The Nervous and Endocrine Systems Flashcards
What is the nervous system?
the network of nerve cells and fibers that transmits nerve impulses between parts of the body.
What is the central nervous system?
brain and spinal cord
-The centre of nervous activity and processes information.
How does the nervous system split?
peripheral splits into somatic and autonomic. Autnomic splits into sympathetic and parasympathetic.
What is the peripheral nervous system?
the sensory and motor neurons that connect the central nervous system to the rest of the body
What does the somatic nervous system do?
controls voluntary movements and reflexes.
What does the autonomic nervous system do?
Governs vital functions in the body such as breathing, heart rate, digestion, sexual arousal and stress responses.
What is the parasympathetic nervous system?
rest and digest
-heart rate/blood pressure decrease.
-Digestion increases.
-Pupils constrict.
-Contracts bladder.
What is the sympathetic nervous system?
fight or flight
-Pupils dilate.
-inhibits digestion.
-increases heart and breathing rate.
-relaxes bladder.
What are reflex actions?
Automatic and rapid actions that do not involve the conscious parts of the brain. They protect us from harm.
-Controlled by somatic nervous system.
What happens after a reflex?
Information sent to brain after, so we can learn from mistakes.
Examples of a reflex arc?
A bee stings finger
Stimulation of the pain receptor
Impulses travel along the sensory neurone
Impulses travel along a relay neurone
Travel along a motor neurone
The muscles react with a contraction
What is a neuron?
nerve cell
Properties of a sensory neuron?
-Cell body is separate from axon.
-Carries impulses from the receptors to the CNS.
Properties of a motor neuron?
-Short dendrites and long axons.
-carries impulses from CNS to effectors.
Properties of a relay neuron?
-No myelin sheath and a shorter axon.
-Carries impulses from sensory to motor.
What is a dendrite?
a short branched extension of a nerve cell, along which impulses received from other cells at synapses are transmitted to the cell body.Wh
What is an axon?
long fiber that carries impulses away from the cell body
What is the myelin shealth?
Insulates the axon to prevent transmission anywhere else.
What are the nodes on ranvir?
gaps in the myelin sheath, which force the impulse to ‘jump’ which speeds up transmission.
What are terminal buttons?
The branched end of the axon that contains neurotransmitters.
How does electrical transmission across synapses occur?
-The impulse arrives at the terminal buttons of the presynaptic neuron.
-Vesicles containing neurotransmitters move towards the presynaptic membrane.
-Vesicles fuse with the synaptic membrane, releasing neurotransmitters into the synaptic cleft.
-They diffuse across the cleft and bind to receptors in the postsynaptic neuron.
-Depending on excitation/inhibitory activity, it increases/decreases the likelihood the impulse will continue.
-Neurotransmitters released back into the synaptic cleft where they are recycled and reabsorbed.
How does electrical transmission occur?
-When a neuron is in resting state, the inside of the cell is more negatively charged than the outside.
-When the neuron is activated, it becomes positively charged which causes action potential, creating the impulse.
What is excitation?
When a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neuron. This increases the likelihood that the neuron will fire and pass on the electrical impulse.
What is inhibition?
When a neurotransmitter, such as serotonin, makes the charge of the postsynaptic neuron more negative. This decreases the likelihood that the neuron will fire and pass on the electrical impulse.
