3.3 Flashcards
Where are hormones produced
Endocrine glands, in very small amounts
Where are hromones secreted into
Directly into the bloodstream where they target one or several organs
Describe the nature of effects produced by hormones with an example
Long-lasting and genrally involved in more long-term processes. e.g. growth and sexual development or control of cell metabolism
Define target cells in relation to the endocrine system
Specialised cells on which hormones act
Membranes on taget cells consist of specific ________
protein recpetor molecules
What is the role of protein hormone recpetor molecules
detect the presence of hormones outside the cell and carry the message across the cel through a series of enzme reactions
What is the pituaitary gland often reffered as
The master gland
What are the two types of hormones
proteins (including peptides) or steroids ( a type of lipid)
what is the role of the pituitary gland
Release a variety of hormones that either have a direct effect or cause other endocrine glands to release their specific hormones. This allows feedback to control the release of a hormone
Exaplin steroid hormones
Lipid soluble (cholestrol) and are able to pass thrugh the cell and nuclear membrane, directly effecting recptor molecules within the cell
Explain protein hormones
Unable to pass through the membrane - instead they bind to protein recpetors on the cell membrane
Name some types of endocrine glands and where they are situated in the body
Brain: Pituitary, hypothalalmus, pineal
Neck: thyroid
Abdomen: Adrenal, pancreas
Pelvis: female gonads (ovaries)
Scrotum: male gonads (testes)
Describe some horomes, where they are released and what their role is
ADH - pituatiary - controls reabsoption of water in the kidneys
Growth hormone - pituitary - growth of body cells and tissues
Follicle stimulating (FSH) - pituaitary - stimulates ovaries adn testicles
TSH - pituaitary - stimulates activity of thyroid gland
Thyroxine - thyroid - stimulates metabolism and heat production
Parathyroid hormone (PTH)- parathyroid - stimulates release of calcium from bones
Pancreas - insulin and glucagon - lowers blood sugar/raises blood sugar
Adrenalin - adrenal gland - increases blood sugar and constricts blood vessels
Testosterone - testes - male charecteristics, sperm production
Oestrogen, progesterone - ovaries - female charecteristics, maintain uterine lining
The rate of hormone secretion and usage by tagert cells is closely related. T or F?
True - the control of hormone levels are closely maintained by negative feedback systems
What does negative feedback do in the endocine system
A mechanism that maintains the balance between hormone levels and the needs ot target cells - endocrine glands will contrinue to secrete hormones until messages come back from the target cells that there is sufficient amounts of the specific hormone present. These messages (enzymes) are secreted by the target cells and inhibit hormone secretion in the endocrine gland
Describe the steps in the thyroid stimulating hormone cycle
Hypothalamus releases thyroid-releasing hormone (TRH)
TRH causes anterior pituitary to release Thyroid stimulating hormone (TSH)
TSH triggers the production + release of thyroxine y the thyroid gland.
An increase in the level of thyroxine in the blood inhibits the hormones from the hypothalamus (TRH) and pituitary (TSH) = negative feedback
Describe body response to blood glucose levels being too high
Rising blood sugar levels (e.g. after eating a meal)
Beta cells of pancrease stimulated to release insulin into the blood
Insulin stimulates the body cells to taje up more glucose, and fro the liver to take up more glucose and store it as glycogen.
This causes blood glucose levels to decline back to the bodys set-point, hence the stimulus for insulin to be released diminishes
Describe the body’s responses to too low blood glucose levels
Low blood glucose levels
Aplha cells in pancrease stimulated to release glucagon into the blood
Alpha cells trigger the breakdown of glycogen into glucose which is released into the blood
Blood glucose rises to setpoint, hence stimulus for glucagon production and rlease diminishes
Why is water content of the body controlled
to protect body cells
How is water content controlled
Lungs when exhaling, skin by sweating, urine produced by the kidneys
describe the bodys response to too little water in the blood
Hypothalamus detetcs too little water
Pituitary gland releases ADH
Kidneys maintain blood water level
Less water is lost in urine (urine is more concentrated)
Blood water levels return to normal
Describe the bodys response to too much water in the blood
hypothalamus detects too much water in blood
Pitutitary gland releases less ADH
Kidneys reduce blood water level
more water reaches bladder (urine more dilute)
blood water level returns to normal
Describe the bodys repsonse to above normal body temp
Body temp above normal
Nervous system siginals dermal blood vesssels to dilate and sweat glands to secrete
Body heat lost to surroundings
Body temp drops back to normal
describe the bodys reponse to below normal body temp
Body temp below normal
Nervous system signals dermal blood vessels to constrict and sweat glands to remain inactive, TSH stimulating hormone increases release of thyroxine by thyroid to increase metabolism, nervous system signals muscles to contract involunatirly
body temp increases
Body temp returns to normal
What are the causes of diseases and disorders in the endocrine system
imbalances in feedback mechanisms
Describe the cause of diabetes
Pancrease either doesn’t produce adequate insulin levels or body doesn;t properly respond to insulin
Explain the release of adrenaline in the fight or flight response
Amygdala reacts to a threat
ypothalamus activates sympathetic nervous system, body releases adrenaline
adrenal cortex releases corisol for continued alertness
Explain some physiological changes during the fight or flight response and the purpose for them
increased heartrate - increase blood flow to organs and increase movement of adrenaline around the body
Increased breathing - increased oxygen intake
pupil dilation - increase light entry into eye to enhance vision
sweat production - regulate temperature
reduction of non-essential functions (e.g. digestion, urination, salivation) - increases energy for other essential functions
Compare the nervous and endocrine systems
Endocrine - made up of secretory cells, uses chemicals (hormones) as mode of transmissions, transmission pathway is blood plasma, slow speed of trasnsmission, long-term effects, response is more widespread
Nervous - made up of neurons, mode of transmission is electrical impulses, nerve fibres are the transmission patheay, fast speed of transmission, short-term effects, response more localised
