Rios Salado Bio202 Exam 1

a. Structural pituitary gland located on sella turcica and infundibulum connects pituitary gland to the hypothalamus (above it) maintains connection through nerve bundles called the hypothalamic-hypophyseal tract b. Functional: action potentials travel down the axons of hypothalamic neurons, causing hormone release from their axon terminals in the posterior pituitary, hypothalamic hormones released into special blood vessels (the hypophyseal portal system) control the release of anterior pituitary hormones

Describe structural and functional relationships between the hypothalamus and pituitary gland

Target cells First Mechanism: Cyclic AMP Signaling Mechanism Second Mechanism: PIP2- Calcium Signaling Mechanism

Describe the two major mechanisms by which hormones bring about their effect on their target tissues

prolonged exposure to high hormone concentrations can decrease the number of receptors for that hormone

Down-regulation

i. Hyposecretion: rare ii. Hypersecretion: Cushing's disease

Effects of abnormal secretion of ACTH

i. Effects of hyposecretion (less): diabetes insipidus ii. Effects of hypersecretion (more): syndrome inappropriate of ADH secretion (SIADH)

Effects of abnormal secretion of ADH

i. Hyposecretion: failure of sexual maturation ii. Hypersecretion: no important effects

Effects of abnormal secretion of FSH

i. Effects of Hyposecretion: pituitary dwarfism in children ii. Effects of Hypersecretion: gigantism in children; acromegaly in adults

Effects of abnormal secretion of GH

i. Hyposecretion: poor milk production in nursing women ii. Hypersecretion: inappropriate milk production, cessation of menses in females, impotence in males

Effects of abnormal secretion of PL

i. Hypersecretion: Cretinism in children, myxedema in adults ii. Hyposecretion: hyperthyroidism; effects similar to those of Graves' disease, in which antibodies mimic TSH

Effects of abnormal secretion of TSH

ductless glands, produce hormones, release hormones into the surrounding tissue fluid, and have a rich vascular and lymphatic drainage that receives their hormones, most cells in these glands are arranged in cords and branching networks (maximizes contact between cells and surrounding capillaries)

Endocrine glands

second great control system of the body that interacts with the nervous system to coordinate and integrate the activity of body cells

Endocrine system

the scientific study of hormones and the endocrine organ

Endocrinology

released in response to stressors, mimics the sympathetic nervous system, response to relax 80%

Epinephrine

responsible for maturation of the reproductive organs and the appearance of the secondary sex characteristics of females at puberty, breast development, and the menstrual cycle

Estrogens and Progesterone (Ovaries)

sustains the fetus during pregnancy, secretes steroid and protein hormones that influence the course of pregnancy

Estrogens, Progesterone, human chorionin gonadotropin (hCG) Placenta

produce non-hormonal substances (sweat and saliva) and have ducts that carry these substances to a membrane surface

Exocrine glands

a. Negative feedback mechanism: reaction that causes a decrease in function (some internal or external stimulus triggers hormone secretion) b. Humoral stimuli: simplest endocrine control, secrete hormones in direct response to changing blood levels of certain critical ions and nutrients (insulin, Ca2+ levels, aldosterone) c. Neural stimuli: nerve fibers stimulate hormone release (stress: norepinephrine or epinephrine) d. Hormonal stimuli: release hormones in response to hormones produced by other endocrine organs (releasing and inhibiting hormones produced by the hypothalamus regulate the secretion of most anterior pituitary hormones)

Explain how hormone release is regulated

a. Aging: connective tissue increases, vascularization decreases, number of hormone secreting cells decreases, GH levels decline (muscle atrophy), structural changes of adrenal glands and anterior pituitary b. Stress: drives up blood levels of cortisol and appears to contribute to hippocampal and memory deterioration, plasma levels of aldosterone decline, gonads (mostly ovaries) change with age, less estrogen produced), glucose tolerance declines, thyroid hormone synthesis decreases

Explain the effects of aging and stress on the endocrine system

ovaries and testes; in females, stimulates ovarian follicle maturation and production of estrogens, in males, stimulates sperm production

Follicle-stimulating hormone (FSH)

a. Thyroglobulin is synthesized and discharged into the follicle lumen b. Iodide is trapped (once trapped inside the follicular cell, iodide moves into the follicle lumen by facilitated diffusion) c. Iodide is oxidized to iodine d. Iodine is attached to tyrosine (attachment of one iodine to tyrosine produces MIT, monoiodotyrosine and attachment of two iodines produces diiodotyrosine, DIT) e. Iodinated tyrosines are linked together to form T3 and T4 (two linked DITs = T4, MIT + DIT = T3) f. Thyroglobulin colloid is endocytosed (to secrete hormones, the follicular cells must reclaim iodinated thyroglobulin by endocytosis and combine the vesicles with lysosomes) g. Lysosomal enzymes cleave T4 and T3 from thyroglobulin and the hormones diffuse from the follicular cell into the bloodstream

Follow the process of thyroxine formation and release

29 amino acid polypeptide, potent hyperglycemic agent, target: liver i. Breakdown of glycogen into glucose, synthesis of glucose from lactic acid and from non-carbohydrate molecules, release of glucose to the blood by liver cells, causing blood glucose levels to rise ii. Lower blood levels of amino acids as the liver cells sequester these molecules to make new glucose molecules iii. Alpha cells prompt glucagon secretion

Glucagon

influence the energy metabolism of most body cells and help us resist stressors, produce metabolic hormones (middle layer: Zona fasciculata) i. Examples: Cortisol (hydrocortisone), cortisone, corticosterone ii. Negative feedback regulates secretion, Cortisol release is promoted by ACTH iii. Affected by stress

Glucocorticoids

weak male sex hormones converted into testosterone or estrogens, produce adrenal sex hormones (inner layer: zona reticularis) i. Stimulated by ACTH; mechanism of inhibition incompletely understood, but feedback inhibition not seen ii. Insignificant effects in males; contributes to female libido, development of pubic and axillary hair in females, source of estrogens after menopause

Gonadocorticoids

regulate the function of the gonads (ovaries and testes)

Gonadotropins

liver, muscle, bone, cartilage, and other tissues: anabolic hormone; stimulates somatic growth; mobilizes fats; spares glucose, growth promoting effects mediated by IGFs

Growth hormone(GH)

inhibits growth hormone release

Growth hormone-inhibits hormone (GHIH)

stimulates growth hormone release

Growth hormone-releasing hormone (GHRH)

the length of time for a hormone's blood level to decrease by half, varies from a fraction of a minute to a week (water-soluble hormones have the shortest half-lives

Half-life

Osteocalcin, increases insulin production and insulin sensitivity

Hormonal function of bone

i. Leptin: tells your body how much stored energy (as fat) you have 1. Brain, suppresses appetite, increases energy expenditure ii. Resistin: insulin antagonist (fat, muscle, liver) iii. Adiponectin: enhances sensitivity to insulin (fat, muscle, liver)

Hormonal function of the adipose tissue

cardiac muscle cells secrete atrial natriuretic peptide (ANP) inhibits sodium ion reabsorption and renin release (kidney), inhibits secretion of aldosterone; decreases blood pressure (adrenal cortex)

Hormonal function of the heart

Erythropoietin, stimulates production of red blood cells (red bone marrow)

Hormonal function of the kidney

Cholecalciferol, stimulates active transport of dietary calcium across cell membrane of small intestine (intestine)

Hormonal function of the skin

Thymulin, thymopoietins, thymosins, mostly act locally as paracrines; involved in T lymphocyte development and in immune responses

Hormonal function of the thymus

long-distance chemical signals that travel in blood or lymph throughout the body

Hormones

a. Amino-acid based: hormones are water soluble and cannot cross the plasma membrane (epinephrine, thyroxine, peptides, protein) b. Steroids: hormones synthesized from cholesterol, lipid soluble and can cross the plasma membrane (only gonadal and adrenocortical hormones are steroids)

How are hormones classified chemically?

a. Blood levels of the hormone b. Relative numbers of receptors for that hormone on or in the target cells c. Affinity (strength) of the binding between the hormone and the receptor

Identify factors that influence activation of a target cell

prevents wide swings in water balance, helping the body avoid dehydration and water overload, substance that inhibits urine formation, stimulates kidney tubule cells to reabsorb water

ADH

outer adrenal gland, encapsulates the medulla and forms the bulk of the gland, glandular tissue derived from embryonic mesoderm

Adrenal cortex

found close to the kidney

Adrenal gland location

pyramid-shaped organs perched atop the kidneys, where they are enclosed in a fibrous capsule and a cushion of fat

Adrenal glands

knot of nervous tissue, part of sympathetic nervous system, one of two adrenal glands

Adrenal medulla

Adrenal cortex; promotes release of glucocorticoids and androgens

Adrenocorticotropic hormone (ACTH)

when one hormone opposes the action of another (insulin lower blood glucose levels, which is antagonized by glucagon which raises blood glucose levels)

Antagonism

composed of glandular tissue, manufacturers and releases hormones

Anterior pituitary lobe

chemicals that exert their effects on the same cells that secrete them, short-distance signals (smooth muscle cells to contract smooth muscle cells)

Autocrines

calcitonin is a polypeptide hormone released by the parafolicular or C cells of the thyroid gland in response to a rise in Ca2+ blood levels, targets the skeleton where it inhibits bone resorption and release of Ca2+ from the bony matrix and stimulates Ca2+ uptake and incorporation into bone matrix

Calcitonin

adrenal cortex synthesizes over two dozen steroid hormones

Corticosteroids

small 51 amino acid protein consisting of two amino acid chains linked by disulfide bonds, lowers blood glucose levels, promotes protein synthesis and fat storage, participates in neuronal development, feeding behavior, and learning and memory i. Circulating insulin lowers blood glucose levels by: 1. Enhances membrane transport of glucose into most body cells, especially muscle and fat cells 2. Inhibits the breakdown of glycogen to glucose 3. Inhibits the conversion of amino acids or fats to glucose, counter any metabolic activity that would increase plasma levels of glucose

Insulin

growth-promoting proteins

Insulin-like growth factors (IGFs)

Ovaries and testes: in females, triggers ovulation and stimulates ovarian production of estrogens and progesterone; in males, promotes testosterone production

Leutinizing hormone (LH)

Permissiveness Synergism Antagonism

List 3 kinds of interaction of different hormones acting of the same target cell

an amine hormone derived from serotonin

Melatonin

regulate the electrolyte concentrations in extracellular fluids (Na+ and K+), hormones that help control the balance of minerals and water in blood (outer layer: Zona glomerulosa) i. Example: Aldosterone 1. Stimulates Na+ reabsorption (increasing blood volume and blood pressure) 2. Causes K+ secretion into the tubules for elimination from the body ii. Renin-Angiotensin Aldosterone Mechanism: triggers aldosterone release and raises blood pressure

Mineralcorticoids

neural functioning plus releases hormones (hypothalamus)

Neuroendocrine organ

response to stress 20% • Release stimulated by the nervous system

Norepinephrine

The heart is a very important muscle in our body that keeps blood flowing to our tissues to keep them nourished with oxygen and help transport carbon dioxide waste to the lungs for gas exchange. The heart uses electrical impulses from specialized nodes to trigger the cardiac muscles to contract, which in turn leads to the continuous pumping function of the heart. The specialized nodes of the heart are the sinoatrial (SA) node and the atrioventricular (AV) node. The SA node is located in the right atrium and is inferior to the superior vena cava entrance. The SA node is the pacemaker of the heart and sets the rate of depolarization that begins the electrical signal that tells the heart to contract. The AV node is located in the lower atrial septum at the junction of the atria and ventricles. The AV node's function is to delay the contraction of the ventricles until the atrial contraction is complete for 0.1s. The sequence of impulse generation in the heart start off at the SA node. The SA node generates an electrical impulse which begins atrial excitation. The signal is then passed to the AV node where the signal is delayed until the atria have finished their contraction. Next, the impulse is passed to Atrioventricular (AV) bundle located superior interventricular septum and is then passed through the left and right bundle branches located in the interventricular septum, which stimulates ventricular excitation. When the impulse reaches the Purkinje fibers in the left and right ventricles, the ventricles contract. The heart contains three layers of muscles called the epicardium, myocardium, and endocardium. The epicardium is the outer muscle of the heart, the myocardium is the middle layer of muscles, and the endocardium is the inner layer of cardiac muscle that actually comes into contact with the blood in the heart. The heart is composed of myocardial muscle cells that make up the walls of the atria and the ventricles that have contractile and elastic properties that aid in cardiac contraction. The contractile properties of the myocardial cells help the heart stretch and allow the chambers to fill with blood. The elastic property of the myocardial cells allow the heart to remain intact and strong after stretching. Due to the fact that the heart must go through constant strain during contraction, it must be able to bounce back from stretching. The heart also contains papillary muscles, which help anchor the chordae tendinae to the walls of the heart. The chordae tendinae are strings of white collagen fibers that are attached to tricuspid and mitral valve to keep them from being blown back into the atria during contraction. Cardiac muscle also contains intercalated discs, which allow an electrical impulse to sent through the whole muscle through gap junctions and allow the heart to contract as one unit. Also, the left side of the heart contains more muscle tissue, because the left ventricle has to use more force to push blood up and out of the heart to the body tissues. The heart is a complex organ with many structures and specialized muscle fibers that help aid in its contraction. The heart is composed of two atria, the right and the left atrium, and two ventricles, the right and the left ventricles. The heart is also composed of four valves, two valves known as the atrioventricular valves that separate the corresponding atria and ventricles and two valves that are known as the pulmonary and aortic semilunar valves that guard the bases of the two large arteries leaving the ventricular chambers. The right atrium and right ventricle are separated by the Tricuspid valve that helps prevent blood from back-flowing into the atria when the ventricles are contracting. The left atrium and left ventricle are separated by the Mitral/Bicuspid valve, which helps prevent backflow into the atria during ventricular contraction. The pulmonary semilunar valve is between the right ventricle and pulmonary artery and the aortic semilunar valve is between the left ventricle and the aorta. The semilunar valves help keep arterial blood from reentering the heart. The cycle of contraction and blood flow begins with deoxygenated blood entering from the superior and inferior vena cava and into the right atrium, through the tricuspid valve, and to the right ventricle. At this point the heart is in diastole, which means the heart is relaxed and not contracting. When the right ventricle is stretched and filled with its full capacity of blood the SA node sends an impulse to the AV node, then to the AV bundle, next to the bundle branches, and finally to the Purkinje fibers to contract the right ventricle and push the deoxygenated blood up through the pulmonary semilunar valve and out the pulmonary trunk and the pulmonary artery to the lungs for gas exchange. At the lungs carbon dioxide is exchanged for oxygen, which concludes the pulmonary circuit. Once the blood is oxygen rich it enters the heart through the pulmonary veins to the left atrium, through the mitral valve and into the left ventricle. Once the left ventricle is filled to its maximum capacity the heart goes from diastole to systole, which is when the heart enters contraction. The SA node sends an impulse to the AV node, then to the AV bundle, next to the bundle branches, and finally to the Purkinje fibers to push the oxygenated blood out of the left ventricle through the aortic semilunar valve and the aorta to deliver oxygen-rich blood to the body tissues. This concludes the systemic circuit. The information of the conduction system and the blood flow of the heart as well as the heart's identifying structures will definitely be useful information to me when I become a Registered Nurse. For example, the results of an electrocardiagram or an ECG test will help me determine my patient's heart rate. From there, I can determine if they have a regular rhythm and their heart is depolarizing and repolarizing normally, which is about 70 beats per minute for an adult. If I noticed that there was a significant increase, such as over 100 beats per minute I would be able to identify my patient with Tachycardia. If my patient had a significantly lower heart rate than average I would diagnose them with Bradycardia, which is a heart rate lower than 60 beats per minute. However, if I inquired with the patient and asked preliminary questions and discovered that the patient was a high-performing athlete, I would not be concerned with the patient's heart rate. I would not be concerned because a lower heart rate in athletes is common because it is a sign of increased cardiac efficiency and there would be no cause for concern or methods of treatment needed.

On Exam 1 you will be presented with an essay question. The essay topic is cardiac impulse generation. You will be asked to compose an essay about the cardiac impulse generation and conduction. a. A discussion cardiac conduction should begin with description of the specialized nodes (autorhythmic character) of the heart and their locations. b. The sequence should be discussed as well as coordinating location in the heart. c. The actual innervation of the cardiac muscle and appropriate structures should be considered. d. Correlation between the stages of impulse should be related to the flow of blood, contraction of the chambers and open and closing of the valves.

stimulates uterine contractions; initiates labor, initiates milk ejection

Oxytocin

1. Intracellular calcium ions (second messenger) ii. Phospholipase C (enzyme) splits a plasma membrane phospholipid, PIP2, into 2 second messengers (DAG: activates protein kinase enzyme and triggers responses within target cell) (IP3: releases Ca2+ from intracellular storage sites, acts as secondary messenger and binds to protein calmodulin which activates enzymes that amplify the cellular response)

PIP2-Calcium Signaling Mechanism

soft tadpole-shaped gland composed of endocrine and exocrine glands located behind the stomach

Pancreas

a mixed gland, located close to the stomach and small intestine

Pancreas location

tiny cell clusters that produce pancreatic hormones o Alpha cells: glucagon synthesizing cells o Beta cells: insulin synthesizing cells

Pancreatic islets

act within the same tissue, but affect cell types other than those releasing the paracrine chemicals (somatostatin released by one group of pancreatic cells inhibits the release of insulin by a different group of pancreatic cells)

Paracrines

one hormone cannot exert its full effects without another hormone being present (lack of thyroid hormone delays reproductive development)

Permissiveness

pinecone-shapes, hangs from the roof of the third ventricle in the diencephalon

Pineal gland

secretory cells of pineal gland

Pinealocytes

composed of neural tissue (pituicytes) and nerve fibers, releases neurohormones received by the hypothalamus, hormone-storage area, not true endocrine gland

Posterior pituitary lobe

breast secretory tissue: promotes lactation

Prolactin (PL)

cells of anterior lobe that produce growth hormone

Somatropic cells

when more than one hormone produces the same effects at the target cell and their combined effects are amplified (both glucagon and epinephrine cause the liver to release glucose to the blood)

Synergism

tissue cells that have receptors for hormonal activity influences, hormone communicates with target cell through water-soluble hormones (amino-acid based hormones, no thyroid, use g proteins) or lipid-soluble hormones (steroid and thyroid hormones) act on receptors inside the cells which directly activates genes, hormone typically produce one or more of these changes: i. Alters plasma membrane permeability or membrane potential, or both, by opening or closing ion channels ii. Stimulates synthesis of enzymes and other proteins within the cell iii. Activates or deactivates enzymes iv. Induces secretory activity v. Stimulates mitosis

Target cells

paired glands suspended in the scrotum

Testes location

initiates the maturations of the males reproductive organs and the appearance of secondary sex characteristics and sex drive, normal sperm production, maintains the reproductive organs in their mature functional state in adult males

Testosterone (Testes)

1. cAMP (second messenger) ii. Hormone binds receptor (hormone acts as first messenger) iii. Receptor activates G protein (G protein activated by GDP: off, GTP: on) iv. G protein activates adenylate cyclase (enzyme) v. Adenylate cyclase converts ATP to cAMP vi. Cyclic AMP activates protein kinases (enzymes that add a phosphate group to proteins, can activate or inhibit certain proteins)

The Cyclic AMP signaling Mechanism

located in the anterior neck, on the trachea just inferior to the larynx, largest pure endocrine gland in the body

Thyroid gland

located in the throat, bilobed gland connected by an isthmus

Thyroid gland location

increasing basal metabolic rate and body heat production by turning on transcription of genes concerned with glucose oxidation (calorigenic effect: heat producing), regulating tissue growth an development (critical for normal skeletal and nervous system development and maturation and for reproductive capabilities), maintaining blood pressure by increasing the number of adrenergic receptors in blood vessels

Thyroid hormone

thyroid gland: stimulates thyroid gland to release thyroid hormones

Thyroid-stimulating hormone (TSH)

regulate the secretory action of other endocrine glands (all anterior pituitary hormones except growth) (cyclic AMP system)

Tropic hormones

persistently low levels of a hormone can cause its targets to form additional receptors for that hormone

Up-regulation

Mineralocorticoids Glucocorticoids Gonadocorticoids

What are corticoids broken down into?

a. Pituitary, thyroid, parathyroid, adrenal, pineal glands b. Pancreas, gonads (ovaries and testes), placenta contain endocrine tissue

What are examples of endocrine organs?

Mineralcorticoids Glucocorticoids Gonadocorticoids

What are the hormones produced by the adrenal gland?

Thyroid hormone (TH) Calcitonin

What are the hormones released by the thyroid gland?

chiefly androgens, but some estrogens are formed • Estrogen • Testosterone

What do gonadocorticoids do?

regulate water and electrolyte balance in the extracellular fluids o Aldosterone: maintenance of salt water balance in the extracellular fluid • Release stimulated by humoral factors (the concentrations of specific nonhormonal substances in the blood or extracellular fluid) o Produced by zona glomerulosa cells

What do mineralocorticoids do?

enable the body to resist long-term stressors, by increasing blood glucose levels o Cortisone: released in response to stressors o Hydrocortisone o Corticosterone o Produced by zona fasciculata cells in the adrenal gland

What doe glucocorticoids do?

regulate blood calcium levels, decreases • Produced by parifollicular cells of the thyroid

What does Calcitonin do?

regulate blood glucose levels, increases • Produced by alpha cells of the pancreatic islets (islets of Langerhans)

What does Glucagon do?

broken into T4/T3: control the rate of body metabolism and cellular oxidation • Release stimulated by another hormone • Produced by follicular epithelial cells of the thyroid • T4 (thyroxine) • Hyposecretion: low BMR, mental and physical sluggishness • Hypersecretion: nervousness, irregular pulse rate, sweating

What does TH do and what is it broken down into?

regulate blood glucose levels, decreases • Release stimulated by the nervous system • Produced by beta cells of the pancreatic islets (islets of Langerhans) • Hyposecretion: diabetes mellitus: loss of glucose in the urine • Hypersecretion: polydipsia, polyurea, polyphagia

What does insulin do?

Epinephrine Norepinephrine

What does the Adrenal Medulla produce?

o Influences metabolic activity by means of hormones (chemical messengers secreted by cells into the extracellular fluid) • Reproduction • Growth and development • Maintenance of electrolyte, water, and nutrient balance of the blood • Regulation of cellular metabolism and energy balance • Mobilization of body defenses

What does the Endocrine system influence?

Corticoids

What does the adrenal cortex produce?

Glucagon Insulin

What does the pancreas produce?

Growth hormone (GH) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PL)

What hormones does the anterior pituitary release?

Glucagon Insulin

What hormones does the pancreas secrete?

Important to our biological clock, bright light suppresses melatonin whereas darkness allows us to produce melatonin to become sleepy, changing melatonin levels may influence rhythmic variation is physiological processes such as body temperature, sleep, and appetite

What is the importance of melatonin?

Oxytocin ADH

What two hormones does the posterior pituitary release?

stomach, intestine, pancreas

Where are enteroendocrine cells located?