A & P Endocrine and Reproductive

what are the major endocrine glands?

* hypothalamus
* pituitary gland
* pineal gland
* thyroid gland
* parathyroid glands
* adrenal/suprarenal glands
* pancreas
* ovaries
* testes

hypothalamus

Pituitary gland

Pineal Gland

Thyroid Gland

Parathyroid glands

Adrenal Glands

also known as suprarenal

Pancreas (what does it release for the endocrine system?

Ovaries

testes

Organs with endocrine functions:

* skin
* adipose tissue
* heart → ANP (atrial neiuritic peptides - decrease BP)
* thymus → above heart
* liver → angiotensinogen
* stomach → gastrin
* small intestine → secretin & CCK
* kidneys → renin, erythropoeitin
* Placenta → HCG

what is HCG hormone? what does it indicate?

* secreted by the pancreas
* measured by pregnancy tests

\

renin does what?

* angiotensinogen → angiotensin I

Functions of the Endocrine system

* regulation
* control of growth and development
* control of reproductive systems
* help establish circadian rhythm
* re-inforce/coordinate w/ nervous system

\

How does endocrine work that is different form the Nervous system?

hormones through the blood stream

What type of cells normally release the hormones into the blood in the endocrine system?

simple cuboidal epithelial

What two types of hormones are in the Interstitial fluid?

local hormone & circulating hormone

Local Hormones do what?

act on nearby cells or releasing cells

ex.) IL-2

local hormones are also known as . . .

‘paracrine’ (nearby cells) & ‘autocrine’ (releasing cells)

Circulating hormones do what?

travel in the blood and act on distant target cells

ex.) insulin, glucagon, ANP

hormone releasing cells are regulated by what?

* NS
* Chemical changes in blood
* other hormones

what must a target cells have in order to be effected by a hormone?

a receptor for that hormone to bind

What happens when there is too much of the hormone being produced/present?

target cells decreases receptors and there for sensitivity - down regulation

What happens when there is too little of the hormone produced/present?

target cells increase receptors and therefore sensitivity

What does the endocrine regulate?

* chemical composition + volume of ECF
* Metabolism + energy balance
* contraction of smooth & cardiac muscle
* immune function
* glandular secretions

What are the different types of hormone interactions?

1. permissive effect
2. synergistic effect
3. antagonistic effect

Permissive Effect

one hormone requires simultanious/recent exposure of another hormone

Synergistic Effect

two hormones together get bigger response than sum of individual responses

Antagonistic Effect

two hormones have opposite actions {insulin & glucagon}

What are the two chemical classes of hormones?

lipid-soluble and water-soluble

what are some examples of a lipid-soluble hormone?

* steroid hormones (e.g. aldosterone, cortisol, testosterone, estrogen, progesterone)
* Thyroid Hormones (e.g. T3 and T4)

What are some examples of water-soluble hormones?

* amines (e.g. epinepherine, norepinephrine, dopamine, histamine, serotonin, melatonin)
* Peptides/proteins (e.g. ADH, oxytocin, insulin, glucagon, calcitonin, gastrin, EPO)

how are lipid-soluble hormones transfered throughout the body?

bound to transport proteins

* temporarily water soluble
* not filtered at kidney
* readily available in blood

How are water soluble hormones transfered throughout the body?

in blood plasma

what are the mechanisms of action for lipid-soluble hormones?

diffuse into target cells →(if present) binds to recepters in cytosol or nucleus → alter gene expression + protein synthesis → alters cell activity

*changes structure = changes function*

what are the Mechanism of action for water-soluble hormones

diffuse near cell → (if present) bind to receptors on plasma membrane → activates 2nd messenger cell (signaling cascade) → alters cell activity

Where are receptors located for lipid-soluble hormones?

inside target cells

where are receptors located for water-soluble hormones?

on plasma membrane of target cells

Mechanism of action for lipid-soluble hormones . . .

1. hormone molecule breaks away from transport protein in the blood
2. free hormone molecule moves from the blood and diffuses through lipid bilayer of plasma membrane into the cell
3. (if target cell) binds to receptors located in cytosol or nucleus
4. gene expression is altered, turning on or off specific nuclear DNA
5. proteins are synthesized on ribosomes
6. new proteins alter the cells activity and cause response to initial hormone

where are receptors specifically located in target cells for lipid-soluble hormones?

cytosol or nucleus

where are proteins synthesized within the target cell?

ribosomes

why are water soluble hormones receptors in the surface of the cell?

amines, proteins and peptide hormones can not diffuse across membrane and must bind to receptors on its surface

what acts as the first messenger in the water-soluble hormone mechanism?

the hormones initial binding to the surface recepters

what are the surface receptors?

integral-transmembrane proteins in plasma membrane

what acts as the second messenger in the water-soluble hormone mechanism?

cyclic adenosine monophosphate (CAMP)

* can be other neurotransmitters, neuropeptides or sensory transduction mechanisms (ex. vision)

Mechanism of water-soluble hormones. . .

1. first messenger (hormone) diffuses from blood into interstitial fluid and binds to external surface receptor
2. hormone receptor complex activates a G protein which in turn activates adenylyl cyclase
3. adenylyl cyclase converts ATP into cAMP
4. Cyclic AMP (second messenger) activates one or more protein kinases that can be free in cytosol or on plasma membrane)
5. activated protein kinases phosphorylate one or more cellular proteins (turning on or off)
6. proteins then cause responses producing physiological reactions

where does adenylyl cyclase convert ATP to cAMP?

inner surface of plasma membrane

what is a protein kinase?

an enzyme that phosphorylates (adds phosphate group) other cellular proteins

* which is taken from ATP that turns into ADP afterward

can different protein kinases exist within the same target cell?

yes!

what inactivates cAMP?

phosphodiesterase

what hormones exert physiological effects through increased cAMP production?

* ADH
* thyroid-stimulating hormone (TSH)
* adrenocorticotropic hormone (ACTH)
* glucagon
* epinepherine
* hypothalamic releasing hormones

how can hormones that bind to plasma membrane receptors create low or high concentration effects?

because of the cascade or chain reaction they cause

* can amplify initial effect with each step

what regulates the secretion of parathyroid hormone?

Calcium concentration within the blood

what stimulates the release of cortisol by the suprarenal cortex?

adrenocorticotropic hormone from anterior pituitary gland

what is know as the “master” endocrine gland?

pituitary gland

* secretes several hormones that control other endocrine glands

what controls/regulates the pituitary gland?

hypothalamus

the hypothalamus and pituitary gland are connected via what structure?

infundibular stalk

what are the two portions of the infundibular stalk?

the anterior pituitary and posterior pituitary

anterior pituitary gland is composed of what tissue?

epithelial tissue

posterior pituitary gland is composed of what tissue?

nervous tissue

what cells are located within the anterior pituitary gland?

* Corticotrophic cells
* prolactin cells
* somatotrophic cells
* thyrotrophic cells
* gonadotrophic cells

\
what do corticotrophic cells secrete? and what hypothalamic releasing hormone stimulates its secretion?

ACTH -adrenocorticotropic hormone

MSH - melanin-stimulating hormone

* corticotropin-releasing hormone (CRH)

what do prolactin cells secrete? and what hypothalamic releasing hormone stimulates its secretion?

PRL - prolactin

* Prolactin releasing hormone (PRH)
* PIH inhibits secretion

what do somatotrophic cells secrete? and what hypothalamic releasing hormone stimulates its secretion?

GH - growth hormone

* growth hormone releasing hormone (GHRH)
* GHIH inhibits secretion

what do thyrotrophic cells secrete? and what hypothalamic releasing hormone stimulates its secretion?

TSH - thyroid-stimulating hormone

* Thyrotropin-releasing hormone (TRH)
* growth hormone inhibiting hormone (GHIH) inhibits secretion

what do gonadotrophic cells secrete? and what hypothalamic releasing hormone stimulates its secretion?

FSH - Follicle-stimulating hormone

LH - luteinizing hormone

* no inhibiting hormone

how many hormones does the hypothalamus secrete to activate anterior pituitary hormone secretion? how many for inhibition?

* 5
* 2

what is the hypophyseal portal system?

the blood vessel pathway for hypothalamus hormones - network of capillairies

{creates important link between nervous system and endocrine system}

what is the pathway for the hypophsyeal portal?

blood capillairies → hypothalamus portal vein → blood capillaries of anterior pituitary gland

\
\*superior hypophyseal arteries → primary plexus of the hyphophyseal portal system → hypophyseal portal veins → secondary plexus of hypophyseal portal system → hypophyseal veins

superior hypophyseal arteries are branches off of what major artery?

common corotid

the primary plexus of the hypophyseal system is composed of what?

divided capillary network in the medium junction between the hypothalamus and the infundibulum

where do the hypophyseal portal veins travel?

down the outside of the infundibular stalk, where they further divide in the anterior pituitary gland

hypophyseal veins drain what?

blood from anterior pituitary

GH - what is its target tissue and principal actions?

Liver

* stimulates liver, muscle, cartilage bone, and other tissues to synthesize and secrete insulin like growth factors - which promote growth of these tissues
* acts directly on target cells and decreased glucose uptake

TSH - what is its target tissue and principal actions?

thyroid gland

* stimulates synthesis and secretion of thyroid hormones by thyroid gland

FSH - what is its target tissue and principal actions?

Ovary and Testis

* in females: initiates development of oocytes and induces ovarian secretion of estrogen
* in males: stimulates testes to produce sperm

LH - what is its target tissue and principal actions?

Ovary and Testis

* in females: stimulates secretion of estrogens, progesterone, ovulation, and formation of corpus luteum
* in males: stimulates testis to produce testosterone

PRL - what is its target tissue and principal actions?

mammary glands

* together with other hormones, promotes mild production by mammary glands

ACTH - what is its target tissue and principal actions?

Suprarenal cortex within adrenal gland

* stimulates secretion of glucocorticoids (mainly cortisol)

MSH - what is its target tissue and principal actions?

brain

* exact role is unknown but may influence brain activity
* when excess is present can cause darkening of skin

does the posterior pituitary gland synthesize hormones?

No! but it does store and secret two

* mainly consists of axons and axon terminals of neurosecretory cells of the hypothalamus

the cell bodies of the neurosecretory cells are in the what?

paraventricular and supraoptic nuclei

axons of the neurosecretory cells form what?

hypothalamic-hypophyseal tract

* begins in hypothalamus and ends near blood capillaries of posterior pituitary

What is the calorigenic effect? And is a result of what?

As cells produce and use more ATP, basil metabolic rate increases and heat is given off → increasing body temperture

* thyroid hormones ( important in body temp. Regulation

Parathyroid hormone is also known as what?

Parathormone(PTH)

What thyroid cells secrete calcitonin?

C- thyrocytes

What cells secrete T3 & T4? Where are they located?

T-thyrocytes; Thyroid

Responses to too much calcium in the blood include . . .

increase of Calcitronin - decrease oesteoclasts, increase bone intake

\
Decrease of parathyroid hormone

Responses to too little calcium in the blood include . . .

Increase in parathyroid → increase osteo coasts (calcium from bones to blood) , decrease bone uptake, increase Ca reabsorption at kidneys

What are the three zona and where are they located?

Zona glomerulosa - aldosterone (sodium reabsorption)

Zona fasciculata - cortisol (stress/metabolism)

Zona reticularis - androgens (reproductive functions)

\
All located in adrenal cortex

What does the adrenal medulla secrete? Function? Controlled by?

Adrenal medulla secretes (catecholemines) epinephrine and norepinephrine → fight or flight response. → sympathetic nervous system

what responses occur when their is low glucocorticoids in the blood and stress?

* increase protein breakdowns
* increase lipolysis
* increase gluconeogenisis
* inhibit WBCs (only inflammatory)

LH stimulates what?

interstitial (laydig) cells

* testosterone (development of male characteristics)

FSH + testosterone stimulates what?

nurse (sertoli) cells to begin spermatogenisis at puberty

estrogen stimulates what?

female characteristics and fat disposition, etc.

* menstruation

Progesterone stimulates what?

pregnancy (maintain endometrium for implantation)

* lactation

Relaxin stimulates what?

relaxes SM of uterus (myometrium) for implantation/pregnancy

inhibin does what function?

negative feedback to FSH

sperm production occurs where?

seminiferious tubules

nurse cells do what?

nourish developing spermatagonium