BIOlogy Final 30S

What are the 4 chambers of the heart?

Right atrium, left atrium, right ventricle, left ventricle. Upper chambers = atria; lower chambers = ventricles.

What are the 3 layers of the heart wall?

Epicardium (outer), myocardium (middle cardiac muscle), endocardium (inner lining).

What is the septum?

A thick wall dividing the heart into left and right halves, preventing oxygenated and deoxygenated blood from mixing.

What does "myogenic contraction" mean?

The heart generates its own electrical signals from within the heart tissue itself — not from the brain.

What is the SA node and what is its role?

The sinoatrial node — the heart's natural pacemaker. Located in the right atrium, it starts each heartbeat by firing an electrical signal.

What is the AV node and why is the delay important?

The atrioventricular node briefly delays the signal (~0.1 sec) so the atria finish emptying before the ventricles contract.

What is the Bundle of His?

Nerve fibres that carry the electrical signal from the AV node down through the septum to both ventricles.

What are Purkinje fibres?

Specialized muscle fibres that conduct impulses 5× faster than surrounding cells, spreading the signal efficiently through the ventricles.

List the steps of the cardiac conduction cycle in order.

SA node fires → atria contract → signal reaches AV node (0.1 sec delay) → signal travels down Bundle of His → Purkinje fibres spread signal → ventricles contract → relaxation (diastole).

What do the P, QRS, and T waves on an ECG represent?

P wave = atrial contraction (systole); QRS complex = ventricular contraction; T wave = ventricular relaxation (diastole).

What is an electrocardiograph (ECG)?

An instrument that records the electrical activity of the heart; the printout is called an electrocardiogram. Used to diagnose heart abnormalities.

What causes the "lub-dub" heart sounds?

"Lub" = AV valves (tricuspid + mitral) closing when ventricles begin to contract. "Dub" = semilunar valves (pulmonary + aortic) closing when ventricles relax.

What are the 4 valves of the heart and their locations?

Tricuspid (right atrium → right ventricle), Pulmonary semilunar (right ventricle → pulmonary artery), Mitral/bicuspid (left atrium → left ventricle), Aortic semilunar (left ventricle → aorta).

What are semilunar valves and what do they do?

Half-moon shaped valves (pulmonary and aortic) that prevent backflow of blood from the arteries into the ventricles after each contraction.

What are Chordae Tendineae and Papillary muscles?

Chordae Tendineae are tendon-like cords connecting AV valves to papillary muscles; they prevent the valves from flipping inside-out (prolapsing) when ventricles contract.

What is an artificial pacemaker and when is it used?

A battery-operated device implanted in the chest that sends electrical impulses to keep the heart beating regularly when the SA node fails.

What is cardiac output and the formula for it?

Cardiac output = stroke volume × heart rate. It represents the volume of blood pumped by the heart per minute.

How does exercise affect cardiac output?

Exercise increases both heart rate and stroke volume, raising cardiac output to deliver more oxygen to muscles.

What hormones affect heart rate and how?

Adrenaline (fear/excitement) and noradrenaline (exercise/rising CO2) cause the SA node to fire faster, increasing heart rate.

What is the sympathetic vs. parasympathetic effect on heart rate?

Sympathetic (fight or flight): speeds up heart rate, increases blood flow to muscles. Parasympathetic (rest and digest): slows heart rate back down. Both act on the SA node.

Trace the full path of blood through the heart.

Body → Superior/inferior vena cava → Right atrium → Tricuspid valve → Right ventricle → Pulmonary valve → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium → Mitral valve → Left ventricle → Aortic valve → Aorta → Body.

What is double circulation?

Two loops: pulmonary circulation (right ventricle → lungs → left atrium) and systemic circulation (left ventricle → body → right atrium).

What is the difference between arteries, veins, and capillaries?

Arteries: thick muscular walls, small lumen, carry blood away from heart under high pressure. Veins: thinner walls, large lumen, one-way valves, return blood to heart. Capillaries: one-cell-thick walls, site of gas and nutrient exchange.

How does blood move through each vessel type?

Arteries: pushed by high pressure from the heart. Capillaries: slow flow allows exchange. Veins: low pressure; skeletal muscle contractions and one-way valves push blood back to the heart.

What is the lumen of a blood vessel?

The hollow interior through which blood flows. Wider lumen = less resistance = lower blood pressure. Narrower lumen (e.g., from atherosclerosis) = higher pressure.

What is systolic vs. diastolic blood pressure?

Systolic = pressure when ventricles contract (top/higher number). Diastolic = pressure when ventricles relax (bottom/lower number). Normal ≈ 120/80 mmHg.

How does a sphygmomanometer measure blood pressure?

A cuff inflates to stop blood flow, then slowly deflates. A stethoscope detects when flow resumes (systolic) and when sound disappears completely (diastolic).

What factors affect blood pressure?

Volume of blood, resistance in vessels, vessel diameter (wider = lower pressure), and elasticity of vessel walls (less elastic = higher pressure).

What are the 4 components of blood and their functions?

Plasma (liquid carrier of nutrients, hormones, wastes), red blood cells (carry O2 via hemoglobin), white blood cells (immune defense), platelets (clotting).

What is hemoglobin?

A protein in red blood cells that binds and transports oxygen throughout the body; also carries some CO2 back to the lungs.

What are the ABO blood types, their antigens, and antibodies?

Type A: antigen A, antibody B. Type B: antigen B, antibody A. Type AB: antigens A and B, no antibodies. Type O: no antigens, both antibodies A and B.

What is the Rh factor?

An antigen on the surface of red blood cells. Rh+ means the antigen is present; Rh− means it is absent.

What is agglutination?

The clumping of red blood cells that occurs when incompatible blood is transfused; antibodies in the recipient attack foreign antigens on donated cells.

Who is the universal donor and universal recipient?

Type O− is the universal donor (no A, B, or Rh antigens). Type AB+ is the universal recipient (has no antibodies to attack any antigens).

What is Hemolytic Disease of the Newborn (HDN)?

Occurs when an Rh− mother is sensitized by Rh+ blood from a first pregnancy. In later Rh+ pregnancies, her anti-Rh antibodies cross the placenta and destroy the baby's red blood cells.

How is HDN prevented?

An Rh− mother is given WinRho (an Rh immunoglobulin developed in Winnipeg) after delivery or miscarriage. It blocks her immune system from recognizing the Rh+ fetal blood before she can produce anti-Rh antibodies, preventing sensitization for future pregnancies.

What makes a blood transfusion compatible?

The donor's antigens must not match any antibodies in the recipient's blood, or agglutination (clumping) will occur and can be fatal.

What is atherosclerosis?

Buildup of fatty plaques in artery walls, narrowing the lumen and reducing blood flow; increases risk of heart attack and stroke.

What is a myocardial infarction (heart attack)?

A blockage in a coronary artery cuts off blood supply to part of the heart muscle, causing that tissue to die from lack of oxygen.

What is the difference between ischemic and hemorrhagic stroke?

Ischemic stroke = a blood clot blocks flow to the brain. Hemorrhagic stroke = a blood vessel in the brain ruptures and bleeds.

What are the FAST signs of stroke?

Face drooping, Arm weakness, Speech difficulty, Time to call 911.

What is an aneurysm?

A bulging, weak spot in a blood vessel wall that can rupture, causing life-threatening internal bleeding.

What is hypertension and why is early detection important?

Chronically high blood pressure (above 130/80 mmHg). Called a "silent killer" — no symptoms, but it steadily damages blood vessels and organs. Early detection allows lifestyle changes or medication before serious damage.

What do beta-blockers do?

They block the effects of adrenaline on the heart, slowing heart rate and reducing blood pressure; used to treat hypertension and certain arrhythmias.

What is TPA?

Tissue plasminogen activator — a clot-busting medication used to dissolve blood clots during ischemic stroke or heart attack; must be given quickly to minimize tissue damage.

What is bypass surgery vs. angioplasty?

Bypass: a healthy blood vessel is grafted to route blood around a blocked artery. Angioplasty: a balloon catheter inflates inside a narrowed artery to widen it, often followed by placement of a stent.

What lifestyle factors help prevent cardiovascular disease?

Regular exercise, healthy diet (low saturated fat/sodium), not smoking, limiting alcohol, managing stress, and maintaining a healthy weight.

What are effects of high vs. low blood pressure?

High BP: damages vessel walls, increases risk of heart attack, stroke, aneurysm. Low BP: reduces blood flow to organs, causes dizziness, fainting, and in severe cases, organ failure.

What are the 3 types of respiration?

External respiration (gas exchange at alveoli between air and blood), internal respiration (gas exchange between blood and body tissues), cellular respiration (ATP production inside cells using O2).

Trace the path of air from nose to alveoli.

Nose/nasal cavity → pharynx (throat) → larynx (past epiglottis and vocal cords) → trachea → bronchi → bronchioles → alveoli.

What does the nasal cavity do to incoming air?

Warms, moistens, and filters it. Blood vessels warm the air; mucus and cilia trap dust, bacteria, and particles.

What is the difference between nasal and oral breathing?

Nasal breathing filters, warms, and humidifies air before it reaches the lungs. Oral breathing bypasses these defenses, delivering cooler, drier, less-filtered air.

What is the pharynx?

The throat — a passageway shared by the respiratory and digestive systems. Air goes to the trachea; food goes to the esophagus.

What is the larynx?

The voice box, located between the pharynx and trachea. Contains the epiglottis (top) and vocal cords.

What is the epiglottis?

A flap of tissue at the top of the larynx that covers the opening to the trachea during swallowing, preventing food from entering the airway.

Why does the trachea have C-shaped cartilage rings?

To keep the trachea open and rigid at all times. The open (C) side faces the esophagus so it can expand when swallowing large pieces of food.

What are bronchi and bronchioles?

The trachea splits into two bronchi (one to each lung), which branch into smaller bronchioles, which continue branching until they end in alveoli.

What are alveoli and why are they well-suited for gas exchange?

Tiny air sacs at the ends of bronchioles. They have walls only one cell thick, over 100 million per lung (~70 m² surface area), and are surrounded by capillaries — maximizing rapid diffusion of gases.

What is external respiration?

Gas exchange at the lungs: O2 moves from alveoli into the blood (capillaries), and CO2 moves from the blood into the alveoli to be exhaled.

What is internal respiration?

Gas exchange at the tissues: O2 moves from blood into body cells, and CO2 moves from body cells into the blood to be carried back to the lungs.

What is cellular respiration?

The process inside cells where O2 is used to break down glucose, producing ATP (energy), CO2, and water.

What role does the diaphragm play in breathing?

Inhalation: diaphragm contracts (flattens), increasing chest cavity volume, lowering pressure — air rushes in. Exhalation: diaphragm relaxes (domes upward), decreasing volume, increasing pressure — air is forced out.

What do intercostal muscles do?

Contract to lift the ribs up and outward during inhalation (expanding the chest); relax to lower ribs during exhalation.

What is the pleura and what does pleural fluid do?

A double-layered membrane surrounding each lung. Pleural fluid reduces friction and creates suction that keeps the lungs pressed against the chest wall, preventing collapse.

What monitors CO2 and triggers breathing?

Chemoreceptors on the surface of the medulla oblongata detect rising CO2 (which lowers blood pH) and signal the diaphragm and intercostal muscles to breathe faster/deeper.

Does the brain primarily monitor O2 or CO2 to control breathing rate?

CO2. Rising CO2 lowers blood pH; chemoreceptors detect this change and trigger increased ventilation to expel the excess CO2.

How do mucus and cilia protect the respiratory tract?

Mucus traps dust, bacteria, and particles. Cilia beat upward (toward the throat) to move the mucus and debris to be swallowed or expelled.

What is the Anti-G Straining Maneuver (AGSM) used by fighter pilots?

Tensing lower body muscles to slow blood pooling in the legs, combined with forceful exhaling against a closed glottis every ~3 seconds, to maintain brain blood pressure under high G-forces.

What are some respiratory "did you know" facts?

~20,000–25,000 breaths per day; alveoli surface area ≈ a tennis court (70 m²); ~1–1.5 litres of mucus produced daily; CO2 — not O2 — triggers the urge to breathe.

What is excretion?

The process of removing metabolic wastes from the body to maintain homeostasis; distinct from egestion (removal of undigested solid waste).

What are the 4 main metabolic wastes and their origins?

Ammonia (from protein/amino acid breakdown, deamination), urea (ammonia converted in liver), CO2 (from cellular respiration), water (byproduct of cellular respiration and other reactions).

Why is ammonia dangerous and how is it dealt with?

Ammonia is extremely toxic to the brain and nervous system even in small amounts. The liver immediately converts it into much less toxic urea, which travels safely in the blood to the kidneys.

How is CO2 transported in the blood?

Most CO2 is converted to bicarbonate ions (HCO3−) in red blood cells for safe transport. At the lungs, it converts back to CO2 gas and is exhaled.

What are mineral salts and how are they managed?

Ions like Na+, K+, Cl− from food. The body uses what it needs; excess is excreted by the kidneys (urine) and skin (sweat) to maintain homeostasis.

What are the excretory roles of each organ system?

Lungs: CO2, water vapour. Skin: water, salts, urea. Liver/digestive system: bilirubin (via bile → feces), drugs and toxins. Kidneys: urea, water, salts, acid-base balance.

What is bilirubin?

A yellow waste product from the breakdown of old red blood cells in the liver; released in bile and excreted in feces and urine.

What are the 3 main functions of the kidneys?

1. Waste filtration and excretion (removing metabolic wastes from the blood)

2. Fluid and electrolyte balance (regulating water, sodium, potassium, and other ion levels)

3. Hormone production (to RBC production, renin to regulate blood pressure)

What is the anatomy of the kidney?

Cortex (outer layer where filtration occurs), medulla (inner layer, packed with vessels and tubules), renal pelvis (central funnel collecting urine), renal artery (blood in), renal vein (blood out), ureter (urine out to bladder).

What is the functional unit of the kidney?

The nephron, approximately 1 million nephrons per kidney. Each nephron filters blood and produces urine.

What are the parts of a nephron in order?

Glomerulus (inside Bowman's capsule) → Proximal Convoluted Tubule (PCT) → Loop of Henle (descending + ascending limbs) → Distal Convoluted Tubule (DCT) → Collecting duct

What are the 3 core nephron processes?

Filtration (at the glomerulus), reabsorption (useful substances returned to blood from tubules), secretion (additional wastes actively moved from blood into filtrate).

What is filtration in the nephron?

Blood is forced under pressure through the glomerulus; water, salts, urea, and glucose pass into Bowman's capsule as filtrate. Blood cells and large proteins stay in the blood.

What happens in the Proximal Convoluted Tubule (PCT)?

~65–70% of reabsorption occurs here: 100% of glucose and amino acids, most water (osmosis), and most Na+, K+, and other ions are returned to the blood. Cells have microvilli (brush border) and many mitochondria for active transport.

What happens in the descending limb of the Loop of Henle?

Permeable to water only — water is drawn out by osmosis as the filtrate descends into the increasingly salty medulla. Filtrate becomes more concentrated.

What happens in the ascending limb of the Loop of Henle?

Na+, K+, and Cl− are actively pumped out into the surrounding tissue; the wall is impermeable to water so water cannot follow. Filtrate becomes more dilute.

What happens in the Distal Convoluted Tubule (DCT)?

Fine-tuning of ion levels and blood pH under hormonal control (aldosterone and ADH); waste secretion (creatinine, excess K+, drugs, H+ ions) into filtrate.

What happens in the collecting duct?

ADH controls how many aquaporin channels are inserted; more ADH = more water reabsorbed = more concentrated urine. Final composition of urine is determined here.

What does aldosterone do?

Released by the adrenal cortex when blood pressure or Na+ is too low; causes the DCT to reabsorb more Na+ → water follows by osmosis → blood volume and pressure increase. Negative feedback restores normal BP.

What does ADH (antidiuretic hormone) do?

Released by the posterior pituitary when blood is too concentrated (high osmolarity); inserts aquaporin channels into DCT and collecting duct → more water reabsorbed → smaller volume of concentrated urine produced.

What are aquaporins?

Protein channels in the cell membranes of kidney tubules that allow water to pass through; their number is regulated by ADH.

Describe the negative feedback loop for ADH.

Stimulus: blood too concentrated → hypothalamus detects → posterior pituitary releases ADH → kidneys reabsorb more water → blood concentration drops back to normal → ADH release decreases.

What is the path of urine out of the body?

Collecting duct → renal pelvis → ureter → urinary bladder → urethra.

What is urine composed of in a healthy person?

Water, urea, mineral salts (Na+, K+, Cl−), creatinine, and some drugs or metabolites. No glucose or protein (their presence signals kidney damage).

What is the difference between the internal and external urinary sphincters?

Internal sphincter: involuntary (smooth muscle), opens automatically when bladder is full. External sphincter: voluntary (skeletal muscle), under conscious control.

What are the main causes of kidney disease?

Diabetes (damages glomerular capillaries — leading cause worldwide), high blood pressure (damages capillary walls), atherosclerosis (reduces kidney blood flow), nephritis (inflammation from infection or autoimmune response), drugs and toxins (tubule damage).

What are warning signs of kidney disease?

Burning or painful urination, blood in urine, swelling in hands/feet/eyes, back/flank pain, high blood pressure, increased urination frequency. PROTEIN OR GLUCOSE IN PEE

What is hemodialysis?

Blood is pumped out of the body through a machine (artificial kidney) that filters wastes, then returned to the body. Done 3× per week, 3–4 hours per session at a clinic. Advantage: highly effective. Disadvantage: clinic-based, time-consuming.

What is peritoneal dialysis?

Dialysate fluid is put directly into the abdomen; waste from blood diffuses into the fluid over several hours, then the fluid is drained and replaced. Done 4× per day at home. Advantage: flexibility. Disadvantage: risk of infection.

What is uremia?

The buildup of waste and water in the blood due to complete kidney failure (End-Stage Renal Disease); causes swelling, fatigue, confusion, and — if untreated — seizures and death.

What are the two main divisions of the nervous system?

Central Nervous System (CNS): brain and spinal cord — the main processing center. Peripheral Nervous System (PNS): all nerves outside the CNS, connecting the body to the CNS.