Human Bio 1 Final Exam

what do blood vessels do?

transport blood to and from the tissue of the body

what are three types of blood vessels?

Arteries, veins, capillaries

Arteries – from the heart

• carry blood away from the heart

• thick walls with 3 layers

3 layers of arteries

• Endothelium (Tunica intima) - the thin, inner epithelium

• Middle layer (Tunica media) - smooth muscle and elastic tissue

  • allows arteries to expand and recoil

• Outer layer (Tunica adventitia) - connective tissue

Arterioles

• Small arteries

• Middle layer mostly smooth muscle

• functions to control blood flow and blood pressure

• contracts to constrict the vessel, reducing blood flow and raising blood pressure

• when relaxes, the vessel dilates, increasing blood flow and reducing blood pressure

Capillaries - sites of exchange

• microscopic vessels between arterioles and venules

• walls are one cell thick (endothelium only)

• primary site of gas, nutrient, and waste exchange

• precapillary sphincters regulate blood flow

  • when closed, blood bypasses via arteriovenous shunt (throughfare channel)

Precapillary Sphincter

• Regulates blood flow into the capillary

• made of smooth muscle that can contract and relax

Capillary Exchange

• Driven by two forces

  • Blood pressure drives fluid out of capillary (arterial end)

    • fluid contains everything blood contains, except cells + plasma proteins

  • Osmotic pressure draws water in capillary(venous end)

• Excess fluid enters lymphatic capillaries which becomes lymph and then is returned to the cardiovascular system

Movement of Fluid into Lymphatic Vessels

The heart’s pumping action creates blood pressure, forcing water (and small amounts of protein) into the extracellular fluid. Excess fluid is collected by lymphatic vessels and returned to the cardiovascular system.

The Lymphatic System

Works with the immune system and assists the cardiovascular system by collecting interstitial fluid and returning it to the blood

when fluid enters the lymphatic vessels, it is called lymph

Veins - To the Heart

• venules receive blood from capillaries

• veins carry blood towards the heart

• they have the same 3 layers as arteries, but less smooth muscle

• Valves prevent backflow (especially against gravity)

• vein walls are thinner than arteries so they can expand more and hold more blood

• during blood loss, veins constrict to help raise blood pressure

blood pressure

• the pressure that blood exerts against a blood vessel wall

• highest in the Aorta, which is right next to the heart

• progressively decreases as blood moves through the body’s vessels

  • arteries, arterioles, capillaries, venules, and finally, the veins

• lowest in the superior and inferior venae cavae, which enters the right atrium

Pulse (heart rate)

• surge of blood into an artery causes the walls to stretch, and then recoil

• usually measured in radial artery at wrist or carotid artery in the neck

• measurement of the hearth rate averages 60-80 beats per min

Regulation of Blood Pressure

• blood pressure moves blood in arteries

• ventricles contracting creates blood pressure, propelling blood through the arteries

• measured with sphygmomanometer, in brachial artery of arm

• Average = 120/80 mmHg (systolic/diastolic)

Systolic Pressure

the highest pressure; when blood is ejected from the heart

Diastolic Pressure

the lowest pressure; when the ventricles relax

Blood Velocity & Pressure in Vessels

• blood flow is regulated

• blood flow is slow in the capillaries

• blood pressure decreases as it flows away from the heart

  • blood flow = slowest in capillaries to increase exchange of gas, nutrients, and wastes

  • blood pressure is adjusted by the precapillary sphincters

Blood Flow in Veins

• blood flow in veins returns blood to the heart

• blood pressure = very low in veins, so doesn’t contribute much the movement of blood

• blood return to the heart depends on:

  • skeletal muscle pump

  • respiratory pump

  • valves present in veins

cardiovascular pathways

• blood flows in two circuits:

  • the pulmonary circuit (to lungs)

  • systemic circuit (to body tissues)

• pulmonary circuit circulates blood through the lungs

• systemic circuit circulates blood through the body

Pulmonary Circuit (Big Picture)

• moves blood between heart and lungs

• purpose: gas exchange

• uses pulmonary arteries and pulmonary veins

Pulmonary Circuit (Step-by-Step)

• right atrium pumps deoxygenated blood into the right ventricle

• right ventricle pumps blood into pulmonary trunk

• pulmonary trunk splits into left and right pulmonary arteries

• into lungs: arteries→arterioles→capillaries

• gas exchange occurs

• capillaries→venules→pulmonary veins

• four pulmonary veins → left atrium

• pulmonary arteries=oxygen-poor

• pulmonary veins=oxygen-rich

systemic circuit (overview)

• left ventricle pumps blood into aorta

• aorta branches to supply all body tissues

• arteries→arterioles→capillaries

• capillaries→venules→veins

• veins lead to superior and interior vena cava

• vena cavae empty into right atrium

Systemic Circuit (Typical Pathway)

• usual route:

  • aorta → organ artery → capillaries → veins → vena cava

• example:

  • aorta → renal artery → kidney → renal vein → inferior vena cava

Hepatic Portal System (Special Route)

• carries nutrient rich blood from digestive tract to liver

• liver then:

  • synthesizes blood proteins

  • stores glucose as glycogen

  • removes toxins and pathogens

• blood exits liver via hepatic veins

• hepatic veins drain into inferior vena cava

cardiovascular disease (CVD)

• leading cause of early death in Western countries

• Includes:

  • Disorders of blood vessels (hypertension, atherosclerosis)

  • Disorders of the heart (heart failure)

Hypertension (High Blood Pressure)

• defined as:

  • systolic pressure of 140 or greater

  • diastolic pressure of 90 or greater

• Called a “silent killer” because few symptoms until it causes:

  • kidney failure

  • heart attack

  • stroke

• treated with diuretics, which increases the production of urine, and other drugss

Heart Failure

• heart no longer pumps properly

• treatments include:

  • wrapping heart to prevent enlargement

  • implantable cardioverter-defibrillator (ICD) - corrects irregular rhythm

  • heart transplant

  • stem cells injections - repairs

  • left ventricular assist device (LVAD) - battery powered pump to assist

  • total artificial heart (temporarily)

Atherosclerosis

• buildup of atherosclerotic plaque in blood vessel walls

• plaque narrows vessels, decreasing blood supply to tissues

• roughened walls in arteries can cause clots

  • thrombus - stationary

  • embolus - clot that breaks off and travels

  • thromboembolism - embolus lodged in a vessel

the respiratory system - function

• ensures that oxygen enters the body

• ensures carbon dioxide leaves the body

• supports cellular respiration

  • cells use oxygen

  • cells produce carbon dioxide

ventilation (breathing)

• ventilation=breathing

• include:

  • inspiration (inhalation)

  • expiration (exhalation)

• air moves through cavities and tubes between atmosphere and lungs

Inspiration vs Expiration + system link

• inspiration

  • air moves from atmosphere into lungs

• expiration

  • air moves from lungs into atmosphere

• depends on the cardiovascular system to:

  • transport oxygen to tissues

  • return carbon dioxide to lungs

the respiratory system and homeostasis

• respiratory + cardiovascular systems maintain homeostasis by:

  • external respiration: gas exchange (oxygen and carbon dioxide) between air and the blood

  • gas transport: blood carries gases between lungs and tissues

  • internal respiration: gas exchange between blood and tissue fluid

• airway blood supply: bronchial artery and vein

• key distinction

  • bronchial vessels: airway tissue

  • pulmonary vessels: gas exchange

upper respiratory tract

• includes:

  • nasal cavities

  • pharynx

  • glottis

  • larynx

• functions

  • conducts air

  • filters/warms/moistens air

  • begins voice production

nose - structure and function

• air enters via nares → nasal cavities

• cavities separated by septum (bone + cartilage)

• hair + mucus filter air

• mucous membrane traps particles and move them to pharynx

• capillary rich submucosa warms and moistens air

• many capillaries makes us prone to nosebleeds

nose - connections

• contains odor receptors (olfactory receptors)

• tear ducts drain into nasal cavity (crying→runny nose)

• connects to sinuses (fluid buildup → headache)

• air flows to nasopharynx (upper portion of pharynx)

• auditory tubes connect nasopharynx to middle ear

  • air pressure in middle ear equalizes air pressure in nasopharynx (“pop”)

Pharynx and Larynx (overview)

• pharynx (throat)

  • funnel-shaped

  • connects nasal/oral cavities → larynx

  • 3 parts: nasopharynx/oropharynx/laryngopharynx

• tonsils

  • lymphoid tissue

  • defence against pathogens

• larynx

  • cartilaginous

  • between pharynx and trachea

• adam’s apple = laryngeal prominence

Larynx - voice and protection

• houses vocal cords - mucosal folds supported by elastic ligaments

• glottis = opening between cords

• air passing through glottis, vibrates vocal cords, producing sound

• the higher tension in vocal cords, the higher pitch

• wider glottis, lower pitch

• swallowing

  • larynx moves upwards against the epiglottis

lower respiratory tract

• includes:

  • trachea

  • bronchial tree

  • lungs

  • diaphragm

• functions:

  • air conduction

  • gas exchange

  • ventilation

trachea

• “windpipe”

• connects larynx to primary bronchi

• c-shaped cartilage rings prevent collapse

  • open side allows esophagus expansion

• lined with pseudostratified ciliated columnar epithelium + goblet cells

  • goblet cells produce mucus, which traps air debris

  • cilia moves mucus to pharynx

• smoking damages cilia → smokers cough

• tracheostomy: tube inserted into trachea

bronchial tree

• two primary bronchi lead from trachea into lungs

• primary bronchi branches into secondary bronchi, continue to branch until they are small bronchioles

• bronchi cartilage disappears as they get smaller

• asthma attack

  • bronchiole smooth muscle contracts

  • contracting constricts airway, causing wheezing

• bronchioles lead to elongated space inclosed by many air sacs (alveoli)

lungs

• made of secondary bronchi, bronchioles, alveoli

• lobes:

  • right lung = 3

  • left lung = 2 (to make room for heart)

• lobes are divided into lobules

• lungs enclosed by pleurae (two layers of serous membrane)

  • produce serous fluid

  • surface tension helps lungs expand

• pleurisy = inflammation of pleurae; painful

alveoli

• lungs contain roughly 300 million alveoli

• each alveolar sac is surrounded by blood capillaries

• alveoli + capillaries have simple squamous epithelium (very thin)

• gas exchange occurs between

  • air in alveoli

  • blood in capillaries

gas exchange big picture

• oxygen is needed to make ATO

• carbon dioxide must be removed

• respiration includes exchange of gases, occurs in lungs and tissues

• governed by diffusion

• gases move from high to low partial pressure

partial pressure

• gases exert pressure

• pressure of each gas = partial pressure

• Written as P O₂ or P CO₂

• if partial pressure differs, it diffuses from higher to lower partial pressure

external respiration

• gas exchange between alveoli and pulmonary capillaries

• co2 diffuses from blood to lungs

• o2 diffuses from alveoli to red blood cells

CO2 transport and pH

• most co2 carried as bicarbonate in plasma

• carbonic anhydrase: speeds breakdown of carbonic acid in red blood cells

• carbaminohemoglobin = hemoglobin carrying co2

• hyperventilation: alkalosis (high blood pH)

• hypoventilation: acidosis (low blood pH)

o2 transport

• o2 diffuses into plasma, then red blood cells in lungs

• hemoglobin takes up oxygen and becomes oxyhemoglobin

internal respiration

• gas exchange between capillaries entering tissues and cells of body tissues

• co2 diffuses out of tissue cells into blood

• o2 diffuses from capillaries into tissue cells

• Gas exchange between systemic capillaries and tissue cells

• blood entering systemic capillaries = bright red because red blood cells have oxyhemoglobin

• Tissue P O₂ is low (cells use O₂)

• Tissue P CO₂ is high (cellular respiration)

Ventilation and Boyle’s law

• ventilation= breathing

• governed by boyle’s law

• at constant temperature, pressure of any given quantity of gas us inversely proportional to its volume

• controls inhalation and exhalation

Inspiration

• active process

• diaphragm contracts and flattens

• external intercostals contract

• rib cage moves up and out

• thoracic volume goes up and alveolar pressure goes down

expiration

• passive process

• diaphragm and intercostals relax

• rib cage moves down and in

• lung recoil and the pressure inside increases, and air flows out

• surfactant prevents alveolar collapse

• pleural pressure keeps lungs open

• punctured thorax leads to lung collapse

Lung Volumes

• tidal volume: amount of air that moves in and out with each normal breath

• vital capacity: max volume that can be moved in plus max that can be moved out (one breath)

  • sum of tidal, inspiratory reserve, and expiratory reserve volumes

• inspiratory + expiratory reserve volume: increased volume of air moving in or out of body with forced inspiration and expiration

• residual volume: air remaining in lungs after exhalation

• dead air space: airways not used for gas exchange

nervous control of breathing

• respiratory control center in the brain controls breathing

• sends nerve signal to diaphragm + internal intercostal muscles, causing inspiration

• signals stop, muscles relax, expiration occurs

• rate and depth are automatic, but influenced by nervous system

• breathing can voluntarily change (speaking, singing, eating)

• forced inspiration activates stretch receptors in airway walls

• stretch receptors send inhibitory nerve impulses

• prevent overstretching lungs

chemical control of breathing

• cells produce co2 during cellular respiration

• it then enters blood, combining with water, forming acid that breaks down and gives off hydrogen ions

  • H+ decrease pH of blood

• chemoreceptors=sensory receptors sensitive to chemical composition of body fluids

• two sets of chemoreceptors, located in:

  • one in medulla oblongata

  • other set in carotid bodies of carotid arteries, and aortic bodies of aorta

  • mostly respond to carbon dioxide levels of the blood

  • when pH decreases, respiratory center increases rate and depth of breathing

  • co2 removal = pH normalizes

  • holding breath= co2 accumulates in blood and pH decreases

  • respiratory center can override a voluntary inhibition of respiration, forcing breathing

overview of digestive system

• organs located within gastrointestinal (GI) tract

• function: break down macromolecules found in food

• subunits: monosaccharides, amino acids, fatty acids, glycerol

• subunits cross plasma membranes using facilitated and active transport

• nutrient are transported by blood cells

processes of digestion

• ingestion: intake of food

• digestion

  • mechanical: chewing, smooth muscle contractions

  • chemical: digestive enzymes breakdown macromolecules into subunits

    • begins in mouth, continues in stomach, and completed in small intestine

• movement: food passes from one organ to next, by contractions of smooth muscle called peristalsis

• absorption: movement of nutrients across GI tract wall into blood

• elimination: removal of indigestible wastes

wall of digestive tract

• lumen: open area of hollow organ or vessel, in GI tract it contains food or feces

• layers:

  • mucosa: innermost, produces mucus and digestive enzymes

  • submucosa: loose connective tissue; contains blood vessels, lymphatic vessels, and nerves

  • muscularis: two layers of smooth muscle that move food along GI tract

    • inner circular

    • outer longitudinal

  • serosa: outer lining; part of peritoneum

pharynx and esophagus

• mouth and nasal passages lead to pharynx

• pharynx opens to

  • esophagus (food)

  • trachea (air)

• two tubes are parallel to each other, with trachea in front

• esophagus: muscular tube leading to stomach

swallowing

• begins voluntary, but once food is pushed back to pharynx becomes involuntary reflex

• food enters esophagus because:

  • soft palate closes nasal passage

  • trachea moves up under epiglottis to cover glottis, opening to larynx

  • prevents food entering nose or trachea

Peristalsis and Sphincters

• peristalsis: smooth muscle contractions that move food

• sphincter: ring of muscle (valve)

  • contract → stop food movement

  • relax → allow food movement

• lower esophageal sphincter failure leads to heartburn

• vomiting: strong abdominal + diaphragm contractions force stomach contents upward

the stomach

• functions:

  • stores food

  • begins protein digestion

  • controls emptying into small intestine

• does not absorb nutrients

• absorbs alcohol

• muscularis has 3 layers of muscles:

  • circular

  • longitudinal

  • oblique

stomach secretions

• mucosa has rugae and gastric pits

• gastric glands produce gastric juice:

  • pepsin - digests proteins

  • hydrochloric acid - pH of 2 - kills bacteria, activates pepsin

  • mucus

• chyme= food+gastric juice

• pyloric sphincter: only allows small amount of chyme to enter the small intestine at a time

small intestine structure

• main digestive organ

• long (6m), small diameter

• regions

  • duodenum

  • jejunum

  • ileum

• villi increase surface area

• microvilli form brush border

• brush border enzymes complete digestion

absorption in small intestine

• nutrients absorbed into villi

• villi contain:

  • blood capillaries

  • lacteal (small lymphatic capillary)

• monosaccarides and amino acids enter the blood capillaries of villi

• fatty acids and glycerol form chylomicrons, which enter lacteal

• blood caries nutrients to all cells

large intestine structure

• includes:

  • cecum

  • colon

  • rectum

  • anal canal

• appendix (off cecum): immune function - fights infections

• appendicitis: inflamed appendix, risk of peritonitis (life threatening infection)

• colon sections:

  • ascending

  • transverse

  • descending

  • sigmoid colon, which enters the rectum, which opens at the anus

functions of the large intestine

• no digestive enzymes

• no nutrient absorption except vitamins

• absorbs water → prevent dehydration

• absorbs vitamin K and B-complex - from bacteria

• forms feces

  • ¾ water

  • ¼ solids (bacteria + fiber)

  • stercobilin (breakdown product of bilirubin) + oxidized iron cause brown colour

defecation

• peristalsis forces feces into the rectum

• stretching of the rectal wall initiates nerve impulses to spinal cord

• rectal muscles contract

• anal sphincters relax, allowing feces to exit

• can delay defecation via external anal sphincter (skeletal muscle)

accessory organs - overview

• digestive system has two main components (accessory organs, GI tract)

• accessory organs

  • salivary glands

  • pancreas

  • liver

  • gallbladder

• accessory organs are NOT part of GI tract

• they assist in physical and chemical digestion

mouth (oral cavity)

• receives food and begins mechanical and chemical digestion

• roof separates oral from nasal cavity and has two parts

  • hard palate (bone)

  • soft palate (muscle)

• soft palate ends in uvula

tonsils

• back of mouth, on either side of tongue

• lymphatic tissue: helps protect from disease

• single pharyngeal tonsil (adenoids) in nasopharynx

tongue

• covered in taste buds

• assists in mechanical digestion

• moves food

• forms bolus (mass of chewed food)

• moves bolus toward pharynx

teeth

• mechanical digestion

• 20 baby teeth, 32 adult teeth

• two main divisions

  • crown: the part above the gum line

  • root: the portion below the gum

• enamel: hard outer layer

• dentin: bone like layer

• pulp: nerves and blood vessels

• periodontal membranes: anchors tooth to jawbone

Salivary glands

• three pairs

  • parotid

  • sublingual

  • submandibular

• secrete saliva

• functions:

  • lubricates mouth

  • dissolves chemicals for taste

  • lysozyme (antibacterial enzyme)

  • begins digestion of complex carbohydrates

    • salivary amylase

pancreas structure

• lies behind stomach

• extends duodenum → spleen

• secretes pancreatic juice via pancreatic duct

• pancreatic juice contains

  • digestive enzymes

  • bicarbonate → neutralizes chyme

pancreas function and control

• secretion controlled by duodenal hormones

• secretin:

  • stimulates watery buffer

  • pH 7.5-8.8

• Cholecystokinin (CCK)

  • stimulates enzyme secretion

pancreatic enzymes

• pancreatic alpha amylase - breaks down starches

• pancreatic lipase - breaks down complex lipids, releases fatty acids

• nucleases - breaks down RNA and DNA

• proteolytic enzymes - breaks down proteins

  • proteases

  • peptidases

liver

• largest visceral organ

• left and right lobes

• under right abdomen, under diaphragm

• made of liver lobules (structural and functional units)

• produces bile

gallbladder

• stores bile

• releases bile during meals

• people with no gallbladder can still digest fat, but may need to intake less

bile

• contains:

  • bicarbonate ions

  • cholesterol

  • phospholipids

  • organic wastes

  • bile salts

• function:

  • neutralize acids

  • aid fat digestion

hepatic circulation

• hepatic artery:

  • from aorta, brings oxygenated blood to liver

• hepatic portal vein:

  • brings nutrient rich blood toward liver from small intestine

• hepatic vein:

  • carries deoxygenated blood away from liver and empties into inferior vena cava

liver functions

• 200+ functions

• includes:

  • Carbohydrate, lipid, amino acid metabolism

  • Waste removal

  • Vitamin & mineral storage

  • Drug inactivation

  • Plasma protein synthesis

  • Phagocytosis

  • Hormone & toxin removal/storage

hormonal control of digestion

• digestive secretions controlled by:

  • nervous system

  • digestive hormones

• parasympathetic nervous system

  • sight/smell of food stimulates gastric secretion

• gastrin

  • released by stomach (protein rich meal)

  • increases gastric gland secretion

secretin and CCK

• secretin

  • released by duodenum

  • triggered by HCl in chyme

• Cholecystokinin (CCK)

  • released when proteins and fats are present

  • causes liver to increase bile production

• both increase pancreatic juice production

urinary system overview

• Maintains fluid balance

• Organs:

  • Kidneys (retroperitoneal)

  • Ureters (retroperitoneal)

  • Urinary bladder

  • Urethra

Kidneys – Location & Features

• One on each side of vertebral column

• Partially protected by rib cage

• Right kidney lower than left (liver)

• Bean-shaped; reddish-brown

• Covered by renal capsule (fibrous connective tissue)

• Retroperitoneal (behind peritoneum)

Kidney Gross Anatomy

• Renal cortex:

  • Outer layer

  • Dips between medulla

• Renal medulla:

  • Cone-shaped renal pyramids

• Renal pelvis:

  • Central space

  • Continuous with ureter

Kidney Blood Supply

• Renal hilum (concave side):

  • Renal artery enters

  • Renal vein + ureter exit

• Renal artery:

  • Branch of aorta

  • Brings blood to kidney

• Renal vein:

  • Carries filtered blood away

  • Empties into inferior vena cava

Nephron – Overview

• Nephron = structural & functional unit

• Filters blood → produces urine

• Parts:

  • Bowman’s (glomerular) capsule

  • Proximal convoluted tubule

  • Loop of Henle

  • Distal convoluted tubule

  • Collecting duct

Nephrons – Organization

• Kidneys contain >1 million nephrons

• Many nephrons → one collecting duct

• Collecting ducts → renal pelvis

• Two types:

  • Cortical nephrons: glomerulus near cortex

  • Juxtamedullary nephrons:

    • Glomerulus near cortex–medulla junction

    • Loop of Henle deep in medulla

Nephron Locations

• Glomerular capsule + convoluted tubules → renal cortex

• Loop of Henle → dips into medulla

• Collecting ducts → medulla

• Collecting ducts give pyramids striped appearance

Blood Supply of the Nephron

• Afferent arteriole → glomerulus

• Glomerulus = knot of capillaries

• Efferent arteriole carries blood away

• Glomerular pressure is very high

  • Efferent arteriole narrower

• High pressure important for glomerular filtration

• Efferent arteriole → peritubular capillary network

• Capillaries surround nephron

• Blood → venule → renal vein

Glomerular Capsule

• Outer layer: squamous epithelial cells

• Inner layer: podocytes

• Podocytes create pores

• Allow molecules to move from blood → capsule

Proximal Convoluted Tubule (PCT)

• Lined with cuboidal epithelial cells

• Many microvilli

• Form brush border

• Increases surface area

Loop of Henle & DCT

• Loop of Henle:

  • Descending limb

  • Ascending limb

  • Different permeabilities to water & solutes

• Distal convoluted tubule (DCT):

  • Ion exchange

• Several DCTs → one collecting duct

• Collecting duct → renal pelvis

Ureters

• Carry urine: kidneys → bladder

• Wall layers:

  • Inner mucosa

  • Smooth muscle

  • Outer fibrous connective tissue

• Peristalsis moves urine

• Works even when lying down

Urinary Bladder – Structure

• Stores urine

• Three openings:

  • Two ureters

  • One urethra

• Rugae flatten as bladder fills

• Transitional epithelium allows stretching

Bladder Control

• Mucosal folds prevent urine backflow

• Two sphincters:

  • Internal sphincter:

    • Smooth muscle

    • Involuntary

  • External sphincter:

    • Skeletal muscle

    • Voluntary

Urethra

• Bladder → external opening

• Female urethra shorter → ↑ infection risk

• Male:

  • Urethra passes through prostate

  • Prostate enlargement → restricted urine flow

• Male urethra:

  • Urine (urination)

  • Sperm (ejaculation)

Urination (Micturition)

• Bladder fills → stretch receptors activated

• Sensory signals → spinal cord

• Motor signals:

  • Bladder contracts

  • Sphincters relax

• Brain controls urination via external sphincter

Urinary System – Functions

• Performs excretion

• Removes metabolic wastes

• Forms & discharges urine

• Maintains salt, water, and pH homeostasis of blood