coordination and response (topic 14) Flashcards
stimulus
A change in the environment that can be detected by an organism.
nervous system
An organ system consisting of the brain, spinal cord and neurones. It responds quickly to changes inside and outside of the body.
neurones
nerve cells in which nerve impulses travel along as electrical impulses
what composes the mammalian nervous system
cns and pns
cns
central nervous system
-brain and spinal cord
-responsible for coordinating all reactions and nervous communication around the body.
pns
peripheral nervous system
-all nerves which arent in the spinal cord or brain
responsible for transmitting the impulses from the CNS to all parts of the body.
what is the role of the nervous system
coordination and regulation of body functions
what are the three main types of neurones
sensory, relay, motor
structure of a sensory neurone
long cell body in the middle of the neurone
strcuture of relay neurone
short, cell body
strucutre of motor neurone
long, cell body at the end
sensory neurones
receive impulses from receptor cells, because of a stimulus, and carries impulse towards cns
relay neurones
make link between sensory and motor neurone
motor neurone
transfer nerve impulses from brain or spinal cord to effectors eg. muscles or glands for a dedicated response
what is a sysnapse
a junction between two neurones
allows an impulse to travel from an axon terminal of one neurone to a dendrite in another neurone
axon terminal
end of an axon in a neurone that releases neurotransmitters from vesicles into the synaptic gap.
dendrite
Further branches at the end of dendrons in a neurone that receive signals from other neurones via the synapse.
what do axon terminals contain
many vessicles which contai neurotransmitters
what do dendrites contain
receptor molecules that bind to these neutrotransmitters
what happens when a nerve impulse arrives at the axon terminal
- vesicles release neurotransmitters into synaptic clef
- neutrotransmitters travel along gap by diffusion
3.neurotransmitter bind with receptor molecules on dendrite
4.nerve impulse triggered in this neurone
reflex action
A means of automatically and rapidly integrating and coordinating stimuli with the responses of effectors (muscles and glands).
involuntary action, rapid, automatic, innate
reflex arc
Pathway through the body that brings about a reflex action.
reflex arc path
receptor → sensory neurone → relay neurone → motor neurone → effector
what are receptors
cell that detects stimulus, make connections with sensory neurones
what are the different types of receptors
touch- skin
sound- ear
light- eye
chemical- nose, tongue, mouth
temperature- skin and brain
effectors
a muscle or gland that produces a response to a stimulus.
what do sysnapses ensure
that impulses travel in one direction only
sense organ
A group of receptor cells that respond to a specific stimulus.
what are the main strcutrues present in the eye
lens, pupil iris, cornea, retina, fovea, blind spot, optic nerve
cornea
transparent outer layer, refracts light, focusing it towards the retina
lens
transparent rounded structure, refracts light, focusing it onto the retina
iris
coloured part of the eye, controls the amount of light passing through the pupil
retina
layer containing receptor cells, responds to light levels and to light of different colours
optic nerve
bundle of neurones, carries nerve impulses from the retina to the brain
blind spot
Area at the back of the retina where the optic nerve enters the eye that contains no light-sensitive cells
what happens to eye in dim light
pupil dilates, letting more light into the eye. To make this happen, the radial muscles contract and the circular muscles relax.
what happens to eye in bright light
the pupil constricts, letting less light into the eye. To make this happen, the radial muscles relax and the circular muscles contract.
how do the muscles in the iris work
in antagonistic pair,
composed of circular and radial muscles
what is accomodation
Changes in the ciliary muscles, suspensory ligaments and lens that allow the eye to focus on distant and near objects.
ciliary muscles
Muscles connected to the lens of the eye by suspensory ligaments.
suspensory ligmants
Structures in the eye that connect the ciliary muscles to the lens.
accomodation in distant objects
light enters in parallel lines
the ciliary muscles relax
the tension in the suspensory ligaments increases
the lens becomes thinner
light is refracted less strongly.
accomodation in near objects
light is diverging as enters the eye
the ciliary muscles contract
the tension in the suspensory ligaments decreases
the lens becomes thicker
light is refracted more strongly.
what are the 2 receptor cells present in the retina
rods and cones
describe cones
Light-sensitive cells in the retina responsible for colour vision, located in the fovea
provide colour vision
3 different types of cones, red green or blue light
fovea
fovea is the part of the retina which produces the clearest, sharpest image.
describe rods
more sensitive to light than cones, allow vision in dim light
located away from fovea, located at the sides of the retina
hormone
A chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.
endocrine system
A system of glands that secrete hormones that help to regulate body functions.
target organ
An organ that is affected by a particular hormone.
what are the 4 main endrocine glands
adrenal gland, pancreas, ovary, testes
what hormone does adrenal gland produce
adrenaline
what hormone does pancreas produce
insulin and glucagon
what hormone does testes produce
testesterone
what hormone does ovaries produce
oestrogen
oestrogen
The main female sex hormone. It plays a major role in the control of the menstrual cycle. produced by ovaries
testesterone
The main male sex hormone. It plays a key role in the primary and secondary sexual systems in males. produced by testes
compare hormonal system to nervous system
hormonal is slower and longer lasting
adrenaline
hormone released in fight or flight situations
effects of releasing of adrenaline
-increased breathing rate(increase the supply of oxygen into the blood and remove carbon dioxide from the blood)
-increased pulse rate. (increase the delivery of glucose and oxygen to muscles around the body)
-pupils dialate
-increase in blood glucose levels from the breakdown of glycogen stored in the liver and muscles
metabolism
All the chemical reactions that happen inside living cells, including respiration.
homeostasis
The maintenance of a constant internal environment in the body. controlled by negative feedback
negative feedback
A response which is the reverse of the change detected
thermoregulation
Process that allows the body to maintain a stable core temperature
what are the structures present in the skin
hair, sweat gland, hair erector muscle, receptor, blood vessels, sensory nerve, fatty tissue
what are 2 mechanisms that help control body temp
shivering- if body too cold
sweating- if body too hot
describe shivering
response to cold enviornment/ stimuli
caused by muscle contraction and relaxing uncontrollably and uncordinatly, respiration releases energy for this movement, this increases body temp
describe sweating
As sweat evaporates, energy is transferred to it by heating from the skin. This cools the skin, helping to reduce body temperature.
vasodilation
body temp too high, arterioles (small arteries) dilate, causing more blood to flow in the skin capillaries, so more heat is lost from the body.
vasocsontriction
body temp too low, arterioles constrict, causing less blood to flow in the skin capillaries, so less heat is lost from the body.
role of insulin limited to glucose
The hormone that stimulates the liver to turn glucose into glycogen. lowers blood glucose concentration, also stimulates tissues such as muscles to take in glucose from the blood ether use this glucose, or convert to glycogen (form of storing glucose in liver or muscles)
glucagon
The hormone that stimulates the breakdown of glycogen into glucose. causing blood glucose concentration to increase
outline what happens when blood glucose concentration is too high
insulin is released causing the concentration to fall.
insulin released by pancreas stimulates glucose uptake from blood by tissue cells or stimultes the conversion of glucose to glycogen which is stored in muscles or liver
in turn this lowers glucose concentration
outline what happens when blood glucose concentration is too low
glucagon is released causing the concentration to rise.
glucagon released by pancreas stimulates breakdown of glycogen in liver which raises glucose concentration in blood
role of insulation in thermoregulation
Layers of fat under the skin provide one way to keep the body warm in a cold environment. This fatty tissue is a good thermal insulator, helping to reduce the transfer of thermal energy from the body to the surroundings.
what is type 1 diabetes
Autoimmune disease in which the insulin-producing cells in the pancreas are attacked, leading to the inability to control blood glucose levels. cant lower blood glucose concentration
symptoms of type 1 diabetes
-frequent urination (because the body is trying to excrete excess glucose)
-increased thirst (resulting from the frequent urination, and also because the body is trying to dilute the blood to reduce the blood glucose concentration).
treatments for type 1 diabetes
They involve careful monitoring of diet and insulin levels, and insulin injections.
tropism
A response by a plant to a stimulus.
gravitropism
a response in which parts of a plant grow towards or away from gravity
phototropism
a response in which parts of a plant grow towards or away from the direction of the light source
positive vs negative tropism
a positive tropism, parts of a plant grow towards the stimulus
negative, grow away from stimulus
outline phototropism in real life example
when plant shoot grows towards light- positive
when root grows away from light- negative
outline gravitropism in real life
when shoots grow against gravity- negative
when roots grow with gravity- positive
what is auxin
Plant hormone that affects the rate of elongation in shoots and roots, causing tropisms in response to stimuli.
explain how auxin works
auxin is only produced in tip of growing shoot or root, auxin is distributed unequally in response to a stimilus eg light or gravity
this effects how rapidly growing cells elongate
what dialates/ constricts in thermoregulation
artery
what is a venule
collects blood from a netweork of the narrowest blood vessel, from capillaries to veins
what is a shunt vessel
redirects blood flow deeper under the surface of the skin, from arterioles to venules
