Organization And Major Fxn Of Ns

Front 1

Overall function of the Nervous System

Back 1

Receive sensory input, intergration of sensory info & motor responses, control muscles and glands, maintain homeostasis, and perform higher fxns (ex. attention, comprehension, problem solving, memory and emotion).

Front 2

CNS

Back 2

Brain (cerebral hemispheres, diencephalon, cerebellum & brainstem) and spinal cord. Important for analysis and integration of sensory and motor info, other "high fxns" such as emotion, memory, reasoning, etc.

Front 3

PNS

Back 3

Cranial nerves and spinal nerves, both include sensory and motor (somatic and autonomic) nerves.

Front 4

The Baroreceptor reflex

Back 4

An example of sensory-motor integration. Nerve endings in the great vessels that monitor BP send info to the brainstem where it is analyzed and an appropriate response motor response is initiated. If BP is too low, the autonomic motor response from the CV center in the brainstem will be to increase sympathetic activity to the CV system.

Front 5

Major structures of the CNS

Back 5

Spinal cord
Brainstem (medulla, pons, and midbrain)
Cerebellum
Diencephalon (hypothalamus and thalamus)
Cerebrum (frontal, parietal, temporal, occipital lobes)

Front 6

Spinal cord

Back 6

31 pairs of nerves enter and exit at various levels
Motor neurons exit through ventral
Sensory neurons exit through dorsal
Gray matter forms the horns, white matter forms around the horns.

Front 7

Gray matter

Back 7

Where neural and glial cell bodies are located, clusters of cell bodies make the darker color

Front 8

White matter

Back 8

Made up of axonal tracts (white b/c of myelination)

Front 9

Brainstem

Back 9

3 divisions: midbrain, pons, medulla
10 of 12 CNs arise from the brainstem [other 2 arise in nasal epithelium (CNI) and the retina (CNII)]

Front 10

Medulla

Back 10

Cardiovascular and respiratory centers, reflexes (coughing, vomiting, swallowing)

Front 11

Pons

Back 11

Balance and posture (vestibular centers), respiratory center, relays nerves b/t cerebrum and cerebellum

Front 12

Midbrain

Back 12

Controlling eye movements, nuclei for relaying visual and auditory info

Front 13

Cerebellum

Back 13

Foliated hemispheres attached to dorsal surface of the brainstem. Responsible for motor fxns like coordination (including head and eye), planning and execution, and posture. Also sensory discrimination b/t objects of different textures.

Front 14

Inputs into the cerebellum

Back 14

Proprioception from spine (orientation of body parts), motor info from cerebral cortex, and vestibular info from inner ear.

Front 15

Diencephalon

Back 15

Made up of the hypothalamus and thalamus, b/t the cerebrum and the brainstem

Front 16

Thalamus

Back 16

Sensory and motor relay to and from cerebrum

Front 17

Hypothalamus

Back 17

Endocrine fxn and homeostatic control (body temp, food intake, and water balance)

Front 18

Cerebrum

Back 18

R & L hemispheres w/connecting commissures. Gray matter in the cortex and nuclei, white matter in the underlying axonal tracts and commissures.

Front 19

Cerebrum fxns

Back 19

Perception, higher motor fxns (fingers and hands), cognition, memory, language and emotion
4 lobes: frontal, parietal, temporal and occipital

Front 20

Frontal lobes

Back 20

Motivation, mood, aggression, controlling voluntary motor fxns

Front 21

Parietal lobes

Back 21

Sensory perception (touch and taste sensation), somatosensory

Front 22

Temporal lobes

Back 22

Perception of auditory and olfactory info, memory storage, recognition, comprehension

Front 23

Occipital lobes

Back 23

Processing visual info

Front 24

Primary cortices

Back 24

Direct processing, fewer synapses, direct perception

Front 25

Association cortices

Back 25

Complex processing, numerous synapses, integration (unimodal and multimodal) for purposeful actions

Front 26

Deep nuclei of the cerebrum

Back 26

Clusters of neural cell bodies (gray matter)
Basal ganglia, hippocampus, amygdala

Front 27

Basal ganglia

Back 27

Regulates motor fxn, input from all cerebral lobes, projects to the frontal cortex via thalamus

Front 28

Hippocampus

Back 28

In the temporal lobe, responsible for memory consolidation

Front 29

Amygdala

Back 29

In the temporal lobe, responsible for emotional processing, projects to the hypothalamus, influences autonomic fxns (controlling body responses to emotions, ex. Fear --> increased HR)

Front 30

Cerebrospinal fluid

Back 30

Functions to cushion and remove debris. ~150ml/day.
Flows from choroid plexus into ventricles and subarachnoid spaces. Emptied into venous blood at the sagittal sinus via arachnoid granulations.

Front 31

Where do you get a sample of CSF?

Back 31

From the subarachnoid space in the lumbar cistern

Front 32

How is CSF recycled?

Back 32

The endothelial cells of the arachnoid villi contain vesicular passages directly through the cells that allows the CSF to flow freely into the blood.

Front 33

How is CSF produced?

Back 33

~500 ml/day. 2/3rds by the choroid plexus, 1/3 by the ependymal surfaces lining ventricles and arachnoid membrane. Secretion is driven by Na movement across epithelium, followed by osmosis, proteins excluded.

Front 34

Choroid plexus

Back 34

Cauliflower like growth of blood vessels covered by a single epithelial layer, found in lateral 3rd and 4th ventricles.

Front 35

CSF production/drainage balance

Back 35

Volume produced must match volume drained into venous blood, otherwise pressure will build up.

Front 36

Hydrocephalus

Back 36

May be caused by blockage of flow in ventricles, subarachnoid space, or across arachnoid villi. Causes the ventricles to swell and compress brain tissue. Very dangerous!

Front 37

Composition of CSF

Back 37

Resembles interstitial fluid. Has about same amount of Na, Cl, HCO3, osmolarity. Low in protein and cholesterol, b/c they're too large to pass through epithelial surfaces at the site where the CSF is being produced.

Front 38

Blood-brain barrier

Back 38

Very tight barrier, brain cells are sensitive to composition of interstitial fluid surrounding them and toxins, cannot be allowed to cross the walls of the capillaries.

Front 39

What forms the BBB?

Back 39

Tight junctions of endothelial cells and astrocyte foot processes.

Front 40

What can cross the BBB?

Back 40

Only lipid-soluble substances diffuse across freely. Hydrophilic substances must have specific transporters in endothelial cell membrane of capillary wall and astrocytes to get through.

Front 41

Leakiness of BBB

Back 41

May result from infection, inflammation, and tumors. Toxins may be able to leak out into the brain tissue

Front 42

Drugs and the BBB

Back 42

Many drugs are specifically designed to be hydrophilic so that they will NOT pass into the brain through the BBB. Ex, older antihistamines were slightly lipophilic and would get into the brain tissue and cause drowsiness, new antihistamines are made hydrophilic.