Lecture 13: CNS Part 2 Flashcards Preview

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Flashcards in Lecture 13: CNS Part 2 Deck (27):
1

What are the 3 regions of the brain stem?

Midbrain, pons, medulla oblongata

2

Label diagram on slide 4

D it

3

Label diagram on slide 5

Do it

4

What is the location of the mid brain? What does in control?

Located between the diencephalon and the pons
Midbrain nuclei:
-control cranial nerves 3 and 4
Has superior colliculi- visual reflex
Inferior colliculi- auditory relay centres

5

Pons
Which cranial nerves sit on it?

Origin of cranial nerves
-5- trigeminal
-6 abducens
-7- facial
Nuclei help maintain normal rhythm of breathing

6

Medulla oblongata
What cranial nerves are associated with the medulla?
What are the autonomic reflex centres in it?

Cranial nerves 8, 9, 10, 12
Autonomic reflex centres:
Cardiovascular centre:
-adjusts force and rate of heart contraction
-adjusts blood pressure regulation
Respiratory centres:
-generates respiratory rhythm
-controls rate and depth of breathing
Additional centres regulate: vomiting, hiccuping, swallowing, coughing, sneezing

7

Cerebellum

Subconsciously provides precise timing and appropriate patterns of skeletal muscle contraction.
-two hemispheres connected by the vermis
-folia-transversely orientated gyri
-arbor vitae- distinctive treelike pattern of the cerebellar white matter

8

Describe the cerebellar processing for motor activity

Cerebellum receives impulses from the cerebral cortex of the intent to initiate voluntary contraction
-signals from the proprioceptors and visual and equilibrium pathways continuously "inform" the cerebellum of the bodies position and momentum
-cerebellar cortex calculates the best way to smoothly coordinate a muscle contraction

9

Limbic system

Emotional brain
Recognises angry or fearful facial expressions, assesses danger, and elicits the fear response
-we can react emotionally to things we consciously understand to be happening
Puts emotional responses to odours eg skunks smell bad
Plays a role in memory

10

Spinal cord
Location
Functions
Protection of cord

Location: starts at foramen magnum
-ends at conus medullaris at L1 vertebra in adults
Functions:
-provides two way communication to and from the brain
-contains spinal reflex centres
Protection of cord:
-bone, meninges, and cerebral spinal fluid (CSF)
-cushion of fat and network of veins in the epidural space between the vertebrae and spinal dura mater
-CSF in subarachnoid space

11

Spinal cord
Number of spinal nerves
Cervical and lumbar enlargements
What is the collection of nerve roots at the inferior end if the vertebral canal

There are 31 pairs of spinal nerves
Cervical and lumbar enlargements
-the nerves serving the upper and lower limbs emerge here
The cauda equina is the collection if nerve roots

12

Be able to label diagram on slide 22

Do it

13

The spinal cord and its meningeal coverings
Label diagram on slide 23

Do it

14

Name the three layers of protective covering of the spinal cord

Deepest
Is pia mater
Arachnoid mater
Spinal dura mater

15

Name the regions of the white matter in the spinal cord

Dorsal horns- afferent: receive somatic and visceral sensory input
Ventral horns- efferent: somatic motor neurons
Lateral horns- (mainly in thoracic region)
-part or sympathetic nervous system
Dorsal root (spinal) ganglia: contain cell bodies of sensory neurons

16

Heat does the white matter consist of in the spinal cord?

Consists of:
Ascending (sensory) tracts
Descending (motor) tracts
Tracts are located in white columns
Each spinal tract is composed if axons with similar functions

17

Ascending pathways: afferent

Via the thalamus
-then to the cortex
-transmits pain, temp, and coarse touch impulses
Directly to the cerebellum
-convey information about muscle if tendon stretch to the cerebellum

18

Descending pathways: efferent

Deliver efferent impulses from brain to spinal cord
-regulates fast and fine (skilled) movements
-axial muscles that maintain balance and posture
-muscles controlling coarse movement
-head neck and eye movements that follow objects.

19

Ventricles of the brain

Connected to one another and to the central canal of the spinal cord
Contain cerebrospinal fluid
-2 C-shaped lateral ventricles in the cerebral hemispheres
-3rd ventricle in the diencephalon
-4th ventricle in the hindbrain, dorsal to the pons, develops from the lumen of the neural tube
Cerebral aqueduct
-channel between third and 4th ventricle

20

Diencephalon

Thalamus: forms the lateral walls of the lateral ventricles
Hypothalamus: forms the inferolateral walls of the 3rd ventricle
-Infundibulum- stalk that connects to the pituitary gland
Epithalamus-forms the posterior wall of the 4th ventricle

21

What features house and protect the brain?

Bone (skull)
Membrane (meninges)
Watery cushion (cerebrospinal fluid)
Blood brain barrier

22

Role of the meninges. Name them all and their functions

Cover and protect the CNS
Contain cerebrospinal fluid (CSF)
Form partitions in the skull
3 layers:
Dura mater
Arachnoid mater
Pia mater

23

Dura mater

Strongest meninges
Has 2 layers of Fibrous connective tissue (around the brain) separate to form dural sinuses
Dural septa limit excessive movement of the brain

24

Arachnoid mater

-Middle layer with web like extensions
-Separated from the dura mater by the subdural space
-subarachnoid space contains CSF and blood vessels
-arachnoid villi protrude into the superior sagittal sinus and permit CSF reabsorption.

25

Pia mater

Layer of delicate vascularised connective tissue that clings tightly to the brain.

26

Cerebrospinal fluid (CSF)

Production of the choroid plexus
-produces CSF at a constant rate
-found in each ventricle
-clusters if capillaries are enclosed by pia mater and a layer of ependymal cells
Reabsorption via the arachnoid villi in dural sinuses
Composition
-watery solution
-constant volume
Functions:
-gives buoyancy to the CNS organs
-protects the CNS from blow and other trauma
-nourishes the brain

27

What is the function of the blood brain barrier. What's its composition

Helps maintain a stable environment for the brain
Separates neurons from some blood borne substances
Selective barrier:
-allows nutrients to move via facilitated diffusion
-allows any fat soluble substances to pass, including alcohol
Composition:
-continuous endothelium of capillary walls
-feet of astrocytes-most abundant CNS neuroganglia