The Nervous System Flashcards
What is a stimulus?
It is a change in the environment that causes an organism to react.
Stimuli can be internal or external, and are detected by receptors.
What is the function of the nervous system?
It serves to coordinate and regulate bodily functions in animals
What are the 2 major components of the human nervous system?
- Central nervous system (brain and spinal cord)
2. Peripheral nervous system (cranial + spinal nerves)
What is the relationship between receptors, central nervous system and effectors?
- Sense organs called receptors receive stimuli and generate nerve impulses (action potentials).
- The nerve impulses are transmitted to the CNS by peripheral nerves along the sensory neurone.
- the CNS will integrate sensory information from receptors. The brain and spinal cord will interpret information and initiate a response.
- a nerve impulse will then be transmitted to the muscle via the peripheral nerves along the motor neurone
- the muscle or gland that defects an action is the effector.
Sketch the structure of a neurone.
- axons
- dendrons dendrites
- Schwann cells
- myelin sheath
- nodes of Ranvier
What is the unction of axons?
Axons carry impulses away from the cell body
What is the function of dendrons?
Carry impulses towards cell body
What are Schwann cells?
They are supporting cells of the nervous system. They wrap themselves around axons or dendrons to form layers of myelin
What is the function of the myelin sheath?
It protects and insulates the axons and dendrons to enhance sped of nerve impulse transmission
What are nodes of Ranvier and their function?
Nodes of Ranvier are gaps between the myelin sheath. Nerve impulses cannot be transmitted through myelin sheath so they can “jump” form one node to the next. This speeds up transmission of nerve impulses along the neurone.
What is the function of sensory neurone, and what is their structure?
Sensory neurone transmit nerve impulses from the receptor to The central nervous system
What is the function of motor neurone, and what is their structure?
Motor neurone transmit nerve impulses from the central nervous system to the effectors.
What is the function of sensory neurone, and what is their structure?
Relay neurones relay impulses from sensory neurone to motor neurone inside the central nervous system.
What is a synapse?
It is a small gap that exists between 2 neurones or between a neurone and an effector.
How are nerve impulses transmitted across the synapse?
Nerve impulses are transmitted across the synapse by chemicals called neurotransmitters. They bind to receptors on the dendrite of the following neurone, which triggers a nerve impulse.
What is the location of grey and white matter in the brain?
Central: white
Outer: grey
What is the location of grey and white matter in the spinal cord?
Central: grey
Outer: white
Grey matter consists mainly of..?
Cell bodies of neurones
White matter consists mainly of..?
Nerve fibres
What is the structure of the spinal cord?
The spinal cord is protected by the vertebral column called the backbone.
The spinal cord consists of white matter (outer part) and grey matter (inner part, H shape) + central canal filled with cerebrospinal fluid + dorsal and ventral roots
What is the function of cerebrospinal fluid?
It nourishes the spinal cord
What does the dorsal root contain?
Nerve fibres of sensory neurones. The cell bodies of the sensory neurones are clustered together in a swelling called the dorsal root ganglion.
What does the ventral root contain?
Nerve fibres of motor neurones, the cell bodies and dendrons of motor neurones lie in the grey matter (inner part) of the spinal cord.
What is a reflex action?
It is an automatic response to a specific stimulus without any conscious control.
It is an example of an involuntary action.
