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MCAT > Hormones, Neurotransmitters, Signaling Molecules > Flashcards

Hormones, Neurotransmitters, Signaling Molecules Flashcards

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MCAT flashcards
1
Q

Somatostatin

A

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
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2
Q

Antidiuretic Hormone (ADH) (Vasopressin)

A

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)

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3
Q

Norepinephrine

Produced by?

A
  • stress hormone inhibits insulin, FIGHT OR FLIGHT

increases blood glucose levels

Produced by adrenal medulla (like epinephrine)

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4
Q

Placenta secretes

A

Human chorionic gonadotropin (hCG) (pregnancy tests test for this)

  • Later progesterone and estrogen to maintain pregnancy
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5
Q

Glutamate

A

Neurotransmitter; excitatory, depolarizes neurons

  • most common neurotransmitter, 90% of neuronal connections in brain
  • learning and memory

Opposite of GABA

*Also an acidic amino acid

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6
Q

Regulation of neurotransmission by exogenous chemicals (from outside the body)

A

Selective Serotonin Reuptake Inhibitors (SSRIs): treatment of depression

Monoamine Oxidase Inhibitors (MAOIs): anti-tuberculosis, anti-depressant

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7
Q

Thyroid secretes (3) hormones

A

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
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8
Q

Salivary amylase

Pancreatic amylase

Brush border disaccharides

Sucrase, maltase, lactase

A

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)
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9
Q

Testes and Ovaries respond to _____

From where?

Function?

A

Leutinizing Hormone and Follicle Stimulating Hormone from anterior pituitary to release testosterone in males and estrogen in women, help develop secondary sex characteristics

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10
Q

Dopamine

A

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

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11
Q

intracrine

A

signals travel the shortest distance

signals act within the cell that synthesizes them

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12
Q

autocrine

A

signals are released, then bind to receptors on the cell that synthesized them

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13
Q

juxtacrine

A

​signals travel between cells in close contact

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14
Q

paracrine

A

​signals travel between nearby cells

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15
Q

endocrine

A

signals (hormones) travel between distant cells via circulatory system

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16
Q

Parathyroid gland releases:

A

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
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17
Q

Estrogen is produced by

A

Ovarian follicle cells, corpus luteum formed from ruptured follicle cells, and placenta

(anterior pituitary forms GnRH which leads to production of estrogen)

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18
Q

Amino acid derived hormones

A

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

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19
Q

Sleep/wakefulness

A

Circadian rhythm: 24 hr sleep/wake cycles

Pineal gland -> melatonin -> drowsiness

Adrenal cortex -> cortisol -> wakefulness

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20
Q

secretin

A
  • regulation of gastric acid, regulation of pancreatic bicarbonate, and osmoregulation.

stimulates secretion of bicarbonate which quickly neutralizes acidic chyme (pH 6-7)

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21
Q

Where are steroid hormones produced?

How are peptide hormones produced

A

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

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22
Q

cAMP

A

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.

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23
Q

GnRH (gonadotropic releasing hormone

Corticotrophin-releasing hormone

A

triggers LH and FSH reproductive hormones

promotes ACTH which releases cortisol from adrenal glands

24
Q

Vitamin D

A

Help body absorb calcium and phosphorus

25
Q

adrenal cortex secretes

A

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

26
Q

Adrenal medulla secretes:

A

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
27
Q

Precursor for serotonin and melotonin

A

Tryptophan (Trp, W), aromatic amino acid

  • W = double ring
28
Q

Histamine

A

Allergic response hormone (without endocrine gland in traditional sense)

Histidine is precursor

Released by basophils and mast cells (inflammatory cells)

29
Q

Prolactin

A

Induces lactation

Stress response, anxiety, depression, contributor to post-partum depression

Produced by anterior pituitary gland, not triggered by hypothalamus

30
Q

Hormones from anterior pituitary not tropically triggered by hypothalamus

A

Prolactin: acts on the mammary glands to stimulate milk production

Endorphins: reduce reception of pain

31
Q

Cortisol

A

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
32
Q

GABA

A

Opposite of glutamate, inhibitory

hyperpolarizes neurons

  • slow or block certain signals in the brain
33
Q

Atrial Natriuretic Peptide

A

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

34
Q

Aldosterone

A

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

35
Q

HDL

High Density Lipoprotein

A

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

36
Q

Acetylcholine

A

Neurotransmitter, muscle contractions

also communicates signals between central NS and autonomic NS

sends signals from parasympathetic neurons to target

37
Q

Androgen

A

Testosterone

38
Q

Estrogen:

A

estradiols, progesterone

39
Q

Peptide hormones

A

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
40
Q

Glucagon

A

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
41
Q

Skeletal hormones

A

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

42
Q

Vitamins

A

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

43
Q

Effect of glucagon on lipid breakdown

A

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

44
Q

3’-5’ exonuclease activity

A

DNA repair

45
Q

Thymus hormone

A

secretes thymosin, hormone that helps T cells develop and mature

46
Q

Serotonin

A

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
47
Q

CCK:

A

stimulates release of digestive enzymes from pancreas and bile from gallbladder

48
Q

How is glycogenolysis regulated differently in liver and skeletal cells?

Whats the main enzyme?

A

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

49
Q

Main enzyme for glycogenesis regulation?

A

Glycogen synthase (responsible for lengthening glycogen branches)

  • Insulin upregulated glycogen synthase, causing cells to make more glycogen
50
Q

parasympathetic nervous system (PNS) releases the hormone

A

acetylcholine to slow the heart rate.

51
Q

Vitamin A

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
52
Q

Deficiency in Vitamin C (ascorbic acid)

A

Common with sailors, no fresh food

  • scurvy: weakness, gum disease, excess bleeding, death

Vitamin C required for collagen synthesis

53
Q

How are peptide hormones produced

A
  1. Peptide hormones produced by transcription of relevant mRNA, translation into polypeptide –> preprohormone
  2. 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
54
Q

Neuroendocrine integration:

A

nervous system senses changes in environmental conditions and communicates to endocrine system

55
Q

Endocrine regulates

A

Blood glucose

Blood calcium

Stress

Fluid balance

Metabolic rate

Sexual development

56
Q

What hormones besides glucagon and insulin affect blood sugar?

A

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

MCAT (8 decks)

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