Module 9

endocrine glands

hypothalamus
pituitary gland
thyroid gland
parathyroid glands
pancreas
adrenal glands
gonads (testes and ovaries).

endocrine hormone

a hormone secreted into the bloodstream that acts on distant target cells
"in" the blood

paracrine hormone

secreted directly into interstitial fluid to act on neighboring cell
"pair"

autocrine hormone

act on the same cell that secreted them
"autobiography"

Melatonin

sleep cycle

Tropic hormone

hormone that stimulates the secretion of another hormone

3 types of hormone

protein, steroid, amino acids (catecholamines, thyroids)

protein hormones

water soluble (can't enter cell)
ie insulin, growth hormone

steroid hormones

lipid soluble (enters cell)
estrogen, testosterone

catecholemines

water soluble (can't enter cell)
epinephrine, norepinephrine

thyroid hormones

lipid soluble (enters cell)
T3 & T4

Hormones of hypothalamus

Anterior: GHRH, GHIH, TRH, CRH, GnRH, PRH, PIH
Posterior: ADH & Oxytocin

Gonadotropin-Releasing Hormone (GnRH)

secretion of Follicle stimulating Hormone (FSH) and Luteinizing Hormone (LH)

Thyrotropin-Releasing Hormone (TRH)

secretion of Thyroid Stimulating Hormone (TSH)

Corticotropin-Releasing Hormone (CRH)

secretion of Adrenocorticotrophic Hormone (ACTH)

Growth Hormone-Releasing Hormone (GHRH)

secretion of Growth Hormone (GH)

Growth Hormone-Inhibiting Hormone (GHIH, somatostatin)

Inhibit secretion of GH

Prolactin-Inhibiting Hormone (PIF, dopamine)

Inhibit secretion of Prolactin (PRL) from Anterior Pituitary

Hormones of the anterior pituitary gland

TSH
FSH
LH
ACTH
GH
Prolactin

Thyroid-stimulating Hormone (TSH)

Target tissue: Thyroid gland
secretion of Thyroxin (T4) and Triiodothyronine (T3)

Follicle-stimulating Hormone (FSH)

Target Tissue: gonads
Male: Sperm production
Female: Follicle development and Estrogen secretion

Luteinizing Hormone (LH)

Target tissue: Ovaries and testes
Male: Testosterone production
Female: Ovulation, Progesterone secretion

Adrenocorticotrophic Hormone (ACTH)

Target tissue: Adrenal cortex
Primary action: Stimulate secretion of Glucocorticoids (Cortisol)

Growth Hormone (GH)

Target tissue: Most tissues
Stimulates tissue growth
Regulation of metabolism

Prolactin

Target tissue: Mammary glands and ovaries
Stimulates milk production
Up-regulation of FSH and LH receptors

Hormones of the posterior pituitary gland

Oxytocin
Antidiuretic Hormone (ADH) (Vasopressin)

Oxytocin

Target tissue: Uterus and mammary glands
Stimulates uterine contractions
Stimulates release of milk
Social and moral feelings (Brain)

Antidiuretic Hormone (ADH) (Vasopressin)

Target tissue: Kidneys and blood vessels
Renal water reabsorption (reduced urine volume)
Vasoconstriction

Hormones of the thyroid gland

Thyroxine (T4)
Triiodothyronine (T3)

Thyroxine (T4)

Target tissue: Whole body
Primary action: Metabolism and growth

Triiodothyronine (T3)

Target tissue: Whole body
Primary action: Metabolism and growth

Parathyroid hormone (PTH)

Target tissue: Bone
Increase blood calcium (break down bones - calcitonin)

Hormones of the pancreas

Insulin and Glucagon

Insulin

Target tissue: Skeletal muscle, Adipose tissue, Liver
Lowers blood glucose levels by increasing glycogen synthase

Glucagon

Target tissue: Liver
Raises blood sugar levels by stimulating glycogen breakdown and glucose synthesis; breaks down a.a.s and fatty acids

Hormones of the adrenal gland

Cortex (glomerulosa): Mineralocorticoids (Aldosterone)
Cortex (Fasciculata): Glucocorticoids (Cortisol)
Cortex (reticularis): Androgens
Adrenal Medulla: Epinephrine and Norepinephrine

Adrenal Cortex: Mineralocorticoids (Aldosterone)

Target tissue: Kidney
Increased Na+ reabsorption and K+ excretion, increased water reabsorption

Adrenal Cortex: Glucocorticoids (Cortisol)

Target tissue: Most tissues
Increased protein and lipid catabolism, Increased glucose anabolism (increased blood sugar), and Anti-inflammatory

Adrenal Cortex: Androgens

Target tissue: Many tissues
Males: secondary sex characteristics
Females: growth of axillary and pubic hair

Adrenal Medulla: Epinephrine and Norepinephrine

Target tissue: Many tissues
Increase blood glucose (glycogen breakdown) and Fight-or-flight response

Hormones of the gonads

Testosterone (male)
Estrogen (Female)
Progesterone (Female)

Testosterone (Male)

Target tissue: Most tissues
Male sexual development and Spermatogenesis

Estrogen (Female)

Target tissue: Most tissues
Female sexual development

Progesterone (Female)

Target tissue: Many tissues
Gestation and Maternal behavior

Hormones of the digestive tract

Gastrin
Cholecystokinin (CCK)
Secretin
Gastric Inhibitory Peptide (GIP)

Gastrin

Target tissue: Parietal cells
Gastric acid secretion

Cholecystokinin (CCK)

Target tissue: Gall bladder, Pancreas, Stomach

Release of bile from gall bladder, Secretion of digestive enzymes by pancreas, and Decreased stomach emptying

Secretin

Target tissue: Pancreas and Liver

Increased bicarbonate secretion by pancreas and liver

Gastric Inhibitory Peptide (GIP)

Target tissue: Beta cells of pancreas

Increased insulin secretion

Hypothalamus

interface between the nervous system and the endocrine system

posterior pituitary gland

neurohypophysis
extension of hypothalamus - contains axons ends of neurons
storage and release of hormones made in hypothalamus

hypothalamohypophyseal tract

connects hypothalamus to posterior pituitary

anterior pituitary gland

adenohypophysis
contains cells that respond to signaling hormones from hypothalamus

hypothalamo-hypophyseal portal system

regulates anterior pituitary gland from hypothalamus
-direct transport of hormones - need less

hormones released from posterior pituitary gland

Antidiuretic hormone (ADH) and oxytocin.
Both are small peptides composed of only nine amino acids.

ADH or vasopressin

increase H2O reabsorption in collecting duct
decrease urine volume
increase blood volume
vasoconstriction

Oxytocin

child birth (stimulates contractions) and milk production
positive feedback mechanisms
"bonding" hormone

growth requirements

growth hormone, thyroid hormones, insulin and the sex hormones, as well as proper nutrition.

Growth hormone stimulation

hypoglycemia and stress
deep sleep \= peak release

Direct actions of growth hormones

Increased a.a. absorption/protein production

increased breakdown of fats (lypolysis)

increased synthesis/release of glucose (gluconeogenesis) into the blood by liver

decreased glucose absorption by muscle/fat cells.

indirect actions of growth hormones

somatomedin secretion (cartilage/bone growth)

Growth hormone inhibitors

Protein, hyperglycemia

growth hormone deficiency

dwarfism or hypopituitary dwarfism

extra growth hormone (pre-puberty)

giantism

extra growth hormone (post-puberty)

acromegaly

thyroid gland

regulates metabolism through hormone secretion
follicular and parafollicular cells

Thyroid hormone action

Stimulates metabolism of all body systems by accelerating the rate of cellular oxygenation

parafollicular cells

secrete calcitonin (Reduce blood calcium levels \= build bone)

follicular cells

secrete thyroid hormone (T3 & T4)

Thyroxine or T4 and Triiodothyronine or T3 are synthesized from?

tyrosine and iodine.

Thyroid hormone synthesis

tyrosine --\> thyroglobulin (TG)

iodide pumped in via Na/cI symporter

iodiode coupled to TG by peroxidase

TG + I --\> MIT --\> DIT
(iodinated thyroglobulins

TSH--\> MIT/DIT uptake into follicular cells --\> digested in lysosome to T3/4 (mostly T4)

protein TBG carries T3/4 in circulation

deiodinase

This enzyme removes an iodine from T4, producing T3.

What is the impact of deiodinase?

1. increasing half-lives of T4
2. provides another level of control

Hyperthyroidism

"Graves disease"
-Increased oxygen consumption (increased metabolic rate)
-Sweating, warm flushed skin
-Increased heart rate and increased blood pressure
-Heat intolerance
-Increased appetite and weight loss
-Insomnia
-Increased nervous system activity, hyper excitability, irritability, insomnia
-Increased muscle protein catabolism resulting in muscle weakness and weight loss.

Treatments for hyperthyroidism

beta blockers to decrease heart rate
radioactive iodine to destroy some thyroid cells surgical removal of thyroid gland (followed by hormone replacement therapy)

Hypothyroidism

"Hashimotos"
-Decreased oxygen consumption (decreased metabolic rate)
-Decreased HR/BP
-Decreased sweating, cold skin
-Intolerance to cold
-Decreased appetite and weight gain
-Apathy, sleepiness
- brittle hair, nails, and dry skin.
-puffy appearance (myxedema).
-Reduced nervous system activity resulting in fatigue and slower processing.

treatment for hypothyroidism?

synthroid, a synthetic form of thyroxine

Adrenal gland composition

outer cortex and an inner medulla, both of which produce hormones.

Adrenal gland production

ADRENAL steroids.

Adrenal Cortex zones

out --\> in
zona glomerulosa, zona fasiculata, and zona reticularis.

zona glomerulosa

mineralocorticoids (aldosterone)

zona fasiculata

glucocorticoids (cortisol)

zona reticularis

androgens

cortisol effects

-Gluconeogenesis
-Protein catabolism
-Lipid catabolism
-suppress inflammation
-Brain function

Hypercortisolism

"Cushing's syndrome"
hyperglycemia (too much glucose)
muscle breakdown
fat breakdown (deposition in face/trunk)
depression and learning difficulties.

Hypocortisolism

"Addison's disease"
Total cortex loss
hyperkalemia
hyponatremia
increased ACTH production since the normal negative feedback control is lost.

Pancreas

exocrine - digestion
endocrine - glucose regulation

pancreatic islets (islets of Langerhans)

produce and secrete endocrine hormones

Beta cells

70% of islets
secrete insulin
activated by high glucose

Alpha cells

30% of islets
secrete glucagon
activated by low glucose

Regulation of Insulin secretion

high Plasma glucose
low Plasma amino acids
high Gastrointestinal hormones
ANS

Diabetes Mellitus

body's inability to process glucose correctly \= high blood glucose levels

What happens if Diabetes Mellitus is left untreated?

diabetes can cause both acute (ketoacidosis -acidic blood pH) and chronic complications (cardiovascular disease, renal failure, blindness, infections, and nerve damage).

Type 1 diabetes mellitus

(10%)
loss of beta cells \= no insulin
under 15 y.o.
acute complications:
acidosis
polyuria
polydipsia
polyphagea

Treatment of type 1 diabetes

insulin injections

Type 2 Diabetes Mellitus

(90%)
reduced response by cells to insulin
over 15 y.o., genetics, lifestyle
few acute complications:'
increase blood sugar

Chronic complication of diabetes

increased LDLS \= plaque formation
decreased blood circulation

Treatment of type 2 diabetes

change in diet and exercise
drug therapy to decrease carb digestion, decrease glucose production in liver, increase target cell sensitivity
insulin administration.

Gestational diabetes

diabetes during pregnancy
increases risk of type 2 diabetes

hormones that raise blood sugar

Glucagon
cortisol
growth hormone