NRCMA Anatomy and Physiology 1 — Questions and Answers
Question 1: Which layer of the heart muscle is responsible for the pumping action?
- Epicardium
- Pericardium
- Myocardium (Correct answer)
- Endocardium
Correct answer: Myocardium
The myocardium is the middle, thick muscular layer of the heart wall composed of cardiac muscle cells responsible for the contraction that pumps blood.
The heart wall has three layers: epicardium (outer serous layer), myocardium (middle thick cardiac muscle), and endocardium (inner epithelial lining of chambers and valves). The pericardium is a surrounding fibrous sac. Cardiomyopathy is disease of the myocardium. Pericarditis is inflammation of the pericardium.
Question 2: The normal pH range of human arterial blood is:
- 6.8–7.0
- 7.35–7.45 (Correct answer)
- 7.5–7.7
- 7.0–7.2
Correct answer: 7.35–7.45
Normal arterial blood pH is 7.35–7.45. Values below 7.35 indicate acidosis; values above 7.45 indicate alkalosis.
The body maintains acid-base balance through buffer systems, the respiratory system (CO2 regulation), and the renal system (H+ and HCO3- excretion). Respiratory acidosis: increased CO2 (hypoventilation). Respiratory alkalosis: decreased CO2 (hyperventilation). Metabolic acidosis: decreased HCO3- (e.g., diabetic ketoacidosis). Metabolic alkalosis: increased HCO3- (e.g., vomiting).
Question 3: Which organ is responsible for producing insulin?
- Liver
- Adrenal gland
- Pancreas (Correct answer)
- Thyroid gland
Correct answer: Pancreas
The pancreatic islets of Langerhans contain beta cells that produce and secrete insulin in response to rising blood glucose levels.
The pancreas has dual functions: exocrine (digestive enzymes) and endocrine (hormones). Alpha cells secrete glucagon (raises blood glucose); beta cells secrete insulin (lowers blood glucose); delta cells secrete somatostatin. Type 1 diabetes results from autoimmune destruction of beta cells; Type 2 from insulin resistance.
Question 4: The anatomical position reference term 'proximal' means:
- Closer to the point of attachment or origin (Correct answer)
- Further from the point of attachment
- Toward the front of the body
- Toward the back of the body
Correct answer: Closer to the point of attachment or origin
Proximal describes a structure closer to the point of origin or attachment (e.g., the proximal humerus is the shoulder end of the upper arm bone).
Directional terms: proximal (toward origin), distal (away from origin), anterior/ventral (front), posterior/dorsal (back), superior/cranial (above), inferior/caudal (below), medial (toward midline), lateral (away from midline). These terms describe location relative to standard anatomical position.
Question 5: The primary function of erythrocytes (red blood cells) is to:
- Fight infection and produce antibodies
- Transport oxygen and carbon dioxide (Correct answer)
- Form blood clots
- Regulate blood pH exclusively
Correct answer: Transport oxygen and carbon dioxide
Erythrocytes contain hemoglobin, which binds oxygen in the lungs and releases it in tissues, also carrying a portion of CO2 back to the lungs.
Blood components: Erythrocytes (RBCs) — oxygen transport via hemoglobin; Leukocytes (WBCs) — immune defense; Thrombocytes (platelets) — hemostasis/clotting; Plasma — fluid carrying proteins, electrolytes, and nutrients. Hemoglobin contains iron (Fe2+) that binds O2. Anemia results from insufficient RBCs or hemoglobin.
Question 6: Which structure of the respiratory system is responsible for gas exchange?
- Trachea
- Bronchi
- Alveoli (Correct answer)
- Larynx
Correct answer: Alveoli
Alveoli are the tiny air sacs in the lungs where oxygen diffuses into pulmonary capillaries and carbon dioxide diffuses out, performing gas exchange.
The respiratory tract leads from the nose/mouth through the pharynx, larynx, trachea, bronchi, bronchioles, and finally to alveoli. Gas exchange occurs only at alveoli due to their thin walls, large surface area (~70 m2), and rich capillary network. COPD, pneumonia, and pulmonary fibrosis impair alveolar function.
NRCMA Anatomy and Physiology 1
Which layer of the heart muscle is responsible for the pumping action?