B9 Coordination and response Flashcards
describe nerve impulse
electrical signal that passes along nerve cells (neurones)
describe the human nervous system (3)
- central nervous system (CNS)
- peripheral nervous system
- coordination and regulation of body functions
CNS consists of…
brain and spinal cord
peripheral nervous system consists of..
motor neurones and sensory neurones
define voluntary action
conscious decisions, it takes longer time and produces different responses everytime
define involuntary action
do not involve conscious decisions, takes short time and produces same responses everytime
explain reflex arc
a neutral pathway that controls reflex
stimuli - receptor - sensory neurone - relay neurone - motor neurone - effector - response
effector example
muscle or gland
identify the structures of the eye (9)
- cornea
- iris
- pupil
- lens
- ciliary muscle
- retina
- optic nerve
- suspensory ligament
- blind spot
function of cornea
refracts light
function of iris
controls the amount of light entering the pupil
function of lens
focuses light into retina
function of retina
contains light receptors, some sensitive to light of different colors
function of optic nerve
carries impulses to the brain
rods are located in … and they are sensitive to …..
peripheral parts of the retina
light - black and white
work well in dim lights
cons are located in … and they are sensitive to …..
fovea
color
works well in bright light
pupil reflex
high light intensity
circular muscle contract
radial muscle relax
pupil size decrease
pupil reflex
low light intensity
circular muscle relax
radial muscle contract
pupil size increase
accommodation
near objects
ciliary muscle contract
suspensory ligament loosen
refraction large
lens shape fat and short
accommodation
far objects
ciliary muscle relax
suspensory ligament tighten
refraction less
lens shape thin and long
define hormones
chemical substance, produces by gland carried by blood, which alters the activity of one of more specific target organs
describe adrenaline in terms of the secretion organ, effects, and when it is secreted
secreted from adrenal gland
increases breathing rate to provide more o2 and glucose to the muscles
widens pupil to detect more light
increases pulse rate
secreted in dangerous situation - ‘fight or flight’
eg. intense exercise, dangerous situation
describe the role of adrenaline
- increase blood glucose concentration
- increase pulse rate
compare nervous system and hormonal control system in terms of speed and longevity of action
nervous system
- fast
- short lasting
hormonal system
- slow
- long lasting
define homeostasis
maintenance of a constant internal environment within a set limit
describe negative feedback
cancels the change made if its excess of deficient of set limit
eg. excess
detected by receptor
effectors stimulated and initiate corrective mechanisms
restoration of set point
describe the control of the glucose content of the blood
excess and deficiency
excess
- blood with too much glucose
- pancreas detect it and release insulin
- blood moves to liver and insulin makes glucose intro glycogen and stores in liver
- blood glucose decreased
deficiency
- blood with too little glucose
- pancreas detects it and release glucagon
- glucagon makes the liver turn stored glycogen into glucose and release to blood
- blood glucose increased
describe the mechanism to reduce body temperature (3)
- hair lie flat
less air is trapped for insulation - sweating
water evaporated and cooling effect - vasodilation
arterioles near the surface of the skin dilate and makes more blood flow through the capillaries in the surface of the skin, to release more heat
describe the mechanism to increase body temperature (3)
- hair stands up
more air trapped for insulation - shivering
muscle contracts and more heat is produced from increased respiration rate - vasocontraction
arterioles contract, release less blood for less heat loss
define gravitropism
plant growing towards or away from gravity
define phototropism
plant growing towards or away from the direction from which light is coming
shoots are …….. ……….
negative gravitropism
positive phototropism
roots are …….. ………
positive gravitropism
negative phototropism
explain the role of auxin of controlling shoot growth (4)
- made in shoot tips
- spreads through the plant from shoot ip
- unequally distributed in response to light and gravity
- stimulated cell elongation
