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34 Cards in this Set
- Front
- Back
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Receptors... |
...detect stimuli |
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Effectors... |
...are cells that bring about a response to a stimulus to produce an effect |
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Receptors.. |
...communicate with effectors via nervous system or hormonal system |
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sensory neurones transmit... |
..electrical impuses from receptors to CNS |
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motor neurones transmit electrical impulses... |
...from CNS to effectors |
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relay neurones transmit... |
...electrical impulses between sensory neurones and motor neurones |
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when an electrical impulse reaches the end of a neurone, chemicals called... |
...neurotramsitters take the info accross to the next neurone, which sends an electrical impulse |
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what's a reflex |
where the body responds to a stimulus without making a concious decision to respond |
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hand withdrawal response to heat: |
1) thermoreceptors detect heat 2) sensory neurone carries impulses to relay neurone 3) relay neurone connects to motor neurone 4) motor neurone sends impulses to effector 5) muscle contracts to withdraw your hand and stop it being damaged |
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why is nervous system communication localised? |
when electrical impulse reaches end of a neurone, neurotransmitters are secreted directly onto target cells |
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the response of neurotransmitters is shortlived becuause... |
neurotransmitters are quickly removed once they'ved done their job |
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why is nervous system communication rapid? |
electrical impulses are really fast, so response is rapid - animals react quickly to stimuli |
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a tropism is the response of... |
...a plant to directional stimulus |
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a taxes is.. |
..a response to a directional stimulus eg light. |
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a kineses is.. |
...a response to a non-directional stimulus eg humidity |
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why are receptors specific? |
they only detect one particular stimulus |
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how receptor cells communicate info via nervous system - 1 |
1) when nervous system receptor is in its resting state, there's a difference in charge the inside and outside of the cell - this is generated by ion pumps and ion channels. This means there's a potential difference accross the membrane |
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2- |
the potential difference when a cell is at rest is called its resting potential. When a stimulus is detected, cell membrane is excited and become more permeable, allowing more ions to move in and out of the cell - altering the potential difference. The change in potential difference due to a stimulus is called generator potential |
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3- |
if generator is big enough it'll trigger an action potential - an electrical impulse along a neurone. An action potential is ony triggered if generator potential reaches a certain level called the threshold level. Action potentials are all one size, so the strength of the stimulus is measured by the frequency of action potentials |
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pacinian corpuscles are mechanoreceptors - what does this mean? |
they detect mechanical stimuli |
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pacinian corpuscles contain sensory nerve endings.. |
...the sensory nerve ending is wrapped in loads of layers of connective tissue called lamllae |
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when a pacinian corpuscle is stimulated... |
...lamellae deformed and press on the sensory nerve ending |
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this causes the neurone's cell membrane to stretch.. |
..deforming the stretch-mediated sodium ion channels. The channels open and sodium ions diffuse into the cell, creating a generator potential |
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if the generator potentail reaches treshhold... |
...it triggers an action potential |
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what does myogenic mean |
the heart can contract and relax without recieving signals form nerves |
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describe the steps of the regular heartbeat |
1) process starts in SAN, in the wall of the right atrium |
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2) the SAN sets the rhythm of the heartbeat by sending out regular waves of electrical activity to the atrial walls |
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3) this causes the right and left atria to contract at same time |
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4) band of non-conducting collagen tissue prevents the waves of electrical activity from being passed directly from the atria to the ventricles |
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5) instead, these waves of electrical energy are transferred from the SAN to the AVN |
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6) the AVN is responsible for passing the waves of electrical activity on to the bundle of His. But there's a slight delay before the AVN reacts to ensure atria have emptied before the ventricles contract |
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7) the bundle of His is a group of muscle fibres responsible for conducting the waves of electrical activity between the ventricles to the apex of the heart. The bundle splits into finer muscle fibres in the right and left ventricle walls, the Purkyne tissue |
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8) The Purkyne tissue arries waves of electrical activity into the muscular walls of the right and left ventricles, causing them to contract simultaneously, from the bottom up |
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