Flashcards in Chap 6 Deck (81):
What is a hormone?
Is the mediator molecule released in the whole body from endocrine glands to specific receptors
What do exocrine glands do?
Secrete their products into ducts carrying secretions into body cavities (e.g., digestive enzymes)
What do endocrine glands do?
Release hormones into the interstitial fluid. Hormones then diffuse into bloodstream (e.g., pituitary gland
List some exocrine glands
Salivary glands that secrete saliva into the mouth
Bile-producing glands of the liver
The portion of the pancreas that secretes pancreatic fluid into the duodenum
What are primary endocrine glands in CNS
Primary Endocrine glands outside of CNS
Gonads (ovaries and testes)
Secondary endocrine glands
What are the targets of hormones
What two mechanisms regulate the number of cell receptors?
Up-regulation (sensitivity increase)
How do circulating hormones move?
use bloodstream as a vehicle to reach their cell targets
What do local hormones do? Give two examples.
act on their surrounding cells or on themselves
Paracrines, act on nearby cell. Autocrine, act on self
How do water soluble hormones circulate
circulate in a free form in blood
Lipid soluble hormones circulate how?
need a vehicle (transport proteins) to reach the target cells
What three functions do transport proteins have?
Make LSH temporally WSH
Delay the filtering mechanism
Provide a LSH reserve in bloodstream
What are the two classes of hormones?
Lipid soluble and water soluble
Three types of lipid soluble hormones and how they are derived.
Steroid hormones derived from cholesterol
Thyroid hormones synthesized from iodine and AA tyrosine
Nitric Oxide (NO) catalyzed by NO-synthase
LSH mechanisms of action (4)
A free LSH diffuses from the blood through the cell
LSH binds and activates the receptor within cytosol or nucleus which in turn will alter gene expression
From this, new proteins are built
These new proteins will trigger an increase or a decrease in LSH level into the cell
WSH mechanisms of action (6)
WSH diffuses from blood to external cell layer and binds with receptor
Adenylyl cyclase converts ATP to cAMP
cAMP serves as second messager to activate protein kinase
Protein kinase phosphorylates other enzymes
This produces million of biochemical reactions
After brief period, cAMP is desactivated
The responsiveness of a target cell to a specific hormone depends on
Number of cell receptors
Influence of antagonist hormones
Hormone secretion is regulated by
Signals from Nervous System
Chemical changes in blood
Influence of antagonist hormones
Hypothalamus is interface between what?
Nervous system and endocrine system
Hypothalamus Influenced by what?
Pain, stress, emotion
Hypothalamus controls what?
ANS, body temperature, thirst, hunger, sex,
Hypothalamus synthesizes how many hormones?
What does anterior pituitary gland do
secretes hormones regulating a wide range of bodily activities
What does posterior pituitary gland do?
contains axons and axon terminals (10 000 neurons) related to the hypothalamus
Neurosecretary cells from hypothalamus have 5 what and 2 what
5 releasing hormones that stimulate secretion and two releasing hormones that decrease secretion
Human growth hormone released from? Main function? What are the target cells? Released where?
Anterior pituitary. stimulate synthesis and secretion of Insulin growth factors. Target cells are liver, skeltal muscle cartlidge and bone. released in blood stream or acts locally
What are some IGF functions?
Increase uptake of AA by cells,decrease AA breakdown, use AA as a substrate for ATP, enhance lypolysis, decrease glucose uptake,
IGF and hGF stimulate release of?
What do somatotrophs do?
Release hGH every few hours mainly during sleep
What does Growth hormone-releasing hormone do
Promotes secretions of hGH
What does Growth hormone-inhibiting hormone do
Supresses secretions of hGH
what is major regulator of GHRH and GHIH?
blood glucose level
High blood glucose stim release of? Low blood glucose?
What does TRH do?
Controls TSH release from hypothalamus
What does TSH do
Stimulates T3 and T4 both in thyroid gland
What do T3 and T4 hormones do?
Inhibit TRH(feedback loop)
How is foccile-stimulating hormone strimulated?
When hypothalamus releases GnRH
FSH stimulates what
Follicular cells to secrete estrogen, sperm producton and development of several ovarian follicles
GnRH and FSH are inhibited by
estrogens and testosterones
H is stimulated by ?
LH triggers what? (3)
ovulation, estrogens, and stimulation of interstitial cells in the testes to secrete testosterones
what do estrogens and progesterone do?
prepare for fertilizing mechanisms and milk secretion
What does prolactin hormone do?
Initiates and maintains lactation
Coticotroph cells secrete what?
what does ACTH do
Controls secretion of cortisol and glucocorticoids
Increased released ACTH how >
posterior pituitary also called
Posterior Pit. doesnt do what? What does it do? Relies on what?
Doesn't synthesize hormones, stores and releases oxytocin and ADH. Hypothalamus
Oxytocin serves mainly as? Stimulates what? involved in what?
Smooth muscle stimulator. Milk ejection, sexual pleasure.
ADH regulates fluid balance by?
Decreasing urine volume, decreasing sweat water loss, increasing blood pressure
What regulates ADH secretion
blood osmotic pressure and blood volume
Thyroid gland releases what?
T3 and T4 and CT
Stores T3 and T4 in small or large quantity?
T3 and T4 formed where, CT formed where?
Follicular, and parafollicular
T3 and T4 hormones do what?
stimulate protein synthesis
Increase glucose and FA uptake for ATP production
Enhance cholesterol excretion
Accelerate body growth
Contribute to CNS development
CT in involved in what
regulation of Ca2+ and phosphates
CT secretion is controlled by ?
What does the parathyroid gland involve?
Ca2+ regulation and Mg2+ regulation
Adrenal gland is subdivided into what?
Adrenal cortex: 80-90% of the gland, and adrenal medulla which is centrally located
Adrenal cortex divided into 3 zones
Glomerulosa, fasciculata, and reticularis
What does each zone of adrenal cortex do
Glomerulosa- Secretes aldosterone, Fasciculata- secretes cortisol, corticosterone and cortisone(increase prot. breakdown. Reticularis- secretes DHEA(growth and sexual functions)
Glucocorticoids and effects
Resistance to stress
Depression of immune system
Adrenal Medulla secrete two hormones
Epinephrine =80% of secreted hormones, norepinephrine=20% of secreted hormones
Pancreas endocrine or exocrine functions?
Pancreatic cells arranged in clusters called? produce what?
Acini-produce digestive enzymes
Four types of hormones that pancreas secretes
Alpha cells, Beta cells, Delta cells, F cells
What do alpha cells do?
Secrete glucagon, raise glucose level
What do beta cells do?
Secrete insulin, lower glucose
What do delta cells do?
Secrete somatostatin, inhibit glucagon and insulin
what do F cells do?
Secrete polypeptide, inhibit somatostatin and digestive enzymes
What is the most important stimulator of inisulin?is that the only stimulator?
Glucose level. No many others
What else will stim release of glucagon?
Sympathetic activity (ANS) and a rise in blood AA parallel with low glucose
Ovaries produce what?
Produce estrogens, progesterone, FSH and relaxin
What does the pineal gland function as?
What does melatonin do?
inhibits reproductive functions in animals
General adaptation syndrom caused by what? Results in what?
stressful conditions, Homeostasis disrupton
fight or flight response initiated by what ?
Hypothalammus through SNS
What does flight or fight response do?
Brings huge amounts of O2 and glucose to brain muscle and heart, inhibits other organ functions