Chap 6 Flashcards
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
Prostate gland
The portion of the pancreas that secretes pancreatic fluid into the duodenum
Gastric glands
Sweat glands
What are primary endocrine glands in CNS
Hypothalamus
Pituitary gland
Pineal gland
Primary Endocrine glands outside of CNS
Thyroid gland Parathyroid gland Thymus Adrenal gland Pancreas Gonads (ovaries and testes)
Secondary endocrine glands
Kidneys Stomach Liver Small intestine Skin Heart
What are the targets of hormones
glycoprotein receptors
What two mechanisms regulate the number of cell receptors?
Down-regulation (suppression)
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
Hormone concentration
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?
9
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?
Liver glucose
What do somatotrophs do?
Release hGH every few hours mainly during sleep
What does Growth hormone-releasing hormone do
Promotes secretions of hGH