Biology- Animal Form and Function 3 Flashcards
Endocrine System
Anterior Pituitary
mainly regulates hormone production by other glands–itself regulated by hypothalamus
- Direct Hormones
- Tropic Hormones
Endocrine System
Anterior Pituitary (Direct hormones)
directly stimulate target organs
- growth hormone (HGH)- aka somatotropin; stimulates bone and muscle growth
- prolactin- stimulates milk production in females
- endorphins- inhibit perception of pain (technically a neurohormone)
Endocrine System
Anterior Pituitary (Tropic hormones)
stimulate other endocrine glands
- Adrenocorticotrophic hormone (ACTH)- stimulates adrenal cortex => release glucocorticoids-involved in regulation of metabolism of glucose
- Thyroid-stimulating hormone (TSH)-stimulates thyroid gland (increase size, cell #) to release thyroid hormone (T4 and T3)
- Luteinizing hormone (LH)- females-stimulates formation of **corpus luteum **/ males- stimulates interstitial cells of testes to produce testosterone
- Follicle-stimulating hormone (FSH)-females- stimulates maturation of ovarian follicles to secrete estrogen/ males- stimulates maturation of seminiferous tubules and sperm prod
Endocrine System
Posterior Pituitary
does not synthesize hormones, stores ADH and oxytocin produced by hypothalumus
- antidiuretic hormone (ADH/vasopressin) increases reabsorption of water by increasing permeability of nephron’s** collecting duct** => water reabsorption and increased blood volume and pressure. Coffee blocks ADH.
- oxytocin-secreted during childbirth- increases strength of uterine contractions and stimulates milk ejection
Endocrine System
Pineal glands
secretes melatonin- plays role in circadian rhythm
Endocrine System
Thyroid
located on ventral surface of trachea
-
Thyroxine (T4) and Triiodothyronine (T3)
- derived from tyrosine and necessary for growth and neurological development in children and increase basal metabolic rate in body (negative feedback on TSH)
- HYPOTHYROIDISM- undersecretion => low heart rate and respiratory rate
- HYPERTHYROIDISM- oversecretion => increased metabolic rate and sweating
- both lead to goiters
- **Calcitonin **(tones down Ca2+) in blood
- decreases plasma Ca2+ by inhibiting its release from bone
- decreases osteoclast activity and number
- Disorders of the thyroid include **anchondroplasia **(AD; dwarfism) and **progeria **(AR; premature aging)
Endocrine System
Parathyroid
four pea-shaped structures attached to back of thyroid
-
Parathyroid hormone (PTH)- antagonistic to calcitonin
- *Raises Ca 2+ *concentrations in blood by stimulating release from bone
- increases osteocte absorption of Ca + P from bone; stimulates osteoblast proliferation
- increases renal Ca reabsorption
- *Raises Ca 2+ *concentrations in blood by stimulating release from bone
Endocrine System
Thymus
involved in immune response
- secretes thymosins that stimulate lymphocytes (WBCs) to become T-cells (identification and destroying of infected body cells)
Endocrine System
Adrenal Gland
on top of kidneys and consist of:
- glucocorticoids (cortisol and cortisone)- raise blood glucose levels (stimulates gluconeogenesis in the liver); affect fat and protein metabolism; stress hormones
-
mineralcorticoids (aldosterone)- increases reabsorption of Na+ and excretion of K+
- cause passive reabsorption of water in nephron => rise in blood volume/pressure
- cortical sex hormones (androgens = male sex hormone) effect is small due to testis
Endocrine System
Adrenal Medulla
_Epinephrine and norepinephrine _ (adrenaline and noradrenaline)- “fight or flight”- the catecholamines
- “fight or flight” (*sympathetic *N.S.); considered stress hormones
- glycogen => glucose, vasoconstrictor to internal organs and skin but vasodilator to skeletal muscle, increased heartbeat
Endocrine System
Pancreas
both exocrine and endocrine; has bundles of cells called **islet of Landerhans **which contains two cell types:
- alpha cells secrete **glucagon **(alpha “active”): catabolic, released when energy charge is low; raises blood glucose levels
- stimulates liver to glycogen => glucose
- beta cells secrete insulin (beta “bumming”): anabolic, released when energy charge is high; lower blood glucose levels
- stimulates liver (and most other body cells) to absorb glucose
- Liver + muscle cells: glucose => glycogen; fat cells: glucose => fat
- **Somatostatin **is released by delta cells of pancreas; inhibits both insulin and glucagon; possibly increases nutrient absorption time
Endocrine System
Testis
testosterone- spermatogenesis, secondary sex characteristics
Endocrine System
Ovaries
- Estrogen: menstrual cycle, secondary sex characteristics
- Progesterone: menstrual cycle, pregnancy
Endocrine System
Gastrointestinal hormones
- _Gastrin _ food in stomach, stimulates secretion of HCl
- Secretin small intestine- when acidic food enters from stomach => neutralize aciditiy of chime by secretion of alkaline bicarbonate
- _Cholecystokinin _ small intestine- presence of fats => causes contraction of gall-bladder and release of **bile **(involved in digestion of fats)
Endocrine System: Source
Posterior Pituitary
Hormone, Target, Action
ADH (antidiuretic hormone), kidney, increases absorption of water
Oxytoxin, mammary glands, milk letdown
