What is the CNS composed of?
the brain and spinal cord
What is the CNS primarily composed of and what are the 5 types?
- ependymal cells
- schwann cells
What 4 things protect the CNS?
- glial cells
- connective tissue
- cerebrospinal fluid
What are the 2 functions of ependymal cells?
- creates barriers between compartments
- acts as a source of neural stem cells
What is the function of astrocytes? (astro = star)
CNS glial cells that develop neural connections and possibly modulate synaptic activity; remove neurotransmitter from synaptic cleft, communicate to neurons through chemical messengers, maintain normal electrolyte composition of ISF in CNS, protect neurons against toxic substances and oxidative stress, protecting against neural degeneration
What do microglia do?
glial cells that serve as phagocytes, cleaning and removing bacteria and dead cells, as well as protecting CNS from oxidative stress by removing reactive oxygen species
bony skull that encases the brain
a spinal cord that runs through a canal surrounded by bony vertebrae
3 membranes that lie between the bones and tissues of the CNS
What are the 3 meninges?
- dura mater (hard mother)
- arachnoid mater (spider mother)
- pia mater (tender mother)
thick, outermost layer of the meninges that protects the brain and spinal cord, directly against the cranium
middle layer thats a network shaped like a spider
innermost layer, delicate, directly against the brain
Protects the CNS by acting like a cushion and maintains a stable ISF environment
- clear watery and salty
Where is cerebrospinal fluid secreted into and where does it flow?
into the ventricles and flows through the subarachnoid space
What forms the lateral ventricles?
the first and second ventricles
Where does the cerebral aqueduct lead?
from the third ventricle in the diencephalon to the fourth ventricle in the brainstem
Where is the third ventricle located?
in the diencephalon
Where is the fourth ventricle located?
in the brainstem
What do villi do?
the fingerlike projections of the arachnoid membrane at which cerebrospinal fluid is reabsorbed into the blood
What does the chorioid plexus do?
circulates the cerebrospinal fluid to subarachnoid space and ventricles
- picks what substrate it transports
What indicates infection?
When the CSF contains protein and/or blood cells (they ain’t supposed to be there)
Concentration of K+ is _____ in the CSF
concentration of H+ is ______ than in plasma
Concentration of Na+ is _______ to that in blood
What is the total volume of CSF in around a 150lb animal
How much CSF does the choroid plexus produce per day and how often is it recycled?
400-500mL/day, recycled 3 times per day
CSF depends on what for energy?
What does the brain rely on for energy?
glucose, oxygen and in extreme cases, ketones (obtained through the metabolism of fatty acids/lipids)
What are capillaries?
sites of exchange between blood and interstitial fluid
What is lactate?
the usable form of glucose that the CNS (brain) uses for energy
What is the blood-brain barrier?
special anatomy of the CNS capillaries that limits exchange (selective - keeps unwanted things from the blood from crossing over into ECF of the CNS)
What are capillaries composed of? (x2)
endothelial cells and pores
What kinda molecules move freely across capillary walls?
What kinda molecules diffuse across the walls of capillaries?
What kinda molecules diffuse through pores in capillary walls?
What kinda molecules are actively transported across capillary walls?
cells and proteins
What are tight junctions?
gaps between cells that regulate the blood brain barrier
What is white matter, how much of the CNS does it compose and what is located there?
- also what makes it white?
- 60% of the CNS
- where myelinated axons (thats what makes it white) and oligodendrocytes are found
What is gray matter, how much of the CNS does it compose and what is located there?
- site of synaptic communication and neural integration
- 40% of the CNS
- composed of neurons
What are projection fibers?
they connect the cerebral cortex with the lower levels of the brain or spinal cord (CNS) (connect top with bottom on both hemispheres)
What are association fibers?
they connect 2 areas of the cerebral cortex on the same side of the brain (connect the same things on either hemisphere of the brain)
What are commissural fibers?
they connect the same cortical regions on 2 sides of the brain (connect both hemispheres of the brain together)
What is the corpus callosum?
the primary location of commissural fibers
How does the spinal cord allow for locomotion and what is it known for?
it has neural networks – is the major communication pathway between the brain and joints, skin and muscles
In what area would you perform a spinal tap aka lumbar puncture?
Sacral part of the spinal cord – 5 pairs of nerves (lower end)
Where would you place an epidural in a sheep?
The cauda equina – middle space (dark brown)
Where is the dorsal region and what is it responsible for?
- gray matter
- sensory functions
Where is the ventral region and what is it responsible for?
- gray matter
- motor functions
What does white matter form?
ascending and descending tracts that connect the spinal cord with the cerebral cortex
What is in the cerebrum and where is it located?
- contains gray and white matter
- consists of the cerebral cortex and the basal nuclei
- c shaped
What is the cerebellum?
aka ‘little brain’; consists of the outer cortex and inner nuclei. bilaterally symmetrical, responsible for motor coordination/balance, coordination of eye and body movements memory
What is the brainstem and what does it consist of and what does it connect to what?
consists of nuclei that regulate various functions
- midbrain, pons and medulla
- connects the forebrain and cerebellum to the spinal cord
What is the midbrain responsible for?
What are the pons responsible for?
- relay station for info between cerebellum and cerebrum
- coordinates control of breathing with the medulla
What is the medulla responsible for? (nuclei)
- coordinates control of breathing with the pons
- also controls blood pressure, swallowing and vomiting
Where are the processing centers for the 12 types of nerves?
10 of them in the brainstem, then the olfactory and optic emerge directly from the cerebrum
What do cranial nerves carry?
sensory and motor info for the head and neck
What is the gyri/gyrus?
a ridge on the cerebral cortex
What is the sulci/sulcus?
a groove on the surface of the brain
What is a lobe?
a part of the cerebrum of the brain (x4)
What is the cerebral cortex?
a thin layer of gray matter on the outermost portion of the cerebrum – performs the highest level of neural processing
ie. perception of environment, formulate ideas (humans) and actions (animals), memory, skeletal muscle movement, processing of sensory info
How many layers does the cortex have?
6 layers of cells
What are the 4 lobes of the cerebrum?
- frontal aka reasoning, planning, speech, movement, emotions, etc.
- parietal aka sensory
- occipital aka visual
- temporal aka auditory
Where is the primary motor cortex?
Where is the primary somatosensory cortex located?
the parietal lobe
What does the central sulcus do?
separates frontal and parietal lobes
What is the primary somatosensory cortex responsible for?
where messages from the sense receptors are registered
What is wernickes area and where is it?
language comprehension in the posterior superior temporal lobe
What occurs in the auditory association areas and where is it?
located in the temporal lobe, where meaningless sounds are transformed into recognisable auditory information.
What occurs in the primary auditory complex and where is it?
located in the temporal lobe, responsible for hearing
What occurs in the limbic association cortex and where is it?
mostly on inner and bottom surface of temporal lobe; motivation and emotion; memory
What occurs in the olfactory cortex and where is it?
- sense of smell
located on the inferior surface of the frontal lobe
What is broca’s area and where is it?
production of speech - an area, usually in the left frontal lobe (cortex of the frontal lobe)
What is the prefrontal association areas job?
idea and plan for voluntary movement, thoughts and personality
What is the premotor cortex and where is it?
Frontal cortex, coordinates voluntary movements
What is the basal nuclei?
islands of gray matter buried within the white matter responsible for inhibition of unwanted movements, selection of purposeful movements, and postural support
What is the globus pallidus?
component of the subcortical nuclei that connects to the thalamus which relays information to the motor areas and the prefrontal cortex
What is the caudate?
component of the subcortical nuclei; the tail-like structure that is part of the striatum
What is the putamen?
large subcortical structure, part of the subcortical nuclei - located in the cerebrum
What is the claustrum?
component of the subcortical nuclei; processes visual information at a subconscious level
Where is the diencephalon and what is it composed of?
lies between brain stem and cerebrum; composed of thalamus, hypothalamus, pituitary, and pineal gland
What is the function of the thalamus?
relay station; almost all sensory information from lower parts of the CNS passes through it, also serves as an integrating center by modifying information passing through it