Endocrinology and Repro

Endocrine system

• humoral communication in body

• control body function via hormones

• glands

glands

• glandular epithelium

• secretes product

modes of transmission

• epicrine

• neurocrine

• paracrine

• endocrine

• exocrine

• autocrine

epicrine

• through the gap junctions

• do not enter extracellular fluid

• substances cross to adjacent cell 

neurocrine

• into the blood instead of synaptic cleft

• secrete chemicals as hormones

• works closely with nervous system

paracrine

• through interstitial fluid

• prostaglandins

• substance crosses to other cells by diffusion

endocrine

• through blood circulation

• secretes hormone into the blood

• ductless

• hormone travels in blood to target tissue which has receptors for that hormone

  • pineal, pituitary, pancreas, ovaries, testes, adrenal, thyroid

  • melatonin

exocrine

• exterior of the body

• product goes through duct outside of the body

  • simple cuboidal epithelium

  • sweat, sebaceous, digestive, mammary

autocrine

• affects the cells itself

• lupus

hormone

• chemical regulator that will target a gland to stimulate specific cells or tissues into action

  • some target many tissues, some only one

hormone chemical makeup

• peptides

• biogenic amines

• steroids and derivatives

• fatty acid derivatives

peptides

• hypothalamus

• short chains of amino acids 

biogenic amines

• tyrosine

• includes thyroid hormones and catecholamines

  • epinephrine, norepinephrine, dopamine

steroids and derivatives

• cholesterol backbone with side chains

• adrenal cortex and gonads

  • sex steroids

fatty acid derivatives

• prostaglandins

  • derived from arachidonic acid

positive feedback

• rare

• when a hormone is produced it stimulates more hormone to be produced

  • oxytocin

negative feedback

• common

• when a hormone produced causes a decrease in production

releasing and inhibiting hormone

• when a hormone from a different endocrine gland causes or inhibits the release of a specific hormone

pituitary

• hypophysis cerebri

• master gland

• anterior lobe

• posterior lobe

anterior lobe

pars

• adenohypophysis

• pars distalis

  • largest

• pars intermedia

  • between

• pars tuberalis

  • arounds talk connecting to brain

Somatotrophs

growth hormones

Corticotrophs

• adrenocorticotropic hormone (ACTH)

Mammotroph

• (lactotropes)

• prolactin

Thyrotrophs

• thyroid stimulating hormone (TSH)

Gonadotrophs

• follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

anterior lobe products

• growth hormone

• gonadotropins

• prolactin

• thyroid stimulating hormone

• Pro-opiomelanocorticotropin (POMC)

growth hormone

• somatotropin

  • tropin means stimulate

  • somato means body

• target

  • mandy body cells

  • bone and muscle

  • in young animals

• effects

  • hypertrophy, hyperplasia

  • metabolism

    • increases protein synthesis, increase fat mobilization, decreases glucose uptake

• control

  • GHRH

    • releasing

  • GHIH

    • inhibiting

gonadotropins

• stimulate gonads

• luteinizing hormone

  • involved with ovulation and corpus luteum formation

  • targets ova to bring on ovulation

  • also stimulates testes to produce testosterone

• follicle stimulating hormone

  • follicular development and ovulation

  • sperm development

• control

  • gonadotropin releasing hormone from hypothalamus

prolactin

• targets mammary cells to increase lactation

• milk production

thyroid stimulating hormone

• thyrotropin

• stimulates thyroid gland to release its hormones

• controlled by thyrotropin releasing hormone from hypothalamus and by cold, stress 

Pro-opiomelanocorticotropin (POMC)

• Large precursor molecule can form several hormones

• Adrenocorticotropic hormone (ACTH): 

  • stimulates adrenal cortex to release its hormones

• Beta-lipotropin:

  •  then converted to beta-endorphin (B-EP)

  • Natural pain reliever

• Melanocyte stimulating hormone (MSH): 

  • pigment movement and color changes, especially in amphibians and reptiles

posterior lobe

• neurohypophysis

• nerve tissue with ends of axons of neurons with somas in nucleus in hypothalamus

  • axons terminate on capillaries

• products are protein hormones

products

• protein hormones

• antidiuretic hormone ADH

• oxytocin

antidiuretic hormone ADH

• vasopressin

• stimulus for release

  • increases blood sodium concentration from dehydration

• target

  • kidney tubules

• effect

  • increase water resorption, decrease urine volume, increased blood pressure

oxytocin

• stimulus

  • neroendocrine reflex of suchling, cervical stimulation

• target

  • myoepithelial cells of mammary gland, smooth muscle in uterus

• effect

  • milk letdown, uterine contraction

pineal

• produces melatonin

  • light/dark cycles, sleep/wake, seasonal breeding, nocturnal activity

thyroid

• in neck near larynx

• bilobed

• cells arranged in follicles with space filled with thyroglobulin

  • storage of thyroid hormone

  • stred as colloid

    • stains pink

• targets all cells in all organs

thyroid hormones

• calcitonin

  • from C cells

  • decreases blood calcium

• triiodothyronine and tetraiodothyronine

  • iodinated conjugate of amino acid tyrosine

  • carried in blood bound to thread binding globulin

  • tri is active version

thyroid control of hormones

• Thyroid releasing hormone (TRH) 

  • from hypothalamus

• Thyroid stimulating hormone (TSH) 

  • from adenohypophysis-anterior pituitary gland

  • Stress, temperature, other hormones

  • Negative feedback of T3/T4 on thyroid, adenohypophysis and hypothalamus

thyroid effects

• increase BMR

• permissive effect on many organ systems

• increases cardiac output

• increases blood glucose

  • increases carbohydrate uptake from GIT

  • increase gluconeogenesis

  • increases glycolysis

  • increased oxidation of fatty acids

parathyroid

• small glands embedded in thyroid or nearby

• produce parathyroid hormone

• increase blood serum calcium

adrenal

• cranial to kidney

• cortex

  • outer portion

  • has zones

  • produced corticosteroids

• medulla

  • sympathetic nerve ganglion

  • produced catecholamines

adrenal hormones

• glucocorticoids

• mineralocorticoids

• Catecholamines

glucocorticoids

• cortisol, corticosterone

• increase blood glucose

• targets muscles/tissues

• stress response via HPA axis

• hypothalamus

  • releases corticotropin releasing hormone

• anterior pituitary releases

  • adrenocorticotropic hormone

• adrenal gland cortex

  • released cortisol

• negative feedback

mineralocorticoids

• aldosterone

• acts on kidneys 

  • to increase sodium retention and water retention in blood out of urine

  • decreases urine volume

• control

  • slightly by ACTH

  • mostly by increased plasma osmolarity

Catecholamines

• Epinephrine, norepinephrine, dopamine

• Short term stress response (fight or flight)

• Control:  

  • sympathetic nerve stimulation

• Target:  

  • viscera, heart, blood vessels, gastrointestinal tract (GIT), many cells

• Effects:  

  • Increase heart rate

  • Increase blood pressure

  • Stimulate ACTH production

  • Decrease GIT activity

  • Increase blood glucose

pancreas

• diffuse gland in first loop of small intestine

  • duodenum

• exocrine

  • most of gland

  • digestive enzymes, mucus and bicarbonate

• endocrine

  • islets of langerhans

pancreas hormones

• insulin

• glucagon

• somatostatin

insulin

• released from beta cells

• stimulated by increase blood glucose

• targets

  • liver, adipose, muscle

• effects

  • decreases blood glucose

  • glycogenesis

  • increase cellular uptake from blood

glucagon

• from alpha cells

• stimulated by decreased blood glucose

• targets

  • liver, adipose, muscle

• effects

  • increase blood glucose

  • gluconeogenesis

  • glycogenolysis 

somatostatin

• from delta cells

• inhibits both alpha and beta cells

testes

• tubular organ

• interstitial cells

  • between seminiferous tubules

  • produce testosterone

    • stimulated by LH from anterior pituitary

• sertoli cells

  • support cell involved in sperm production

  • stimulated by FSH

ovaries

• follicular organ

• tunica albuginea

  • fibrous CT

  • follicles of different stages throughout

  • primary, secondary, tertiary

    • graafian/mature