Nervous System Flashcards
What are the 3 main functions of the Nervous System?
Sensory function (perception), Information transfer and processing, and Motor function
What makes up the CNS?
Central Nervous System: Brain and Spinal Cord
What are the divisions of the PNS?
Peripheral Nervous System: Sensory (afferent) division and the Motor (efferent) division
What is the function of Sensory nerves?
Sensory (afferent) nerves transmit impulses towards the CNS from the body
What is the function of Motor nerves?
Motor (efferent) nerves transmit impulses from the CNS to the body
What do most Neurons consist of (include how many)?
1 Cell body, many Dendrites and 1 Axon
Describe the cell body
Where the nucleus & other cellular organelles are found
Describe dendrites
The receiving or input portions of a neuron that carry impulses towards the cell body
Describe Axon
Long, thin portion of the neuron which transmits electrical signals from the cell body to the axon terminals. Neurons communicate with each other via chemicals called synaptic bulb ends
How do myelin sheaths affect neurons?
Neurons with axons covered with myelin sheaths can conduct electrical impulses much faster than those that do not.
They also protect nerve cells
How do Nodes of Ranvier affect Neurons?
Nodes of Ranvier assist in the rapid transmission of nerve impulses
i.e. The greater the number of Nodes of Ranvier, the faster the transmission.
How does a Myelinated neurone differ from a non-Myelinated neurone?
A non-Myelinated neurone has a continuous Myelin sheath, there are no Nodes of Ranvier and only one Schwann cell.
A Myelinated neurone will have at least one Node of Ranvier, and is made up of multiple Schwann cells
What is a Schwann cell?
Schwann cells have multiple functions within the PNS.
Importantly, concentric Schwann cells form Myelin sheath
What are Neuroglia?
Non-impulse generating/conducting cells in the nervous system
What are some of the roles of the Neuroglia?
Providing structural support for neurons.
Creating a blood-brain barrier.
Restricting movement of substances between the blood & tissue fluids within the CNS.
There are neuroglia that take on the role of phagocyte, removing debris & damaged tissue.
What makes up the cranial Vault?
Brain - 80%,
Cerebral blood - 12%,
Cerebral spinal fluid - 8%
What are the 4 major sections of the brain?
Brain stem,
Cerebellum,
Diencephalon, and
Cerebrum
What makes up the brain stem?
Mid Brain,
Pons Varolli, and
Medulla Oblongata.
Together they control level of consciousness
What is the function of the Medulla Oblongata?
Relays sensory & motor input between other parts of the brain & spinal cord.
Contains centres to manage heart rate, BP & breathing.
Contains origins of a number of cranial nerves
What is the function of the Pons Varolla?
Relays nervous impulses from one side of the cerebellum to the other & between medulla & midbrain.
Contains origins of a number of cranial nerves.
Contains centres to regulate breathing
What is the function of the Mid Brain?
Relays motor output from the cerebral cortex & sensory input from the spinal cord to the thalamus.
Controls & co-ordinates movement.
Contains origins of two cranial nerves
What is the structure and function of the Cerebellum?
Made up of two hemispheres.
It is responsible for coordinating complex & skilled movements (i.e. muscle memory).
Regulates posture & balance
What is the structure and function of the Diencephalon?
Connects the cerebrum with the brain stem.
It is comprised of the thalamus & hypothalamus, and is the link between the nervous system & the endocrine system (hormones)
What is the function of the Thalamus?
Relays sensory input to the cerebral cortex.
Provides perception of touch, pressure, pain, and temperature
What is the function of the Hypothalamus?
Controls & integrates autonomic nervous system activity.
Regulates behavioural patterns & circadian rhythms.
Controls body temperature.
Regulates eating & drinking
Describe the anatomy of the Cerebrum
The largest part of the brain which is split into two hemispheres.
Has an outer rim of grey matter & an internal region of white matter.
The outer rim of grey matter contains the cerebral cortex, which, although thin contains billions of neurons.
What are the 4 lobes of each hemisphere of the Cerebrum?
Frontal,
Parietal,
Temporal, &
Occipital
What are the 3 Meninges?
Dura Mater
Arachnoid Mater
Pia Mater
Describe the Dura Mater
Tough outer layer consisting of connective tissue
Describe the Arachnoid Mater
Middle layer. The sub-arachnoid space is filled with CSF
Describe the Pia Mater
Delicate inner layer containing small blood vessels that supply O2 and nutrients to the brain
What does CSF stand for?
Cerebrospinal fluid
What is Cerebrospinal Fluid (CSF)?
A clear, colourless liquid
Protects the brain and spinal cord from physical and chemical injury
Carries O2, glucose and other nutrients essential for normal brain function
Removes waste products
How many and what are the vertebrae in the vertebral column?
33 total 7 Cervical 12 Thoracic 5 Lumbar 5 Sacral 4 Coccygeal
Where does the spinal cord extend between and what is the cone-like structure formed?
Medulla oblongata to the superior border of 2nd lumbar vertebrae
The cone-like structure is the conus medullaris
What do the nerves that originate distal to the conus medullaris form?
Cauda equine (horses-tail)
How many pairs of spinal nerves are there? (Break it down!)
31 total 8 Cervical 12 Thoracic 5 Lumbar 5 Sacral 1 Coccygeal
What does the Somatic Nervous System allow you to do and how?
Also known as Voluntary Nervous System
Allows a person to consciously control their skeletal muscles due to somatic nerve fibres that conduct impulses from the CNS to the skeletal muscles
What are the 3 parts of the Autonomic Nervous System?
Sympathetic nervous system
Parasympathetic nervous system
Enteric nervous system
What is the Enteric Division?
Part of the ANS, its an expansive network of neurons within the walls of the gastrointestinal (GI) tract, pancreas and gall bladder
How does the Enteric Division work?
Part of the ANS, sensory nervous function enables monitoring of the mechanical state of the alimentary canal and the chemical status of the stomach and intestines
It outputs motor signals to modify the motility and secretions of the gut
Controls diameter of local blood vessels
What does the Sympathetic Division do?
Part of the ANS, it prepartes the body to respond to stress Stimulates cardiac activity Opens the airways Dilates skeletal blood vessels Reduces gastric activity
What does the Parasympathetic Division do?
Part of the ANS, known as the ‘rest-and-digest division’
Has a general peacemaker effect
Stimulates digestion and absorption of food
Slows down cardiac and respiratory activities
What does S.A.M.E stand for?
Sensory
Afferent
Motor
Efferent
