Endocrine Sysem Flashcards
Hormonal Release Mechanisms
- Humoral release-release of hormones due to concentrations of substances in the blood (humerous).
ie. blood sugar - insulin & glucagon - Nervous System - nervous system stimulate the release of a hormone.
ie. sympathetic n.s.->adrenal medulla/adrenal gland->epinephrine - Hormonal-hormone released from a gland, acts on another endocrine gland, to release a hormone.
Anterior pituitary release tropic (1st) hormone->TSH,ACTH,LH,FSH->endocrine gland->release hormone
Functions of the
Endocrine System
Release hormones into the blood circulatory system or lymphatic system
Release hormones, which act on -> target tissues (organs)->organs have receptor sites for the specific hormone
Alter cellular activity:
- Increase or decrease mitosis
- Turn enzymes on or off
- Make new proteins for enzymes
- Alter membrane permeability, which will increase or decrease extracellular or intracellular environment
- Secretory activity
Chemical Types of
Hormones
- Amino acid based/protein based
- made from amino acids
- most common in the body
- act on cells by secondary messenger system
- ex: vasopressin, TSH, angiotensin - Steroid based hormones
-made from cholesterol (fat)
Cortisol, estrogen, sex hormones
-direct gene messenger activation system
Secondary Messenger Action
Steps
-hormone react with receptor on cell surface
-receptor activates G-protein
-G-protein then activates adenylate cyclase (enzyme)
adenylate cyclase converts ATP->C amp (cyclic amp)
C amp activate protein kinase, which will either make proteins, effect enzyme action, or turn off enzyme
Direct Gene Activation System
- steroid hormone diffuses thru cell membrane
- enters nucleus, combine with receptor complex to alter gene expression, transcription, and translation
-Glucocorticoid effects in 60-90 mins, however negative feedback effect on ACTH secretion occurs within minutes
-complex alter the DNA (2 strands)
DNA controls everything & works quickly
Hypothalamus
Most important homeostatic organ
Link between nervous & endocrine systems
Release excitatory & inhibitory hormones for anterior pituitary
Hormonal control
No blood brain barrier-so hormones can move freely in & out
Produce oxytocin & ADH (anti-diuretic hormone)
Controls autonomic nervous system
Define tropic hormones
Acts on another endocrine gland to cause it to release a hormone
Anterior Pituitary Gland
Glandular Tissue
Tropic: TSH -> thyroid gland ACTH -> adrenal cortex gland LH -> gonads FSH -> gonads
Non-tropic:
Growth hormone -> bones & muscles
Prolactin -> mammary glands
MSH -> melanocyte stimulating hormone acts on skin
Posterior Pituitary Gland
Nervous tissue
- connect to hypothalamus
- store & release oxytocin & ADH (anti-diuretic hormone), but made in the hypothalamus
Thyroid Gland
TSH acts on thyroid gland
A) follicular cell
-use iodine (from salt)-only cell in body that uses iodine
-secrete thyroid hormone (T7) - regulate basal metabolic rate (BMR)-how fast do we burn calories or metabolism
T3-thiodothyromine
T4-thyroxine
B) para follicular cells - do not use iodine
- located in between follicle cells in the thyroid
- secrete calcitonin - tones down blood calcium levels by activating osteoblasts (builds bones)
- example of humoral release - takes Ca+ out of blood, put into bones to store
Parathyroid Gland
- dorsal side of thyroid
- secretes parathyroid hormone, which raise blood Ca+ levels by activating osteoclasts. Osteoclasts break down bone, which releases Ca+
- increase absorption in intestines
- decrease excretion in the kidneys
Hyperactive parathyroid gland can cause osteoporosis . Osteoclasts tearing down bone, which makes bones thinner & weaker
Adrenal Gland
A. ACTH acts on adrenal cortex - cholesterol based hormones
- Mineral corticoids-ie. aldosterone - acts on DCT, Na+ will be re absorbed & H2O will follow. Helps maintain pH
- Glucocorticoids-ie. cortisol & hydrocortisone
- Gonado corticoids - ie. androgens, sexual development, secondary growth (breasts, facial, & pubic hair)
B. nervous system acts on adrenal medulla, secretes epinephrine (sympathetic response)
Ie. working out and some salty or sugary foods- gives euphoric feeling
Pancreas
Endocrine & exocrine
Islet cells
Beta cells release insulin - lowers blood sugar
Alpha cells release glucagon - raise blood sugar
Gonads
LH & FSH act on gonads
Gonads produce gametes (egg & sperm)
A. Ovaries - development/growth of a primary follicle with egg/oocyte, ovary rupture, release egg, follicle stays in ovary
Estrogen & progesterone help regulate ovarian & uterine cycle
Egg & sperm have 23 chromosomes each. Only place in the body that doesn’t have 46 chromosomes
B. development of sperm
Interstitial cells in testes produce testosterone
Spermatogenesis (production of sperm) -> meiosis 4 daughter cells unique to each other, each cells has 23 chromosomes
Thyrotropin releasing hormone (TRH)
Where is produced
What does it stimulate
From hypothalamus
Stimulates anterior pituitary to produce TSH,
Which then Stimulates the thyroid to produce thyroxine
