Flashcards - CNS structure and function

Includes the brain and spinal cord

Central Nervous System (CNS)

Includes cranial nerves and spinal nerves

Peripheral Nervous System (PNS)

Send messages (nerve signals)

Neurons

Support and protect neurons

Neuroglia

Carry messages from the body to the brain/spinal cord

Sensory (afferent) neurons

Carry messages from the brain/spinal cord to the body

Motor (efferent) neurons

Controls voluntary muscle movement (like moving your arms or legs)

Somatic system

Controls involuntary functions like heartbeat, breathing, digestion

Autonomic system

Fight or flight (emergency/stress response)

Sympathetic system

Rest and digest (relaxation, digestion, normal functions)

Parasympathetic system

Electrical signal sent along a neuron

Action potential

Sodium enters the cell, making it less negative

Depolarisation

Potassium (K+) leaves the cell, making it more negative again

Repolarisation

Restores balance in the neuron by pushing Na+ out and K+ in

Na+/K+ pump

Affected by axon size and if it's covered in myelin

Signal travel speed

The gap between two neurons

Synapse

Signal reaches end → calcium enters → vesicle releases neurotransmitter → crosses gap → binds to next neuron

Neurotransmitter release steps

Contains neuron cell bodies

Grey matter

Contains myelinated axons (nerve fibers)

White matter

Spaces filled with cerebrospinal fluid (CSF)

Brain ventricles

Frontal, parietal, temporal, occipital, insula

5 lobes of the brain

Controls thinking, memory, movement, and senses

Cerebrum

Relays sensory messages to the brain

Thalamus

Controls temperature, hunger, emotions, and automatic functions

Hypothalamus

Controls breathing, heart rate, reflexes

Brainstem

Controls balance and coordination

Cerebellum

Controls emotions and memory

Limbic system

Helps with alertness and staying awake

Reticular activating system

Sends messages between brain and body, controls reflexes

Spinal cord

31 segments (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)

Spinal cord segments

Protected by skull, vertebrae, meninges, CSF, blood-brain barrier

CNS protection

A blood vessel ring that helps brain circulation

Circle of Willis

Dura mater, arachnoid mater, pia mater

Meninges layers

Cushions the brain, provides nutrients, removes waste

Cerebrospinal fluid (CSF)

Made in the ventricles (choroid plexus)

CSF production

Absorbed by arachnoid villi into the bloodstream

CSF removal

Protects the brain from harmful substances

Blood-brain barrier

Water, gases, small fat-soluble substances, glucose

Substances crossing blood-brain barrier

Hypothalamus and vomiting center in the medulla

Weak blood-brain barrier areas