Biology

Part I: Sections I-V

(Emphasis is on Human Physiology)


It is important to read the Preface at the beginning of Part I as this will help you with the Biology series.

At the beginning of each of the 10 sections in the Biology Review Books (2017 edition) is a page listing the "Top 10 Section Goals" for that particular section. After reading the text in each section and completing the accompanying MCAT-style passages, we feel that you will have a better conceptual understanding of the material important to the Biological and Biochemical Foundations of Living Syetems (formerly Biological Sciences) section of the MCAT.

Section I: Nerve and Muscle

Top 10 Section Goals

  1. The four general classes of biological tissues to consider are epithelial, connective, muscle, and nervous. Have a general understanding of their functions.

  2. Know the relative intracellular and extracellular concentrations of sodium, potassium, and chloride. Be familiar with the Nernst equation and how to calculate a membrane voltage.

  3. Understand depolarizations, repolarizations, hyperpolarizations, and refractory periods. Be familiar with the differences between skeletal muscle and cardiac muscle action potentials.

  4. Understand how a signal is propagated from the presynaptic membrane to the postsynaptic membrane. Know how neurotransmitters are released and how they are degraded.

  5. Be aware of how the different components of muscle interact in order to give a response. Know the differences between actin, myosin, troponin, tropomyosin, and their interaction with calcium.

  6. The three primary divisions of the brain are the forebrain, midbrain, and hindbrain. Know the components of each and how they relate to the body as a whole.

  7. Understand the differences between motor and sensory neurons and how they relate to the spinal cord.

  8. The two major divisions of the nervous system are the central nervous system (CNS) and the peripheral nervous system (PNS). Know the subdivisions of the PNS and their general actions.

  9. CNS and PNS neurotransmitters include acetylcholine, epinephrine, and norepinephrine. Understand why some neurotransmitters or hormones are called amines, peptides, or steroids.

  10. Sensory input can come from mechanoreceptors, chemoreceptors, thermoreceptors, and photoreceptors. Be familiar with the action of each receptor type.

Passages and Solutions

Section I includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to the nervous and muscular systems. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section II: Heart and Lungs

Top 10 Section Goals

  1. Know how to describe the heart in the anatomical position, and understand the relationship to the other major organs of the body.

  2. Be able to trace the path of blood flow through the heart. Starting with the vena cavas, blood flows into the right atrium, to the right ventricle, to the right and left lungs, to the left atrium, to the left ventricle, and then out to the systemic circulation.

  3. Understand how blood flows through the systemic circulation. Blood leaving the heart passes through the aorta, to arteries, arterioles, capillaries, venules, and back to the veins before entering the heart again by way of the vena cavas.

  4. Know the actions of the sympathetic and parasympathetic nervous systems on the heart. Be able to trace the waves of electrical activity through the heart and how they relate to heart function.

  5. Understand the relationship between the opening and closing of the valves of the heart and how they relate to pressure and volume changes.

  6. Understand the relationship of the lymphatic system to the systemic and pulmonary circulations. Be familiar with the concept of edema.

  7. Have a mental picture of how the thoracic cage, diaphragm, visceral pleura, parietal pleura, and intrapleural space relate to one another. Review the mechanics of inspiration and expiration.

  8. Have a general feel for the different partial pressures of oxygen and carbon dioxide, both at the level of the lungs and tissues. Be familiar with the gradients of exchange for each of these gases.

  9. Know why the sigmoidal saturation curve shifts to the right or to the left. Be able to relate this shift to the effects of pH, hydrogen ion concentration, partial pressure of oxygen, partial pressure of carbon dioxide, temperature, and 2,3-BPG concentration.

  10. Know the basis of the Bohr Effect and how this relates to ventilation. This is tied into the concept of metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis. Be able to read and interpret graphs when presented with these events.

Passages and Solutions

Section II includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to the heart and lungs. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section III: Gastrointestinal Tract and Kidneys

Top 10 Section Goals

  1. Be familiar with the anatomy of the gastrointestinal tract. Know how food passes from the mouth, down the esophagus, into the stomach, through the intestinal system, and how it is eliminated as feces.

  2. Understand the interactions between the various gastrointestinal secretions. The four gastrointestinal peptide hormones of importance are gastrin, cholecystokinin, secretin, and glucose-dependent insulinotropic peptide. Be aware of their functions.

  3. Be familiar with the process of digestion and the areas of nutrient absorption. Know what types of nutrients are broken down in the stomach and what types are degraded in the intestines. Understand how peristalsis is related to the movement of chyme in the system.

  4. Be familiar with the anatomy of the kidneys. Understand how molecules are filtered at the glomerulus and which ones are reabsorbed from the different parts of the nephron tubular system.

  5. Be aware of the effect of the autonomic nervous system on the kidneys. Know how the kidney responds to sympathetic and parasympathetic stimulation. Know the difference between vasoconstriction and vasodilation at the level of the glomerular arterioles.

  6. Understand how the renin-angiotensin-aldosterone system functions. This system stimulates the reabsorption of sodium in the distal convoluted tubule and in the collecting duct. Understand why this is important to the body.

  7. Be aware of the different types of transport systems that line the tubules. Understand the differences between passive reabsorption (no energy required) and active reabsorption (energy required) and generally where and what is reabsorbed along the tubules.

  8. Understand how the kidneys respond to a decrease in arterial blood pressure. Be aware that there is a short-term adjustment and a long-term adjustment for a decrease in arterial blood pressure. Understand how this works in terms of the glomerular filtration rate.

  9. Be familiar with diabetes mellitus and diabetes insipidus. A key feature of diabetes mellitus is elevated blood glucose levels due to insulin problems, while a key feature of diabetes insipidus is a vasopressin deficiency. Both lead to a large urine loss.

  10. Be familiar with some of the conditions brought about by renal failure. The two most life-threatening consequences of renal failure involve the retention of potassium, due to poor tubular secretion of potassium, and metabolic acidosis, due to improper tubular secretion of hydrogen ions.

Passages and Solutions

Section III includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to the gastrointestinal tract and kidneys. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section IV: Reproduction and Development

Top 10 Section Goals

  1. Be familiar with the male reproductive anatomy. Know how to trace the passage of sperm from the testis, through the epididymis, into the vas deferens, by the ejaculatory duct and prostate, into the urethra, and out to the free world.

  2. Know how sperm are produced during spermatogenesis. Be familiar with the actions of LH and FSH on developing sperm. Know the different cell types involved in sperm production. Make sure you understand both mitosis and meiosis.

  3. Be familiar with the female reproductive anatomy. Know the general steps of how an ovum develops within the ovary. Be aware of the different types of cells within the ovary and their relationship to the developing egg.

  4. Know how eggs are produced during oogenesis. Be familiar with the actions of LH and FSH on developing ova. Know the different cell types involved in egg production. Make sure you understand both mitosis and meiosis.

  5. Be able to compare and contrast male and female gamete production. Understand why the male Leydig cells are analogous to the female theca cells and why the male Sertoli cells are analogous to the female follicle cells.

  6. Understand how to read the hormonal curves for a woman's monthly cycle. Understand the relationship between LH, FSH, estrogen, and progesterone during both the follicular phase and the luteal phase of ova production.

  7. Be familiar with the different hormonal feedback mechanisms at the brain. In the male, testosterone leaves the testes and acts back at the level of the brain. In the female, estrogen and progesterone leave the ovaries and acts back at the brain. Understand why.

  8. Understand what happens once fertilization of the egg takes place. Be familiar with the process of fertilization, where it is most likely to occur, and where the fertilized egg is most likely to implant in the uterus.

  9. Understand the hormonal relationships associated with fetal development. Be familiar with how placental hCG affects the corpus luteum and how estrogen and progesterone from the corpus luteum affects the anterior pituitary and the mammary glands.

  10. Be familiar with the different stages of embryonic development. Development begins with fertilization and proceeds through cleavage, gastrulation, neurulation, neural crest formation, organogenesis, and eventually parturition. Be familiar with these stages.

Passages and Solutions

Section IV includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to reproduction and development. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.


Section V: Endocrinology and Immunology

Top 10 Section Goals

  1. Be familiar with catecholamine hormones and their actions. Catecholamines like dopamine, norepinephrine, and epinephrine all contain a catechol ring (a benzene ring with two adjacent hydroxyl groups). They act at the level of the CNS and PNS.

  2. Be familiar with peptide hormones and their actions. Peptide hormones contain two or more amino acids linked together by a peptide bond. These hormones are secreted by a wide range of structures and have a variety of actions.

  3. Be familiar with the actions of the G-protein and adenylate cyclase. Understand what happens when a hormone like epinephrine binds to a cell surface receptor. Be familiar with the action of the G-protein and conversion of ATP to cAMP by adenylate cyclase.

  4. At a general level understand how phosphorylation events activate proteins. A classic example involves the phosphorylation of glycogen phosphorylase by protein kinase A. Phosphorylated glycogen phosphorylase is activated and can convert glycogen to glucose.

  5. Be familiar with steroid hormones and their actions. The common precursor to all steroid hormones is cholesterol. Steroid hormones are not stored after their synthesis, but instead are used right away. Know the major groups of steroid hormones.

  6. Be familiar with the mechanisms by which homeostasis is maintained. Understand the concept of negative feedback. Understand what is meant by endocrine, neuroendocrine, paracrine, and autocrine regulation.

  7. Know the peptide hormones of the pituitary. It is important to know where the 8 major hormones of the anterior and posterior pituitary are synthesized and stored. Know why and how they are released into the circulatory system.

  8. Be aware of the different cell types involved with the immune system. White blood cells, or leukocytes, are involved in the body's immune response. The 5 different types of leukocytes are neutrophils, eosinophils, basophils, monocytes, and lymphocytes.

  9. Understand the basic structure and function of an antibody. Know the 5 classes of antibodies (IgA, IgD, IgE, IgG, and IgM) and what they do. Have a general feel for their anatomy.

  10. Be familiar with the differences between humoral and cellular immunity. Understand the workings of macrophages, MHC receptors, the different interleukins, the T cells and B cells, the different interferons, and how they relate to foreign antigens.

Passages and Solutions

Section V includes 15 MCAT-style passages with detailed solutions. Passage topics are centered around information important to endocrinology and immunology. Also included are 15 MCAT-style free standing questions with just the letter choice indicating the best answer.

Two Full Diagnostics

At the end of Book I are two full diagnostics, each with 10 passages, free standing questions, and detailed solutions.

SAMPLE PASSAGE




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