Endocrine Glands and hormones Flashcards
(33 cards)
Homeostasis
the maintenance of a relatively constant internal environment despite fluctuations in the external environment.
List of endocrine glands (12)
pineal gland
Hypothalamus
pituitary gland
thyroid gland
Parathyroid gland
thymus
Adrenal gland
kidneys
pancreas
ovaries
uterus
Testes
exocrine gland
Gland that secretes into a duct that carries the secretion to the surface of the body cavities
endocrine gland
Secrete hormones into the extracellular fluid that surrounds the cells that make up the gland
secretion then usually passes into the capillaries to be transported by the blood
Sometimes called ductless gland
hormones
Chemicals secreted by endocrine system and transported in bloodstream.
changes the function of cells by activating certain genes in nucleus so a particular enzyme or protein is produced.
Hormone receptor
each type of receptor will bind wt only one specific molecule
Saturation
once all receptor molecules are occupied by hormone molecules, the addition of more hormones does not produce any greater effect.
Negative feedback loop
feedback that reduces the effect of, or eliminates, the original stimulus.
Body responds to a change (stimulus) -> new hormone made -> circulates -> back to original endocrine gland -> stops sending out anymore.
pancreas
Both endo and exo
exo - amylase, protease, lipase (pancreatic enzymes)
Endo - insulin and glucagon
lock and key model
Hormone will only work on a part of the body if it ‘fits’
if hormone binds to receptor on cell membrane, hormone can have effect.
Cells with no specific receptors can’t be affected by certain hormones.
3 types of hormones
Protein
Steroid
Amine
Protein
Those secreted by the pituitary gland and pancreas
steroid
Made from cholesterol, an important lipid.
secreted by gonads and adrenal cortex
Amine
made of small amino acid molecules
Hormone pathway into cell - protein and amine hormones
are water soluble.
Attach to receptor proteins on cell membrane of target cell. This triggers a secondary messenger called cyclic AMP (cAMP) in cytoplasm to activate enzymes to alter cell metabolism.
cAMP may move through cell, activating genes and causing a change in the cells function.
Quick to cause a response, but effect short lasting.
enzymes
Are proteins that increase speed of reactions ‘organic catalyst’
enzymes adjust chemical activity of cells, the speed of reactions will either increase or decrease
Hormone pathway into cell - steroid hormones
lipid/fat soluble, can diffuse through cell membrane through lipid bilayer.
Water soluble hormones (Protein/amine)
Hormones made from pituitary and pancreas
lipid soluble hormones (Steroids)
Hormones made by gonads and adrenal cortex
hypothalamus
Controls the pituitary gland and is attached to it by the infundibulum
secretes factors: releasing factors (rf) - stimulates secretions, inhibiting factors (if) - slows down secretion
Factors flow through blood vessels to reach anterior lobe of pituitary gland, whereas for posterior lobe of pituitary gland, hormones pass through nerve fibres in the infundibulum from the hypothalamus.
pituitary gland
“The master” gland because it regulates the functions of the other endocrine glands and many body functions.
Factors travel down through blood vessels to the anterior lobe.
other hormones are made by the hypothalamus and pass along nerve fibres to the posterior lobe where they are released.
Anterior pituitary hormones (6)
Growth hormone (GH)
Thyroid stimulating hormone (TSH)
Adenocorticotropic hormone (ACTH)
Prolactin (PRL)
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Posterior pituitary hormones (2)
Antidoretic Hormone (AH)
Oxytocin (OT)
Growth hormone (GH)
Target - all cells
effect - promotes body growth, bone and muscle, protein synthesis. Maintains size of body organs through life.
