Midterm 2 study guide

• What are the two types of glands that release hormones?

  Endocrine and exocrine glands
• What are the three biochemical classes of hormones?

  Biogenic amines, steroid hormones, and peptide hormones
• What is the difference between affinity and specificity?

  Affinity = tightness of binding, specificity means that receptors can distinguish between slight differences in structures of their ligands (hormones and neurotransmitters). Efficacy = the ability of a neurotransmitter, hormone, or other extracellular effector molecule to promote an effect once bound to a cell surface receptor.
• What are the roles of secondary messengers in signal transduction pathways?

  Provides a way for signals generated by activated cell surface receptors to be conveyed to multiple downstream targets/processes. Secondary messengers are typically responsible for signal amplification
• What are the two major downstream effects of hormones on cellular metabolism?

  Cytoplasmic enzyme activation and transcriptional activation
• Know the functions that are regulated by the hypothalamus

  Hunger, body temperature, thirst, osmolarity, reproduction, lactation, metabolic rate, circadian cycles, fatigue, emotional responses
• How do the anterior and posterior pituitary differ?

  The anterior pituitary is an endocrine gland that is responsible for secretion of hypophysiotropic hormones while the posterior pituitary contains axons that project from the hypothalamus leading to neuroendocrine secretion of two additional hormones
• What are hypophysiotropic hormones?


  Produced by hypothalamus and promote release of pituitary hormones
• Know the hypophysiotropic hormones and the hormones that each controls.

  TRH, DA, and CRH, GHRH, and SS, leading to release of TSH, prolactin, ACTH, and GH, respectively. Note that SS inhibits GH release.
• Which hormones are produced by the posterior pituitary? What are their roles?

  ADH/vassopressin and oxytocin
• Know the types of pituitary disorders and their symptoms

  Pituitary Tumors: may be hormone-secreting or non-secreting; most are benign; may cause visual disturbances and headaches as they grow and compress surrounding tissues; may produce an excessive amount of one pituitary hormone and decreases in others.

  Growth Hormone Deficiency: from a variety of causes; in children it causes delayed growth and short stature; in adults it can lead to muscular weakness, fatigue, decreased bone mass, and obesity.

  Hypopituitarism: from a variety of causes including tumors, trauma, decreased pituitary blood supply, infection, sarcoidosis, an autoimmune process, radiation, surgical removal of the pituitary, or a side effect of pituitary surgery; results in a general decrease in pituitary hormone production.

  Hyperprolactinemia: a pituitary tumor that secretes prolactin or a tumor that prevents the regulation of prolactin production; can cause galactorrhea, amenorrhea, and decreased sex drive in men.

  Empty Sella Syndrome: the sella is the space within the bony structure that divides the nasal cavity from the cranial cavity that surrounds the pituitary gland. For unknown reasons the bone in this region may expand and put pressure on the pituitary gland; rarely, the gland shrinks and hormone production decreases, leading to hypopituitarism.
• Know steps involved in thyroid hormone production and the mechanisms that regulate thyroid hormone production and release.

  Cotransport of iodide with Na+ into follicle cell, diffusion into follicle lumen where it is linked to thyroglobulin via action of thyroid peroxidase, endocytosis of iodinated thyroglobulin into follicle cell, digestion of thyroglobulin and release of thyroid hormones into interstitial fluid and subsequent entry into bloodstream
• Know the functions of thyroid hormone and the disease states that result from hyper and hypothyroidism.

  TH promotes breakdown of lipids to fatty acids, breakdown of glycogen to glucose, gluconeogenesis, enhancement of glucose entry into cells, childhood growth, development of the CNS, enhancement of blood flow
• Know the functions regulated by the adrenal gland and the hormones it releases.

  The adrenal gland is responsible for the stress response: Increased heart rate, blood flow to muscles, increased respiration, and decreased blood flow to skin and major organs. Metabolic effects vary dependent on short vs long term stress. Short term: glycolysis; long term gluconeogenesis, glycogen synthesis, inhibition of fat formation, immunosuppression. Hormones include epinephrine and cortisol. Also vasopressin which is released in response to the renin-angiotensin pathway.
• What is gluconeogenesis?


  Conversion of amino acids, pyruvate, lactic acid, and glycerol into glucose i.e. formation of glucose from non-carb molecules.
• How is cortisol secretion regulated?

  Its release is promoted by CRH (hypothalamus) and ACTH (pituitary). Can also be released in response to sympathetic NS activation.
• Know the diseases associated with the adrenal gland

  Primary (Addison's disease) and secondary adrenal insufficiency (too little ACTH) adrenal give rise to cortisol deficit. Addison's is typically due to autoimmune atrophy of the adrenal gland. Tumors of the pituitary and adrenal gland often result in cortisol excess. The latter is known as Cushing syndrome.
• What type of growth is primarily regulated by growth hormone?

  Linear growth i.e. growth that determines body height
• What specific cellular processes are regulated by growth hormone?

  Increased protein synthesis, fat breakdown (lipolysis), gluconeogenesis, DNA synthesis. This leads to an increase in cell number and size in many organs.
• What pathological conditions are associated with too much or too little growth hormone?

  Gigantism and acromegaly from too much GH prior to adulthood or during adulthood, respectively and dwarfism from too little GH prior to adulthood.
• What factors regulate growth hormone release?

  GHRH and somatostatin
• How is calcium metabolism regulated and what diseases result from abnormal levels of this ion?

  Parathyroid hormone stimulates the enzyme required to convert vitamin D to its active form, 1,25 hydroxy Vitamin D, which is needed for the absorption of calcium from the intestine and urine. Parathyroid hormone also stimulates the activity of osteoclasts which deminearalize bone, allowing calcium to be reabsorbed into the blood.
• What physical factors determine the rate of blood flow within a blood vessel?

  The difference in pressure between two points, the radius/diameter of a vessel, blood viscosity, and length of the vessel (Poiseuille's law).
• What is the purpose of heart valves?

  Maintains proper direction of blood flow; prevents mixing of oxygenated and deoxygenated blood
• What are the effects of the autonomic NS and adrenal gland on the cardiovascular system?

  Sympathetic and adrenal: Increase in heart rate, force of heart contraction, vasoconstriction. Local vasodilation of arterioles that carry blood to skeletal muscle and skin surface to increase blood flow.

  Parasympathetic: decreased heart rate, reduced force of atrial contraction
• How do the action potentials of cardiac cells differ from those of neurons?

  An action potential in a neuronal cell occurs as a consequence of opening and closing of Na+ and K+ channels. In cardiac nodal/pacemaker cells, calcium channels have a direct role in the depolarization phase of the action potential. In cardiac contractile cells the opening of calcium channels significantly delays repolarization and gives rise to the force of heart contraction. The prolonged depolarization gives rise to a long refractory period which helps to assure the directionality of action potential propagation. The prolonged refractory period also prevents tetanus which would likely be fatal.
• What enables pacemaker/nodal cells to undergo spontaneous contractions?

  The If Na+ channels initiate the action potential at a less negative voltage than is the case for Na+ channels in most other excitatory cells. When K+ channels repolarize the membrane, they do so gradually. The net result is the absence of a steady resting potential.
• What does the ECG actually measure?

  An ECG trace is a summation of the coordinated firing of cardiac muscle cells as the action potential spreads from atria to ventricles in a wave-like manner. It is actually a measure of the current flow from the heart into intracellular fluid.
• What general types of information can be obtained from an electrocardiogram?

  An ECG tells you if there is any abnormality in the electrical currents that give rise to contractile rhythm of the heart, such as a heart block or ventricular fibrillation.
• What information can be obtained from an echocardiogram?


  An "echo" provides a way of measuring stroke volume and can also be useful in detecting cardiac valve defects.
• What events in the cardiac cycle do the P wave, QRS complex, and T wave correspond?

  P wave: atrial depolarization/contraction

  QRS complex: ventricular depolarization/contraction

  T wave: ventricular repolarization/relaxation
• What changes in contraction and relaxation of the L. ventricle are associated with systole and diastole? How do these relate to the corresponding terms that are used to describe the two components of blood pressure measurement?

  Systole is the period of L. ventricular contraction and ejection. Diastole is the period during which the L. ventricle relaxes and fills. These terms are also used to describe the maximum and minimum blood pressures during the cardiac cycle.
• What is meant by cardiovascular compliance?

  Compliance is a measure of the elasticity of a blood vessel, ΔV/ΔP. Compliance decreases as a greater change in pressure is required to promote expansion of the lungs.
• What do the two pressures, diastolic and systolic pressure represent in terms of the cardiac cycle?

  The diastolic pressure is the pressure in the cardiovascular system just before ventricular ejection. The systolic pressure is the pressure at ventricular ejection.
• What three factors are the primary influences on stroke volume?

  Ventricular end diastolic volume, sympathetic activity, and arterial blood pressure
• What are the steps involved in atherosclerotic plaque formation?

  Injury to endothelial layer, absorption of oxidized LDL-cholesterol to injury site, macrophage infiltration as part of inflammatory response, ingestion of oxidized LDL-Cholesterol by macrophage turning them into foam cells, plaque formation involving deposition of macrophages, proliferation of smooth muscle and connective tissue in the vessel wall, rupture of the smooth muscle layer of the plaque, accumulation of platelets at the site of rupture leading to formation of a blood clot. It the blood clot breaks free of the vessel surface it may lodge in smaller blood vessels resulting in a complete blockage of an artery or vein. This may lead to heart attack, stroke, or pulmonary embolism.
• What are the two primary mechanisms by which statin drugs stop the progression of existing atherosclerotic plaques and prevent the formation of new ones?

  Statins block cholesterol synthesis and increase the uptake of cholesterol by increasing the number LDL-receptors on the surface of liver cells
• What agents increase arteriolar compliance?

  Decreased blood pO2, elevated levels of K+, CO2, H+, nitric oxide, and epinephrine released from the adrenal gland acting on arterioles with adrenergic β2 receptors
• How are proteins exchanged between blood in capillaries and the ECF?

  Endocytosis and exocytosis
• What factors affect stroke volume?

  Preload, contractility, and various exogenous factors contribute to stroke volume. Venous pressure is the major determinant of preload. Contractility is affected by synthetic stimulation and the hormones epinephrine, thyroid hormone, and glucagon. Vascular resistance and thyroid hormone influence afterload.