Nervous System Flashcards
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.
What are ascending tracts in the spinal cord?
Sensory axons that carry impulses upwards towards the brain
They are part of the white matter structure.
What are the four lobes of the brain?
- Frontal
- Parietal
- Occipital
- Temporal
Each lobe has specific functions related to sensory processing and higher-order thinking.
What type of receptor is stimulated by heat or cold?
Thermoreceptors
They are located in the skin.
What do chemoreceptors detect?
Particular chemicals
They are involved in regulating heart rate and breathing.
What is the role of baroreceptors?
Detect changes in blood pressure
They are located in the heart and arteries around the heart.
What is the central nervous system composed of?
Brain and spinal cord
It processes incoming messages and initiates outgoing messages.
What are undifferentiated cells capable of?
Repeated mitosis and differentiation into specialised cells
What is cell therapy used for in relation to PD and AD?
To transplant neural stem cells that can form new neurons
What is a major challenge in using neural stem cells for AD/PD patients?
They might only offer temporary help before more neurons are lost
What must neural stem cells do to be effective in brain repair?
Travel to damaged areas, produce various types of neurons, integrate effectively
What are the two divisions of the Nervous System?
Somatic and Autonomic
What does the somatic division control?
Voluntary movements via skeletal muscles
What does the autonomic division control?
Involuntary functions like heart rate and digestion
What neurotransmitter is primarily used by the somatic nervous system?
Acetylcholine
What are the two sets of nerve fibres in the autonomic nervous system?
Sympathetic and Parasympathetic
Fill in the blank: The sympathetic division prepares the body for _______.
Strenuous activity
What is the main function of the parasympathetic division?
To maintain conditions during quiet states
What type of control does the autonomic nervous system usually have?
Involuntary control
What happens to heart rate under sympathetic stimulation?
It increases
What happens to bronchioles under parasympathetic stimulation?
They constrict
What is the effect of the sympathetic division on the digestive system?
Decreases peristalsis
What are the main differences between the autonomic and somatic divisions?
- Pathway structure
- Effectors
- Control type
- Neurotransmitters used
What type of message does the nervous system use?
Electrical impulses and neurotransmitters
What type of message does the endocrine system use?
Hormones
What is a reflex?
A rapid, automatic response to a change in environment
What is the pathway a nerve impulse follows called?
Reflex arc
What are the basic components of a reflex arc?
- Receptor
- Sensory neuron
- Interneuron
- Motor neuron
- Effector
What is the role of the receptor in a reflex arc?
To react to a change and initiate a nerve impulse
True or False: Reflexes are spontaneous actions.
False
What is one example of a learned reflex?
Muscular adjustments to balance while riding a bike
