Response and Regulation 1 Flashcards
What is the role of the nervous system?
It controls and coordinates responses and senses in your body
What do we use to detect stimuli?
Receptors
Which sense organ & receptors detects movement?
Ear & skin
Position receptors
Pressure receptors
Which sense organ & receptors detect changes in heat?
Skin & blood vessels
Heat receptors
Where are the different taste receptors in the tongue located?
Front: Sweet
Between front and side: Salty
Side: Sour
Back: Bitter
What two parts is the human nervous system comprised of?
Central nervous system (CNS) - Brain and spinal cord
Peripheral nervous system - Nerve cells that carry information to or from the CNS
Electrical signals called ____ travel along ____
1) Impulses
2) Neurones
How are nerve cells (neurones) adapted to carry electrical impulses?
Long fibre (axon) to carry messages over long distances Insulated by a fatty sheath (myelin sheath) which increases speed of nerve impulses Tiny branches (dendons) which branch out into dendrites - these receive incoming nerve impulses from other neurons
What are receptors?
Groups of specialised cells in sense organs that respond to specific stimuli
What are effectors?
Parts of the body that produce a response to a stimulus e.g. muscles and glands
What are nerves?
Bundles of neurones that connect receptors and effectors to CNS
What is a synapse?
The gap between the ends of two neurones
How do synapses work?
The electrical impulse reaches the end of the neurone before the synapse which triggers the release of chemicals called neurotransmitters. These diffuse (move down a concentration gradient) across the synapse. The neurotransmitters bind to receptors on the next neurone. The presence of the neurotransmitter causes the production of an electrical impulse in the next neurone.
What is the point of synapses?
They help to regulate the speed and direction of impulses.
+ If the stimuli affects too few neurones the impulse is not transmitted across the cleft. This allows the ‘filtering out’ of continual unnecessary or unimportant background stimuli.
What are reflex actions?
Automatic, rapid responses, often to harmful situations
What are voluntary actions?
Responses coordinated by the brain
What is the role of a sensory neurone?
To carry impulses from the RECEPTOR to the SPINAL CORD
What is the role of a relay neurone?
To carry impulses from SENSORY to MOTOR neurones
What is the role of motor neurones?
To carry impulses from CNS to EFFECTORS
Describe the journey from detecting a stimulus to carrying out an action
RECEPTORS —sensory neurones—> CNS —motor neurones—> EFFECTORS
Why do we have reflex actions?
A way for the body to automatically and rapidly respond to stimulus to minimise any damage to the body
Do reflex actions involve the brain?
NO, they don’t have to go through neurones in the brain
Where in the nervous system do relay nerves live?
Peripheral nervous system
Which direction do nerve impulses travel?
From dendrites to axon terminals
What is the name given to the path taken by a nerve impulse in a reflex action?
The reflex arc
What are some examples of reflex actions?
Sneezing
Knee jerk
Blinking
What name is given to all 3 types of neurone in the reflex arc?
Coordinators
What are the components of the reflex arc?
- Stimulus
- Receptors
- Coordinators
4 Effectors - Response
What factors can affect human reaction time?
Caffeine and exercise
What roles does the eye serve?
1) Detect light and dark/different intensities of light
2) Detect colours or tones
3) Protect the light detecting surface
4) Be able to focus on objects at different distances
5) Adjust level of light to alter level of brightness hitting sensory surface
6) Prevent light being reflected on its way to sensory surface
What is the cornea?
The transparent frontal part of the eye that refracts light
What comprises the retina?
Full of receptor cells sensitive to light intensity and colour
What is the white of the eye called and what does it do?
The SCLERA
Protective outer coat
What does the optic nerve do?
Transmits (sends) visual information (as electrical impulses) from the retina to the brain
What is the choroid?
Layer between the sclera and the retina that contains blood vessels to supply the retina + prevents internal refraction of light inside the eye
What does the lens do?
Changes shape to refract light and focus it on the retina
What does the iris do?
Iris muscles control pupil diameter
How does the iris react to different levels of light and why?
In bright light the iris muscles contract to make the pupil smaller and let less light through
In dim light the iris muscles relax to make the pupil larger and let in more light
How do we focus on a near object?
Ciliary muscles contract
Suspensory ligaments loosen
Lens gets thicker
Light rays refracted more strongly
How do we focus on a distant object?
Ciliary muscles relax
Suspensory ligaments pulled tight
Lens pulled thin
Light rays refracted less strongly
When does short-sightedness occur?
When the eyeball is too long for the strength of the lens or the cornea is too sharply curved
What is short-sightedness?
When the image produced falls short of the retina
How can short-sightedness be corrected?
A concave lens which diverges the light rays before they enter the eye
When does long-sightedness occur?
When the lens is too weak because it’s not thick enough, the eyeball is too short, or the cornea is not curved enough
What is long-sightedness?
When the image produced falls behind the retina
How can long-sightedness be corrected?
A convex lens which converges the light rays before they enter the eye
Which part of the eye connects the ciliary muscles to the lens?
Suspensory ligaments
