Ch. 12 Coordination and response Flashcards
What are stimuli?
Changes in the organism’s environment
What are stimuli sensed by?
Receptors
What are effectors?
Part of body which responds to stimulus
What is necessary between receptors and effectors?
Communication
What’s coordination?
The way in which receptors detect stimuli and pass information to effectors
What are nerves?
A group of neurone axons lying together
What are ways into which informations are transmissed?
- Nerves
- Chemicals (hormones)
What are neurones?
Cells used to conduct electrical impulses rapidly
What do neutrons contain?
Nucleus, cytoplasm, cell membrane
What is an axon?
A fibre of cytoplasm that extends from body cell of a neurone, allows it to pass information quickly
What are dendrites?
Shorter fibres of cytoplasm extending from cell body
What are nerve impulses?
Electrical signals that pass rapidly along an axon
What are nerve impulses picked up by? What are they passed to?
Picked up by dendrites, passed to cell body, then to axon, then to next neurone
What are the two nervous system?
- CNS
- PNS
What’s CNS? What is it made up by?
- Central nervous system
- Made up by brain and spinal chord
What’s PNS? What is it made up by?
- Peripheral nervous system
- Made up by nerves extending from brain and spinal chord
How does neurone transmission work?
Sensory receptor detects something
Receptor starts off electrical impulse
Sensory neurone carries impulse from sensory receptor
Relay neurone passes impulse to brain and to motor neurone
Motor neurone passes impulse to effector
What is a reflex arc?
The pathway the nerve impulse (sensory neurone, relay neurone, motor neurone) passes
What’s a reflex action?
A means of automatically and rapidly integrating and coordinating stimuli with the response of effectors
What are synaptic gaps?
Gaps between a pair of neurones
What are synapses?
End of two neurones + small gap between them
How do synapses work?
Ends of neurone contain vesicles
vesicles contain neurotransmitter
electrical impulse causes vesicles to move
vesicles attach to end of neurone
vesicles empty content (neurotransmitter)
neurotransmitter attach to receptor proteins
this binding causes an electrical impulse
Why are synapses important?
They are a one way valve which ensures travel in only one direction
What are sense organs?
A group of cells that respond to a specific stimulus
What is the retina?
A tissue at the back of the eye that contains receptor cells that respond to light
Why are eyes always humid?
Because a fluid containing lysozyme (bacteria killer enzyme) is washed across eye by eyelids
Where does retina send electrical impulse?
Through optic nerve
What is the blind spot?
The part where optic nerves leaves ad where there are no receptor cells
What is the fovea?
The part where the receptor cells are packed most closely together
What are rods?
A kind of receptor which is sensitive to dim light but not colour
What are cones?
A kind of receptor which is sensitive to colour but only functions when we have bright light
What does fovea contain and where?
Cones packed tightly in centre of cornea
Rods packed less tightly and found further out on the retina
What’s the iris?
The coloured part of an eye, contains muscles that can alter the size of the pupil
What’s the pupil?
The circular gap in the middle of the iris
What are circular muscles?
Muscles contained in iris
Where are circular muscles arranged in?
In circles around the pupil
What happens when circular muscles contract?
They make pupils get smaller
Where are radial muscles?
Run outwards from the edge of the pupil
What happens when radial muscles contract?
They make the pupil dilate
What’s the iris reflex?
An automatic response to a change in the light intensity
What are antagonistic muscles?
A pair of muscles whose contraction has opposite effect
What is refraction?
Bending light rays
What is the cornea?
A transparent layer which refracts the rays entering the eye
How does light entering the eye work?
Rays enter, cornea makes most refraction, lens make adjustments
What is the lens?
A transparent structure in eye which changes shape to focus retina
How are the rays from a distant object?
Diverging only lightly
How is the lens when focusing a distant object?
Very thin
Why is lens so thin when focusing distant object?
Because the light needs to be refracted very lightly
How are rays coming from nearby object?
Diverging a lot
Thicker the lens?
More the bent
What is accommodation?
The adjustment in the shape of the lens
What is lens held in suspension by?
By suspensory ligaments
How is the shape of the lens altered?
By means of ciliary muscle
What happens when ciliary muscle contracts?
- Suspensory muscles relax
- Lens is allowed to bulge
hat happens when ciliary muscle relaxes?
- Suspensory muscles contract
- Lens is pulled tight
What are hormones?
Chemicals that are produced by a gland and carried in the blood (plasma)
What do hormones target?
A specific organ
Where are hormones made?
In special glands called endocrine glands
What are target organs?
Organs whose activity is altered by a hormone
Adrenal gland, what hormones does it produce, what does the hormone do
Produces adrenaline, prepares body for vigorous exercise
Pancreas, what hormone does it produce, what does the hormone do
- Insulin –> reduces concentration of glucose in blood
- Glucagon –> increases the concentration of glucose in the blood
Testis, what hormone does it produce, what does hormone do
Testosterone, causes the development of male secondary sexual characteristics
Ovary, what hormone does it produce, what does hormone do
Oestrogen, causes development of female secondary sexual characteristics
Where are the adrenal glands?
One above each kidney
What does adrenaline do?
Trigger fight or flight response
What does fight or flight response consist in? Why?
Accelerates heart rate, more breathing –> muscles can carry out aerobic respiration more quickly
What else does adrenaline do? What happens with extra it?
Causes liver to release glucose –> muscles increase metabolic activity
How do plants react to stimuli?
By changing their direction of growth
What are growth responses called?
Tropisms
What is phototropism?
Growth response to light
What is gravitropism?
Growth response to gravity
How can tropisms be?
Positive (towards something) or negative (away from it)
What is auxin?
A plant hormone made in the tips of shoots
What does auxin do?
Cause cells to elongate
What happens when we shoot light on only one side of plant?
Auxin concentrates on the other, causes that side to grow more so plant bends towards light
