Intro to Human Phys - Ch 9: Endocrine System

endocrine system

second controlling system of the body

endocrinology

science that studies the endocrine system - hormones, their effects and the organs that secrete them

hormones control what

reproduction, growth and development, regulation of metabolism, mobilization of body defenses, maintenance of much of homeostasis

types of chemical messengers

autocrine signaling, paracrine signaling, endocrin signaling

autocrine signaling

same sell

paracrine signaling

around, compound doesn’t travel far

endocrine signaling

travels through the bloodstream, no ducts

amino acid-based

proteins, peptides, and amines

steroids - cholesterol-based

very potent, direct gene activation

hormone binding to receptors produces…

changes in the plasma membrane permeability or electrical state, promotion of secretory activity, synthesis of proteins, activation or inactivation of enzymes, and stimulation of mitosis

direct gene activation

goes through pores of nucleus, only steroid hormones

second-messenger system

binds to receptor which then catalyzes an enzyme

what are blood levels mostly maintained by

negative feedback

what is negative feedback?

a stimulus, or low hormone level in the blood, triggers the release of hormone and continues to release until an adequate response or level of hormone is reached

types of stimuli

hormonal stimulus, humoral stimulus, neural stimulus

hormonal stimulus

the release of a hormone in response to another hormone

humoral stimulus

control of hormone release in response to changes in extracellular fluid (eg. blood or ion concentration

neural stimulus

hormones that are released by the glands of the endocrine system

what are the two lobes of the pituitary gland?

posterior, anterior

oxytocin

stimulates contractions of muscles

antidiuretic hormone (ADH)

inhibits urine production by promoting water reabsorption by the kidneys

antidiuretic hormone deficiency

diabetes insipidus; huge output of urine and intense thirst

hypophyseal portal system

a capillary network that allows for the transfer of hormones that are secreted by the hypothalamus to maintain its high concentration when it enters the anterior pituitary

hormones that have effect on non-endocrine targets

growth hormone (GH) and prolactin (PL)

hormones that stimulate other endocrine glands

thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH)

what do all anterior pituitary hormones have in common?

amino acid-based/proteins, act through second-messenger systems, and regulated by hormonal stimuli or negative feedback

growth hormone (GH)

general metabolic hormone, major effects on skeletal muscles and long bones. increases blood glucose

what is growth hormone release regulated by?

growth hormone-releasing hormone (GHRH), growth hormone-inhibiting hormone (GHIH)

growth hormone disorders

pituitary dwarfism, gigantism, acromegaly

pituitary dwarfism

results from hyposecretion of GH during childhood

gigantism

result from hypersecretion of GH during childhood

acromegaly

result from hypersecretion of GH during adulthood

prolactin (PL)

stimulates and maintains milk production following childbirth

what regulates prolactin (PL)?

dopamine (-) and prolactin-releasing factors (+)

adrenocorticotropic hormone (ACTH)

regulates endocrine activity of the adrenal cortex

what stimulates adrenocorticotropic hormone(ACTH)?

corticotropin-releasing hormone (CRH) from hypothalamus

thyroid-stimulating hormone (TSH)

controls growth and activity of the thyroid gland

what stimulates thyroid-stimulating hormone (TSH)?

thyrotropin-releasing hormone (TRH) from hypothalamus

gonadotropic hormones

secreted in response to gonadotropin-releasing hormone (GnRH) from hypothalamus, and regulates hormonal activity in gonads

follicle stimulation (FSH)

stimulates female follicle development and sperm development in males

luteinizing hormone (LH)

triggers female ovulation and testosterone production in males

what does the thyroid gland produce?

thyroid hormones and calcitonin

what is the thyroid gland composed of?

follicles that produce the glycoprotein thyroglobulin

what does the number of iodide atoms in the thyroid gland produce?

thyroixine (T4) and triiodothyronine (T3)

what are the functions of the thyroid hormone

increases basal metabolic rate and heat production

what does the thyroid hormone help regulate?

blood pressure, tissue growth, development of skeletal and nervous systems, memory and cognitive function, and reproductive capabillities

what regulates thyroid hormone synthesis?

thyroid-stimulating hormone (TSH) secreted by the anterior pituitary

what regulates thyroid-stimulating hormone?

thyroid-releasing hormone (TRH) from the hypothalamus

calcitonin

regulates calcium level in blood - hypocalcemic effect

hypothyroidism diseases

goiter, congenital hypothyroidism (cretinism), myxedema

gotier

thyroid glands enlarge due to lack of iodine

myxedema

physical and mental sluggishness, puffy face, poor muscle tone, low body temp., obesity

hyperthyroidism (thyrotoxicosis)

high BMR, weight loss, heat intolerance, tachycardia, agitation and restlessness, mental alterations

how does hyperthyroidism usually present?

usually a tumor of the thyroid gland

graves disease

results in exothalmos and thyroid gland hyperplasia

parathyroid glands

secrete parathyroid hormone

hyperparathyroidism

bones soften and deform, elevated calcium

hypoparathyroidism

follows gland trauma or removal

parts of the adrenal glands

adrenal cortex, adrenal medulla

adrenal cortex

outer glandular tissue of the adrenal gland

adrenal medulla

inner neural tissue, part of sympathetic nervous system

where is mineralocorticoids (mainly aldosterone) produced?

in the zona glomerulos

what is the target of mineralocorticoids?

the kidneys

what is the function of mineralocorticoids?

regulates mineral (sodium + potassium) content of blood and water and electrolyte balance

what stimulates mineralocorticoids?

decreased blood pressure (indirect pathway) and increase potassium (direct pathway)

what inhibits the production of mineralocorticoids?

atrial natriuretic peptide (ANP)

where is glucocorticords (cortisone and cortisol) produced?

in the zona fasciculata of the adrenal cortex

when is cortisone and cortisol released?

released in response to increased blood levels of ACTH, stress, and patterns of eating and activity

what is the function of cortisone and cortisol?

promote normal cell metabolism and help resist long-term stressors

how does cortisone and cortisol affect the immune modulators

increase anti-inflammatory and decrease proinflammatory proteins

what are the metabolic effects of cortisone and cortisol?

promote rises in blood glucose, fatty acids, and amino acids

where is gonadocorticoids (sex hormones) produced?

in the zona reticulata of the adrenal cortex

what can sex hormones contribute to?

the onset of puberty, appearance of secondary sex characteristics, and sex drive

addison disease

hyposecretion of all cortical hormones, low blood pressure, weak muscle tone, loss of sodium an dwater, bronze skin, and suppressed immune functions

hyperaldosteronism

adrenal hyperplasia or secondary to overactivity of the renin-angiotensis-aldosterone axis. metabolic alkalosis (pH of blood is too high)

cushing syndrome

caused by hypersecretion or excessive intake of cortisol. characterized by a “moon face” and “buffalo hump”, high blood pressure, hyperglycemia, weak bones, depression, diabetes

masculinization

hypersecretion of adrenal sex hormones

where is the pancreas located?

in the upper left quadrant of the abdomen

glucagon

alpha cells; allows glucose to cross into cells

insulin

beta cells; allows glucose to cross into cells

somatostatin

delta cells; regulates/inhibits alpha and beta cells

pancreatic polypeptide (PP)

gamma cells; anagonist of CCK

what is a major target of glucagon?

the liver

glycogenolysis

breakdown of glycogen to produce glucose

gluconeogenesis

synthesis of glucose from lactic acid and noncarbohydrates

what converts glucose to fatty acids in the liver and adipose tissue?

insulin

diabetes mellitus (DM)

due to hyposecretion or hypoactivity of insulin

type 1 diabetes mellitus

autoimmune destruction of bata-cells of the pancreas resulting in absolute insulin deficiency

type 2 diabetes mellitus

multifactoral syndrome; combined influence of genetic susceptibility, resulting in insulin resistance in cells requiring insulin for glucose uptake

gestational diabetes

occurs when pregnant women without a previous history of diabetes develop hyperglycemia

what are three sign if diabetes mellitus?

polyuria, polydipsia, polyphagia

polyuria

huge urine output

polydipsia

excessive thirst

polyphagia

excessive hunger and food consumption

pineal gland

small gland hanging from roof of third ventricle

melatonin

production is light dependent

thymus

produces thymuiln, thymopoietins and thymosins, matures some types of white blood cells

what regulates gonads?

follicle-stimulating hormone and luteinizing hormone

what hormones do ovaries produce

estrogena dn progesterone

progesterone

prepares the uterus for implantation, decreases contractility of uterine smooth muscle and inhibits lactation during pregnancy but prepares mammary gland