Week 2 Flashcards
1
Q
Nervous System
A
Central Nervous System and Peripheral Nervous System
2
Q
Central Nervous System
A
Brain and spinal cord
3
Q
Peripheral Nervous System
A
Somatic Nervous System and Autonomic Nervous System (ANS), also
Enteric Nervous System (Gut)
4
Q
Autonomic Nervous System (ANS) Efferent Nerves
A
Parasympathetic Nervous System and Sympathetic Nervous System
5
Q
Afferent Nerves
A
(Incoming)
6
Q
Efferent Nerves
A
(Outgoing)
7
Q
Central Nervous System (CNS)
A
Brain and spinal cord
Encased in bone
Networks of interconnected neurons
Processing of information
8
Q
Peripheral Nervous System (PNS)
A
Outside the skull and spine
Nerves – bundles of separate neurons
Transmission of information
Connects the CNS with the rest of the body
9
Q
Peripheral Nervous System (PNS)
Somatic Nervous System (SNS)
A
Voluntary
Interaction with the environment
10
Q
Peripheral Nervous System (PNS)
Autonomic Nervous System (ANS)
A
Involuntary
Regulate the body
11
Q
Somatic Nervous System (SNS)
Afferent
A
Incoming signals
Sensory info into the CNS
Exteroceptive sense organs
Information to enable interaction with the world
12
Q
Somatic Nervous System (SNS)
Efferent
A
Outgoing signals
Motor commands from the CNS
Skeletal Muscle
Facilitate bodies interaction with the world
13
Q
Autonomic Nervous System (ANS)
Afferent
A
Incoming signals
Sensory info into the CNS
Interoceptive sense organs (viscera and blood vessels)
Information about the body’s internal state
14
Q
Autonomic Nervous System (ANS)
Efferent
A
Outgoing signals
Motor commands from the CNS
Smooth and cardiac muscle and glands
Change the body’s internal state
15
Q
ANS Efferents
Sympathetic
A
Fight or flight Stimulate organs and release hormones to wind things up Mobilise energy sources Increase blood flow and respiration Supress non-essentials
16
Q
ANS Efferents
Parasympathetic
A
Rest and digest
Counteract sympathetic to wind things down
Stimulate digestion and restorative functions
Conserve energy
17
Q
Cranial Nerves
A
12 pairs
Connect directly to the brain
Some purely sensory, some purely motor, some both
18
Q
Spinal Nerves
A
31 pairs
Connect to the spinal cord
All are both sensory and motor
19
Q
What are the Cranial Nerves
A
Olfactory (smell) (S) Optic (sight) (S) Occulomotor (eye movement) (M) Trochlear (eye movement) (M) Trigeminal (facial sensations, chewing) (B) Abducens (eye movement) (M) Facial (taste - front 2/3 of tongue) (B) Auditory/Vestibular (S) Glossopharyngeal (taste - back 1/3 of tongue) (B) Vagus (organs) (B) Spinal Accessory (neck, shoulders, head) (M) Hypoglossal (tongue movement) (M)
20
Q
Spinal Nerves
A
Dorsal root, Dorsal root ganglion
Ventral root, Ventral root ganglion
21
Q
Parasympathetic
From brain, lower back
A
thetic stimulates flow of saliva slows heartbeat constricts bronchi stimulates peristalsis and secretion stimulates release of bile contracts bladder
22
Q
Sympathetic
From chest, mid-lower back
A
tic dilates pupil inhibits flow of saliva accelerates heartbeat dilates bronchi inhibits peristalsis and secretion conversion of glycogen to glucose secretion of adrenalin and noradrenaline inhibits bladder contraction
23
Q
Neurons
A
Main functional cells of the nervous system
Collect, integrate and transmit information
24
Q
Glia
A
Glia support neurons
Numerous types and many function
25
Neuron Terminology
Clusters of cells within the CNS - Nuclei
Clusters of cells in the PNS – Ganglia
Clusters of axons within the CNS - Tracts
Clusters of axons in the PNS - Nerves
26
4 main types of neuron
unipolar
bipolar
multipolar
multipolar interneuron
27
Unipolar neuron
Sensory neurons transfer information from receptor cells to higher nerve cells
28
Bipolar neuron
Connecting adjacent cells typically in sensory system (e.g. retina)
29
Multipolar Neuron
Transfer information between cells usually long distance; can collect and integrate info from many cells
30
Multipolar Interneuron
Local connections collect and integrate info from many cells
31
4 Main Types of Glial Cell
Oligodendrocytes
Schwann Cells
Microglia
Astrocytes
32
Oligodendrocytes
Myelination in CNS
33
Schwann Cells
Myelination in PNS
34
Microglia
Immune function
35
Astrocytes
Numerous structural and functional support
36
The Spinal Cord
13-14 million neurons
Protected by the vertebral column (and meninges)
Doesn’t go full length of the spine
Loose bundle of nerves below L2 – Cauda Equina (horses tail)
Messages to and from the brain
Also simple processing – reflex arcs
37
The Spinal Cord
| Unipolar
afferent neurons join the dorsal horn - both somatic (skeletal / sensory) and autonomic (internal organs) systems.
38
The Spinal Cord
| Multipolar
efferent neurons have their cell bodies in the ventral root. Their axons project out to somatic and autonomic systems.
39
Spinal reflex arc
receptors in skin signal message through sensory neuron via spinal cord (CNS) to brain and relay neuron which via motor neuron signals to the effector = muscle to move
40
The Brain
| Development of the neural tube
convergence of the neural plate at the neural plate border with the epidermis to form a neural fold which forms the neural tube, neural crest and epidermis
41
The Brain
| formation
Cells proliferate and the tube thickens
3 bulges form at the rostral end- forebrain, midbrain, hindbrain and spinal cord
then forms telecephalon (cerebral hemispheres), Diencephalon, Mesencephalon (midbrain), Metencephalon, Myelencephalon and spinal cord
42
Diencephalon not brainstem
Connects forebrain to spinal cord
White matter outside with grey matter inside in discrete nuclei
3 major levels
Myelencephalon
Metencephalon
Mesencephalon
All head muscles supplied by cranial nerves from the brainstem
43
Myelencephalon
Medulla
Caudal brainstem – blends into spinal cord
Primarily axonal tracts
Pyramidal tracts – ‘decussation of the pyramids’
Head and neck movement
Vital functions
Portion of reticular formation (net-like formation) - arousal.
44
Metencephalon
Pons and Cerebellum
Tracts of nerves and a portion of the reticular formation.
Pons – vital functions relay centre – ‘bridge’; head muscle control
Cerebellum - sensory and motor control; cognitive
45
Mesencephalon
Midbrain
```
tectum
and tegmentum
Tectum
superior and inferior colliculi
Visual and auditory orienting of attention
Multisensory integration
```
Tegmentum
Portion ventral to tectum
Periaqueductal grey matter
Substantia nigra
46
Mesencephalon
| Parkinson’s Disease
```
Loss of dopamine neurons in SN
Project to basal ganglia
Important for movement control
Tremor or shaking
Muscle rigidity or stiffness
Slowing of movement
Stooped posture
Balance problems.
```
47
Diencephalon
Forebrain
2 major parts
Thalamus
Hypothalamus
2 major endocrine glans
Pituitary gland
Pineal gland
48
Thalamus
Relay station – all sensory except smell relays through thalamus
Also receives many cortical projections
Integration of bottom-up inputs and top-down
Many separate nuclei
Lateral Geniculate Nucleus first synapse after the optic nerve leaves the eye
Medial Geniculate Nucleus Auditory relay
Ventro Posterior Nucleus Sensorimotor relay
49
Hypothalamus
Ventral part of diencephalon
Control centre for autonomic nervous system
Inputs from many brain and body systems
Outputs to brainstem (ANS) and pituitary gland (endocrine)
Homeostasis
Regulation of motivated behaviours – eating, sleeping, sexual
50
Telencephalon
Forebrain
Collection of subcortical nuclei
Cerebral cortex
51
Basal Ganglia
Control of movement
Learning and motivation
Striatum – caudate + putamen
52
Limbic System
Midline structures circling the thalamus
Regulation of motivated behaviours - The Four Fs
Affect/emotion
Amygdala – learned fear response; recognition of emotion in others
Hippocampus – long term memory
53
Cerebral Cortex
Layer of grey matter covering the cerebral hemispheres
Folded – Gyri (ridges) and Sulci (fissures)
2 Hemispheres connected by corpus collosum
4 lobes
Many regions or areas based on location (e.g. PFC), function (e.g. FEF), or cytoarchitecture (e.g. Brodmann areas)
28 billion neurons
>1 trillion synapses
>80% human brain mass
54
Cerebral Cortex
| Frontal Lobe
Thinking, planning, executive functions, motor execution
55
Cerebral Cortex
| Parietal Lobe
Somatosensory perception, spatial perception
56
Cerebral Cortex
| Temporal Lobe
Auditory, language, long term memory, emotion
57
Cerebral Cortex
| Occipital Lobe
Visual
58
Main Neuron Types
Pyramidal
Most common cortical neuron
Large bodies, multipolar, long axon goes down and inward through layers
Projection neurons – connect disparate brain regions or leave the brain (to spinal cord)
Stellate
small, star-shaped short / no axons; transmit info laterally
Local – interneurons
59
Layers of Neocortex
Most cortex neocortex – new
6 layered outer covering of the cerebral hemisphere
Each layer differs in the relative concentration of stellate and pyramidal cells, in the relative size and concentration of cell bodies
Layer IV is thick in sensory areas – Input
Layer V – mainly pyramidal cells with long axons - in motor areas - output
60
Protecting the Brain
```
Physical protection from mechanical injury
Skull
3 Meninges (Dura Mater, Pia Mater, Arachnoid) – membranous coverings around the brain and spinal cord
Cerebrospinal fluid (CSF) – supports and cushions
```
Chemical protection – maintaining chemical balance
The blood-brain barrier
Tightly packed cells along the blood vessel walls of the CNS prevent entry of many (large) molecules.
Good and bad (eg L-Dopa)
61
Physical Protection
Scalp, Skull, Dura Mater, Pia Mater, Arachnoid, Subarachnoid
| space, Sinus
62
The Ventricles
Lateral- between the telencephalon (cerebral hemispheres)
Third- between the diencephalon
Cerebral aqueduct- between the mesencephalon (midbrain)
Fourth between teh metencephalon
Central Canal- between the spinal cord
63
Cerebrospinal Fluid
Produced by choroid plexuses in ventricles
Circulates subarachnoid space, ventricles and central canal
Excess drains into sinuses in the dura mater
If drainage is blocked - hydrocephalus
64
Commisurotomies / callosotomies
Antecedent: usually sever epilepsy
Procedure: callosotomy, anterior commissurotomy
Consequence: reduction of seizures
Behavioural consequence: very little
Experimental consequence: sensory information presented to one hemisphere is not available to guide behaviour in the other hemisphere
65
Split Brains
Visual information – left visual field to right hemisphere and right visual field to left hemisphere
Intact brain – information can cross between hemispheres via the corpus callosum
Callosotomy – lose communication
Left hemisphere ignorant of left visual field
Right hemisphere ignorant of right visual field
66
Key Learnings
Divisions in pairs
CNS – processing / PNS – transmitting
Afferent/efferent – SNS and ANS
Sympathetic vs parasympathetic
Communicate to body via cranial (12 pairs) and spinal (31 pairs) nerves
2 cell major cells – neurons and glia (4 types of each)
Spinal cord – central grey and peripheral white; unipolar afferents, multipolar efferents
Brain – development for 5 major divisions
Brainstem – myelencephalon, metencephalon, mesencephalon
Diencephalon – thalamus and hypothalamus
Telencephalon – cortex and subcortical nuclei (basal ganglia and limbic system)
Cortex – lobes, neuron types, layers
Protecting the brain – 3 meninges, CSF (ventricles)
Split brain patients
