Nervous System 2.0 Flashcards
What does the nervous system carry?
Electrical messages
What does the endocrine system carry?
Chemical messages
What is an adaptation of the nervous system?
It is divided into two parts, CNS & PNS.
What is the Central Nervous System (CNS) composed of?
The brain and spinal cord.
What is the Peripheral Nervous System (PNS) composed of?
Nerves in all other body parts that carry messages to and from the CNS.
What is a neuron?
A nerve cell that is specialised to carry impulses in the body.
What are the 3 types of neurons in the PNS?
Sensory neuron, Interneuron, motor neuron.
What do sensory neurons do?
Carry impulses towards the CNS.
What do motor neurons do?
Carry impulses away from the CNS.
What is the function of an interneuron?
Connects motor & sensory neurons.
Do interneurons have a myelin sheath?
No
What is an effector?
Organ or tissue that carries out an action in response to a signal from the nervous system.
Why are sensory and motor neurons white?
Due to the presence of the myelin sheath.
What are nerves made up of?
A bundle of many axons.
Why won’t 2 electrical signals collide?
As sensory & motor neurons carry signals in one direction.
What is the threshold?
Minimum stimulus required to carry an impulse.
What is the all or nothing law?
If the threshold is not reached, no impulse is carried.
How is an impulse conducted?
Ions
What is the refractory period?
The short timespan after a neuron has carried an impulse during which a stimulus fails to carry a response.
What does the speed of an impulse depend on?
Presence & abundance of myelin sheath.
What is a synapse?
Region where 2 neurons come in close contact.
What is the synaptic cleft?
Tiny gap between the 2 neurons at the synapse.
What is the function of neurotransmitter chemicals?
Controls impulse direction.
EG: Dopamine
What are the main bone structures associated with the CNS?
The skull and spine - to provide protection.
What encloses the brain & skull?
3 membranes called meninges.
What infection is associated with the meninges?
Meningitis
What is the difference between white matter and grey matter?
White matter has myelin sheath & grey has none.
Where is cerebrospinal fluid located?
Between the two inner meninges.
What is the function of cerebrospinal fluid?
Helps absorb the impact that may occur, hence protects structures.
What is the cerebrum composed of?
Left & right hemispheres. The right side controls the left & vice versa.
What are the 4 parts of the cerebrum?
Frontal lobe, Temporal lobe, Parietal lobe, Occipital lobe.
What are the functions of the cerebrum?
Language, Speech, Touch, Hearing.
Where is the cerebellum located?
At the back of the head, underneath the occipital lobe of the cerebrum.
What is the function of the cerebellum?
Responsible for the control & coordination of movements, particularly fine-tuning of movements.
What does the medulla oblongata control?
Non-voluntary actions in the body, e.g., BP, breathing & swallowing.
What is a reflex action?
An automatic, unconscious or involuntary response to a stimulus.
What are examples of reflex actions?
Knee jerking, Pulling hand away from hot object, Blinking.
Why carry out reflex actions?
Protection, Faster action, if necessary.
What is the hypothalamus?
Links brain & endocrine, secretes neurohormones - controls pituitary gland, controls Body Temp.
What is the function of the spinal cord?
Sends messages to & from brain, active role in reflex actions.
What is the movement of messages in the spinal cord?
A sensory neuron enters the dorsal root, reaches the synapse, neurotransmitter chemicals pass across the synaptic cleft to an interneuron, then to a motor neuron, and exits through the ventral root.
What does white matter contain?
Sensory & motor neurons & myelin sheath.
What does grey matter contain?
Only interneurons, cell bodies & dendrites but has no myelin sheath.
What is the central canal?
The centre of grey matter - filled with cerebrospinal fluid.
What is the dorsal root?
Where sensory neurons enter the spinal cord.
What is the ventral root?
Where motor neurons exit the spinal cord.
What is the dorsal root ganglion?
Contains cell bodies of sensory neurons.
What is the method of reflex action when placing hand on a hot object?
Finger receptors detect hot object, impulse travels along sensory neuron to spinal cord, splits at spinal cord, half to interneuron, half to brain, then impulse travels out through motor neuron to muscle for response.
What is a disorder of the nervous system?
Parkinson’s disease.
Cause: body fails to produce dopamine. Symptoms: Difficulty walking. Prevention: No known cause, so no known cure. Treatment: Physiotherapy.
What is the function of dendrites?
Carry impulses toward the cell body.
What is the function of the axon?
Carries impulses away from the cell body.
What is the function of the cell body?
Receives impulses and produces neurotransmitter chemicals.
What is the function of the myelin sheath?
Speeds up impulses.
What are Schwann cells?
Type of cell that forms myelin sheath.
What are axon terminals?
Found at the end of axons.
What are neurotransmitter swellings?
Found in axon terminals. Produce neurotransmitter chemicals at the synapse.
How is a nerve impulse transmitted across a synaptic cleft?
Impulse arrives as an electrical impulse, changes to chemicals at the synaptic cleft, diffuses across, and is received by the next neuron to change back to an electrical impulse.
