Responding to the environment

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What is the pathway of a reflex arc?
stimulus--> receptor-->sensory neurone-->CNS-relay nueurone in spinal cord-->motor neurone-->effector--> response
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What is the generator poteintial? How does it become an action potential?
change in potential difference due to stimulus. Becomes an action potential when threshold level is reached.
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Describe the refractory period for nervous impulses?
after action potential-Na+ channels closed during repolarisation, K+ channels closed during hyperpolarisation so neurone can't be stimulated again straight away, ensure action potentials dont overlap and are unidirectional
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What are the 3 types of muscle?
1--involunarty contraction found in walls of internal organs, 2-cardiac-same but only found in heart 3-skeletal-voluntary contractions
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Explain the differenced between slow and fast twitch muscle fibres
slow-good for endurance activities as energy released from aerobic respiration, lots of mitochndria near edge of cells and rich in myoglobin whereas fast-short burst of energy as fatigue- lactate from anerobic respiration, few mitochondria/myoglobin
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Describe hormonal communication
Glands stimulated by impulse or concentration change they secret hormones which diffuse into blood then bind to receptors on target cells to trigger a response
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What is a chemical mediator? How is it difference from a hormone?
Chemical messanger released by cells 1-not just glands 2-target cells nearby so quicker and more localised response
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Give 2 examples of chemical mediators and their purpose
1-histamine= stored in mast cells, increase permeabilty of capillaries near infection to allow more immune system cells to get to it 2-Prostaglandis-involved in inflammation, fever and blood pressure regulation
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Card 2

Front

What is the generator poteintial? How does it become an action potential?

Back

change in potential difference due to stimulus. Becomes an action potential when threshold level is reached.

Card 3

Front

Describe the refractory period for nervous impulses?

Back

Preview of the front of card 3

Card 4

Front

What are the 3 types of muscle?

Back

Preview of the front of card 4

Card 5

Front

Explain the differenced between slow and fast twitch muscle fibres

Back

Preview of the front of card 5
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