Neurones Flashcards
Describe the structure of a motor neurone.
- Many short dendrites carry nerve impulses from the CNS to the cell body.
- Once long axon carries nerve impulses from the cell body to the effector cells.
Describe the structure of the sensory neurone.
- One long dendrite carries nerve impulses from receptor cells to the cell body.
- One short axon carries nerve impulses from the cell body to the CNS.
Describe the structure of relay neurones.
- Many short dendrites that carry nerve impulses from censory neurones to the cell body.
- Many short axons carry nerve impulses from the cell body to motor neurones.
What are receptors?
They detect a stimuli. These can be cells or proteins on cell surface membranes.
What are effectors?
Effectors are cells that bring about a response to a stimulus to produce an effect. Effectors include muscle cells and cells found in glands e.g. the pancreas.
There are 3 main types of neurones. What are their functions?
- Sensory Neurones - transmit impulses from receptors to CNS – the brain and spinal cord.
- Motor Neurones - transmit electrical impulses form the CNS to effectors.
- Relay neurones - transmit electrical impulses between sensory and motor neurones.
Describe how the nervous system responds to a stimulus.
- Stimulus is detected by receptor cells and electrical impulse is sent along sensory neurone.
- When an electrical impulse reaches the end of a neurone, neurotransmittors are released across the synaptic cleft to the next neurone, which sends an electrical impulse.
- The CNS process the information and sends impulses along motor neurones to an effector.
How does the eye respond to dim and bright light?
What is a hormonal system made up of?
Glands and hormones.
What is a gland and what are the two types?
Glands are a group of cells that secrete a substance.
- Endocrines: secrete hormones (usually into the blood stream) ductlessly. It’s an integrated system of small organs which produce hormones to control many internal bodily functions.
- Exocrines: secretes enzymes via ductsand have imediate destination.
What are hormones?
They are chemical messengers that diffuse directly into the blood where they’re taken around the body via the circulatory system. Hormones bind to specific receptors.
What are adrenaline and noradrenaline examples of? What do they do?
Hormones.
- Adrenaline – Produced within the adrenal glands (located at the tops of kidneys), adrenaline works with noradrenaline to produce the “fight or flight” response, increasing supply of oxygen to the brain and muscles, dilating the pupils, and suppressing bodily functions not useful in an emergency situation (e.g. digestion).
- Noradrenaline – works with adrenaline to help the endocrine system produce the “flight or flight” response; in emergency situation, boosts the oxygen supply to the brain and the supply of glucose to the muscles.
Describe the process of how hormones trigger responses etc.
Describe what happens to the eye in high light intensities in detail (not referring to the simple diagram).
- Photoreceptors such as rods in the retina cause nerve impulses to pass along the optic nerve to a group of nerve cells in the brain.
- These then send impulses along the parasympathetic motor neurones to the circular muscles to the iris.
- The muscles contract, reducing the diameter of the pupil so less light can enter the eye, thus preventing damage to the eye.
Describe what happens to the eye in low light conditions in detail (not referring to the simple diagram).
- Fewer impulses reach the coordinating center (the optic nerve) in the brain.
- Impulses are sent down the sympathtic motor neurones to the radial muscles of the iris instead [of the parasympathetic].
- This causes the radial muscles to contract (and the circular muscles to relax) and the pupil becomes dilated, allowing more light to reach the retina.
