Response and Regulation Flashcards
What is the human nervous system?
the central nervous system (CNS) – the brain and spinal cord
the peripheral nervous system – nerve cells that carry information to or from the CNS
What is a neuron?
Neurones are long cells which carry electrical signals along their length.
How does information travel in the nervous system?
Information is brought to the central nervous system and taken away by nerves which are bundles of neurones.
Where two neurones meet there is a tiny gap called a synapse. The signal passes chemically across the synapse to the next neurone where the electrical impulse continues.
What is an effector?
The organ, tissue or cell that produces the response?
How does information flow in the nervous system?
Receptors *sensory neurons* Coordinator *motor neurons* Effectors
What are stimuli?
Changes in the environment detected by receptors
What are receptor cells?
A cell that detects stimuli inside or outside the body
What stimulus can skin detect?
Temperature, pressure and pain
What stimulus can the tongue detect?
Chemical tastes (in food and drink)
What stimulus can the nose detect?
Chemical smells (in the air)
What stimuli can the eye detect?
Light
What stimuli can the ear detect?
Sound
What are effectors?
They produce a response to a detected stimulus, eg muscles
Examples of effectors?
muscle contracting to move an arm
a muscle contracting to alter pupil diameter in the eye
a gland releasing a hormone into the blood
Order to effector to from receptor?
A receptor cell passes an electrical impulse along the sensory neurone.
The sensory neurone reaches the coordinator, the CNS.
The sensory neurone connects to a relay neurone, via a synapse, inside the CNS.
The relay neurone connects to a motor neurone, via a synapse, inside the CNS.
The motor neurone leaves the CNS and the impulse is carried to the effector.
What do reflex actions need to be?
Automatic, rapid and protective
What is the process of a reflex arc?
stimulus → receptor → sensory neurone → relay neurone → motor neurone → effector → response
What happens to the iris in dim light?
- radial muscles of the iris contract
- circular muscles of iris relax
- pupil dilates to let more light in
What happens to the iris in bright light?
- radial muscles of iris relax
- circular muscles of iris contract
- contracted pupil to let less light in
What is the function of the cornea?
Clear area of the sclera, it refracts light - bends it as it enters the eye.
What is the function of the iris?
Muscles which alter the size of the pupil, controlling the amount of light entering the eye.
What is the function of the lens?
Focuses light onto the retina.
What is the function of the retina?
Contains the light receptor cells.
What is the function of the optic nerve?
Carries impulses between the retina and the brain.
What is the function of the sclera?
White, tough outer layer.
What is the function of the choroid?
Pigmented middle layer with many blood vessels. It absorbs light to avoid reflection and nourishes the retina.
What is the function of the blind spot?
Where the optic nerve leaves the retina so lacks receptor cells.
What is the function of the pupil?
Small hole at the centre of the iris through which light enters the eye.
What is the definition of negative feedback?
A change from optimal, normal conditions resulting in the body responding to create optimal conditions.
State 3 factors that are controlled within the body to maintain optimum conditions.
Temperature
Glucose
Water levels
Suggest 2 reasons why blood glucose could drop for someone with insulin dependant diabetes.
- they haven’t eaten in a while, so glucose isn’t being consumed
- they have been exercising so the glucose in the body has been used up
