14. Coordination and Response Flashcards
What travels along neurones?
electrical impulses
What two systems comprise the mammalian nervous system?
central nervous system (CNS)
peripheral nervous system (PNS)
What does the CNS consist of?
brain and spinal cord
What does the PNS consist of?
nerves outside of brain and spinal cord
What is a nerve?
tissue made of many different neurones
What is the role of the nervous system?
coordination and regulation of body functions
What is the order of the reflex arc?
receptor, sensory neurone, relay neurone, motor neurone, effector
What does a sensory neurone do?
receives electrical impulses from a receptor and sends it to a relay neurone (towards CNS)
What are some different types of receptors?
visual
olphatory
auditory
touch
taste
What does a relay neurone do?
receives electrical impulses from a sensory neurone, sends it to a motor neurone.
information received is processed in the brain for an appropriate response.
What does a motor neurone do?
receives electrical impulses from a relay neurone (from the CNS) and sends it to effectors
Where are effectors found?
muscles and glands
What is the structure of a sensory neurone, simply?
cell body in the middle, long
What is the structure of a relay neurone, simply?
cell body at the top, short, no myelin sheath
What is the structure of a motor neurone, simply?
cell body at the top, long
Which neurone(s) do(es) not contain myelin sheath?
relay neurone
What are dendrites?
extension of cell membrane that captures electrical impulses
What is an axon?
extension of cell membrane that conducts the electrical impulse
What are synaptic ends?
branches of the axon that will connect to another neurone
What is a myelin sheath?
fat layer that insulates the axon
What is the role of the myelin sheath?
allows a faster electrical impulse by insulation the axon
Define the term ‘reflex action’.
a means of automatically and rapidly reacting to stimuli by coordinating our effectors (muscles/glands)
or
autonomic/involuntary reaction of the body against dangerous situations
What is a synapse?
a junction between two neurones
Describe the events at a synapse.
- impulse stimulates release of neurotransmitters from vesicles into synaptic gap
- neurotransmitters diffuse across synaptic gap
- neurotransmitters bind to receptor proteins on postsynaptic neurone
- impulse stimulated in postsynaptic neurone
What happens to neurotransmitters once an impulse is sent?
they are recycled or destroyed
What do synapses ensure?
impulses flow in one direction only
What does a sense organ consist of?
a group of receptor cells that respond to specific stimuli
What is the function of the cornea?
refracts light
What is the function of the iris?
controls how much light enters the pupil
What is the function of the lens?
focuses light onto the retina
What is the function of the retina?
contains light receptors, some sensitive to light levels, some to light of different colours
What is the function of the optic nerve?
carries impulses to the brain
What does the iris consist of?
radial and circular muscles
What happens to your iris when exposed to bright light?
circular muscles contract
radial muscles relax
What happens to your iris when exposed to dim light?
radial muscles contract
circular muscles relax
What correlation do radial and circular muscles have?
they are antagonistic
How does light from far away objects enter the eye?
in almost parallel lines
How does light from near objects enter the eye?
diverging lines
What happens to ciliary muscles when seeing far away objects?
relax
What happens to the tension in the suspensory ligaments when seeing far away objects?
increases
What happens to the lens when seeing far away objects?
becomes thinner and flatter
What happens to light refraction when seeing far away objects?
light is refracted less strongly
What happens to ciliary muscles when seeing near objects?
contract
What happens to the tension in the suspensory ligaments when seeing near objects?
decreases
What happens to the lens when seeing near objects?
becomes thicker and fatter
What happens to the light refraction when seeing near objects?
light is refracted more strongly
How are rods distributed in the retina?
equally, except in fovea, where there are no rods
How are cones distributed in the retina?
concentrated in the fovea
What is the function of rods? What are they sensitive to?
rods are sensitive to light, responsible for vision in dim light
What is the function of cones?
provide colour vision
How many kinds of cones are there? Why?
3, to absorb different coloured light
Where is the fovea?
next to the blind spot, middle of retina
What is the function of the fovea?
where visual acuity is the highest, where we focus our vision onto
Define ‘hormone’.
a chemical substance which alters the activity of one or more specific target organs
Where are hormones produced?
glands
Through what are hormones carried?
by the blood
Where is adrenaline produced?
adrenal glands
Where is insulin produced?
pancreas
Where is testosterone produced?
testes
Where is oestrogen produced?
ovaries
In what type of situation is adrenaline secreted?
‘fight or flight’ situations
What are three effects of adrenaline?
- increased breathing rate
- increased heart rate
- increased pupil diameter
Compare the speed of action in nervous and hormonal control.
nervous - fast
hormonal - slow
Compare the duration of effect in nervous and hormonal control.
nervous - short-term
hormonal - long-term
Where is glucagon secreted from?
pancreas
What are 2 ways in which adrenaline controls metabolic activity?
- increases blood glucose concentration
- increases heart rate
Define ‘homeostasis’.
the maintenance of a constant internal environment
What does insulin do?
decreases blood glucose concentration
How does the negative feedback system work?
- change in internal conditions
- body returns conditions to normal
- done by nervous and hormonal systems
How can Type 1 diabetes be treated?
- pancreatic transplant
- transplant of specific insulin-producing cells in the body
What happens to arterioles when body temperature is too high?
widen (vasodilation)
Why does vasodilation occur when body temperature is too high?
increases blood flow through skin capillaries, rate of energy transfer to surroundings increases
What happens to arterioles when body temperature is too low?
constrict (vasoconstriction)
Why does vasoconstriction occur when body temperature is too low?
reduces blood flow to skin, rate of energy transfer to surrounding decreases
Define ‘geotropism’.
a response in which parts of a plant grow towards or away from gravity
Define ‘phototropism’.
a response in which parts of a plant grow towards or away from the direction of a light source
What are two examples of chemical control of plant growth?
phototropism and geotropism of a shoot
Explain how auxin controls shoot growth.
- auxin produced in shoot tip
- diffuses through plant
- auxin unequally distributed due to light and gravity
- auxin stimulates cell elongation
What is the role of a sensory neurone?
receives electrical impulses from a receptor and sends electrical impulses to a relay neurone, towards the CNS
What is the role of a relay neurone?
receives electrical impulses from a sensory neuroneinformation is processed in the brain for a sensible responsethe impulse is sent to a motor neurone
What is the role of a motor neurone?
receives electrical impulses from relay neurones (from the CNS) and sends it to glands/muscles (effectors)
What are dendrites?
extensions of cell membranereceives electrical impulses
What are axons?
extension of cell membraneconducts electrical impulses
What are synaptic ends?
branches of axon that connect to another neurone
What are myelin sheaths?
fat layer, insulates the axonmakes the electrical impulse travel quicker
What is a synapse?
junction between two neurones, since they do not touch each other
How does an electrical impulse travel?
travels along first axontriggers nerve ending of the presynaptic neurone, fusing with the presynaptic membranethe presynaptic neurone will release chemical messengers called neurotransmittersthese diffuse across the synaptic gap and bind with receptor molecules on the second neurone the electrical impulse will travel down this neuronethe neurotransmitters are destroyed to prevent continued stimulation of his neurone
What do synapses ensure?
that impulses travel in one direction only
In the synapses, are messages chemical or electrical?
chemical this is the place where drugs like heroin works, due to this
Name 5 sense organs.
skin tongue ear nose eye
What is the skin sensitive to?
pressure, temp. and pain (aka se a mari te bater, sua skin sente :D)
What is the tongue sensitive to?
chemicals in food and drink chocolate
What is the nose sensitive to?
chemicals in the air
What are the eyes sensitive to?
light
What is the ear sensitive to?
sound and movement
Explain the reflex arc.
arrival of stimulus
receptor activated
sensory neurone activated
information processing in CNS
relay neurone activated
motor neurone activated
response by effector
What are synaptic ends?
branches of axon that connect to another neurone
branches of axon that connect to another neurone
synaptic ends
Explain the role of auxin in controlling shoot
growth
(a) auxin is made in the shoot tip
(b) auxin diffuses through the plant from the
shoot tip
(c) auxin is unequally distributed in response to
light and gravity
(d) auxin stimulates cell elongation
sensory
relay
motor
