Coordination Flashcards
Homeostasis
Homeostasis is the control or regulation of the internal conditions of a cell or organism
2 types a communication systems
The nervous system
The endocrine system
things homeostasis controls
temperature
pH
blood pressure
glucose conc.
water
where is body temperature controlled
thermoregulatory centre
how does skin controls temperature
contains temperature receptors
stimulus
change in environment
receptor
what detects a stimuli
coodination centre
brain, spinal cord, pancrease
receives and processes information from receptors
effector
what brings a response to bring back to optimum levels
2 things plants need to respond to
light and response to gravity
tropisms
directional growth responses made by plants in response to light and gravity
positive tropism
if it grows towards stimuli
2 trophisms in plants
phototropism and geotropism
what are plant growth regulators called
auxin
where is auxin produced
tip ofo the shoot and roots
auxin in shoots
promotes cell elongation
auxin in roots
inhibits cell elongation
what is distribuition of auxin affected by in shoots
light and gravity
what is distribuition of auxin affected by in roots
gravity
what happens if a shoot is placed on its side
auxin accumulates along the lower side
lower side grows faster than upper side
how does auxin distribute down the shoot
diffusion
what happens if light shines evenly around the tip
auxin is distributed evenly
what happens when auxin shines on one side
auxin concentrates on the shaded side so it grows faster on the shaded side
the nervous systems
info sent through as electrical impulses. they pass along nerve cells as neurones
what does nervous systems allow
rapid responses to stimuli
CNS
Brain and spinal cord
endocrine system
info is sent through as chemical substances known as hormones
how are hormones carried through the body
blood
where are hormones produced
endocrine glands
what does the endocrine system target
target cells in specific tissues
what does human nervous system consist of
PNS - periphiral nervous system
ALL NERVES IN BODY
CNS- brain and spinal
neurones
nerve cells in which electrical signals pass through
nerve
bundle of neurones
what do neurones consist of
cell body
cytoplasmic extensions (axons and dendrites)
axon
main long fibre of neurone
why do humans have one long neurone instead of multiple short ones
less time is wasted transferring electrical impulses from one cell to another
what is an axon insulated by
fatty myelin sheath
what are uninsulated sections of axon called
nodes
how do electrical impulses travel to axon
jumps from one node to the next
how are axons and dendrites helpful
neurones can connect to many other neurones forming a network
types of neurones
sensory
relay
motor
sensory neurones
carries impulses from sense organs to the CNS
Relay neurones
found inside CNS
connects sensory and motor neurones
motor neurones
carries impulses from CNS to effectors
how to identify sensory neurones
long and have a cell body branching off the middle of the axon
how to identify relay neurones
short and have small cell body at one end with many dendrites branching off it
how to identify motor neurones
long and have a large cell body at one end with long dendrites branching off it
pathway of nervous system
stimulus
sensory neurone
relay neurone
motor neurone
effector
response
what happens when a receptor is stimulated
it produces electrical impulse
synapse
when dendrites of 2 neurons meet
what is the small gap in between neurones called
synaptic cleft
what happens at the synaptic cleft
electrical signals are briefly converted to a chemical signal to cross the gap.
neurotransmitters
chemical signalling molecules used to transfer the signal between neurones
how are impulses sent across a synapse
1) electrical impulse travels along the first axon which triggers the end of the presynaptic neurone to release chemical messengers
2) these fuse with presynaptic membrane which releases contents to the cleft
3) neurotransmitters diffuse across the synaptic cleft and bind with the receptor molecules on the membrane of the postsynaptic membrane which stimulates second neurone to generate impulse
4) neurotransmitters are destroyed to prevent continued stimulation
what do synapses ensure
that impulses travel in one direction only
what is a reflex action
an involuntary response which is automatic and rapid which does not involve the concious part of the brain as the coordinator.
what do reflex action prevent
minmist damage and aids survival
what is a reflex arc
pathway of a reflex response
reflex arc for a pin touching finger
The pin (the stimulus) is detected by a (pain/pressure/touch) receptor in the skin on the person’s foot
A sensory neurone sends electrical impulses to the spinal cord
An electrical impulse is passed to a relay neurone in the spinal cord
A relay neurone synapses with a motor neurone
A motor neurone carries an impulse to a muscle in the leg (the effector)
When stimulated by the motor neurone, the muscle will contract and pull the foot up and away from the sharp object (the response)
what does the retina contain
rods
cones
rods
receptor cells that are sensitive to light
cones
receptor cells which are sensitive to colour
cornea
transparent lens that refracts light as it enters eye
iris
controls how much light enters the pupil
lens
transparent disc that can change the shape to focus light onto the retina
retina
Contains light receptor cells and cones
optic nerve
sensory neurone that carries impulses between the eye and the brain
pupil
hole that allows the light to enter the eye
ciliary muscle
ring of muscle that contracts and relaxes to change the shape of lens
suspensory ligaments
ligaments that connects the cilliary muscle to lens
sclera
strong outer wall of the eyeball that helps keep an eye in shape and provides a place for muscles to attach
fovea
region in retina with highest density of cones where eyes sees good detail
aqeous humour
watery liquid between cornea and lens
vitreous humour
jelly like liquid filling eyeball
choroid
pigmented layer of tissue lining the inside of the scelera that prevents the reflection of light rays inside the eyeball
blind spot
point at which optic nerve leaves eye with no receptor cells
accomoodation
the way lens brings out fine focusing
adapatation of lens
elastic and its shape can be changed when suspensory ligaments attached to it
staring at a close image
- cilliary muscles contract
- suspensory ligaments loosen
- lens becomes fatter
- light is refracted more
staring at a faw away object
- cillary muscles relax
- suspensory ligaments tighten
- suspensory ligaments pull lens
- lens becomes thinner
- less light refracted
pupil reflex
reflex action carried out to protect the retina from damage
pupil in dim light
dilates to allow as much light into eye
pupil in bright light
constricts to prevent light from entering eye and damaging retina
cooling mechanisms in body
- vascodilation: greater volume of blood in capilarries. arterioles go near skin and dilate
- increased sweat to cool off by evaporation
- hair erector muscles relax so hair lies flat to prevent trapping heat
what detects change in temperature in the body
temp receptors and hypothalamus
hormone
chemical substance produced by a gland and carried by the blood which alters the activity of one or more specific target organs
hormones in body
adrenaline
insulin
testosterone
progesterone
oestrogen
role of adrenaline
- fight of flight
- produced when body is in danger
- prepares for movement
what does adrenaline do
- increases heart rate and breathing rate
- diverts blood flow to muscles
- dilation of blood vessels inside muscles
- breaking down of stored glycogen to glucose
what does too high glucose levels lead to
cells losing water by osmosis
what does low glucose levels lead too
insufficient glucose for respiration leading to death
what works together to control blood glucose levels
pancreas and live
what produces insulin
pancreas
what happens if blood glucose levels are high
- pancreas produces insulin
- stimulates live to take up glucose and store is a glycogen
what happens if glucose levels are low
- pancreas produced glucagon
- causes glucagon stored in liver to convert into glucose and to be released in blood
where is testosterone produced
male testes
testosterone
responsible for development of secondary sexual characteristics
where is progesterone produced
ovaries
progesterone
responsible in maintaining the uterine lining during pregnancy
where is oestrogen produces
female ovaries
oestrogen
responsible for development of secondary sexual characteristics and regulating the menstrual cycle
Advanced hormones
Antidiuretic
follicle- stimulating
luteinising
ADH
controls water levels
what happens when water content in blood falls
- blood is conc.
- pituitary glands release ADH
- causes collecting ducts to be mroe permeable
- water is reabsorbed
what releases ADH
Pituitary glands
what happens when water content is high
- blood dilute
- less ADH
- collecting duct is less permeable
- less water reabsorbed
- larger volume of urine which is less conc.
what releases FSH
Pituitary gland
role of FSH
Causes ovary to develop a mature egg cell
effect of FSH
Stimulates development of egg cells in ovary and the release of oestrogen
What releases LH
Pituitary glandd
role of LH
Causes ovary to release a mature egg cell
effect of LH
Stimulates the release of an egg cell from ovary and the release of progesterone
what produces progesterone
corpus luteum
