Nervous System Flashcards
What are the anatomical divisions of the NS their components (with numbers), and function?
The NS has 2 divisions:
- CNS - central controller
- Brain
- Spinal cord
- PNS: all other nerve tissue not within CNS
- Cranial nerves (12 pairs) - connect with brain
- Spinal nerves (31 pairs) - connect with spinal cord
- ANS - involuntary regulation of our internal environment
- Organs
- Visceral afferents
- Smooth Muscle
- Glands
- Sympathetic NS
- Parasympathetic NS
What are the functions of the nervous system?
- NS allows us to sense our environment and to effect an appropriate response
= Sensory part and a motor (responsive) part and central connections (in the brain or spinal cord) between the two parts
- Protective: helps to “keep us safe”
– External environment (hot/sharp things etc)
– Internal environment (heart, lungs, intestines etc….)
What is the functional unit of the NS?
What are its parts?
A neuron (nerve cell) is the functional unit of the NS - nerve body + axon
Parts:
- Nerve body (soma)
- Dendrite (extension of the cell body - is part of it)
- Axon (nerve fibre)
- coated in myelin sheath
- Axon Terminal + dendrite of next neuron = sypanse with synaptic cleft
What are ganglia?
A ganglia is a collection of multiple cells bodies outside the CNS (in the PNS)
What is a named nerve?
When a lot of axons (nerve fibres) are bundled together, it is called a named nerve
What are the different types of nerve fibres and their function?
What is an important characteristic of nerve fibres?
There are six different types of nerve fibres:
- Somatic motor function: tell a skeletal muscle to contract
- Somatic sensory function: tell the spinal cord/brain about pain somewhere on the body wall
- Special sensory function: tell the brain about a “special” sensation: sight, smell, taste, sound, balance
- Visceral afferent function: tell the spinal cord/brain about pain from an organ
- Sympathetic function: tell cardiac or smooth muscle to contract or a gland to secrete
- Parasympathetic function: tell cardiac or smooth muscle to contract or a gland to secrete
A single nerve fibre (axon) can only conduct action potentials for ONE of the above functions
What is a mixed nerve?
Give some examples
A “mixed nerve” (e.g. intercostal nerve; phrenic nerve; vagus nerve) can carry two or more functional types of nerve fibre to any given region of the body or structure
How do neurons communicate with each other?
By releasing neurotransmitters at the synapse with the dendrite of the next neuron
What is the main part of the brain called? Name its parts and subdivisions
How are they named?
The main part is called the cerebrum or cerebral hemisphere. It has 2 parts:
- Right cerebral hemisphere
- Left cerebral hemisphere
Each hemisphere is divided into 4 lobes - named according to cranial bone they lie deep to:
- Frontal lobe
- Parietal lobe
- Temporal lobe
- Occipital lobe
Label the lobes and name their functions
Label the diagram
Describe the surface features of the brain
List the functions of the smaller part of the brain
A gyrus = undulation that sticks out
A sulcus = undulation that dives in
What is the outermost layer of the brain called?
What is the colour/constituents of the brain in cross section?
How does this relate to the spinal cord?
The outermost layer of the cerebral hemispheres is -cerebral neocortex (cortex)
It is grey in colour: cell bodies
The deep aspect of the brain is white in colour: myelinated axons (myelin gives the white appearance)
– brain neurons reache inwards into brain stem
In the SPINAL CORD the white matter is superficial and the grey matter is deep
– spinal cord neurons reach outwards to spinal nerves
Why are the cranial nerves so named?
How are they numbered?
They are called cranial nerves bc they leave the brain and exit the skull through
- cranial foramina (a hole in the base of the skill) or
- cranial fissures (a slot in the base of the skull)
Generally numbered according to the order from anterior to posterior (or medial to lateral) in which they connect with the brain.
Always use ROMAN NUMERALS (ordinal number is INCORRECT)
How many cranial nerves are there?
Name them
12 pairs of cranial nerves (one on each side)
- Olfactory (nose anterior to eyes!): CN I
- Optic: CN II
- Oculomotor: CN III
- Trochlear: CN IV
- Trigeminal: CN V
- Abducent: CN VI
- Facial: CN VII
- Vestibulocochlear: CN VIII (Auditory: mnemonic)
- Glossopharyngeal: CN IX
- Vagus: CN X
- Spinal accessory: CN XI
- Hypoglossal: CN XII
On Occasion Of Tea Time Attractive Faces Are Generally Viewed Some How
List the functions of each cranial nerve
What kind of nerve fibre does not exist in cranial nerves?
NO sympathetic axons in cranial nerves
- Olfactory (nose anterior to eyes!): CN I
- smell (special sensory)
- Optic: CN II
- vision (special sensory)
- Oculomotor: CN III
- eyeball/eyelid movement (somatic motor)
- pupil shape (parasympathetic)
- Trochlear: CN IV
- eye movement (somatic motor)
- Trigeminal: CN V
- V1 Ophthalmic: facial sensation (somatic sensory)
- V2 Maxillary: facial sensation (somatic sensory)
- V3 Mandibular: facial sensation and chewing (sensory AND motor)
- Abducent: CN VI
- eye movement (somatic motor)
- Facial: CN VII
- sense of taste (special sensory)
- facial expressions (motor)
- facial expression (parasympathetic)
- Vestibulocochlear: CN VIII (Auditory: mnemonic)
- hearing (special sensory)
- equilibrium (special sensory)
- Glossopharyngeal: CN IX
- sense of taste (special sensory)
- oral sensation (somatic sensory)
- swallowing (somatic motor)
- saliva secretion (parasympathetic)
- Vagus: CN X
- throat, cardiovascular, and GI (somatic sensory)
- (somatic motor)
- (parasympathetic)
- Spinal accessory: CN XI
- moving neck and shoulders (somatic motor)
- Hypoglossal: CN XII
- movement of tongue: swallowing, speech (somatic motor)
On Occasion Of Tea Time Attractive Faces Are Generally Viewed Some How