Endocrine glands, hormones, and functions

hypothyroidism

"insufficient" thyroid hormone production results in slowed metabolic weight. - Results in weight gain and fatigue

parathyroid hormone (PTH)

- opposes effects of calcitonin -> increases circulating calcium levels - promotes calcium absorption in the intestine (due to its effect on Vitamin D) - Reduces calcium storage in bone (stimulates bone reabsorption - osteoclasts break down bone and release Ca+ into circulation). - Reduces calcium excretion in urine

Calcitonin

- reduces calcium concentration in the bloodstream - promotes calcium stores in bone - increases urinary excretion of Ca+ "toning down the calcium concentration in blood"

Fluid regulation hormones

Aldosterone and ADH (vasporessin) - increase fluid retention and raise blood pressure

Digestive hormones

Gastrin, secretin, cholecystokinin

What hormones raise blood glucose levels?

Glucagon, cortisol, epinephrine, GH

Corticoid steroid classes

Glucocorticoid (cortisol) - sugar Mineralocorticoids (aldosterone) - salt Sex hormone (androgens and estrogens) - sex stimulated by adrenocorticotropic hormone ACTH (from anterior pituitary - TROPIC HORMONE)

Mineralocorticoids (aldosterone)

Influence fluid and "mineral", or salt, balance Ex: Aldosterone - promotes fluid retention by increasing sodium uptake in DCT and collecting duct. produced in the adrenal cortex

Sexual development

LH from anterior pituitary causes ovaries to produce higher levels of estrogen and developing secondary sex characteristics during puberty. in males LH causes testes to produce testosterone: promotes facial hair and voice deepening.

prolactin

Released from anterior pituitary. - Acts on mammary glands to stimulate milk production during breast feeding

Sex hormone (androgens and estrogens)

The adrenal cortex only produces these hormones in low levels - higher levels are produced in the testes and ovaries

Metabolic rate regulated by T3 and T4

Triiodothyronine (T3) - 3 iodine atoms (more potent than T4) thyroxine (T4) - 4 iodine atoms, thought to be a precursor (prohormone) to T3. Secreted from thyroid stimulating hormone (TSH) from the anterior pituitary. - hypothyroidism can be cause from lack of dietary iodine - hyperthyroidism

Cortisol

a glucocorticoid released by the adrenal cortex - increases blood glucose in the fasting state - activates gluconeogenesis and glycogenolyis in the liver

hyperthyroidism

accelerates metabolic weight - Results in weigh loss and increased heart rate

Pituitary gland

anterior and posterior lobe - both receive input from the hypothalamus (two lobes function differently) - release tropic hormones (only peptide hormones) Anterior: receives input from hormonal signals Posterior: receives input via neuronal signals

Testes and ovaries

both respond to LH and FSH released from anterior pituitary. Ovaries: release estrogen Testes: release testosterone important in stimulating the development of secondary sex characteristics.

epinephrine and norepinephrine and acute stress response

catecholamines derived from amino acid tyrosine, released from adrenal medulla when sympathetic NS is activated. - work to increase blood glucose levels - increased HR and breathing rate other fight or flight responses

Dysregulation of aldosterone

excess aldosterone can cause dangerous increases in BP. - ACE inhibitors treat hypertension

Thymus (immune system)

immune system organ that secretes thymosin - helps T cells develop and mature

Growth hormone (GH)

increases blood glucose levels under conditions of intense physical stress and during periods of growth and development

Posterior lobe

large a bundle of neuronal axons who's cell bodies originate in the hypothalamus (think of it as an extension of the hypothalamus) - all of the hormones released by the posterior pituitary are synthesized int he hypothalamus. - receives neuronal signals, not hormonal Hormones then travel down neuronal axon and put into storage in the axon terminals in the posterior pituitary. - When the signaled from the hypothalamus, these hormones are leased into systemic circulation

Low blood pressure (too little fluid)

less fluid is available to exert pressure on the vessel walls. - increases blood osmolality due there being less fluid, but solute concentration stays the same = dehydration

thyroid gland

located anterior surface of the trachea - secretes T3 and T4 - increase metabolic rate - Secretes hormone calcitonin

Hypothalamus

located in forebrain - "bridge between nervous and endocrine systems" controls autonomic activities (body temp, metabolism, fatigue, and sleep) and oversees pituitary activity. - secretes tropic hormones that allow the anterior pituitary to secrete more tropic hormones

Pancreas

located posterior to the stomach. Pancreas has specialized cells that produce specialized hormones: - Alpha cells -> glucagon - Beta cells -> insulin - Delta cells -> somatostatin - Other: PP cells and epsilon cells

parathyroid gland

located posteriorly on the thyroid gland - releases parathyroid hormone (PTH)

high blood pressure (too much fluid)

more fluid means more pressure on the vessel walls - solutes are more dilute so blood osmolality declines.

Calcium regulation

necessary for proper bone development, muscle concentration, signal transduction intracellular second messenger. - Ca+ travels through blood stream Regulated by: - Parathyroid gland -> releases PTH when calcium levels are low (stimualtes bone reabsorption and releases calcium into circulation) - Thyroid gland -> releases calcitonin in response to high calcium levels (inhibits osteoclast activity) (osteoclast break down bone) - Vitamin D

Two main hormones released by the posterior pituitary:

oxytocin and antidiuretic hormone (ADH) ADH - helps maintain fluid balance in the body, when blood volume is too low, and the salt concentrations is too high, this hormone blocks diuresis (urine production) and helps bodies retain water. - promotes water retention in kidneys by inserting aquaporins in the collecting duct -> increases blood pressure Oxytocin - promotes smooth muscle contractions during labor to promote childbirth and lactation and also promotes social bonding.

Anterior pituitary - hypophyseal portal system

physicality connects the blood supply of the hypothalamus to the pituitary gland via a system of blood vessels at the base of the brain (hypophyseal portal system) - not shared with the posterior lobe these vessels are extremely permeable: allows for exchange of hormones and other molecules between the portal system and the hypothalamus and pituitary gland - this is how hormones act directly on anterior pituitary to regulate its secretion

Insulin

produced by beta cells in the pancreas in response to elevated blood glucose Insulin binds to receptors on wide range of target cells. Each cell then mobilizes glucose transport proteins to the membrane, allowing glucose enters the cell through these receptors. - lowers glucose cncentration sin the blood

Atrial natriuretic peptide (ANP)

produced by muscles cells in the heart - helps regulate fluid balance (opposes aldosterone and ADH) - released in response to high blood volume - decreases blood pressure by promoting fluid loss

Glucagon

produced by pancreatic alpha cells well blood glucose levels are low. - increased blood glucose levels via gluconeogenesis and glycogennoylsis

Atrial natriuretic peptide (ANP) in fluid regulation

produced in muscle cells of heart (cardiomyocytes) - released in response to high blood volume - decrease sodium reabsorption in the DCT and collecting duct increase filtration rate in glomerulus to speed up filtration. - inhibits aldosterone release (promotes fluid loss) -> decreases blood pressure

epinephrine

produced in the adrenal medulla - raises blood glucose by stimulating glycogenolysis in liver and muscle cells. - in fight or flight response

Adrenal medulla

produces catecholamines (epinephrine (=adrenaline) and norepinephrine - AA derived hormones) - these hormones are water soluble molecules named for their catechol and amine structural components Mediates fight or flight response - increased blood flow to skeletal muscles - pupil dilation - elevated HR - glucose liberation into the blodostream

Fluid balance

refers to blood volume and osmolality in body's vascular system too much fluid: raises blood pressure too little fluid: too little blood pressure

Cortisol and chronic stress response

released by adrenal cortex - increases blood glucose levels by stimulating gluconeogenesis (opposes insulin) - suppresses inflammation and used to treat: Rheumatoid Arthritis, Lupus, MS, Asthma.. Abnormal cortisol levels are associated with mood disorders - Addision's disease (hypocortisolism) - Cushings syndrome (hypercortisolism) - anxiety - depression

ADH (antidiuretic hormone/vasopressin)

released by posterior pituitary in response to low blood pressure and high plasma osmolality. - ADH does not promote reabsorption of ions, - it increases permeability of the collecting duct to water by increasing the expression of aquaporins (allows water to flow along its concentration gradient from kidney filtrate back into bloodstream. ADH initially reduces blood osmolality by increasing water absorption. Aldosterone maintains plasma osmolality by promoting sodium reabsorption, which in turn drives water reabsorption until homeostasis is reached. - both solve the problem of dehydration by promoting fluid retention promotes fluid retention in the nephron while decreasing plasma osmolality

Gonadotropin-releasing hormone (GnRH)

released by the hypothalamus - stimulates release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the anterior pituitary Plays roles in reproductive roles related to growth. In males: - LH: stimulates Leydig cells in testes to release testosterone - FSH: promotes spermatogenesis In females: - LH: stim estrogen production in ovaries - FSH: maturation of ovarian follicles

Thyrotropin-releasing hormone (TRH)

released by the hypothalamus - stimulates release of thyroid stimulating hormone (TSH) in the anterior pituitary. TSH acts ont he thyroid gland to stimulate production of T3 and T4 thyroid hormones

Endorphins

released from anterior pituitary - reduce your perception of pain

Growth hormone-releasing hormone (GHRH)

released from hypothalamus and stimulates the anterior pituitary to produce growth hormone (GH) during times of stress of accelerated growth involved in cell growth and regeneration can raise blood glucose levels during periods of stress.

Corticotropin-releasing hormone (CRH)

released from the hypothalamus and stimulates release of adrenocorticotropic hormone (ACTH) from the anterior pituitary. ACTH travels to adrenal gland and initiates production of corticosteroids (stress response and circadian rhythms)

Cortisol (glucocorticoid)

released in from adrenal cortex in response to stress and low blood glucose - increases blood glucose levels and suppressing inflammatory immune responses produced in the adrenal cortex

chronic stress

repeated exposure to stressful situations can have lasting effects on the body. Cortisol is associated with long term stress

Acute stress

results from specific events that involve unpredictability, threats, or novelty. associated with fight or flight response from sympathetic nervous system - epinephrine and norepinephrine

Aldosterone as a fluid regulator

secreted from adrenal cortex in response to low blood volume Regulated by RAAS - juxtaglomerular cells sense decrease in fluid levels and release Renin enzyme - renin cleaves angiotensinogen (from liver) to release angiotensin I. - Angiotensin-converting enzyme (in the lungs) converts angiotensin I to angiotensin II. - Angiotensin II travels to adrenal gland where it promotes release of aldosterone. - Aldosterone promotes sodium reabsorption in the distal tubule and collecting duct - Water follows its gradient from the kidney filtrate into bloodstream by osmosis, increasing blood volume and pressure. Aldosterone also increases excretion of H+ and K+ in the urine. - promotes fluid retention in the nephron without increasing plasma osmolarity NEGATIVE FEED BACK LOOP (oncce blood pressure returns to normal)

Pineal gland

secretes melatonin (derived from serotonin) - regulates sleep cycles and wakefulness - near the brain stem

Stress

short term and long term

Adrenal glands

sit on top of the kidneys; consists of the adrenal cortex and the medulla which synthesize hormones that affect blood glucose levels. Cortex secretes steroid hormones: corticoid-steroids (regulates: sugar, salt, and sex) Medulla produces AA-derived hormones epinephrine and norepinephrine

Alpha cells

specialized pancreatic cell - produce glucagon which is secreted in response to low blood glucose levels Glucagon can increase blood glucose levels via gluconeogenesis and glycogenolysis (release free glucose molecules into the blood stream) - glycogenolysis (breakdown of glycogen into glucose - gluconeogenesis (production of glucose from non-carbohydrate carbon substances)

Beta cells

specialized pancreatic cell - produces insulin and is secreted in respoonse to high blood glucose levels Insulin reduces blood sugar by promoting glucose uptake into body tissues - usually happens during a meal

Delta cells

specialized pancreatic cell - produces somatostatin (growth hormone inhibiting hormone) Reduces stomach acid secretion and blocks the release of other digestive hormones in an effort to slow down digestion Tells body to focus less on digesting food when there is other nutrients around

Blood glucose regulation

too little: tissues will starve too much: glucose not being stored, physiological consequences Insulin and glucagon main regulators (GH, epinephrine, coritsol also play role). - insulin and glucagon can also affect lipid and protein metabolism

Vitamin D in calcium regulation

two major forms of (D): D2 and D3 Calcitriol (D3) - hormonally active form of vitamin D - regulates calcium homeostasis - increases serum calcium levels - Promotes Ca+ absorption from the GI tract - reduces secretion of Ca+ in urine - stimulates bone resorption via osteoclast activation