6.5-6 Flashcards
What 2 parts does the nervous system consist of?
The central nervous system and peripheral nerves
What are the different parts of the central nervous system?
Brain and spinal cord
What are the 2 branches off the peripheral nervous system?
Motor neurones and sensory neurones
What are the two branches off motor neurones?
The automatic nervous system and the somatic nervous system
What are the different parts of the automatic nervous system?
Sympathetic nervous system and parasympathetic nervous system
What nerves do the automatic nervous system include?
Nerves from internal receptors and nerves attached to smooth muscle
What nerves do the somatic nervous system include?
Motor neurones attached to the skeletal muscles and sensory neurones attached to the receptor sense organs
What do dendrites do?
Receive electrical impulses from other neurones
What is the myelin sheath?
A layer of schwann cells wrapped around the axon for insulation
What happens in the node of ranvier?
It is where the nerves pass through
What does a Schwann cell do?
It insulates the axon, making nerve impulses faster
What is the order of movement of a nerve impulse in a reaction?
Stimuli- receptor- sensory nerve- relay nerve- motor neuron- effector- response
What is resting potential?
When there is an electrical potential across a cell membrane when not conducting an impulse. ( -70mV)
What is action potential?
The localised depolarisation and then repolarisation if electrical potential between the inside and outside of a neurones as the impulse moves along it
What happens at resting potential in a neurone?
Na+ and K+ ion channels are closed
What happens at depolarisation in a neurone?
Na+ voltage channels opens, sodium flooding into the cytosol causing the voltage to rise
What happens at the rising phase of action potential?
More sodium channels open once the voltage reaches -55mV and Na+ floods into neurones
What happens at the falling phase of action potential?
Na+ channels close and K+ channels open and rush outside to reverse concentrations- this begins to reduce the voltage
What happens at hyperpolarisation?
The sodium channels open and the sodium returns to the outside of the neurone, making the inside overall negative, reducing the voltage. Then potassium channels and potassium returns to the inside of the neurone at resting potential
Why must ion pumps used to create action potential use active transport?
As they are moving ions against the concentration gradient
What voltage is action potential?
30mV
What is a synapse?
The junction between 2 neurones
What is the synaptic cleft?
The fluid filled space between the axon terminal and end of a dendrite. It is the location of communication between neurones and glands or muscles
What are the stages as a chemical signal crosses a synapse?
- Nerve impulses pass electrical or chemical signals to their target cells
- When an action potential reaches the end of a neurone, the Ca+ ion channels open to allow Ca+ to flow in, which causes exocytosis of a neurotransmitter.
- Neurotransmitter diffuses across the synaptic cleft and then binds to a post-synaptic receptor.
- The post synaptic membrane becomes polarised, causing the Na+ ion channels to open.
- An action potential is created in the post synaptic neurone. The post synaptic membrane then becomes depolarised.
- The K+ ion channels open to cause hyper polarisation of the post-synaptic membrane
- An enzyme binds to the neurotransmitter to hydrolyse it and prevent future function.
How do neonicotinoid pesticides work and what are the consequences of them?
Artificially made pesticides that block the post- synaptic membrane used for breaking down acetylcholine and fit into the binding site of the post- synaptic neurotransmitter receptor so acetylcholine can’t bind. It prevents action potential in the post synaptic neurone and leads to paralysis and death of bees, reducing pollination and biodiversity of plants
What is the endocrine system?
The hormone system, that consists of glands that release hormones to our cells.
How to hormones travel?
They circulate through the bloodstream from glands