Nervous System Flashcards
(54 cards)
What are the basic structural and functional units of the nervous system?
Nerve Cells (Neurons)
Neurons vary in shape and size and consist of a cell body, axons, and dendrites.
What part of the neuron contains the nucleus?
Cell Body (Soma)
Responsible for normal functioning of the cell.
What are dendrites?
Short extensions of the cytoplasm of the cell body that carry messages into the cell body
Dendrites are highly branched.
What is the function of the axon?
Carries nerve impulses away from the cell body
Axons are usually longer than dendrites and can vary in length.
What is a myelin sheath?
A layer of fatty tissue that covers most axons
Myelinated fibres are associated with white matter, while unmyelinated fibres are associated with grey matter.
What is the function of the neurilemma?
Helps to repair injured fibres
It is the outermost coil formed from Schwann cells.
What are the types of functional neurons?
- Sensory (receptor) neurons
- Motor (effector) neurons
- Interneurons
Sensory neurons carry messages to the CNS, motor neurons carry messages from the CNS, and interneurons link sensory and motor neurons.
What is a neuron?
A single nerve cell
Neurons are the basic building blocks of the nervous system.
Define nerve fibre.
Any long extension of cytoplasm of a nerve cell body, usually refers to the axon
Nerve fibres are essential for transmitting nerve impulses.
What is a nerve?
A bundle of nerve fibres held together by connective tissue
Nerves are part of the peripheral nervous system.
What is a synapse?
A small gap/junction between branches of adjacent neurons
Neurons do not physically join at synapses.
What is a nerve impulse?
Message in the form of an electrochemical change that travels along a nerve fibre
It involves a change in electrical voltage due to ion movement.
What happens during depolarisation?
Inside becomes more positive as Na+ moves into the cell
This occurs when sodium channels open after a stimulus.
What is repolarisation?
Voltage gated Na+ channels shut and voltage gated K+ channels open, causing K+ to diffuse out
This makes the inside of the cell more negative.
What is hyperpolarisation?
When too much K+ moves in, causing the inside of the cell to become more negative than resting potential
K+ channels eventually close after this phase.
What is the all-or-none response?
Size of response is always the same, regardless of the strength of the stimulus
An action potential occurs only if the threshold is met.
What role does the cerebral cortex play?
Interprets impulses from receptors, controls muscular movements, and processes intellectual and emotional functions
It contains 70% of all neurons in the CNS.
What is the function of the cerebellum?
Controls posture, balance, and fine coordination of voluntary muscle movement
It receives sensory information from the inner ear and stretch receptors.
What is the hypothalamus responsible for?
Maintaining homeostasis and regulating various body functions
Functions include regulating heart rate, body temperature, and emotional responses.
What is Parkinson’s Disease?
An ongoing degenerative disease characterized by tremors and muscular rigidity
Caused by the degeneration of cells in the middle area of the brain that leads to a lack of dopamine.
What are beta amyloid plaques?
Proteins that build up and interfere with the function of neurons in Alzheimer’s disease
They contribute to memory and thinking skill decline.
What is cell replacement therapy?
Replacing lost or injured cells with new healthy cells to restore function
Stem cells are often used in this therapy.
What is the role of the medulla oblongata?
Regulates cardiac, respiratory, and vasomotor functions
It is controlled by the hypothalamus.
What is cerebrospinal fluid (CSF)?
Clear watery fluid that acts as a shock absorber and supports the brain
It circulates around the CNS and returns nutrients to cells.
