Hormones, Neurotransmitters, Signaling Molecules Flashcards
Somatostatin
Somatostatin: halts pro-digestion hormones- gastrin, secretin, CCK
also stalls stomach emptying and halts release of pancreatic insulin and glucagon
- also inhibits growth hormone release
Empty stomach promotes appetite, inhibits digestion
Full stomach inhibits appetite and stimulates digestion
- stomach acid and pancreatic secretion are stimulated
Antidiuretic Hormone (ADH) (Vasopressin)
Promotes water retention by increasing water reabsorption in collecting duct of kidneys
- promotion of aquaporins in collecting duct cells
Vasoconstriction, increases blood pressure and volume
HOWEVER, reduces osmolarity of blood (no effect on solute)
Norepinephrine
Produced by?
- stress hormone inhibits insulin, FIGHT OR FLIGHT
increases blood glucose levels
Produced by adrenal medulla (like epinephrine)
Placenta secretes
Human chorionic gonadotropin (hCG) (pregnancy tests test for this)
- Later progesterone and estrogen to maintain pregnancy
Glutamate
Neurotransmitter; excitatory, depolarizes neurons
- most common neurotransmitter, 90% of neuronal connections in brain
- learning and memory
Opposite of GABA
*Also an acidic amino acid
Regulation of neurotransmission by exogenous chemicals (from outside the body)
Selective Serotonin Reuptake Inhibitors (SSRIs): treatment of depression
Monoamine Oxidase Inhibitors (MAOIs): anti-tuberculosis, anti-depressant
Thyroid secretes (3) hormones
Non tropic hormones T3 and T4 which increase metabolic rate
- Hypothyroidism: slow metabolic rate - weight gain, fatigue
- Hyperthyroidism: accelerates metabolic rate - weight loss, tachycardia
calcitonin: reduces calcium concentration in the blood stream
- promotes storage of Ca in bone, increases urinary excretion of calcium
- “toning down” calcium in blood
Salivary amylase
Pancreatic amylase
Brush border disaccharides
Sucrase, maltase, lactase
Salivary amylase breaks starches into trisaccharides and disaccharides
- Stomach doesn’t enzymatically digest carbs but does so mechanically, increasing surface area exposed to enzymes in small intestine
Cholecystokinin induces pancreatic digestive hormones when chyme enters duodenum
- Pancreatic amylase hydrolyzes polysaccharides into di- and tri-
Brush border disaccharidases secreted by enterocytes in small intestine turn disaccharides into monosaccharides
sucrase: sucrose into glucose and fructose
maltase: maltose into two glucose
lactase: lactose into glucose and galactose
individuals deficient for lactase can’t digest lactose from milk/dairy
- indigested lactose passes to large intestine and fermented by bacteria –> results in gas (bloating, discomfort, flatulence)
Testes and Ovaries respond to _____
From where?
Function?
Leutinizing Hormone and Follicle Stimulating Hormone from anterior pituitary to release testosterone in males and estrogen in women, help develop secondary sex characteristics
Dopamine
Neurotransmitter; reward pathways and addiction
- increased by psychoactive drugs, euphoria
- mediates motor functions
loss of dopamine-secreting neurons in substantia nigra leads to Parkinsons disease
intracrine
signals travel the shortest distance
signals act within the cell that synthesizes them
autocrine
signals are released, then bind to receptors on the cell that synthesized them
juxtacrine
signals travel between cells in close contact
paracrine
signals travel between nearby cells
endocrine
signals (hormones) travel between distant cells via circulatory system
Parathyroid gland releases:
Release parathyroid hormone: opposes effects of calcitonin in order to increase calcium levels in blood
- promotes calcium absorption in the intestines
- reduces calcium storage in bone and calcium excretion in urine
Estrogen is produced by
Ovarian follicle cells, corpus luteum formed from ruptured follicle cells, and placenta
(anterior pituitary forms GnRH which leads to production of estrogen)
Amino acid derived hormones
Some behave like peptide hormones, some behave like steroids
Small molecules derived from a SINGLE amino acid
ex. T3 and T4 hormones derived from tyrosine - both hydrophobic, behave like steroid hormones w/ long lasting effects
Others like epinephrine and norepinephrine are water-soluble and act like peptide hormones - powerful but short lived
Some are amphipathic
Sleep/wakefulness
Circadian rhythm: 24 hr sleep/wake cycles
Pineal gland -> melatonin -> drowsiness
Adrenal cortex -> cortisol -> wakefulness
secretin
- regulation of gastric acid, regulation of pancreatic bicarbonate, and osmoregulation.
stimulates secretion of bicarbonate which quickly neutralizes acidic chyme (pH 6-7)
Where are steroid hormones produced?
How are peptide hormones produced
Steroid hormones synthesized from cholesterol in the smooth ER and diffuse directly through cell membrane into bloodstream
Peptide hormones produced by transcription of relevant mRNA, translation into polypeptide –> preprohormone
- preprohormone is secreted into rough ER and modified into prohormone –> golgi apparatus
in golgi, cleaved by peptidases and sometimes modified by glycosylation into peptide hormones
leave golgi in vesicles
cAMP
Not a hormone- regulates pivotal physiologic processes including metabolism, secretion, calcium homeostasis, muscle contraction, cell fate, and gene transcription. cAMP is a cyclic nucleotide that serves as a vital second messenger in several signaling pathways.
GnRH (gonadotropic releasing hormone
Corticotrophin-releasing hormone
triggers LH and FSH reproductive hormones
promotes ACTH which releases cortisol from adrenal glands
Vitamin D
Help body absorb calcium and phosphorus
adrenal cortex secretes
adrenal cortex: secretes steroid hormones corticosteroids
Release of corticosteroids is stimulated by adrenocorticotropic hormone (ACTH) from anterior pituitary
1. glucocorticoids (cortisol): sugar
- cortisol released in response to stress and low blood glucose, also suppresses inflammation
2. mineralocorticoids (aldosterone): influence fluid and salt balance
- aldosterone promotes fluid retention by increasing sodium reuptake
3. sex hormones (androgens and estrogens): low level production, moreso in sex organs
Adrenal medulla secretes:
interior region of each gland surrounded by the cortex
produces amino acid derived hormones epinephrine and norepinephrine (catecholamines)
- sympathetic fight or flight
- epinephrine used in Epi-Pens to treat anaphylaxis
Precursor for serotonin and melotonin
Tryptophan (Trp, W), aromatic amino acid
- W = double ring
Histamine
Allergic response hormone (without endocrine gland in traditional sense)
Histidine is precursor
Released by basophils and mast cells (inflammatory cells)
Prolactin
Induces lactation
Stress response, anxiety, depression, contributor to post-partum depression
Produced by anterior pituitary gland, not triggered by hypothalamus
Hormones from anterior pituitary not tropically triggered by hypothalamus
Prolactin: acts on the mammary glands to stimulate milk production
Endorphins: reduce reception of pain
Cortisol
adrenal cortex: secretes steroid hormones corticosteroids
Release of corticosteroids is stimulated by adrenocorticotropic hormone (ACTH) from anterior pituitary
- in response to low blood glucose, also suppresses inflammation
GABA
Opposite of glutamate, inhibitory
hyperpolarizes neurons
- slow or block certain signals in the brain
Atrial Natriuretic Peptide
Produced by cardiomyocytes in heart in response to high blood pressure: to decrease blood pressure by triggering blood vessel dilation and excretion of sodium in urine
Aldosterone
aldosterone: secreted by adrenal cortex in response to low blood pressure, low sodium, sympathetic NS
regulated by Renin-angiotensin-aldosterone system (RAAS)
promotes Na reabsorption, maintains osmolality
HDL
High Density Lipoprotein
Picks up stray cholesterol and other lipids and brings them back to the liver
Cholesterol transporter
High HDL = good cardiovascular health, decreased risk of atherosclerosis: unhealthy narrowing of blood vessels from plaque buildup
Acetylcholine
Neurotransmitter, muscle contractions
also communicates signals between central NS and autonomic NS
sends signals from parasympathetic neurons to target
Androgen
Testosterone
Estrogen:
estradiols, progesterone
Peptide hormones
Chains of amino acids, large and polar
- Can’t diffuse into cell, must interact via membrane receptors and secondary messengers (QUICK ONSET< SHORT LASTING)
- Steroid hormones diffuse through membrane, interact with cytosolic or nucleic receptors
Glucagon
Blood glucose is low, inhibits glycolysis, glycogenesis
- Promotes glycogenolysis, gluconeogenesis
Inhibits protein synthesis and allows proteins to be broken down
- amino acids can be taken up by liver cells for new glucose molecules via gluconeogenesis
Skeletal hormones
1. Parathyroid (PTH)- released by parathyroid glands
increases blood calcium
promotes osteoclast bone resorption
promotes absorption of dietary calcium in GI tract
2. Calcatriol- derivative of vitamin D which the body manufactured at the skin in response to UV light
increases blood calcium
3. Calcitonin- secreted from thyroid gland in response to high blood calcium
decreases blood calcium levels
inhibits activity of osteoclasts
reduce absorption of dietary calcium
Vitamins
Organic molecules with lots of carbon-hydrogen bonds
- Often serve as coenzymes for essential processes
ex. vitamin K a coenzyme in blood clotting
Vitamin D in calcium reabsorption
Effect of glucagon on lipid breakdown
Glucagon promotes lipolysis: triglyceride breakdown
- activates protein kinase A which activates hormone sensitive lipases in adipose tissue
Increases fatty acid conc in blood
glycerol can also be used for energy in liver and kidneys
3’-5’ exonuclease activity
DNA repair
Thymus hormone
secretes thymosin, hormone that helps T cells develop and mature
Serotonin
Regulates mood, appetite, sleep, intestinal movement
- current hypothesis is depression associated with low serotonin
Antidepressants: selective serotonin reuptake inhibitors (SSRIs)
- prevent serotonin from being taken up by neurons, stays in synapse longer
CCK:
stimulates release of digestive enzymes from pancreas and bile from gallbladder
How is glycogenolysis regulated differently in liver and skeletal cells?
Whats the main enzyme?
Glycogen phosphorylase is regulated by epinephrine hormone in skeletal cells
- when epinephrine binds to receptors on skeletal cells, kicks off signaling cascade which activated glycogen phosphorylase
- releases G1P
In the liver, glucagon activates glycogen phosphorylase to raise blood glucose when you haven’t eaten in a while
Main enzyme for glycogenesis regulation?
Glycogen synthase (responsible for lengthening glycogen branches)
- Insulin upregulated glycogen synthase, causing cells to make more glycogen
parasympathetic nervous system (PNS) releases the hormone
acetylcholine to slow the heart rate.
Vitamin A
Retinal and retinol
- essential for vision
interacts with opsin to form rhodopsin, which is present in the rods of the retina
- Used for low light vision
- Fat soluble
Deficiency in Vitamin C (ascorbic acid)
Common with sailors, no fresh food
- scurvy: weakness, gum disease, excess bleeding, death
Vitamin C required for collagen synthesis
How are peptide hormones produced
- Peptide hormones produced by transcription of relevant mRNA, translation into polypeptide –> preprohormone
- preprohormone is secreted into rough ER and modified into prohormone –> golgi apparatus
- in golgi, cleaved by peptidases and sometimes modified by glycosylation into peptide hormones
- leave golgi in vesicles
Neuroendocrine integration:
nervous system senses changes in environmental conditions and communicates to endocrine system
Endocrine regulates
Blood glucose
Blood calcium
Stress
Fluid balance
Metabolic rate
Sexual development
What hormones besides glucagon and insulin affect blood sugar?
Cortisol (glucocorticoid released by adrenal cortex): increases blood glucose in fasting state by activating gluconeogenesis and glycogenolysis in the liver
Epinephrine (adrenal medulla): raises blood sugar by stimulating glycogenolysis in liver and muscle cells; fight or flight response
Growth hormone: increases blood glucose under intense physical stress or periods of growth and development
