Lecture 4 - Nervous System Flashcards
What is in the CNS
Brain and Spinal Cord
What is in the PNS
Composed of nerves that connect the brain or spinal cord with muscles, glands and sense organs
What are neurotransmitters
Chemical messengers released from neurons in response to electrical signals
What are processes
Long extensions that connect neuron’s to each other (dendrites, axon etc…)
What Is the Soma
Cell body containing nucleus and ribosomes - protein synthesis
What are Dendrites
Branched outgrowths receive inputs
What are Dendritic Spines
Knob-like outgrowths
increase the surface area, contain ribosomes
What is the axon
Sometimes called the “nerve fiber”
is a long process extending from the soma that carries output to target cells
What is axon collateral
Signal that can go sideways
What is an axon terminal
End of the branch
What are Varicosities
bulging areas where
signal can be released
What is the range for an axon length
μm to > 1m
(eg. spinal cord down to toe)
What are neuron’s wrapped in?
Myelin
What is Myelin
20-200 layers of modified plasma membrane, speeding up transduction signalling
What is myelin made of in the CNS
Oligodendrocytes
What is myelin made of in the PNS
Schwann Cells
What are the gaps in Myelin called
Nodes of Ranvier
What is axonal transport and its purpose
To maintain structure and function, organelles must move >1m between the soma and the
axon terminals
What is anterograde movement
Kinesins: from cell body to axon terminals (e.g., nutrients, neurotransmitter
filled vesicles)
What is Retrograde movement
Dyneins: axon terminals to cell body (e.g., recycled membrane vesicles, growth factors)
What are the 3 classes of neurons
Afferent, Efferent, Interneurons
What do afferent neurons do
Convey information from tissues/organs TOWARDS the CNS
What do efferent neutrons do
Convey information AWAY from the CNS to effector cells
What do interneurons do
Convey information WITHIN the CNS (>99% all neurone)
What is a synapse
Anatomically specialised junction between neurons
What are nerves
Groups of afferent and efferent neutrons together with connective tissue and blood vessels
What do glial cells do
“glue”, surround soma, axon, dendrites and provide physical and metabolic support
What types of glial cells are there
Astrocytes
Microglial cells
Ependymal cells
What do Astrocytes do
Regulate extracellular fluid
by removing potassium and
neurotransmitters
- stimulate epithelial cells
to form tight junctions:
blood brain barrier
What do microglial cells do
- Specialised macrophage-
like cells (remove
pathogens, dead/damaged
neurons)
What do Ependymal cells do
In fluid filled cavities, regulate flow of
cerebrospinal fluid
What is the name for a group of axons
traveling together in
the CNS
Pathway or a tract
What is a commissure
If the group of axons
links the right and left
halves of the CNS
What are ganglia
The cell bodies of neurons with similar
functions in the PNS
What is a nerve
A group of many axons traveling together to and from the same
general location in the peripheral nervous system
(there are no nerves in the CNS)
What is the larger component of the forebrain
Cerebrum
What is the central core of the forebrain called
Diencephalon
Where is grey matter located
Outer shell of the cerebral cortex - giving brain a grey appearance
What is the inner layer of the cerebral cortex made from
White matter - myelinated fibre tracts
What do subcortical nuclei do
important role in movement/posture
[basal nuclei most
predominant]
What are corpus callosum
Each cortex area is separated by a deep longitudinal division, but are connected by a massive bundle of nerve fibers
What are brain ridges called
Gyri (gyrus si.)
What are brain grooves called
Sulci (sulcus si.)
What are the 2 types of cell in the cerebral cortex
Pyramidal cells (major output, excitation)
Non-pyramidal cells (Major input cells, receive signals)
What are the 4 parts of the brain
Frontal, Temporal, Occipital Parietal
What are the Sections of the forebrain
Cerebrum and Diencephalon
What are the parts of the brainstem
Midbrain, Pons, Medulla oblongata
What are cerebral ventricles
The brain also contains four interconnected cavities which are
filled with cerebrospinal fluid
What does the diencephalon contain
Thalamus
Hypothalamus
Epithalamus
What is the thalamus
Collection of several large nuclei
Role of General arousal
Controlling movement/posture
Focusing Attention
What are nuclei
The cell bodies of neurons with similar
functions in the CNS
What is the Hypothalamus
1% of the brain mass
Homeostatic regulation of internal environment
What does the Epithalamus do
Controls biological rhythms
(via pineal gland - produces melatonin)
What are the roles of the hypothalamus
master command center for neural and endocrine coordination
Behaviours having to do with preservation of the individual (e.g. eating and drinking)
Behaviours to do with preservation of the species (e.g. reproduction)
Where does the Hypothalamus lie
Directly above and is connected to the pituitary gland
What dies the pituitary gland do
Master gland - controlling several hormones, including thyroid, adrenal, ovaries and testicles
What does the Cerebellum do
Cerebellum does not initiate
voluntary movements:
an important center for coordinating movements
and for controlling posture and
balance.
receives information from the
muscles and joints, skin, eyes and
ears and the parts of the brain
involved in control of movement
What does the brainstem do
It receives and integrates input from all regions of the central nervous
system and is involved with
- motor functions
- cardiovascular, respiratory control, swallowing
- regulates sleep, wakefulness and attention, eye movement
How is the brain protected
Cranium
Meninges - Dura mater, Arachnoid mater, pia mater
What is the job of the meninges
- Cover and protect the CNS
- Protect blood vessels and enclose the venous sinuses
- Contain cerebrospinal fluid
- Form partitions in the skull
What does Cerebrospinal fluid (CSF) do
protects and cushions
the structures
What is the blood-brain barrier
A protective mechanism that helps maintain a stable environment for the brain.
Capillaries are the least permeable in the body: a very selective barrier. Things that are highly lipid-
soluble cross easily.
What are the Dorsal Horns (Spinal Cord)
Grey matter projecting toward
the back of the body
What are ventral horns (spinal cord)
Grey matter oriented toward the
front of the body
Where do afferent fibres arrive at the spinal cord enter from the peripheral nerves
Dorsal Roots (slide22)
Where do efferent fibres exit the spinal cord from
Ventral roots (slide22)
What nerves comprise the PMS
43 total pairs
12 pairs of Cranial (table 6-8 vanders)
31 pairs of spinal nerves (designated by vertebral levels where they exit
Where are the 31 pairs of spinal nerves
8 cervical neurones (control: muscles and glands, input: neck, shoulders, arms, hands)
12 Thoracic (chest and upper abdomen)
5 Lumbar (lower abdomen, hips, legs)
5 Sacral (genitals, Lower digestive tract)
1 Coccygeal (tail bone
What is the PNS separated into
Somatic and Autonomic nervous system
Somatic vs Autonomic
Slide 25
Parasympathetic vs sympathetic
Slide 25
Where do neurons leave the CNS from in the sympathetic nervous system
Thoracic and lumbar regions
Where do neurons leave the CNS from in the parasympathetic nervous system
Brainstem and Sacral region
Where are the ganglia located in the sympathetic nervous system
Close to spinal cord (sympathetic trunk)
Where are the ganglia located in the parasympathetic nervous system
Ganglia within or close to organs they innervate
What is dual innervation
Some tissues/organs are innervated by both the sympathetic and parasympathetic
nervous system
What is the difference in response of sympathetic and parasympathetic nervous system
S - tends to respond as a single unit
PS - tends to activate specific organs in patterns tailored to each situation
What does the sympathetic system increase under physical or psychological stress
Fight or flight response
What does the parasympathetic nervous system increase in activity
Rest or digest
Revisit A level Resting membrane flashcards
Slide 31
