbes in food.
Pepsin= enzyme that breaks down proteins into peptides
Gastric lipase= enzyme that breaks down triglycerides and phospholipids into fatty acids
Mechanical Digestion
When a bolus enters and mixes with gastric juices, the mix becomes known as “chyme”
The stomach sense the presence of chyme and undergoes contractions known as “mixing waves”
These mixing waves cause some chyme to squirt into the duodenum
Typically chyme from a meal spends about 3 hours in the stomach
Chemical Digestion
Carried out by pepsin, gastric lipase, and lingual lipase (like gastric lipase but secreted by the tongue and swallowed along with the bolus)
Absorption
Not much absorption can occur because the thick mucus lining prevents absorption
Certain drugs can be absorbed to an extent these include: alcohol, aspirin
GERD (gastroesophageal reflux disease)
Aka “heart burn”
Caused by cardiac sphincter not closing completely and chyme splashes up the esophagus and burns/damages its mucosa
Treatments= avoid overeating, greasy food, spicy food, alcohol, tobacco, chocolate, mint, onions, tomatoes, coffee, acidic juice (foods containing vinegar/citrus).
Antacids= tablets or solutions containing bicarbonate (HCO3-). It acts as a buffer and neutralizes chyme.
Drugs that act on stomach’s mucosa cells and block HCI secretion
Small Intestine
3 sections: duodenum (first 10 inches), jejunum (middle 6ft), ileum (last 12ft)
3 Type of structures lining its wall that increases the surface area of contact with chyme
Circular Folds= large ridges
Villi= fingerlike structures
Microvilli= microscopic fingerlike structures on surface of mucosa cells (microvilli have digestive enzymes embedded in them)
Mechanical Digestion in the Small Intestine
When chyme fills a segment/region of the small intestine that region contracts and squishes the chyme. These contractions are called “segmentations”.
Also, every 2 hours there’s a wave of peristalsis down the whole length of the small intestine this pushes the chyme further along.
Chyme from a meal spends about 4 hours in the small intestine.
Chemical Digestion in the Small Intestine
Where most of the chemical digestion along the digestive tract occurs.
Pancreatic juice= secreted into duodenum when chyme enters
Contains:
bicarbonate= neutralizes acidity of the chyme from the stomach (prevents damage)
pancreatic amylase= breaks down starch into glucose
Pancreatic lipase= breaks down triglycerides and phospholipids into fatty acids
Proteases and peptidases= breaks down proteins and peptides into amino acids
Nucleases= break down DNA and RNA molecules
Bile= produced by the liver, stored in the liver and gallbladder. Chyme in the duodenum triggers the release of bile into the duodenum.
Contains:
Bile salts= modified cholesterol molecules. Interact with lipid droplets in chyme and break them apart into microscopic droplets and bile salts emulsify lipid droplets. This allows pancreatic lipase to break down the fats and phospholipids in chyme more efficiently
Bilirubin and Biliverdin= orange and green waste molecules derived from hemoglobin breakdown
Brush Border Enzymes- digestive enzymes in the microvilli
Sucrase, maltase, lactase, peptidases, nucleases
sucrase, maltase and lactase break down sugars into glucose, fructose, and galactose
Peptidases breaks down peptides into amino acids
nucleases breakdown DNA and RNA into tiny chemicals
Absorption in the Small Intestine
Where most absorption occurs which includes:
Water, electrolytes, vitamins, minerals, glucose, fructose, galactose, amino acids, fatty acids, drugs, bile salts, cholesterol,
Larges Intestine
About 5 ft long and includes: appendix, cecum, ascending, transverse, descending and sigmoid colon, rectum, and anus
Contains healthy bacteria within it
Appendix= functions as a reservoir for the large intestine’s healthy bacteria
When we have diarrhea the appendix serves as a safe house for bacteria to recolonize the large intestine after recovery.
Haustra= bulges along the length of the large intestine
Tenia Coli= contracted bands along the large intestine
Mechanical Digestion in the Large Intestine
3 Processes
Haustral Churning= occurs when feces builds up within a haustrum and the haustrum contracts and squishes down on feces. (promotes digestion and absorption)
Peristalsis= occurs about 4 times a day (typically following a meal)
Pushes feces further along the large intestine and towards the rectum
Defecation= Basic term for “Pooping”.
Reflex that's triggered when feces builds up in the rectum and the rectum stretches.
The rectum then contracts while at the same time the internal anal sphincter relaxes (Smooth muscle= involuntary). This allows feces to enter the anus and we feel the urge to poop.
2 scenarios:
We relax the external anal sphincter consciously (skeletal muscle=voluntary control) = you poop.
We consciously contract the external anal sphincter= you hold it.
Chemical Digestion in the Large Intestine
Carried out by the large intestines bacteria:
Any sugars or amino acids that bypass absorption in the small intestine spill over into the large intestine where they’re broken down.
Bacteria break down sugars into the gasses methane (CH4), H2 (these are flammable)
Bacteria break down amino acids into the gasses H2S, Indole, skatole (these are the stinky)
Also, bacteria convert the bilirubin and biliverdin into urobilinogen and stercobilin
Urobilinogen= absorbed into the blood and excreted in the urine (what makes the urine yellow colored)
Stercobilin= remains in feces and makes feces brown
Lactose Intolerance
Condition where a person lacks the enzyme lactase in their small intestine.
If lactose is consumed it bypasses digestion in the small intestine and ends up in the large intestine where the bacteria break it down and leads to increased levels of gas and flatulence and diarrhea.
Absorption in the Large Intestine
Some h2o, electrolytes, vitamins, that are produced by our healthy bacteria (vitamin K and B vitamins)
Urobilinogen is also absorbed and excreted in urine
Feces:
Made of:
Undigested food/drink molecules (mostly fiber)
Stercobilin
Live and dead large intestine bacteria
Dead mucosa cells shed from the large intestine
H20, mucous, electrolytes
Smell comes from:
Indole, skatole, H2S, H2, CH4
When feces leaves the body it’s known as stool.
Defecation issues:
Diarreha (Watery feces)= due to feces not spending enough time/moving too quickly through the large intestine and leads to lack of water absorption.
Leads to dehydration
Constipation = when feces spends too long in the long intestine
Feces builds up, becomes dry and hard and becomes difficult to defecate
Treatments= high fiber diet, exercise, hydration.
Fiber=
Plant carbohydrates that our digestive system is unable to chemically break down. When eaten, they pass right through us
Fiber molecules function as structural molecules in plants
2 Basic Types: Both types are healthy in the diet
Soluble Fiber
Dissolves in water
Found in fruits, beans, vegetables
Insoluble Fiber
Does not dissolve in water
Found in stems, seeds, coverings of fruits/vegetables/beans (husks of seeds, peel of fruit, covering of corn kernel)
Both types are healthy in our diet
They help prevent constipation
They make us feel full without contributing to caloric intake: healthy if trying to lose or maintain weight.
Also, soluble fiber binds to any sort of nutrient molecule and prevents nutrients from being absorbed so we end up pooping out the nutrients (this includes cholesterol, bile salt, and dietary cholesterol) along with the soluble fibers (healthy if you're trying to lose or maintain weight)