Week 7 - Central Nervous System Flashcards
1
Q
What are the brain regions?
A
- cerebral hemispheres (2 hemispheres)
- diencephalon
- brain stem
- cerebellum
2
Q
Describe the cerebral hemispheres.
A
- they are paired (left and right)
- superior parts of the brain
- include more than half of the brain mass
- the surface is made of elevated ridges (gyri/gyrus) and grooves (sulci/sulcus)
- fissures are deeper grooves
- loves are named for the cranial bones that lie over them
3
Q
What are the 3 main regions of the cerebral hemisphere?
A
- cortex is superficial gray matter
- white matter
- basal nuclei are deep pockets of gray matter
4
Q
What is part of the cerebral hemispheres?
A
- cortex: gray matter
- basal nuclei
5
Q
What is part of the Diencephalon region?
A
- thalamus
- hypothalamus
- limbic system — a functional system
6
Q
What is part of the Cerebral hemispheres?
A
- midbrain
- pons
- medulla oblongata
- reticular fromation — a functional system
7
Q
What is part of the Cerebellum?
A
- cerebellum
8
Q
Function of Cortex: gray matter
A
- localizes and interprets sensory inputs
- controls voluntary and skilled skeletal muscle activity
- acts in intellectual and emotional processing
9
Q
function of basal nulclei
A
- subcortical motor centers help control skeletal muscle movements (figure 7.14)
10
Q
function of thalamus*
A
- relays sensory impulses to the cerebral cortex
- relays impulses between cerebral motor cortex and lower motor centers
- involved in memory
11
Q
function of hypothalamus*
A
- **KEYWORD - REGULATION
- chief integration center of the autonomic (involuntary) nervous system
- regulates body temperature, food intake, water balance, and thirst
- regulates HORMONAL OUTPUT of anterior pituitary gland and acts as an endocrine organ (producing ADH and oxytocin)
12
Q
function of limbic system — a functional system
A
- includes cerebral and diencephalon structures (e.g. hypothalamus and anterior thalamic nuclei)
- mediates emotional response; involved in memory processing
13
Q
anatomy of midbrain
A
- contains visual and auditory reflex centers
- contains subcortical motor centers
- contains nuclei for cranial nerves III and IV
- contains projection fibers (e.g. fibers of the pyramidal tracts)
14
Q
anatomy of pons
A
- relays information from the cerebrum to the cerebellum
- cooperates with the medullary centers to control respiratory rate and depth (breathing)
- contains nuclei of cranial nerves V-VII
- contains projection fibers
15
Q
anatomy of medulla oblongata
A
- relays ascending sensory pathway impulses from skin and proprioceptors
- contains nuclei controlling heart rate, blood vessel diameter, respiratory rate, vomiting, etc.
- relays sensory information to the cerebellum
- contains nuclei of cranial nerves VIII-XII
- contains projection fibers
- site of crossover pyramids
- where the motor pathway crosses over
16
Q
function of reticular formation — a functional system
A
- RAS
- maintains cerebral cortical alertness; filters our repetitive stimuli
- helps regulate skeletal and visceral muscle activity
17
Q
function of cerebellum
A
- process information from the cerebral motor cortex, proprioceptors, and visual and equilibrium pathways
- provides “instructions” to the cerebral motor cortex and subcortical motor centers, resulting in smooth, coordinated skeletal muscle movements
- responsible for proper balance and posture
18
Q
What is the primary somatic sensory area (cerebral cortex)?
A
- located in parietal lobe posterior to central sulcus
- receives impulses from the body’s sensory receptors
—– pain, temperature, light touch (except for special senses) - sensory homunculus is a spatial map
left side of the primary somatic sensory area receives impulses from right side (vice versa)
19
Q
Cerebral areas involved in special senses
A
- visual area (occipital lobe)
- auditory area (temporal lobe)
- olfactory area (temporal lobe)
20
Q
What is the primary motor area (cerebral cortex)?
A
- located anterior to the central sulcus in the frontal lobe
- allows us to consciously move skeletal muscles
- motor neurons form pyramidal (corticospinal) tract, which descends to spinal cord
- motor homunculus is a spatial map
21
Q
What is the Broca’s area / motor speech area (cerebral cortex)?
A
- involved in our ability to speak
- usually in left hemisphere
22
Q
Other specialized areas in the cerebral cortex
A
- anterior association area (frontal lobe)
- posterior association area (posterior cortex)
- speech area (for sounding out words)
23
Q
Describe Cerebral white matter
A
- composed of fiber tracts deep to the gray matter
- corpus callosum connects hemispheres
- tracts, such as the corpus callosum, are known as “commissures”
- association fiber tracts connect areas within a hemisphere
- projection fiber tracts connect the cerebrum with lower CNS centers
24
Q
Describe Basal nuclei
A
- “islands” of gray matter buried within the white matter of the cerebrum
- regulate voluntary motor activities by modifying instructions sent to skeletal muscles by the primary motor cortext
25
Q
Describe Diencephalon
A
- sits on top of the brain step
- enclosed by the cerebral hemispheres
26
Q
What 3 structures is the Diencephalon made of?
A
- thalamus
- hypothalamus
- epithalamus
27
Q
describe diencephalon: thalamus
A
- encloses the third ventricle
- relay station for sensory impulses passing upward to the cerebral cortex
- transfers impulses to the correct part of the cortex for localization and interpretation
28
Q
describe diencephalon: hypothalamus
A
- makes up the floor of the diencephalon
- important autonomic nervous system center
- – regulates body temperate
- – regulates water balance
- – regulates metabolism
- houses the limbic center for emotions
- regulates the nearby pituitary gland
- houses mammillary bodies for olfaction (smell)
29
Q
describe diencephalon: epithalamus
A
- forms the rood of the third ventricle
- houses the pineal body (an endocrine gland)
- includes the choroid plexus (forms cerebrospinal fluid)
30
Q
What is the brain stem?
A
attaches to the spinal cord
31
Q
What are the brain stem?
A
- midbrain
- pons
- medulla oblongata
32
Q
describe midbrain
A
- extends from the mammilary bodies to the pons inferiorly
- cerebral aqueduct (tiny canal) connects the third and fourth ventricles
- two bulging fiber tracts, cerebral peduncles, convey ascending and descending impulses
- four rounded protrusions, corpora quadrigemina, are visual and auditory reflex centers
33
Q
describe pons
A
- rounded structure protruding just below the midbrain
- mostly composed of fiber tracts
- includes nuclei involved in the control of breathing
34
Q
describe: medulla oblongata
A
- the most inferior part of the brain stem that merges into the spinal cord
- includes important fiber tracts
- contains important centers that control:
- – heart rate
- – blood pressure
- – breathing
- – swallowing
- – vomiting
- fourth ventricle lies posterior to pons and medulla
35
Q
What is reticular formation?
A
- diffuse of gray matter along the brain stem
- involved in motor control of visceral organs
- reticular activating system (RAS)
- —- plays a role in awake/sleep cycles and consciouness
- —- filter for incoming sensory information
36
Q
describe the cerebrum
A
- two hemispheres with convoluted surfaces
- outer cortex of gray matter and inner region of white matter
- controls balance
- provides precise timing for skeletal muscle activity and coordination of body movements
37
Q
What protects the central nervous system (CNS)?
A
- meninges
- cerebrospinal fluid (CSF)
- blood-brain barrier
38
Q
What are the 3 Meninges?
A
- dura mater
- arachnoid mater
- pia mater
39
Q
What is the dura mater?
A
- outermost leathery layer
- double-layered external covering
—– periosteum => attached to the inner surface of the skull/bone
— dural venous sinuses (open space) => collect venous blood
— subdural space
—– meningeal layer => outer covering of the brain - folds inward in several areas
(falx cerebri and tentorium cerebelli)
40
Q
What is the Arachnoid mater?
A
- middle layer
- weblike (spider webs) extensions span the subarachnoid space to attach it to the pia mater
- subarachnoid space is filled with cerebrospinal fluid (CSF)
- arachnoid granulations protrude through the dura mater and absorb cerebrospinal fluid into the venous blood
41
Q
What is the Pia mater?
A
- internal layer
- clings to the surface of the brain and spinal cord
42
Q
What is the Cerebrospinal fluid?
A
- similar to blood plasma in composition
- formed continually by the choroid plexuses
- —- choroid plexus => capillaries in the ventricles of the brain
- CSF forms a watery cushion to protect the brain and spinal cord
- circulated in the arachnoid space, ventricles, and central canal of the spinal cord
- clear, colourless fluid in the brain and spinal cord
- produced by the choroid plexus of the ventricles
- absorbed into the dural sinuses via the arachnoid granulations
- similar in composition to plasma, but with LESS protein
- should NOT contain red blood cells
- protects the brain from trauma
- helps the brain float (so the weight of the brain doesn’t cut blood supply to neurons in the lower part of the brain)
43
Q
What is the Cerebrospinal fluid circulation?
A
- CSF is produced by the choroid plexus of each ventricle
- CSF flows through the ventricles and into the subarachnoid space via the median and later apertures. Some CSF flows through the central canal of the spinal cord
- CSF flows through the subarachnoid space
- CSF is absorbed into the dural venous sinuses via the arachnoid villi
44
Q
What is the blood-brain barrier?
A
- includes the least permeable capillaries of the body
- capillaries allow water, glucose, and amino acids to pass through the capillary walls
- excludes many potentially harmful substances from entering the brain (wastes, urea, toxins, drugs)
- useless as a barrier against some substances
- does not keep out respiratory gases and lipid-soluble molecules (alcohol, nicotine, and anesthetics)
- neuroglial cells called “astrocytes” contribute to the barrier
45
Q
Anatomy of the Spinal cord?
A
- extends from the foramen magnum of the skull to the first or second lumbar vertebra
- 3 layers of meninges end farther down
- **meninges don’t end where the spinal cord ends
- “cauda equina” => a collection of spinal nerves at the inferior end of the vertebral canal
- provides a two-way conduction pathway to and from the brain
- 31 PAIRS of spinal nerves arise from the spinal cord (part of PNS)
- **spinal nerves are NOT part of the CNS
46
Q
What is the Gray matter of the spinal cord and spinal roots?
A
- internal gray matter is mostly cell bodies
- dorsal (posterior) horns house interneurons
- —- receive information from sensory neurons in the dorsal root; cell bodies housed in dorsal root ganglion
- anterior (ventral) horns house motor neurons of the somatic (voluntary) nervous system
- —- send information out ventral root
- gray matter surrounds the central canal, which is filled with cerebrospinal fluid
- organized in HORNS
47
Q
What is the white matter of the spinal cord?
A
- organized in COLUMNS
- composed of myelinated fiber tracts
- three regions: dorsal, lateral, ventral columns
- sensory (afferent) tracts conduct impulses toward the brain
- motor (efferent) tracts carry impulses from brain to skeletal muscles
48
Q
What does R.A.S. stand for?
A
Reticular
Activating
System
49
Q
What is the R.A.S.?
A
- a group of neurons within the reticular formation
- have a role in consciousness and the sleep/wake cycle
- filter sensory input coming from the spinal cord
50
Q
Where is the R.A.S?
A
in the brain stem
51
Q
What are meninges?
A
connective tissue membrane
52
Q
Functions of the spinal cord
A
- reflex centre
- two-way conduction pathway to and from the brain
