General Human Physiology & Biochemistry, Nutrition & Dietetics - Flashcards Review

Flashcards cover key physiologic and biochemical concepts likely to appear in General Human Physiology & Biochemistry, Nutrition & Dietetics exams. Topics include erythropoiesis, cardiac cycle, BP regulation, thyroid function, menstrual cycle, micturition, surfactant, GFR, vitamin absorption, oxygen transport, glycolysis, beta-oxidation, urea cycle, vitamin D, LFTs, sickle cell, essential fatty acids, isoenzymes, Bohr effect, and related mechanisms.

Describe the stages of erythropoiesis and factors affecting it.

Stages: rubriblast (pronormoblast), prorubricyte, rubricyte, metarubricyte, reticulocyte, mature erythrocyte. Regulation: erythropoietin (EPO) from kidneys in response to hypoxia; iron availability; growth factors; bone marrow microenvironment; and hormonal influences (e.g., testosterone) affecting erythropoiesis.

Define the cardiac cycle and describe the mechanical changes occurring during the cycle.

Cardiac cycle is the sequence of events from one heartbeat to the next, including atrial systole, ventricular systole, and diastole. Mechanical events: isovolumetric contraction, ventricular systolic ejection, isovolumetric relaxation, ventricular diastole with rapid and then slow filling; valve closures generate the heart sounds (S1 with AV valves, S2 with semilunar valves).

What factors regulate neural control of blood pressure?

Baroreceptors (carotid sinus, aortic arch) sense BP and modulate autonomic output to heart and vessels. Chemoreceptors respond to O2/CO2/pH. CNS integrates signals; RAAS and ADH contribute to long-term BP regulation; higher brain centers can modulate responses.

List the main functions of thyroid hormone.

Increases basal metabolic rate and heat production; stimulates protein synthesis; supports growth and development; increases sensitivity to catecholamines; influences carbohydrate and lipid metabolism; stimulates Na+/K+ ATPase activity and CNS maturation.

Describe the neural regulation of the menstrual cycle endometrium.

Endometrium thickens under estrogen during the proliferative phase; after ovulation, progesterone from the corpus luteum drives secretory changes preparing for implantation; if fertilization does not occur, corpus luteum degenerates, leading to menses and cyclic regeneration.

Explain the micturition reflex.

Bladder stretch receptors send afferent signals to sacral spinal cord and pontine micturition center; parasympathetic efferents cause detrusor muscle contraction; internal sphincter relaxes; voluntary relaxation of external sphincter permits urination.

What is peristalsis?

Coordinated, wave-like smooth muscle contractions that propel luminal contents through the GI tract via sequential circular and longitudinal muscle activity.

Describe the lung surfactant: composition and function.

Surfactant reduces alveolar surface tension, preventing collapse; major component DPPC (dipalmitoyl phosphatidylcholine); produced by type II pneumocytes; increases lung compliance and stabilizes alveoli.

First heart sound (S1) is caused by what event?

Closure of the AV valves (mitral and tricuspid) at the onset of ventricular systole.

Which heart structure normally acts as the natural pacemaker of the heart?

SA node initiates the cardiac impulse; AV node can act as a secondary pacemaker if SA node fails.

Normal Glomerular Filtration Rate (GFR) value?

Approximately 125 mL/min (about 180 L/day in a healthy adult with normal renal function).

Why are defective parietal cells associated with malabsorption of vitamin B12?

Parietal cells produce intrinsic factor, which is essential for vitamin B12 absorption in the ileum; defective parietal cells impair intrinsic factor production, reducing B12 absorption.

How does vitamin C affect iron absorption?

Vitamin C (ascorbic acid) enhances non-heme iron absorption by reducing ferric to ferrous iron and forming a soluble complex, increasing uptake.

What is the role of hemoglobin in oxygen transport?

Hemoglobin binds O2 in the lungs and releases it to tissues; it also carries CO2 back to the lungs for exhalation. Its affinity for O2 is modulated by pH (Bohr effect) and CO2 levels.

Which hormone is responsible for milk ejection?

Oxytocin from the posterior pituitary stimulates milk ejection during lactation.

Glycolysis: general energy yield and regulation.

Net ATP yield per glucose is 2 ATP (glycolysis); produces NADH. Regulation occurs at key steps by enzymes such as hexokinase, phosphofructokinase-1 (PFK-1), and pyruvate kinase; RBCs rely on glycolysis for ATP as they lack mitochondria.

Beta-oxidation: overview, net energy yield and regulation.

Beta-oxidation occurs in mitochondria to hydrolyze fatty acids into acetyl-CoA, producing NADH and FADH2. Regulation involves CPT1 and malonyl-CoA; energy yield depends on fatty acid length and saturation.

Glycogenesis basics.

Synthesis and storage of glucose as glycogen, primarily in liver and muscle, regulated by insulin via UDP-glucose and glycogen synthase pathways.

Outline the urea cycle and its regulation.

Liver cycle converting ammonia to urea for excretion; key steps include CPS1 (carbamoyl phosphate synthetase I) and ornithine transcarbamylase; regulated by N-acetylglutamate as an allosteric activator; defects cause hyperammonemia.

Vitamin D: sources, functions and deficiency manifestations.

Source: sunlight exposure, fatty fish, fortified foods. Functions: calcium and phosphate homeostasis, bone mineralization. Deficiency: rickets in children, osteomalacia in adults.

What is meant by Liver Function Tests (LFTs)?

A panel of enzymes and proteins (AST, ALT, ALP, GGT, bilirubin, albumin) used to assess liver injury, cholestasis, and overall hepatic function.

Sickle cell anemia: cause and features.

Hemoglobin S mutation in the beta-globin gene causes RBCs to sickle under deoxygenated conditions, leading to hemolysis and vaso-occlusive crises; autosomal recessive inheritance.

Essential fatty acids: examples and importance.

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) are essential; required for growth, membrane structure, and eicosanoid synthesis; deficiency leads to dermatitis, poor growth.

Isoenzymes concept.

Different molecular forms of the same enzyme, often tissue-specific; used in clinical diagnosis to localize tissue injury or metabolic status.

Bohr effect in oxygen transport.

A decrease in pH or increase in CO2 shifts the oxyhemoglobin dissociation curve to the right, promoting O2 release to tissues; converse occurs with higher pH/low CO2.

What is the role of NADPH in fatty acid synthesis?

NADPH provides reducing equivalents for the anabolic steps in fatty acid synthesis, especially in the cytosol via the pentose phosphate pathway and malic enzyme pathways.

What quantity best describes the energy yield of one turn of the TCA cycle (Citric Acid Cycle)?

Each turn yields approximately 10 ATP (3 NADH ~ 7.5 ATP, 1 FADH2 ~ 1.5 ATP, 1 GTP ~ 1 ATP).

Describe the stages of erythropoiesis and factors affecting it.

Stages: rubriblast (pronormoblast), prorubricyte, rubricyte, metarubricyte, reticulocyte, mature erythrocyte. Regulation: erythropoietin (EPO) from kidneys in response to hypoxia; iron availability; growth factors; bone marrow microenvironment; and hormonal influences (e.g., testosterone) affecting erythropoiesis.

Define the cardiac cycle and describe the mechanical changes occurring during the cycle.

Cardiac cycle is the sequence of events from one heartbeat to the next, including atrial systole, ventricular systole, and diastole. Mechanical events: isovolumetric contraction, ventricular systolic ejection, isovolumetric relaxation, ventricular diastole with rapid and then slow filling; valve closures generate the heart sounds (S1 with AV valves, S2 with semilunar valves).

What factors regulate neural control of blood pressure?

Baroreceptors (carotid sinus, aortic arch) sense BP and modulate autonomic output to heart and vessels. Chemoreceptors respond to O2/CO2/pH. CNS integrates signals; RAAS and ADH contribute to long-term BP regulation; higher brain centers can modulate responses.

List the main functions of thyroid hormone.

Increases basal metabolic rate and heat production; stimulates protein synthesis; supports growth and development; increases sensitivity to catecholamines; influences carbohydrate and lipid metabolism; stimulates Na+/K+ ATPase activity and CNS maturation.

Describe the neural regulation of the menstrual cycle endometrium.

Endometrium thickens under estrogen during the proliferative phase; after ovulation, progesterone from the corpus luteum drives secretory changes preparing for implantation; if fertilization does not occur, corpus luteum degenerates, leading to menses and cyclic regeneration.

Explain the micturition reflex.

Bladder stretch receptors send afferent signals to sacral spinal cord and pontine micturition center; parasympathetic efferents cause detrusor muscle contraction; internal sphincter relaxes; voluntary relaxation of external sphincter permits urination.

What is peristalsis?

Coordinated, wave-like smooth muscle contractions that propel luminal contents through the GI tract via sequential circular and longitudinal muscle activity.

Describe the lung surfactant: composition and function.

Surfactant reduces alveolar surface tension, preventing collapse; major component DPPC (dipalmitoyl phosphatidylcholine); produced by type II pneumocytes; increases lung compliance and stabilizes alveoli.

First heart sound (S1) is caused by what event?

Closure of the AV valves (mitral and tricuspid) at the onset of ventricular systole.

Which heart structure normally acts as the natural pacemaker of the heart?

SA node initiates the cardiac impulse; AV node can act as a secondary pacemaker if SA node fails.

Normal Glomerular Filtration Rate (GFR) value?

Approximately 125 mL/min (about 180 L/day in a healthy adult with normal renal function).

Why are defective parietal cells associated with malabsorption of vitamin B12?

Parietal cells produce intrinsic factor, which is essential for vitamin B12 absorption in the ileum; defective parietal cells impair intrinsic factor production, reducing B12 absorption.

How does vitamin C affect iron absorption?

Vitamin C (ascorbic acid) enhances non-heme iron absorption by reducing ferric to ferrous iron and forming a soluble complex, increasing uptake.

What is the role of hemoglobin in oxygen transport?

Hemoglobin binds O2 in the lungs and releases it to tissues; it also carries CO2 back to the lungs for exhalation. Its affinity for O2 is modulated by pH (Bohr effect) and CO2 levels.

Which hormone is responsible for milk ejection?

Oxytocin from the posterior pituitary stimulates milk ejection during lactation.

Glycolysis: general energy yield and regulation.

Net ATP yield per glucose is 2 ATP (glycolysis); produces NADH. Regulation occurs at key steps by enzymes such as hexokinase, phosphofructokinase-1 (PFK-1), and pyruvate kinase; RBCs rely on glycolysis for ATP as they lack mitochondria.

Beta-oxidation: overview, net energy yield and regulation.

Beta-oxidation occurs in mitochondria to hydrolyze fatty acids into acetyl-CoA, producing NADH and FADH2. Regulation involves CPT1 and malonyl-CoA; energy yield depends on fatty acid length and saturation.

Glycogenesis basics.

Synthesis and storage of glucose as glycogen, primarily in liver and muscle, regulated by insulin via UDP-glucose and glycogen synthase pathways.

Outline the urea cycle and its regulation.

Liver cycle converting ammonia to urea for excretion; key steps include CPS1 (carbamoyl phosphate synthetase I) and ornithine transcarbamylase; regulated by N-acetylglutamate as an allosteric activator; defects cause hyperammonemia.

Vitamin D: sources, functions and deficiency manifestations.

Source: sunlight exposure, fatty fish, fortified foods. Functions: calcium and phosphate homeostasis, bone mineralization. Deficiency: rickets in children, osteomalacia in adults.

What is meant by Liver Function Tests (LFTs)?

A panel of enzymes and proteins (AST, ALT, ALP, GGT, bilirubin, albumin) used to assess liver injury, cholestasis, and overall hepatic function.

Sickle cell anemia: cause and features.

Hemoglobin S mutation in the beta-globin gene causes RBCs to sickle under deoxygenated conditions, leading to hemolysis and vaso-occlusive crises; autosomal recessive inheritance.

Essential fatty acids: examples and importance.

Linoleic acid (omega-6) and alpha-linolenic acid (omega-3) are essential; required for growth, membrane structure, and eicosanoid synthesis; deficiency leads to dermatitis, poor growth.

Isoenzymes concept.

Different molecular forms of the same enzyme, often tissue-specific; used in clinical diagnosis to localize tissue injury or metabolic status.

Bohr effect in oxygen transport.

A decrease in pH or increase in CO2 shifts the oxyhemoglobin dissociation curve to the right, promoting O2 release to tissues; converse occurs with higher pH/low CO2.

What is the role of NADPH in fatty acid synthesis?

NADPH provides reducing equivalents for the anabolic steps in fatty acid synthesis, especially in the cytosol via the pentose phosphate pathway and malic enzyme pathways.

What quantity best describes the energy yield of one turn of the TCA cycle (Citric Acid Cycle)?

Each turn yields approximately 10 ATP (3 NADH ~ 7.5 ATP, 1 FADH2 ~ 1.5 ATP, 1 GTP ~ 1 ATP).

What is the primary role of insulin?

Insulin is a hormone produced by pancreatic beta cells. It lowers blood glucose by promoting glucose uptake into cells, glycogen synthesis (glycogenesis), fat synthesis (lipogenesis), and protein synthesis.

What is the primary role of glucagon?

Glucagon is a hormone produced by pancreatic alpha cells. It raises blood glucose levels primarily by stimulating glycogenolysis (glycogen breakdown) and gluconeogenesis (glucose synthesis from non-carbohydrate sources) in the liver.

Describe the main components of blood plasma.

Plasma is the liquid component of blood, making up about 55\% of total blood volume. It primarily consists of water (92\% by weight) and contains vital proteins (albumin, globulins, fibrinogen), electrolytes, hormones, nutrients, and waste products.

What is the primary function of platelets?

Platelets (thrombocytes) are small, anucleated cell fragments derived from megakaryocytes. Their primary function is to seal breaks in blood vessels (hemostasis) by forming a plug and contributing to clot formation.

What is the basic function of B lymphocytes?

B lymphocytes (B cells) are a type of white blood cell central to the humoral immune response. They produce antibodies that neutralize pathogens and toxins, and can also present antigens to T cells.