Pancreas/Gonads/Pineal/Misc Flashcards by Cal Schiller

endocrine and exocrine gland

endocrine secretes directly into circulation

Pancreas

but almost ALL exocrine

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A flattened organ located in the curve of the duodenum (the first part of the small intestine)

Contains a head, body and tail

Pancreas

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In the middle of the exocrine acini lie 1-2 million endocrine cells called ____ (Islets of Langerhans)

(Pancreas Endrocrine cells)

pancreatic islets

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4 types of islet cells

Alpha
Beta
Delta
F (aka PP)

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20% of islet cells, secrete GLUCAGON

Alpha (A) Cells

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75% of islet cells, secrete INSULIN

Beta (B) Cells-

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4% of islet cells, secrete somatostatin (GHIH)

Delta (D) Cells

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1% of islet cells, secrete pancreatic polypeptide

F Cells (aka PP cell)

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Stimulates liver to break down stored glycogen (glycogenolysis)

Stimulates liver to take up serum amino acids and convert them into glucose (gluconeogenesis)

Stimulates the break down of triglycerides into free fatty acids and glycerol (lipolysis)

Glucagon

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Receptors located in pancreas sense low blood glucose levels which trigger a release of

glucagon

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Glucagon regulated through ___ feedback from serum glucose levels

negative

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lowers blood glucose levels

insulin

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Presence of food in small intestine triggers release of glucose-dependent insulinotropic peptide (GDIP; aka Gastric Inhibitory Peptide[GIP])

This triggers release of insulin from pancreas

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Continued nutrient absorption raises blood glucose levels which further stimulate pancreas to continue to release insulin

insulin

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Facilitates glucose uptake into cells

Stimulates glycolysis (metabolism of glucose for generation of ATP)

Stimulates glycogenesis (excess glucose into glycogen in liver)

Promotes triglyceride and protein synthesis

Insulin

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Insulin Regulated through negative feedback from ___ levels

serum glucose

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Acts in paracrine manner by inhibiting both insulin and glucagon release

Acts in an endocrine manner by inhibiting release of hGH from anterior pituitary gland

Somatostatin (aka GHIH)

also found in pancreas! (from Delta cells)

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Inhibits somatostatin release

Inhibits gallbladder contraction

Inhibits secretion of bicarb and certain enzymes from pancreas

Thought to play a role in appetite suppression

Pancreatic polypeptide

from F cells

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_____ inhibits release of insulin, stimulates secretion of glucagon from alpha cells of pancreas

Hypoglycemia

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Glucagon acts on ___.

Stimulates conversion of glycogen into glucose (glycogenolysis)

Stimulates gluconeogenesis. Glucose is then released by hepatocytes into blood stream

hepatocytes (liver cells)

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glycogen into glucose

(glycogenolysis)

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inhibits the release of glucagon, stimulates secretion of insulin by beta cells

Hyperglycemia

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Facilitates diffusion of glucose into cells

Speeds conversion of glucose into glycogen (glycogenesis)

Increases uptake of amino acids to increase protein synthesis

Speeds synthesis of fatty acids (lipogenesis)

Insulin (acts on various cells in the body)

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synthesize and secrete estrogen, progesterone, inhibin, relaxin

Ovaries

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___, ____ along with LH and FSH (from ant pituitary) regulate the menstrual cycle, maintain pregnancy, prepare the mammary glands for lactation

Estrogen, progesterone

*Inhibin and Relaxin are only produced in large quantities when ___ occurs, otherwise negligible levels exist

pregnancy

Inhibin is used to inhibit ___. | Deters follicle development

FSH

Relaxes the cartilage of the pubic symphysis for passage of the baby Helps to relax/widen the cervix

Relaxin

produce testosterone, inhibin

Testes

Stimulates decent of testes before birth Regulates production of sperm Regulates male secondary sex characteristics

Testosterone

Inhibin inhibits FSH (concentration based). FSH stimulates ____. Inhibin therefore inhibits ____ when concentration is high enough

spermatogenesis

Pineal gland secretes

melatonin Melatonin is thought to contribute to the setting of the body’s biological clock As more melatonin is secreted in hours of darkness than light, it is thought to promote sleepiness

Synthesized/secreted by muscles cells of heart atria when stretched too far. Has blood pressure reducing effects

Atrial-Natriuretic Peptide (ANP; aka A-type natriuretic peptide)

Synthesized/secreted by muscle cells of the heart ventricles when stretched too far. Has blood pressure reducing effects

B-type natriuretic peptide (BNP)

Kidneys secrete?

Renin Calcitriol Erythropoetin

stimulates release of aldosterone

Renin

aids in absorption of calcium in GI tract

Calcitriol

stimulates new RBC synthesis in bone marrow

Erythropoietin

Leptin – promotes satiety signal being sent to the brain Adiponectin – helps to reduce insulin resistance

Adipose Tissue

promotes satiety signal being sent to the brain

Leptin

helps to reduce insulin resistance

Adiponectin

modified to form Vitamin D

Cholecalciferol (from skin)

Produces multiple hormones that promote maturation of T-Cells (WBC’s that destroy microbes)

Thymus

Thymosin Thymic humoral factor Thymic factor Thymopoietin

Thymus | ATROPHIES WITH AGE

From liver: raises BP (part of renin-angiotensin-aldosterone system)

angiotensinogen

From liver, stimulates increase in platelet production

thrombopoietin

From liver, blocks release of iron into body fluids

hepcidin

Gastrin Cholecystokinin (CCK) Glucose-dependent insulinotropic peptide (GDIP) aka gastric inhibitory peptide (GIP) Secretin

Gastrointestinal Tract

Secreted by G Cells in stomach Stimulated by Ingestion of protein containing meal Distention of stomach Vagal stimulation

Gastrin

Promotes H+ ion secretion from gastric parietal cells (leading to churning/vomiting) Stimulates growth of gastric mucosa

Gastrin

Secreted by I cells of the small intestine Stimulated by: Meals containing fats and proteins Monoglycerides and fatty acids present in luminal contents Small peptides and amino acids present in luminal contents

Cholecystokinin (CCK)

Causes gallbladder contraction Slows gastric emptying Stimulates secretion of pancreatic enzymes Stimulates bicarb secretion from pancreas Stimulates growth of exocrine pancreas and the gallbladder *Thought to provide sense of satiety (fullness)

Cholecystokinin (CCK)

Secreted by K cells of the small intestine Stimulated by: presence of the following in luminal contents Glucose (carbohydrates) Fatty acids (fats) Amino acids (proteins)

Glucose-dependent Insulinotropic Peptide (aka gastric inhibitory peptide)

Stimulates insulin release | Inhibits H+ ion secretion by gastric mucosa

Glucose-dependent Insulinotropic Peptide (aka gastric inhibitory peptide)

Secreted by S cells of the small intestine

Secretin

``` Stimulated by presence of the following in luminal contents Fatty acids (fats) Contents with pH <4.5 arrive in small intestine (increase in H+ ions) ```

Secretin

Stimulates secretion of pancreatic bicarb Stimulates secretion of biliary bicarb (gallbladder) Inhibits effects of gastrin

Secretin

Found in all cells in the body except RBC’s Act as local (paracrine, autocrine) hormones in response to chemical or mechanical stimuli Present in the blood briefly due to rapid inactivation

Eicosanoids

alter smooth muscle contraction, glandular secretions, blood flow, reproductive processes, platelet function, respiration, nerve impulse transmission, lipid metabolism, immune responses

Prostaglandins (PG’s) Eicosanoids

stimulates chemotaxis* of WBC’s and mediates inflammation

Leukotrienes (LT’s) Eicosanoids

Synthesized in any tissue that has mast cells (most tissues) and in platelets Stimulated by: Physical trauma to cells containing histamine Immune response to foreign pathogens (allergens)

Histamine

Contraction of smooth muscle in lungs, uterus, stomach Dilation of blood vessels in general (lower BP) Stimulates gastric acid secretion in stomach Increases permeability of capillaries and post-cap venules to WBC’s

Histamine

Synthesized by cells in the intestines, brain, CNS Stimulated by numerous situations and carries multiple functions depending on the type of serotonin receptor that gets activated Mood, anxiety, sleep, appetite, temperature, eating behavior, sexual behavior General body movement, gastrointestinal motility Depending on concentration, can act as a vasoconstrictor or a vasodilator

Serotonin

Alarm Stage (usually minutes to hours) The Resistance Reaction (hours to weeks) The Exhaustion Response

Stress Respnse

raise blood glucose levels

glucagon

GDIP (glucose-dependent insulinotrophic peptide) is what actually triggers...

insulin | GDIP; aka Gastric Inhibitory Peptide[GIP]

liver takes up serum amino acids and convert them into glucose

gluconeogenesis

break down of triglycerides into free fatty acids and glycerol

lipolysis

Presence of food triggers _____ which then trigger inslulin from pancreas

glucose-dependent insulinotropic peptide (GDIP; aka Gastric Inhibitory Peptide[GIP])

Insulin performs:

facilitates glucse uptake by cells stimulates glycolysis stimulates glycogenesis promotes triglyceride/protein synthesis

used to inhibit FSH | gonads

Inhibin

Deters follicle development

inhibin

relaxes cartilage of public symphisis for delivery | gonads

relaxin

inhibits FSH (concentration based) | in men

inhibin

Secretes melatonin

pineal gland

IGF 1 Angiotensinogen Thrombopoietin Hepcidin

Liver

Causes gallbladder contraction

CCK

gastric empyting

CCK

secretion of pancreatic enzymes

CCK

bicarb secretion

CCK

Secreted by K cells of the small intestine

Glucose-dependent Insulinotropic Peptide (aka gastric inhibitory peptide)

Stimulated by presence of the following in luminal contents Glucose (carbohydrates) Fatty acids (fats) Amino acids (proteins)

Glucose-dependent Insulinotropic Peptide (aka gastric inhibitory peptide)

Secreted by S cells of the small intestine

Secretin

``` Stimulated by presence of the following in luminal contents Fatty acids (fats) Contents with pH <4.5 arrive in small intestine (increase in H+ ions) ```

Secretin

Synthesized by cells in the intestines, brain, CNS Estimated that 90% of total serotonin is made in the intestines as a reaction to the bacterial colonies present Although not synthesized in platelets, platelets uptake free serotonin from blood stream and store it until needed

Serotonin

Mood, anxiety, sleep, appetite, temperature, eating behavior, sexual behavior General body movement, gastrointestinal motility Depending on concentration, can act as a vasoconstrictor or a vasodilator

serotonin

The body attempts to counteract all stress with stress response

Also called general adaptation syndrome (GAS) | Thought to be controlled from the hypothalamus

Initiated by any stressor (emotional, physical, mental) Indirectly, adrenal cortex stimulated to release glucocorticoids (cortisol) Circulating levels of lymphocytes and eosinophils decrease (impairs the immune response) Activity of the sympathetic nervous system and adrenal medulla increase significantly

Alarm Stage (usually minutes to hours)

After the stressor has ceased, but still dealing with the psychological aftermath Considered to be a normal “recovery phase” after the initial alarm stage

The Resistance Reaction (hours to weeks) Glucocorticoids (cortisol) levels should decline Immune system begins to replenish its lymphocytes and eosinophils Sympathetic stimulation reduces HR/SV/CO to return to normal levels Vascular tone decreases (decreases BP) Parasympathetic system stimulated Allows for return to normal digestion Return to normal rest patterns for the body and mind

If the stressor is not removed successfully, or the resistance reaction (stage 2) was not sufficient, only then will the body move into the exhaustion phase Depletion of physical and psychological energy levels The body can no longer “cope” with the stressor

The Exhaustion Response Prolonged exposure to cortisol Prolonged stimulation of sympathetic nervous system

This stage is where mental and physical illnesses begin to surface

The Exhaustion Response

hGH production is reduced causing muscle atrophy

Aging

T3/T4 production reduced by worn-out thyroid causing a reduction in metabolism leading to increase in body fat and ultimately hypothyroidism

TRH/TSH increases though as we age because of lack of negative feedback*

In aging,Increased PTH levels likely due to decreased dietary calcium intake

Calcitriol and calcitonin levels reduced as well leading to bone injury

In aging, adrenal cortex becomes fibrous leading to decreased cortisol and aldosterone

Medulla is usually unaffected though because the cortex fibroses around the medulla, therefore protecting it

In aging, pancreas releases insulin more slowly (if at all) and receptor sensitivity to glucose declines (due to overuse)

Leads to blood glucose levels remaining elevated

Ovaries decrease in size and eventually stop responding to gonadotropins in aging

Decreased production of estrogen leading to osteoporosis, hyperlipidemia, atherosclerosis Leads to menopause (its all downhill from here…)

___ decrease in size but still produce testosterone in viable levels in aging.

Testes

Effects of decreased testosterone production aren’t usually seen until advanced age

Usually same number of sperm produced but the quality is lacking Morphologically abnormal Decreased sperm motility