endocrine system 1 Flashcards
nervous system vs endocrine system
nervous
- communicates via AP and release of NT
- extremely rapid (less than a sec)
- frequency
- neurons going to a specific site
endocrine system
-communicates via hormones into the blood stream
-slow ( minutes hours days)
-amplitude modulation
-receptor specificity (hormone will only bind to that spot)
tissues and cells capable of secreting and responding to hormones
endocrine system overview
includes endocrine glands that secret hormones and hormone secreting cells located in various organs
endocrine vs exocrine
endocrine glands are DUCTLESS and release hormones into the blood (this class)
exocrine glands secrete their products into a duct, then either exit body or enter lumen/another organ (can be duct or ductless) (more 132)
hormones
chemical messengers that are formed in one organ or part of the body and carried in the blood to another organ or part
- target cells
- can alter the functional activity of just one organ or of various numbers of them
- heavily depends on target receptors and target cells
3 classes of hormones
peptide/protein
steroid
amine
hypothalamus
considered part of endocrine system
-portal system or blood system that connects hypothalamus to anterior pituitary gland
anterior pituitary gland
produces hormones with diverse actions related to metabolism, reproduction, growth and others
-ACTH, FSH, LH, GH, PRL, TSH
HPA axis
interaction between hypothalamus-pituitary gland and adrenal gland
a single gland can secrete
a single cell type can secrete
single gland can secrete multiple hormones
single cell types can secret only one hormone**
hormones can be secreted by certain endocrine glands but also other cell type and serve in these other locations as NT’s, paracrine or autocrine substances
paracrine activation hormone vs autocrine
paracrine hormone is released to cell adjacent to the cell that is releasing
autocrine is releasing itself
amine hormones derivatives of what
amino acid tyrosine
amine hormones water soluble?
are water soluble
examples of amine hormones
- thyroid hormones (produced by thyroid gland)
- epinephrine and norepinephrine (produced by adrenal medulla)
- dopamine (produced by hypothalamus)
thyroid hormones produced by what? where
produced by thyroid gland on trachea
-just above the sternum
epinephrine and norepinephrine produced by ? where? which hormone is secreted more?
adrenal medulla
sits on top of kidney, medulla middle
- epinephrine is secreted 4x more than norepinephrine
- it is secreted more because it eventually gets converted to norepi by PMMT?
dopamine produced by?
synthesized by neurons in hypothalamus (catecholamine hormone = produced in brain/nerve tissue/adrenal gland)
posterior pituitary vs anterior pituitary
posterior still neural tissue
anterior is seperate
can develop cancer in this region
peptide and protein hormones made of?
polypeptides
- can be short polypeptides (peptides)
- can be long polypeptides with tertiary structure (proteins)
→these range from small peptides to large proteins which contain carbohydrates which makes them glycoproteins = peptide hormones
- are water soluble
- doesn’t require secondary transporter, diffuse right into blood
peptide hormones sequence of events
Synthesized on ribosome of endocrine cells as larger molecules known as pre-prohormones which are then cleaved to pro hormones by protealytic envymes in the rough endoplasmic reticulum.
Then pro hormone is packaged into secretory vesicles by the Golgi apparatus. When cell is stimulated to release contents of the secretory vesicles by exocytosis, there are other peptides that are secreted along with the hormone. Eg. Insulin and c-peptide
steroid hormones produced by
adrenal cortex (outside) and the gonads (testes/ovaries)
-are lipid soluble, NOT water soluble
→require a fat bubble to transport them through blood, still through blood but need help
steroid hormones formation
Steroid hormones are based on cholesterol** is a very distinct structure
DHEA- precursors to steroid hormone
Hormone producing cells are stimulated by the binding of an anterior pituitary gland hormone to its plasma membrane protein. The receptors are linked to G proteins which activated adenylyl cyclase and cAMP production. Protein kinase A then gets activated by cAMP and results in phosphorylation of numerous intracellular proteins. This leads cholesterol to energy several enzymatic conversions and become the final steroid hormone which is diffused into blood
hormones of the adrenal cortex - Aldosterone
known as mineralocorticoid
- production is under control of angiotensin 2 (orginally from liver)
- many effects on maintaining salt balance in blood.
- were able to retain or lose water as we need, water follows salt, able to regulate salt in urine
- if we retain water we increase blood volume and in turn increase BP
-renin is activator of the entire pathway which gets release of the condition of low blood pressure
hormones of AC - cortisol and corticosterone and glucocorticoids functions?
- metabolism of glucose and other organic nutrients
- facilitation of the body’s responses to stress and regulation of the immune system
“glucocorticoids” bc they have an important effect on metabolism of glucose
-also release sugar into bloodstream when you are stressed
high stress= high cortisol=high chance of diabetes
- glucocorticoids suppress release of pro inflammatory cytokines
- regulates immune cell maturation, regulate hydration, regulate apoptosis (cell death)
AC hormones -DHEA and Androstenedione
- DHEA and androstenedione belong to class of steroid hormones called androgens
- functions in adult female and female and male in the fetus and at puberty
gonads hormones -testes and ovaries
testes- secrete testosterone
ovaries - secrete estrogens (estradiol and estrone)
-secretes progesterone (maintaining corpus luteum)
estradiol expressed in large amounts
breakdown of peptide/protein/ steroid/ amine characteristics
check last slide
examples of peptide/ protein, steroid and amine hormones
peptide/protein : pituitary hormones
steroid : testosterone, estrogen and cortisol
amine : catecholamines and thyroid hormone
precursors for peptide/ protein, steroid and amine
peptide/protein : amino acids
steroid : cholesterol
amine: tyrosine
solubility of protein/peptide, steroids and amines
peptide/protein: dissolves
steroid : bound to blood proteins
amine : depends
time before onset of action for each
peptide/protein : quick
steroid : slow
amine : depends
