Homeostasis and Hormones Flashcards
Definition of homeostasis
maintenance of a constant internal environment within set limits
Define hormones (2)
chemical substance produced by gland
alters activity of one or more target organs
Where are hormones produced
endocrine glands
How are hormones transported (2)
secreted into blood
carried around the body dissolved in plasma
Effects of adrenaline (4)
increased pulse rate
increased depth of breathing
dilate pupils
causes liver and muscle cells to release glucose
Where is adrenaline produced
adrenal glands above kidneys
Functions of adrenaline
released in crucial moments during flight/fight response
Hormones vs Nervous Systems form of transmission (2)
hormones is chemical
neurons = electrical impulses
Where is glucagon secreted
pancreas
Hormones vs Nervous Systems transmission pathway (2)
nervous = nerves
hormones = blood
Hormones vs Nervous speed (2)
nervous faster
hormones slower
Hormones vs Nervous duration (2)
nervous shorter
hormones longer (until hormone broken down)
Hormones vs Nervous location of response (2)
nervous = specific
hormones = widespread though target organ may be specific
Hormones vs Nervous what they consist of (2)
Nervous = neurons
hormones = glands
Define the endocrine system
series of glands that produce/secrete hormones
Define a gland
organ/tissue which produces/secretes chemical substances/hormones
Glucoregulation steps for lack of glucose (4)
brain detects low blood glucose level
pancreas releases glucagon hormone into bloodstream
liver converts glycogen to glucose and releases to blood stream
blood glucose level rises
Effect of increased pulse rate on adrenaline (2)
circulate blood more rapidly
deliver glucose and oxygen to muscle cells for more rapid contraction
Effect of increased depth of breathing on adrenaline (2)
take more oxygen quicker
remove more CO2 quicker
Effect of dilated pupils for adrenaline
better vision
Effect of releasing glucose for adrenaline (3)
increase blood glucose concentration
more glucose for muscle respiration
release more energy for muscle contraction
Glucoregulation steps for excess glucose (4)
brain detects high glucose blood levels
pancreas releases insulin hormone into bloodstream to liver
insulin causes liver to store glucose as glycogen
blood glucose level decreases
Examples of homeostasis in sweat (3)
body temperature too high
sweat released from sweat glands
evaporation releases energy
Examples of homeostasis in vasodilation (4)
arterioles near surface of skin dilate (widen)
more blood flows through capillaries
easier for heat to be transferred to skin
heat to environment by radiation and conduction
Define negative feedback
stimulus change causes response which produces opposite change
Homeostasis in vasoconstriction (4)
if body temperature too low arterioles near surface of skin constrict (narrower)
reduces amount of blood flowing through capillaries
warm blood kept deeper in skin
reduces heat loss by conduction
Homeostasis reactions to low body temperature (2)
body hair raised by muscles in skin –> trap air as an insulator
muscles shiver - muscle contraction used to produce contractions which release energy and warm the body
Which gland secretes testosterone
testes
Which gland secretes insulin
pancreas
Which gland secretes oestrogen
ovaries
Example of positive feedback (childbirth) (5)
baby head pushes cervix
nerve impulses from cervix transmitted to brain
brain causes pituitary gland to produce oxytocin
oxytocin carried in blood to uterus
oxytocin causes uterus contractions and pushes baby to cervix
Example of positive feedback in blood clotting (4)
break in blood vessel wall
clotting - platelets adhere to damage and release chemicals
clotting continues until break sealed
released chemicals attract more platelets
