1 - The Nervous System Flashcards
Branches of the nervous system
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
Branches of the CNS and PNS
CNS
- Brain
- Spinal Cord
PNS
- Motor Neurons (from CNS to muscles and glands)
- Sensory Neurons (from sensory organs to CNS)
Branches of motor neurons
Somatic Nervous System
- voluntary movements
Autonomic Nervous System
- involuntary responses
Branches of the Autonomic Nervous system
Sympathetic Division
- Fight or Flight
Parasympathetic Division
- Rest or Digest
Anatomical Planes (5)
Medial Plane Lateral Plane Horizontal Plane Coronal Plane Sagittal Plane
Ipsilateral and Contralateral
Ipsilateral items lie on the same lateral side
Contralateral items lie of different sides of the body
Anatomical Relationships (spatial) (4)
Rostral = up (beak) Caudal = down (tail)
Ventral (anterior) = belly
Dorsal (posterior) = back
These axes line up when you look up, so in normal anatomical position, for the head:
Dorsal = superior
Ventral = inferior
Basic Divisions of the brain (3)
Forebrain
Midbrain
Hindbrain
10% of brain volume but 50% of the brain’s cells
Cerebellum
Divisions of the Forebrain
- Telencephalon
> olfactory bulbs (for olfactory stimuli)
> cerebral hemispheres (regulation of sensory and motor function) - Diencephalon (sensory gateway / regulation of internal environment)
Divisions of the Hindbrain
- Cerebellum
(movement coordination / learning of motor skills) - Pons
(relay point between cerebellum and cerebral cortex in mammals) - Medulla
(regulation of internal environment)
Divisions of the Midbrain
- Optic Tecta
(processing of sensory {mainly visual} stimuli) - Tegmentum
(aspects of motor control)
Divisions of the cortex into lobes (forebrain)
Frontal Lobe
- motor control
- executive functions
Temporal Lobe
- hearing
Parietal Lobe
- bodily sensations
- spatial relationships
Occipital Lobe
- vision
Brodmann’s areas
Divided the brain into areas according to structural divisions
However an apparent difference in structure does not mean a difference in function
Cranial Nerves
The structures that carry information into the brain
There are 12 cranial nerves in humans, the first 2 emerge from the cerebrum and the other 10 emerge from the brainstem
Cranial Nerves are part of the Peripheral Nervous System (sensory neurons)
Overview of brain functions:
- cerebral cortex
- basal ganglia
- thalamus, hypothalamus
- cerebellum
- pons and medulla
- midbrain
Cerebral cortex
- cognition
- sensory processing
- motor control
- learning
Basal Ganglia
- voluntary and learnt motion
Thalamus, Hypothalamus
- sensory integration and relay
- attention
- consciousness
- emotion
- homeostasis
Cerebellum
- motor coordination
- muscle tone and balance
Pons and Medulla
- involuntary body functions (i.e. sleep)
- cognitive motor skills (i.e. typing)
Midbrain
- audio/visual relay
- posture
- alertness
Ganglia
A group of related nuclei
Divisions of the spinal cord and what they innervate
8 Cervical nerves
- neck / shoulders / arms / hands
12 Thoracic nerves
- trunk of the body / arms
5 Lumbar nerves
- lower back / front of the legs
5 Sacral nerves
- back of legs + ass / genitals
Dorsal column-medial lemniscal pathway
Transmits sensory information but NOT pain
- from proprioceptors or mechanoreceptors
Pathway:
- Afferent (first-order) neuron from the receptor goes into the dorsal root ganglion of the spinal cord
- Passes up the Dorsal Column to the Medulla Oblongata, where it synapses onto a second-order
- 2nd order neuron travels out of the Dorsal Column and passes over the Medial-Lemniscus to the other side of the Medulla Oblongata and up into the Thalamus
- In the Thalamus, it synapses onto a third-order neuron and terminates in the Primary Somatosensory Cortex
Spinothalamic Tract (a pathway)
Transmits pain information
- from nociceptors or thermoreceptors
Pathway:
- Afferent neuron from the receptor goes into the dorsal root ganglion of the spinal cord
- Immediately synapses onto an interneuron in the dorsal horn and passes into the other side of the spinal cord
- This travels up to the thalamus where it synapses onto an efferent neuron and onto the Primary Somatosensory Cortex
What the dorsal column-medial lemniscal pathway and spinothalamic tract tell you about spinal damage
If damaged on one side of the spina cord:
- sensory information from below that same side will not travel up
- pain information from that opposite side will not travel up
- due to the way each pathway passes over to the other side of the spinal cord
Sympathetic vs Parasympathetic effects of the Autonomic Nervous System
Sympathetic
- dilates pupils and inhibits tears
- relaxes airways
- increases heart rate
- inhibits salivation and digestion / stimulates glucose release from the liver
- relaxes bladder and rectum
- stimulates orgasm
- stimulates release of adrenalin and noradranalin
Parasympathetic
- constricts pupils an stimulates tears
- constricts airways
- slows heart rate
- stimulates salivation and digestion / stimulates insulin release from the liver
- constricts bladder and rectum
- stimulates sexual arousal
Changes to the Autonomic Nervous system (by exercise and trauma)
Exercise
- recreational athletes show a shift towards the sympathetic nervous system
> if persistent this can cause high blood pressure and cardiovascular disease
- long term intensive athletic training causes a shift towards the parasympathetic nervous system
Trauma
- PTSD causes a heightened sensitivity in the autonomic nervous system
- tends to have persisting effects
Brain facts
- Brain is 2% of the body mass but receives 15% of the body’s blood supply and receives 20% of the body’s oxygen
- no brain cell is further than 50 um (micrometers)
