endocrine system

what are the two systems that coordinate human body activities

nervous and endocrine

the nervous system is quick in response and uses

neurotransmitters

endocrine is _____ in response and uses _______

slow, hormones

endocrine system discipline is called

endocrinology

endocrine glands are what size

small and unimpressive

two type of glands in the human

• exocrine

• endocrine

endocrine glands include

• pituitary

• adrenal

• thyroid

• parathyroid

• pineal and thymus

• gonads

• pancreas

neuroendocrine organs are

• walls of stomach

• small intestine

• kidney

• heart

• hypothalamus

hormones are what kind of substances

chemical substances

hormones are secreted by?

endocrine cells into the blood (extracellular fluid) that then are transported into organs

hormones bind to what?

bind to receptor on the target organs and regulate metabolic activities

airborne waves and appliances fit?

hormone actions

what are the two categories of hormones

• amino acid based (water soluble)

• steroid based (fat soluble)

chemical messengers in the blood are?

hormones

what do hormones accomplish (there mechanism)

1. changes in plasma membrane permeability

2. synthesis of proteins or regulatory molecules

3. enzyme activation or deactivation

4. induction of secretory activities of cells

5. stimulation of mitosis

changes in plasma membrane permeability

for certain action they must change the permeability of the target organs

ex: insulin changes permeable membranes to sugar

synthesis of proteins or regulatory molecules

go and command cells to produce proteins

_____ rather than speed is more important in the mechanism of hormone action

duration

hormones have slow action but

very effective action

amino acid based hormones are

water soluble

hormones that are amino bases cannot do what?

enter the cell membrane due to the membrane being selectively permeable

due to water not being able to pass a mechanism comes into play and this is through

a second messenger

that second messenger is most understood through which mechanism

cAMP

• cyclic adenosine monophosphate mechanism

cAMP has 3 proteins involved

1. hormone receptor

2. signal transducer

3. effector enzyme

what is the hormone receptor

a protein in a target cell

what is a signal transducer

a g protein

what is an effector enzyme

adenylate cyclase

what do the three proteins in cAMP do or accomplish?

help hormone get into cell and will accomplish the job

the first messenger is the

hormone

the second messenger is the

cAMP

cyclic adenosine monophosphate

steroid based hormones

are lipid soluble (fat soluble)

steroid hormones can pass the membrane in what way?

easily through the target cell membrane

due to steroid hormones being able to pass the membrane this mean they have no?

receptor on the membrane

in the steroid hormones the interaction with dna leads to what happening?

the genes to produce mRNA for specific protein synthesis that can later alter target cell activities

pituitary glands (hypophysis) histology

• located at base of brain

• 0.5mg in weight

pituitary glands have two major subdivision

1. posterior pituitary

2. anterior pituitary

posterior pituitary has three different regions

1. median eminence

2. infundibular stem

3. infundibular process

posterior pituitary has 2 major nuclei

1. supraoptic

2. paraventricular

the cells in the posterior pituitrary are

large and with eccentric nuclei and abundant cytoplasm

herring bodies (in posterior pituitary)

axons with numerous dilatations containing neurosecretory granules

what are the supporting cells in the posterior pituitary

pituicytes

the posterior pituitary doesn’t synthesize what?

any hormones

even thought the posterior pituitary does not produce hormones it????

stores hormones that are produced in the hypothalamus for later release

posterior pituitary hormones MAIN two

• antidiuretic hormone (ADH) or Vasopressin from supraoptic nucleus

ADH (antidiuretic hormone) or Vasopressin function

retention of water and vasoconstriction of artierolar smooth muscle

oxytocin function

stimulation of uterine smooth muscle contraction for childbirth, and milk ejection from mammary glands

adh from

supraoptic muscles

oxytocin from

paraventricular nucleus

anterior pituitary has 3 subdivision

1. pars distalis (distal)

2. pars tuberalis (tubalar)

3. pars intermedia (intermediate part)

hypophyseal portal system contains

inferior and superior arteries coming out of the internal carotid into here

pars distalis consists of

• cords (rolls) of parenchymal cells

• thin walled sinuses and non secretory cells

two categories of cells in the pars distalis

1. glandular cells

2. non secretory cells

glandular cells have two categories

1. chromophilic cells

   • attraction to color (stains or dyes = acidophils & basophils)

2. chromophobic cells

   • no attraction to stains or dyes

non secretory cells

do not produce any secretions

known as Follicular (Stellate) cells (supporting cells)

chromophilic (acidiphilic) cells produce 2 hormones

1. somatotrophs (growth hormone)

2. mammoptrophs (prolactin)

somatotrophs produce

growth hormone

mammotrophs produce

prolactin (milk synthesis)

chromophilic cells (basophils) produce 3 hormones

1. Thyrotrophs

2. Coricotrophs

3. Gonadotrophs

the chromophilic cells will have….

three kinds of hormones, pink staining and with PAS+ cytoplasm

thyrotrophs

stimulates to produce a thyroid gland (TSH)

located: periphery

corticotrophs

round and ovoid cells with small granules that will produce….. adenocorticotrophic hormone (ACTH)

gonadotrophs

produce follicle stimulating hormone (FSH) and lutenizing hormone (LH)

the choromophobic cells

in the interior of pars distalis cords

• less cytoplasms make up 65% of all cells of pars distalis

• s

NOT FUNCTIONAL AT ALL/THERE FOR NO REASON

in the pars tuberalis (anterior pituitary) there is a tube that has been formed and this tube creates a?

thin sleeve around hypohyseal stalk

the pars tuberalis the “most”

vascularized subdivision

• meaning that there is lots of blood circulation

what is a distinctive feature of pars tuberalis

has a longitudinal arrangement of epithelial cell cords

what are the cell shapes in pars tuberalis

cuboidal and low columnar

in the pars intermedia what is separted and by what?

the pars distalis and the pars nervosa is separated by a cleft

pars intermedia becomes discontinous when?

in the postnatal period

what is histological feature of the pars intermedia

Rathke’s cysts or pouches in adults

the pars intermedia is not?

distinguishable in adult humans

• not a clear section that can be seen compared to an infant

what hormones does the pars intermedia secrete?

melanocyte stimulating hormone

the thyroid gland is located where?

below the larynx

what is the thyroid gland composed of?

2 lobes that are connected by a thin bridge aka the isthmus

the whole thyroid glands in enclosed in what?

a capsule

how does the thyroid gland completes its function

functions under the effect of a thyroid stimulating hormone (tsh)

what kind of hormones does the thyroid gland produce?

hormones for normal growth and development

thyroid gland has two groups of hormones

• T4 (thyroxin) & T3 (triiodothyronine)

• calcitonin

T4 (thyroxin) & T3 (triiodothyronine) do what?

regulate the rate of metabolism

calcitonin does what?

regulates calcium in the extracellular fluid and what gets deposited into the bone

thyroid gland is UNIQUE for

extracellular storage (holds its hormones outside the cells not inside)

since thyroid glands hold the hormones outside where are they located

in the luminal follicles

what are these follicles bounded by?

simple cuboidal epithelium

the follicle cells are?

polarized (meaning facing a certain direction) toward the lumen

the lumen in which these follicle cells are in is what

a gelantinous substance aka a COLLOID

what is stored in the colloid

t3 & t4 = thyroglobulin + hormone

thyroglobulin

is a glycoprotein that must be hydrolyzed to release hormones

there are two kinds of cell types in the thyroid gland

• principle or follicular cells

• parafollicular cells

the principle and follicular cells produce

T3 & T4

parafollicular cells

• btwn bases of principal cells

• WAY larger than principal cells (can be seen under microscope)

what do parafollicular cells produce

calcitonin

main function of thyroid gland?

to produce hormones in response by tsh

what is the mechanism of hormone action of thyroid gland

cAMP

the t3 and t4 affect stimulation at

transcriptional level (go to dna and control what genes turn on and off affecting what the cell will do)

two conditions of the thyroid gland

• hypothyroidism

• hyperthyroidism

hypothyroidism & hyperthyroidism means

low or more quantity of hormones

hypothyroidism

decreased metabolism and stunted growth

hyperthyroidism

increased metabolism

• weight loss

• fatigue

• increased heart rate (palpitations)

so calcitonin by regulating calcium it really

decreases blood calcium

parathyroid gland has

• small oval bodies on posterior side of thyroid gland

• 4 in number