Cardiovascular System
This node, located in the wall of the right atrium, initiates every heartbeat and is known as the natural pacemaker.
What is the SA (sinoatrial) node?
This dome-shaped muscle below the lungs is the primary muscle responsible for breathing.
What is the diaphragm?
This part of the neuron receives incoming signals from other neurons.
What are dendrites?
This blood component is responsible for clotting at the site of a wound.
What are platelets (thrombocytes)?
This hormone is released by the posterior pituitary and increases water reabsorption in the collecting duct.
What is ADH (antidiuretic hormone)?
The 'lub' sound of the heartbeat is caused by the closing of these two valves.
What are the AV valves (tricuspid and bicuspid/mitral valves)?
Name the three types of respiration and where each occurs.
External respiration (lungs/alveoli-blood), internal respiration (blood-body tissues), cellular respiration (inside cells/mitochondria).
The cerebellum is responsible for these three functions.
What are coordination, balance, and posture (also accept fine motor control / motor learning)?
A person with type O negative blood is often called the universal donor. Explain why using antigens and antibodies
Type O negative blood has NO A, B, or Rh antigens on RBCs. Recipients of any blood type will not have matching antibodies to trigger agglutination (immune attack), making it safe for anyone to receive in an emergency.
A person is dehydrated. Trace the negative feedback loop involving ADH from stimulus to restoration of normal blood osmolarity.
High blood osmolarity → hypothalamus detects change → posterior pituitary releases ADH → aquaporins inserted in DCT and collecting duct → more water reabsorbed into blood → blood osmolarity drops → ADH release decreases.
Blood leaving the right ventricle passes through this valve and travels to the lungs via this vessel.
What are the pulmonary valve and the pulmonary artery?
When the diaphragm contracts, describe what happens to chest volume, lung pressure, and airflow.
The diaphragm flattens downward, increasing chest cavity volume. Lung pressure decreases below atmospheric pressure. Air flows IN (inhalation).
Compare the role of the thalamus and the hypothalamus where are they, and what does each control?
Both are in the diencephalon. Thalamus: sensory relay station — routes incoming sensory signals to the correct cortex region. Hypothalamus: master of homeostasis regulates temperature, hunger, thirst, sleep, ANS activity, and hormone release via the pituitary gland.
An Rh-negative mother is pregnant with her second Rh-positive baby. Explain the risk to the fetus and the mechanism by which it occurs.
During the first pregnancy, fetal Rh+ blood may enter the mother's circulation, causing her immune system to produce anti-Rh antibodies (sensitization). In the second pregnancy, these antibodies cross the placenta and attack the fetal RBCs, causing Hemolytic Disease of the Newborn (HDN) severe anemia and jaundice.
Explain how aldosterone and ADH work together when a person has both low blood pressure AND is dehydrated.
Low BP triggers adrenal cortex to release aldosterone → increased Na+ reabsorption in DCT → water follows by osmosis → blood volume rises → BP increases. Simultaneously, dehydration (high osmolarity) triggers ADH → more water reabsorbed in collecting duct → urine becomes concentrated. Both hormones together maximize water and Na+ retention to restore fluid balance.
A patient's ECG shows a normal P-wave but the QRS complex is delayed. Which part of the conduction system is most likely malfunctioning, and what would happen to ventricular contraction?
The AV node (or Bundle of His). The ventricles would contract late or not at all the atria would contract but the impulse would not reach the ventricles on time, reducing cardiac output.
Explain why the medulla oblongata monitors CO₂ rather than O₂ to regulate breathing rate, and describe what would happen if you hyperventilated for 30 seconds.
CO₂ dissolves in blood to form carbonic acid, lowering pH a more sensitive and immediate signal than O₂ drop. After hyperventilation, blood CO₂ is extremely low so chemoreceptors stop signaling the medulla. The drive to breathe drops, causing breath-holding (not because of high O₂ but because of low CO₂).
A patient suffers a stroke affecting Broca's area. Describe the specific deficit they would experience and explain which lobe and hemisphere are most likely affected.
Broca's area controls speech production. The patient could understand language but not produce fluent speech (Broca's/expressive aphasia). It is located in the left frontal lobe in most right-handed individuals. The left hemisphere is dominant for language.
A patient receives a type A+ blood transfusion but actually has type B- blood. Describe exactly what happens at the cellular level and what the patient would experience.
Type B- blood has anti-A antibodies in the plasma. These antibodies bind to A antigens on the transfused RBCs, triggering agglutination (clumping) and hemolysis (destruction of RBCs). The patient would experience fever, chills, back/flank pain, dropping blood pressure, and potentially renal failure from the release of hemoglobin into the bloodstream : a life-threatening transfusion reaction.
A patient is prescribed a diuretic medication that blocks aldosterone receptors in the DCT. Predict three specific physiological consequences and explain the mechanism behind each.
1) Increased Na+ excretion — aldosterone cannot signal Na+ reabsorption, so Na+ stays in filtrate and is excreted.
2) Increased urine output since Na+ is not reabsorbed, water cannot follow by osmosis, so more water is excreted.
3) Decreased blood pressure, reduced blood volume lowers pressure. (Bonus: possible hyperkalemia K+ is also not secreted properly, raising blood K+ levels.)
A patient has atherosclerosis in the coronary arteries and hypertension. Explain the chain of events that connects these two conditions to a myocardial infarction, referencing blood pressure, vessel structure, and oxygen delivery to cardiac muscle.
Hypertension damages arterial walls over time. Atherosclerotic plaques narrow the coronary arteries, reducing lumen diameter. Increased blood pressure forces more blood through a narrowed vessel. If a plaque ruptures, a clot can fully block the artery. Cardiac muscle downstream is deprived of oxygen cells die (infarction).
A patient with severe kidney failure stops producing urine. Explain, using your knowledge of nephron function, ADH, and aldosterone, why this patient would develop edema (tissue swelling), high blood pressure, and elevated blood urea levels — and how dialysis addresses each problem.
Without filtration, urea accumulates in blood (uremia). Water and Na+ cannot be excreted — blood volume rises, causing hypertension. Excess fluid leaks into tissues = edema. Aldosterone has no effect without functional nephrons to reabsorb Na+. ADH cannot concentrate urine. Dialysis removes urea and excess water/ions using a concentration gradient across a semipermeable membrane, mimicking nephron filtration and partially restoring fluid balance.
A marathon runner at kilometer 35 experiences elevated heart rate, dilated pupils, reduced digestive activity, and increased sweat production. Identify the division of the ANS responsible, name the specific neurotransmitter involved (if you can), and explain why these responses are collectively beneficial then explain what happens physiologically once the race ends.
Sympathetic nervous system (fight-or-flight). Neurotransmitter: norepinephrine (and epinephrine from adrenal medulla). Responses redirect blood to skeletal muscles, improve vision, increase O₂ delivery, and remove heat. Once the race ends, the parasympathetic division takes over (rest-and-digest): heart rate drops, digestion resumes, pupils constrict, and homeostasis is restored. Acetylcholine is the main parasympathetic neurotransmitter.
Hemoglobin carries oxygen via iron-containing heme groups. Carbon monoxide (CO) binds to hemoglobin 200x more tightly than oxygen. Using your knowledge of hemoglobin function, external respiration, and internal respiration, explain why CO poisoning is so dangerous even when lung function is normal and why high-flow oxygen is used as treatment.
CO displaces O₂ from hemoglobin, forming carboxyhemoglobin. Even though the lungs are performing external respiration normally (gas exchange at alveoli), RBCs are carrying CO instead of O₂. Internal respiration fails tissues receive no O₂ despite normal breathing. High-flow 100% O₂ increases the partial pressure of O₂, competitively displacing CO from hemoglobin and restoring O₂ transport. Hyperbaric oxygen accelerates this further.
A patient with Type 1 diabetes has no functional insulin. Explain how this would affect kidney function, urine composition, and the hormonal response even though insulin is not a kidney hormone. Reference the nephron, osmolarity, ADH, and what would appear in the urine.
Without insulin, blood glucose cannot enter cells and remains very high (hyperglycemia). At the nephron, the PCT reabsorbs glucose via transport proteins but these become saturated at high glucose concentrations.
Excess glucose remains in the filtrate and is excreted (glycosuria). Glucose in the filtrate raises osmolarity of the tubular fluid, drawing water out by osmosis and increasing urine volume (osmotic diuresis). High urine output lowers blood volume → blood osmolarity rises further → ADH is released but cannot fully compensate. The patient is chronically dehydrated despite drinking large amounts. Urine is large in volume, glucose-positive, and dilute relative to expectation.