Anatomy and Physiology Sample

Question 1

Which structure is responsible for setting the heart's intrinsic rhythm?

Accepted Answer

The sinoatrial node sits in the right atrium near the entry of the superior vena cava and depolarizes spontaneously about 60 to 100 times a minute. Because it fires faster than any other part of the conduction system, it sets the pace for normal sinus rhythm.

The AV node, bundle of His, and Purkinje fibers are part of the same conduction system but kick in only as backup pacemakers if the SA node fails. Their intrinsic rates are progressively slower the further downstream you go.

Question 2

Which organelle is most directly responsible for ATP production through oxidative phosphorylation?

Accepted Answer

Mitochondria contain the inner membrane proteins of the electron transport chain and ATP synthase. Together they couple electron flow to a proton gradient that powers ATP production from ADP and inorganic phosphate. Cells with high energy demand, like cardiac muscle, are packed with mitochondria.

Ribosomes build proteins, lysosomes break things down, and smooth ER handles lipid synthesis and detoxification. None of those produce ATP through oxidative phosphorylation.

Question 3

The diaphragm contracts during which phase of respiration?

Accepted Answer

Diaphragmatic contraction flattens the dome of the diaphragm, increasing thoracic volume. The drop in intrathoracic pressure pulls air into the lungs. This is inspiration. During quiet expiration, the diaphragm relaxes back to its dome shape and air leaves passively.

Forced expiration adds the action of abdominal and internal intercostal muscles but the diaphragm is no longer the engine. Apnea simply means no breathing is happening.

Question 4

Which kidney structure is the primary site of filtration?

Accepted Answer

The glomerulus is a tuft of capillaries inside Bowman capsule. Hydrostatic pressure pushes water and small solutes across the filtration barrier into the tubule, leaving cells and large proteins behind. The remaining nephron segments fine tune what is reabsorbed and secreted.

The loop of Henle establishes the medullary gradient, the distal convoluted tubule and collecting duct adjust electrolytes and water under hormonal control, but only the glomerulus filters at scale.

Question 5

Which neurotransmitter is most associated with parasympathetic effects on the heart?

Accepted Answer

Vagal parasympathetic fibers release acetylcholine onto muscarinic receptors in the SA and AV nodes, slowing heart rate and conduction. This is the rest and digest brake on the cardiovascular system.

Norepinephrine is the sympathetic transmitter that speeds the heart. Dopamine and glutamate have other roles and are not the parasympathetic cardiac transmitter.

Question 6

Which structure prevents food from entering the trachea during swallowing?

Accepted Answer

The epiglottis is a flap of cartilage that folds down over the larynx during the pharyngeal phase of swallowing. This redirects bolus into the esophagus and protects the airway. Loss of this reflex is a major cause of aspiration in older adults and clients after stroke.

The uvula and hard palate close off the nasal passages but not the airway. The glottis is the opening that the epiglottis covers.

Question 7

Which blood vessel returns oxygenated blood to the heart from the lungs?

Accepted Answer

Pulmonary veins are the only veins in the body that carry oxygenated blood. They run from the lungs into the left atrium, where the blood then enters the left ventricle and is pumped through the aorta to the body. Reversing this anatomy in your head is one of the most common A and P mix ups.

The pulmonary artery carries deoxygenated blood from the right ventricle to the lungs, the superior vena cava brings deoxygenated blood from the upper body, and the aorta sends oxygenated blood to the body, not back to the heart.

Question 8

Which hormone is released by the posterior pituitary to regulate water balance?

Accepted Answer

Antidiuretic hormone, also called vasopressin, is produced in the hypothalamus and released from the posterior pituitary. It increases water reabsorption in the collecting ducts of the kidney by inserting aquaporin channels. The result is more concentrated urine and a higher plasma volume.

Aldosterone is from the adrenal cortex and acts mainly on sodium. Cortisol and thyroxine are not water balance hormones in the same direct way.

Question 9

Which type of muscle tissue is striated, voluntary, and multinucleated?

Accepted Answer

Skeletal muscle fibers are long, multinucleated cells with sarcomeres that produce the striated banding pattern. They are under voluntary motor control through somatic nerves. Cardiac muscle is also striated but involuntary and typically uninucleated. Smooth muscle lines hollow organs, lacks striations, and is involuntary.

Connective tissue is not a muscle type at all. The triple combination of striated, voluntary, and multinucleated points to skeletal muscle every time.

Question 10

Which part of the brain is primarily responsible for balance and coordination?

Accepted Answer

The cerebellum sits at the back of the brain and integrates input from the vestibular system, proprioceptors, and motor cortex to produce smooth, coordinated movement and balance. Damage causes ataxia, intention tremor, and a wide based gait.

The frontal lobe handles planning and motor initiation, the thalamus relays sensory traffic, and the medulla controls vital autonomic functions like respiration. None of those is the coordination center.