B13 - coordination & response, hormones, homeostasis Flashcards
roles of nervous system
-coordination
-regulation
define neureons
-nerve cells which transmit electrical impulses
note: CNS = central nervous system
what does CNS consist of
-brain
-spinal cord = control involuntary actions
what does peripheral nervous system consist of
nerves outside of CNS (sensory & motor neurons)
which neurons are found where
sensory & motor - peripheral nervous system
relay - CNS
function of relay neuron
-connect sensory neurons to motor neurones
function of sensory neuron
-carry electrical impulse from receptors to CNS
function of motor neuron
-carry electrical impulses from CNS to effector
where are cell body in sensory, relay & motor neurons
sensory - near the end of neuron
relay - center of neuron
motor - in dendrites
where are dendrites in sensory, relay & motor neurons
sensory - end of neuron
relay - both ends
motor - attached to cell body
part of sensory neuron
-dendrites
-cell body
-nucleus
-axon - inside myelin
-node of ranvier - gap btw myelin
-myelin
-receptor
(direction of impulse is to CNS)
define reflex action
-rapid automatic response to stimulus
-for protection for emergency
-happens before brain is aware
part of motor neuron
-dendrites
-cell body
-nucleus
-axon - inside myelin
-node of ranvier - gap btw myelin
-myelin
-motor end plates
-muscle (effecotr)
part of relay neuron
-dendrites
-cell body
-nucleus
-axon
(no myelin & node of ranvier)
reflex arc
-stimulus
-receptor
-sensory neuron
-relay neuron
-motor neuron
-effector
-response
define reflex action
rapid & automatic response to a stimulus
define receptor
-cell that detects stimulus & generates an electrical impulse
receptor cells & sense organs for light
receptor cells: photoreceptors
sense organs: eye
receptor cells & sense organs for sound, body movement
receptor cells: balance receptors
sense organs: ear
receptor cells & sense organs for chemical (smell)
receptor cells: chemoreceptors
sense organs: nose
receptor cells & sense organs for chemical (taste)
receptor cells: chemoreceptors
sense organs: tongue
define hormnoes
chemical substance produced by a gland (endocrine) & carried by the blood which alters the activity of 1 or more specific target organs
receptor cells & sense organs for temp, pressure, touch, pain
receptor cells: thermoreceptors, pressure/ pain/ touch receptors
sense organs: skin
parts of an endocrine system
-endocrine gland = releases hormones in blood
-target organs = receptor that respond to specific hormone
types of endocrine gland & their hormones
note: they’re transported by blood
adrenal gland = adrenaline
pancreas = insulin & glucagon
testes = testosterone
ovaries = oestrogen & progesterone
note: pancreas is an exocrine & endocrine gland
exocrine - hormones don’t go in blood
endocrine - hormones go in blood
why is adrenaline the fight or flight hormone
-prepares the body for flight/ flight when brain detects a stressful, dangerous or exciting situation
effects of adrenaline
-increase breathing rate: faster aerobic respiration for more energy release for muscle contraction
-increase heart rate: more O2 & glucose to cells (more CO2 away from cells) = more aerobic respiration for more energy for muscle contractions
-increase pupil diameter: more light in, photoreceptors have clearer coloured vision in bight light
examples of situations where adrenaline secretion increases
-start of race
-start of test
-skydiving
define effector
muscle/ gland which responds to stimuli
where is adrenal gland found in the body
above the pancreas, beside the kidneys
difference when identifying images of a sensory & motor neurone
sensory - cell body outside like a pimple
motor - cell body inside dandrites
what do all sense organs contain
receptors
note: when a reflex happens, it happens without control of the brain
define homeostasis
maintenance of constant internal environment within narrow limits
examples of homeostasis
-temp; kept at 37C - for optimum enzyme activity
-blood glucose concentration; kept at same water potential like cells - prevent osmosis & cell damage
-water concentration; kept at same water potential like cells – prevent osmosis
what happens if there is too much or little blood glucose concentration
much - cell shrinks
little - cell bursts
define negative feedback
deviation from a set point sets of a response that cancels out the change
how does negative feedback work
-there’s a set point
-deviation from norm (stimulus); up or down
-detected by receptors
-effector (muscle/ gland) is stimulated & corrective mechanisms are done
-restoration of set point
skin tissue structure
-receptors
-hair
-hair erector muscle
-blood capillaries
-sweat gland
-arteriole
-sensory neuron
-muscles
-adipose tissue (fat cells)
define themoregulation
-control of internal body temp
note: liver & pancreas produce lots of heat which is transport around the body by blood
thermoregulatory mechanisms
down = reduce temp.
up = increase temp.
-insulation (maintain temp)
-role of brain (maintain temp)
-shivering (up)
-vasoconstriction (up)
-sweating (down)
-vasodilation (down)
why must body temp. be maintained at a constant level
keep enzymes at their optimum
how does insulation work & its effect
-adipose tissue prevents heat loss
-maintains body temp
how does vasodilation work & its effect
-arterioles relax for more blood flow to capillaries so more heat is lost from skin surface by radiation
-increases heat loss
how does role of brain work & its effect
-coordinates response based on signals form body & skin temp receptors & activates necessary effectors to keep body temp. just right
-maintains body temp
how does shivering work & its effect
-skeletal muscles contract & relax involuntarily to generate heat
-increases body temp.
how does vasoconstriction work & its effect
-arterioles constrict for less blood flow to capillaries so less heat is lost from skin surface by radiation
-reduces heat loss
how does sweating work & its effect
-sweat gland release sweat onto skin surface to evaporate for a cooling effect
-reduces body temp.
define arterioles & their function
-branches of arteries that deliver blood to capillaries (near skin surface)
-contract & relax to control blood flow to capillaries
blood sugar concentration negative feedback
-deviation from set point detected by pancreas
-deviation up = pancreas release insulin; activate enzymes to allow glucose to be converted to glycogen by liver
-deviation down = pancreas release glucagon; activate enzymes to allow glycogen to be converted to glucose from liver
-negative feedback
-back set point
how does blood glucose concentration increase & decrease
increase - after a meal
decrease - exercise, skip meals
blood glucose concentration will continue increasing until…
insulin released
3 points about type 1 diabetes
-cannot produce insulin
-must inject insulin before every meal
-low sugar diet
2 hormones that increase blood glucose concentration
-adrenaline
-glucagon
what is control of blood glucose concentration called
negative feedback
similarities & differences btw sensory & motor neuron
same - both carry electrical impulses quickly over long distances
diff - sensory carries impulses to CNS, motor carries impulses away from CNS
describe the role of arterioles in vasodilation
-arterioles expand
-more blood flows to the skin surface
-more heat loss by radiation
