Human Physiology Flashcards
Digestion
Breakdown of food into smaller pieces for effective absorption by the villi into the bloodstream.
Mouth
Voluntary control of eating and swallowing, mechanical digestion of chewing and chemical starch digestion by saliva, which contains lubricants and enzymes
Esophagus
Movement of food by peristalsis from mouth to the stomach
Stomach
Churning and mixing with secreted water and acid to kill foreign bacteria and other pathogens in food and to initiate protein digestion
Small Intestine
Final stages of digestion, neutralizing stomach acid and absorb nutrients
Pancreas
Lipase, amylase and protease secretion to aid digestion
Liver
Secretion of surfactants in bile to break up lipid droplets
Gallbladder
Storage and regulated release of bile
Large intestine
Re - absorption of water, further digestion especially of carbohydrates, formation and storage of feces
Digestion Full Process
- Food is chewed in the mouth, turned into bolus by amylase
- Bolus enter the esophagus, move to the stomach by peristalsis
- Stomach churns food with acid, becoming chyme. Acid kills bacteria and starts protein digestion
- Chymes enters small intestine, where acid needs to be neutralized. Enzymes in SI have optimum pH for digesting lipids or further digest carbohydrates and proteins. Absorption starts at the beginning of the ileum
- Food enters large intestine: undigested material and digestive juices. Water, vimatins K and B, minerals reabsorbed
- Feces formed in LI stored in the rectum before egestion
Peristalsis
The longitudinal muscle contracts to widen the lumen, allowing the bolus to move down. The circular muscle contracts to constrict the lumen, pushing it further down.
Mechanical Digestion
Physically breaking down food through chewing, grinding, churning into smaller pieces
Chemical Digestion
Breaking down food into its basic components using enymes.
Pancreatic Amylase
Secreted by the pancreas into the small intestine, breaks down starch into maltose. Optimal pH of 7
Pepsin
Secreted by the stomach into the stomach, breaks down proteins into amino acids. Optimal pH of 2
Pancreatic Lipase
Secreted by the pancreas into the small intestine, breaks down triglycerides into glycerol and fatty acids. Optimal pH of 7.2
Lipid Digestion
- Fat globule separated into smaller micelles by bile (amphiphilic)
- The hydrophobic side attaches to the emulsified droplets, exposing the hydrophilic side to the exterior to prevent the droplets from reforming
- The pancreas secretes lipase after to conduct hydrolysis
Protein Digestion
- Pepsin in the stomach breaks protein chains into peptones and proteoses
- In the small intestine, trypsin and chymotrypsin break peptones and proteoses into single or double amino acid units
- Hydrolysis occurs to separated amino acids
Carbohydrate Digestion
- Salivary amylase breaks up long chains
- In the small intestines, pancreatic enzymes break dissacharides into monosaccharides
Acinar Cells
Found in the pancreas, secrete digestive enzymes
Path of Pancreatic Enzymes from Stomach to SI
Pancreatic juice containing the enzymes, carried through the pancreatic duct to the duodenum, released into the lumen of the SI
Examples of SI Enzymes
- Nuclease break down DNA and RNA
- Maltase breaks down maltose into glucose
- Lactase: lactose into galactose and glucose
Absorption
The movement of nutrients from the digestive system into the body through the bloodstream. Mostly occurs in the small intestine
Structure of the Small Intestine
- Folds in the lining increases SA with villi and microvilli
- Layers from inner to outer: mucosa, submucosa, muscularis and serosa
Muscularis Layer of the Small Intestine
Two smooth muscle layers. One thin outer longitudinal layer that shortens and elongates the intestine. Two a thicker inner circular layer causes constriction. Nerves lie between these two layers and allow them to work together to propagate food proximal (closer) to distal (further): peristalsis
Villus
- Present in a large amount to increase SA
- Rich blood supply to aid in absorption of nutrients into the blood, including bases of nucleic acids, vitamins and minerals
- Microvilli present as outward folds of the plasma membrane to increase SA
- Contain lacteals to aid in lipid absorption
- Intestinal crypts, glandular cells that secrete fluids to aid in movement of chyme through the intestine
- Thin epithelium to increase diffusion rate
- Capillaries to absorb glucose and amino acids
Methods of Absorption: Villi
Simple and facilitated diffusion, active transport and pinocytosis
Functions of the 4 Layers of the Small Intestine
- Mucosa: epithelium formed by enterocytes, goblet cells and endocrine cells
- Submucosa: contains blood vessels and connective tissue
- Muscularis: conducts peristalsis
- Serosa: single layer of epithelial cells with connective tissue
Enterocyte
Cells with microvilli, absorb glucose
Goblet Cells
Produce mucus
Lipid Absorption (5 Step Process)
- Fatty acids enter the epithelial cell
- Synthesis of fats in endoplasmic reticulum
- Fats form chylomicrons, a lipoprotien particle that transport fats
- Chylomicrons enter the lacteal
- Lymph transports chylomicrons
Dialysis Tubing
Models absorption
- A partially permeable membrane cellulose tubing containing microscopic pores that allow water, small molecules and ions to pass
- Separation of smaller molecules from large molecules in solution by selective diffusion
- Iodine: black if starch is present, orange if absent
- Benedict’s becomes brick red if glucose is present, blue if absent
2 Functions of the Respiratory System
- Gas exchange for cellular respiration
- Ventilation
Nasal and Oral Cavity
Where air enters the respiratory system
Pharynx
The membrane lined cavity behind the nose and mouth, connecting them to the esophagus or trachea
Larynx
Hollow muscular tube forming a passage to the lungs and holding the vocal cords
Trachea
Tube reinforced by rings of cartilage, extending from the larynx to the bronchi, conveying air to and from the lungs
Lungs
RIght lungs has three lobgs, left two. Conduct inspiration and expiration to bring in oxygen and removed carbon dioxide
Bronchi, bronchioles
Pathways of air into the lungs
Alveoli
Tiny air sacs at the end of bronchioles
Pathway of Air into the Respiratory System
Nasal and oral cavity, pharynx, larynx, trachea, lungs, bronchi, bronchioles, alveoli
Alveolar Cells
Type 1 and II pneumocytes
Type I Pneumocytes
Extremely flat and thin alveolar cells to increase SA for diffusion. Amniotic and unable to replicate but can form from type II pneumocytes.
Type II Pneumocytes
Secretes surfactants that create a moist surface and increases gas exchange, preventing alveoli from sticking to each otherS
Surfactant
Water based solution containing phospholipoproteins
Gas Exchange Summary
Replacing carbon dioxide with oxygen in the blood in lungs
How Gas Exchange Supports Cellular Respiration
Obtains oxygen and removes carbon dioxide for ATP synthesis.
Gas exchange occurs through diffusion, driven by the difference in [O] between x and y, a and b
x: cells
y: blood
a: lungs
b: external environment
Purpose of Branching of Airways in the Respiratory System
Increase surface area to increase efficiency of gas exchange
The longer air remains in the alveolus, the a the [O], b the concentration gradient that drives diffusion of oxygen
a: lower
b: decreasing
Alveolar [O] compared to [O] in blood that flows past the alveoli
Higher
Alveolar [CO2] comapred to [CO2] in blood that flows past the alveoli
Lower
2 Locations of Gas Exchange
- Blood and external environment at the alveoli
- Cells and blood at the capillaries
Ventilation Definition
Muscle movement to move fresh air into alveoli
Ventilation Responsibility
Maintaining a concentration gradient for exchange to occur between air in the alveoli and blood in capillaries
Gas Laws
Charles: V/T
Boyle: PV
Gay - Lussac: P/T
Combined: PV/T
Inspiration
- External intercostal muscles contract
- Internal relax
- Diaphragm contracts (drops)
- Abdominal muscles relax
- Pressure decreases, volume increases, air enters
- Rib cage expands
Expiration
- Internal intercostal muscles contract
- External intercostal muscles relax
- Diaphragm relaxes, rises
- Abdomoinal muscles contract
- Pressure increases, volume decreases, air escapes
Antagonistic muscles
Move in opposite directions to move body parts: external and itnernal intercostal msucles
Tidal Volume
Volume of air that enters and leaves the lungs during a single breath
Regulation of Breathing
- Brain sends nerve signals to the rib cage and diaphragm causing contraction and relaxation
- Rate of breathing controlled by CO2 levels in the blood
- CO2 produced dissolves in blood, creating carbonic acid
- Low pH sensed by medulla oblongata, which sends signals to increase breathing
- Increased oxygen levels causes pH to return
Emphysema
- Collapsed alveoli
- Airways unable to hold shape during exhalaiton
- Loss of elasticity causes alveoli to become thicker, larger and full of mucus
- Caused by long term exposure to chemical irritants
- Symptoms: shortness of breath, wheezing, chest pain, phlegm production, infections
Lung Cancer
- Uncontrolled growth of lung cells
- Coughing up blood, wheezing, weight loss, tumor rpessing on other organs
- Caused by smoking, air pollution, infections and genetic predispositions
Type of Circulatory System in Humans
Double circulatory system: two separate pathways that blood follows
Galen vs Harvey
Galen: arteries veins separate systems, heart is pump for blood
Harvey: blood circulates around the body with heart acting as pump, valves in veins
5 Components of Blood
- Plasma: carries dissolved substances, e.g. proteins, hormones, CO2, glucose, vitamins and minerals
- Erythrocytes: contains hemoglobin proteins to transport oxygen
- Leukocytes: agents of the immune system
- Platelets: blood clot
- Water
Interstitial fluid
- Tissue fluid
- Liquid part of blood that passes through the capillary wall to bathe tissue cells
- Consists of waeter, sugars, salts, fatty acids, amino acids, coenzymes and hormones, and waste products
- Cells exchange materials with the fluid
- After exchange: tissue fluid reabsorbed into capillaries, draining into venules
Hemostasis
Prevention of bleeding an maintenance of blood volume
Event Initiating Blood Clotting
Tearing or puncturing of a blood vessel
Purpose of Blood Clotting
- Coagulation to prevent blood loss
- Prevent pathogen entry
Clotting Factor Absent in Hemophiliacs
8
Blood Clotting Process (7 Steps)
- Injury exposes collagen fibers to blood
- Platelets stick to collagen fibers
- Platelets and damaged cells release clotting factors that initiate a cascade of reactions
- Clotting factors convert prothrombin to thrombin
- Thrombin hydrolyzes fibrinogen to fibrin
- Fibrin clot traps eryothrocytes
- Platelets become sticky to each other, clump together to form a platelet plug
Inflammation Response Definition
- Defense system for damage
- The more severe the symptoms, the more pathogens have entered, the more leukocytes have arrived to kill them
4 Symptoms of Inflammation Response
Pain, redness, heat, swelling
3 Purposes of the Inflammation Response
- Destroy the cause of the infection
- Limit the effects on the body due to the infection
- Replacing and repairing tissue damaged by the infection
Inflammation Response Process (5 Steps)
- Increased diameter (vasodilation) and permeability of blood vessels caused by histamine release
- Increaed blood flow to the injury site
- Increased mvoement of material into tissue spaces
- Phagocytic cells arrive and destroy microbes
- New tissue created to replace dead/damaged
Artery
- 3 layers
- Thicker tunica media than in vein
- Thick muscle and elastin fibers
- No valves
- Thicker walls with narrower lumens than veins
Vein
- Three layers
- Thinner tunica media than in artery
- Thinner muscle and elastin fibers than artery’s
- Have valves
- Thinner walls with larger lumens than arteries
- Transport blood back from the tissue to the heart
- Slower blood flow than in arteries
Capillary
- One layer of endothelial cells
- No tunica media
- No muscle or elastin fibers
- No valves
- Tiny lumen, one cell thick wall
- Form a network between arteries and veins
- Connection between arterioles and venules
- Highly permeable to allow fast exchange of materials, oxygen and nutrients
- Slow flowing blood to allow time for exchange
4 Layers of Arteries and Veins
From inside out: endothelial layer, elastin layer, smooth muscle layer, connective tissue layer
Tunica Intima
- Innermost layer of the vein/artery
- Direct contact with blood
- Endothelium and inner elastic membrane
Tunica Media
- Thickest layer of vein/artery
- Just the smooth muscle
Tunica Adventitia
- External elastic membrane and the connective tissue of vein/artery
- Tough collagen fibers
Arterioles
- Smalelr arteries
- Branch off in the body to supply blood to organs, limbs
- Higher muscle density, more susceptible to hormonal and nervous control of vasoconstriction/dilation
Skeletal Muscles and Veins
Skeletal muscles squeeze the veins to support flow, especially during exercise
Valves in Veins and Skeletal Muscles
- Valves open when muscles contract, allowing blood to return to the heart
- Valves close when muscles relax, preventing backwards flow
Cardiac Cycle (13 Steps)
- Oxygen poor blood enters the heart through the interior and superior vena cava
- Oxygen poor blood enters the right atrium
- The heart contracts, pushing blood from the right atrium into the right ventricle through the open tricuspid valve
- Once the ventricle is full, it begins to contract
- Increased blood pressure against the tricuspid forces it shut
- Contraction forces the blood to leave the heart through the pulmonary valve into the pumonary vein
- Blood flows to the lungs, where it is oxygenated
- Oxygenated blood carried to the left atrium by the pulmonary vein
- As the atrium contracts, blood flows from the left atrium to the left ventricle through the open bicuspid
- Once the ventricle fills, it begins to contract
- Increase in pressure forces the bicuspid to close
- As the ventricle contracts, blood leaves the heart through the aortic valve
- Oxygenated blood is distributed through the body
Pulmonary Circulation
Right side of the heart
Systemic Circulation
Left side of the heart
Diastole
Cardiac muscle relaxes, blood pours into the ventricles through the AV valves. Lower pressure than systole
Systole
Cardiac muscle contracts, pushing blood into the pulmonary and aortic valves. Higher pressure than diastole
Myogenic
Generates its own contractions. The heart is myogenic
Sound of AV Valves Closing
Lub
Sound of Semilunar Valves Closing
Dub
Regulation of Heart Rate 15 Steps
- Increased activity
- More oxygen consumed
- More carbon dioxide expelled
- Decreased pH as CO2 reacts with water to produce a hydrogen ion
- Decreased pH sensed by the cardiovascular center, sending impulses down the cardiac accelerator
- Signals sent to the SA node
- SA node sends electrical signal to initiate contraction
- Signal passes through interatrial septum to the AV node
- From the AV node, signal relayed through bundle of His (AV bundle) to the apex (ventricles meet)
- Signal spreads from the top to the ventricles through the Purkinje fibers
- Heart pumps faster
- More oxygen sent
- More carbon dioxide removed
- Increased pH
- Signals sent down vagus nerve
Double Displacement Reaction of Carbon Dioxide and Water
CO2 + H2O ->H2CO3 -> H+ + HCO3-
Defibrillator
- Contracts everything at once, then stops the signal, hopefully jump starting the heart
- Used when the heart stops or when the ventricles don’t work in synchronization
Neurotransmitters
Chemicals that activate nerve cells and allow them to communicate with each other and with muscle cells
Norepinephrine/noradrenaline and epinephrine/adrenaline
Stimulate the sympathetic nervous system, speed up heart, secreted by the medulla
Acetylcholine
Stimulates parasympathetic nervous system, lowers heart rate
Stroke Volume
Volume of blood pumped during each heartbeat
Cardiac Output
Volume of blood pumped within a minute
Stenosis
Narrowing of lumen, fatty deposits develop in the arteries. A cause of occlusions
Occlusion Formation (7 Steps)
- Fatty deposits develop in the arteries
- Stenosis: lumen narrows
- Increase in pressure: restriced flow increases pressure in the artery, leading to damage to the arterial wall
- Decrease in elasticity: damaged artery repaired with fibrous tissue
- Plaque formation: smooth lining of the artery progressively degraded, lesions form
- Clot formation: blood clotting triggered by plaque ruptures, forming a thrombus, obstructing blood flow
- Embolus: dislodged thrombus, causing a blockage in an arteriole
5 Consequences of Occlusions
- Arteriosclerosis
- Atherosclerosis
- Embolism
- Myocardial infarction
- Stroke
Arteriosclerosis
Hardening of arteries
Atherosclerosis
Hardening of arteries due to plaque build up
Embolism
Blocking of artery
Myocardial Infarction
Insufficient blood flow to the heart muscle from narrowing of the coronary artery. Plaque formation prevents oxygen and nutrients from being transported to the heart
2 Treatments of Blockages of Coronary Arteries
By - pass surgery or balloon angioplasty
Stroke
Blood clot stops blood flow in an artery in the brain
Three Levels of the Immune System
- Protective layers
- Non - specific response
- Specific response
Non - Specific (Innate Response)
- No memory or lasting protective immunity
- Primitive responses, limited collection of recognition molecules
Specific Response (Acquired or Adaptive Immunity)
- Antigen specificity allows for the generation of responses to target specific pathogens
- Memory for previous pathogens
- No limit to the collection of recognition
Antigen
Any molecule that enters the body and triggers an immune response
First Line of Defense from the Immune System
- The skin: continuous layer preventing pathogens from entering without cuts
- Sweat glands contain lysozymes, enzymes that digest bacterial cell walls
- Mucous membranes lining all body cavities and canals that come in contact with the air contain goblet cells that trap pathogens
- Cilia in the nose, throat and lungs glush potential pathogens either out of the body or into the stomach where the acids kill
Non - Specific Response Process (5 Steps)
- Extravasation: phagocytic leukocytes move into body tissues
- Histamine released by site of infection, recognized by phagocytic leukocytes
- Endocytosis: pathogens engulfed as pseudopodia surround the pathogen and fuse, sequestering it in a vesicle
- Vesicle fused with lysosomes and phogosomes: pathogen broken into small fragments
- Some antigenic fragments presented on the surface of the macrophage to stimulate antibody production
Specific Response Process
- B lymphocyte divides rapidly through mitosis (clonal selection)
- Clones become plasma cells, making and secreting large quantities of the antibody to circulate in the blood
- Antibodies produced can bind to antigen, allowing phagocytes to recognize then destroy it
- Antibodies produced can bind to proteins in the coat of a virus, preventing it from entering other human cells
- Some become memory cells, respond to the antigen if it re - enters
- Once the pathogens are killed, plasma cells undergo suicide
- Memory cells remain in the bloodstream and lymph nodes
Lymphocyte
Type of leukocyte that responds to antigens
B Lymphocyte
Type of lymphocyte that recognizes antigens through receptors
Monoclonal Antibody Production (5 Steps)
- Antigens injected into the body
- Plasma cells produced
- Plasma cells fused with tumor cells
- Becomes a hybridoma, has the ability to reproduce rapidly while retaining the characteristics of the plasma cell
- Produces an endless supply of monoclonal antibodies
3 Usages of Monoclonal Antibodies
- Diagnose presence of pathogens
- Pregnancy tests
- Treatment: potential to use to target cancer by delivering treatment specifically to those cells
Pregnancy Test
Enzyme - linked immunosorbent assay
Pregnancy Test (7 Steps)
- Urine dripped on exposed end of strip
- Fluid travels up absorbent fibers
- Antibodies (attached to enzymes that activate dye molecules) latch onto HCGs in the reaction zone
- More antibodies stick to HCGs in the test zone
- HCG sandwiched by a AB1 and AB2 enzyme; stick to the test zone, allowing the enzyme to activate dye molecules
- If there are no HCGs, the urine passes on
- Control zone confirms that the test is working properly, as unbound AB1 enzymes activate dye here
HIV
Human immunodeficiency virus
- Retrovirus: RNA turned into DNA and combined with host’s DNA
- Causes symptoms called AIDS (acquired immuno -defiiency syndrome)
HIV Infection (6 Steps)
- Infects a cell through the proteins on the surface of tis envelop, makes a DNA copy from its RNA helped by enzyme reverse transcriptase
- New DNA inserted into host cell’s genome
- Virus unddergoes period of inactivity: clinical latency: infected helper T lymphocytes reproduce
- Virus becomes active, spreads, destroys T lymphocytes: lysogenic cycle
- Antibodies not produced: decreased immunity
- Body vulnerable to infections
HIV Transmission (3 Examples)
Exchange of body fluids: sex, blood transfusions, breastfeeding
Characteristic of HIV Immunes
WIthout CD4+ receptor on T lymphocyte cells
Treatment of HIV
Antiviral drugs that target reverse transcriptase activity
Immunization
Use of a vaccine to provide recipient with artificially acquired immunity
Immunity
Ability to fight off or resist a pathogen
Natural Active Immunity
Disease procured naturally, by chance, causing the body to make antibodies and develop memory cells on its own. Occurs during infection
Artificial Active Immunity
Artificial exposure that activte T and B cells to provide long lasting immunity
Natural Passive Immunity
Getting antibodies from another source under natural settings. No memory cells developed, antibodies break down over time
Example of Natural Passive Immunity
Mother to child through placenta or milk
Artificial Passive Immunity
Instant but temporary, memory cells not created, e.g. injecting antitoxins to fight tetanus
Whole Agent Vaccines
Live attenuated: live attenuated modified microorganism alive, but weakened. Able to replicate but cannot cause disease. Risk of infection when virus mutates back into active, virulent form but stronger.
Inactivated: kills microorganism, whole/pieces put into the vaccine, weak antigens, multiple doses for strong immune response. No risk of infection but weaker
Subunit Vaccines
- Contain antigens
- Less likely to induce unfavorable immune reactions
mRNA Vaccines
- Introduction of mRNA sequence coding for a disease specific antigen into a host’s cell (T cell)
- Antigen produced
- Faster, cheaper, safer than whole agent and subunit vaccines
