1. Introduction Flashcards
What does the CNS comprise of?
Brain
Spinal cord
What are the 2 sub-divisions of the PNS?
Motor (effector)
Sensory (detects changes)
What are the 2 sub-divisions of the motor PNS?
Autonomic: Regulates function of viscera: internal organs, smooth muscle, blood vessels
Somatic: controls motor and sensory function for the body wall e.g. skin, skeletal muscles
What are the 2 arms of the autonomic nervous system?
Sympathetic “fight or flight”
Parasympathetic “rest and digest”
Efferent flow
Brain to periphery
CNS to PNS
Exit brain
Afferent flow
Periphery to brain
PNS to CNS
Arrive to brain
4 lobes of the brain + cerebellum
Frontal: personality, conscious decision making
Parietal: somatosensory cortex, sensory info from somatic PNS
Occipital: Visual cortex, seeing and processing
Temporal: Audariry, personality, fear and anxieties
Cerebellum: Fine motor skills
What is under the cerebellum?
Brain stem
Contains centres that control HR, BP, breathing and feeding
Where does the brainstem lead?
Spinal cord
Why is the cortex highly folded?
To increase SA to increase number of neurones for processing info
Corpus collosum
Fibre tract that allows for communication between the 2 hemispheres
Pituitary gland
Endocrine organ
Secretes hormones
What are the ridges and valleys of the brain?
Ridges= Gyri Valleys= Sulci
How many cranial nerves are there and what is their main function?
12
mainly control things to do with the face and neck
What are the 12 cranial nerves?
ooh, ooh, ooh, to touch and feel very good velvet. such heaven
Olfactory I Optic II Oculomotor III Trochlear IV Trigeminal V Abducens VI Facial VII Vestibulocochlear VIII Glossopharyngeal IX Vagus X Accessory XI Hypoglossal XII
Give the functions of nerves I, II, III, and X
Olfactory I= Smell receptors
Optic II = Sight, transmits vision to back of brain
Oculomotor III= moving eyes
Vagus X= Longest cranial nerve, brain to gut, sensory and motor nerve (both efferent and afferent aspects). Involved in feeling full and HR
What is the accessory nerve XI also known as?
Spinal accessory nerve
3 Layers of the meninges
DURA MATER: Outside layer
ARACHNOID
PIA MATER
What is the brain covered by?
3 layers of protective tissue
= The meninges
What is found between the layers of the meninges?
Blood vessels
Which nervous system are the dorsal and ventral roots emerging from the spinal cord part of?
PNS
Grey matter
Site of neurone cell bodies, where processing occurs
White matter
Site of axons of neurones
Ventral horn
Info from CNS to body
=Efferent pathway
Dorsal horn
Info from PNS to spinal cord
either reflexes in spinal cord or goes up to brain
Describe axon packaging into nerves
Spinal nerves contain both afferent and efferent axons
Bundled into fascicles surrounded by perineurium.
Whole nerve is in a tough epineurium capsule.
Individual axons are also wrapped with myelin and endoneurium
Describe the process of an action potential
Voltage of -70mV inside cell
Activation of a neural cell: influx of Na+
Changes relative voltage between inside and outside = Depolarisation (opening of voltage gated Na+ ion channels, allowing Na+ in)
When are K+ channels opened?
+40 mV
Relative electrical charge decreases
Name 5 neuroglia
Astrocytes Ogliodendrocytes Schwann cells Microglial cells Ependymal cells
Function of astrocytes
Form blood-brain barrier
Recycle neurotransmitters
Foot like processes that wrap around blood vessels
Function of microglia
Immune cells
Name 2 myelin producing cells
Ogliodendrocytes
Schwann cells
What are the differences in regenerative capacity between CNS and PNS?
Axons in PNS can regenerate after injury
Axons in CNS have limited regenerative capability
Dorsal column-medial lemniscus pathway
Conveys fine touch, vibration and 2-point discrimination
Injury to this pathway will stop you from being able to physically feel things
Dorsal column-medial lemniscus pathway sides of body
Right side of brain senses info and controls left side of body
(and vice-versa)
Contralateral movement
Spinothalamic pathway
Conveys pain and temperature sensation
Spinothalamic pathway sides of body
Immediately switches side in spinal cord
Motor pathways
Efferent pathways
Precentral gyrus to Brain stem
Switches to other side of nervous system
Travel down spinal column on ipsilateral side of target (injury on 1 side of spinal cord effects organs on same side)
What does injury to motor pathways cause?
Injure one side of spinal cord effects organs on same side
What may injury to 1 side of the spinal cord result in?
E.g. damage on left side of cord
Able to feel sensation from contralateral side of body, but not feel pain or sense temperature on contralateral side
Vestibulospinal tract
Receives input from vestibular system (inside ear)
Allows you to keep balance
Vestibulospinal tract side of body
Ipsilateral: Goes down one side of body (doesn’t cross over)
