Nervous System & Eye Infections

Question 1

what is the nervous system composed of and what is it divided in

Answer 1

brain, spinal cord and nerves

• divided into Central Nervous System (CNS) & Peripheral Nervous System (PNS)

Question 2

what does the CNS consist of?

Answer 2

Brain and spinal cord

Question 3

what does the PNS consist of and what is its function

Answer 3

network of nerves that connect the rest of the body to the CNS

• Function: responsible for communicating between CNS and the rest of the body by collecting info from sensory neurons (Sensory Organs) and motor neurons ( muscles and glands)

Question 4

what is the function of the nervous system?

Answer 4

to coordinate and send signals from one cell to another and from one body part to another

Question 5

what are the names of the layers that make of the meninges? what is the meninges?

Answer 5

• Dura mater, archnoid mater, pia mater
• the meninges are the layers of tissue that surround the brain

Question 7

the PNS can be further divided into other systems, what are they?

Answer 7

Somatic Nervous System (SNS)

Automatic Nervous System (ANS)

Question 8

what is the

Question 9

what is the function of the Somatic Nervous System (SNS)

Answer 9

part of the PNS

Function: transmits impulses from receptors to CNS and from CNS to skeletal muscles

Question 10

the automatic system can be divided into further categories, what are they?

Answer 10

Sympathetic system: spinal nerve only

Parasympathetic system: spinal and cranial nerves

Question 11

what does the sympathetic system consist of and what does it control?

Answer 11

part of the Autonomic nervous system, it controls the “rest and digest” and contains only spinal nerves

Controls:

• constrict pupils
• stimulate saliva
• slow heartbeat
• constrict airways
• stimulate activity of stomach
• inhibit release of glucose; stimulate gallbladder
• stimulate activity of intestine
• contract bladder
• promote erection of genitals

Question 12

what does the sympathetic system control

Answer 12

part of the automatic nervous system. consist of spinal nervous only

Controls: fight or flight

• dilate pupils
• inhibit salivation
• increase heartbeat
• releax airways
• inhibit activity of stomach
• stimulate release of glucose’inhibit gallbladder
• inhibit activity of intestines
• secrete epinephrine and norepinephrine
• relax bladder
• promote ejaculation and vagina contractions

Question 13

what are the functions of the meninges?

Answer 13

• protect the brain and spinal cord from mechanical trauma
• support blood vessels
• form continuous cavity in which cerebral spinal fluid (CSF) passes

Question 14

describe the spinal cord pathway

Answer 14

the cerebrum sends an impulse down the spinal cord. the impulse is then directed by an interneuron which directs signal to motor neuron that connects to muscles in the arm. motor neuron carries impulse to receptors in arm muscle and when the receptors are stimulated by impulse the arm moves

cerebrum sends impulse⇒interneuron⇒motor neuron⇒receptors⇒effector

Question 15

what are the types of cells in the nervous system?

Answer 15

Neurons

Neuroglia (supportive cells)

Question 16

what is the function of a neuron and what are its different parts?

Answer 16

Function: cells the receive and transmit information in the nervous system

Parts:

• Dendrites: branch extension from body, they receive signals from other neurons
• Soma: body, life support center
• Axon: covered in myelin sheath, sends message away from cell body to other neurons
• Terminal branches of axon: branched ending of axon, forms junctions with other neurons

Question 17

Glial Cell

Answer 17

hold neurons in place, provide nutrition, remove waste products and prevent harmful substances from passing the blood-brain barrier

Question 18

neurotransmitters

Answer 18

made by the brain and consumer artificially through Rx

can be Excitatory (increase neuron firing) or inhibitory (decrease neuron firing)

Question 19

how do nuerons communcate

Answer 19

signal is sent from one neuron to the next

Question 20

Acetylcholine (ACh)

Answer 20

A neurotransmitter

Function: enables muscle action, learning and memory

Question 21

Dopamine

Answer 21

a nuerotransmitter

influences movement, learning, attention, and emotion

Question 22

Serotonin

Answer 22

A neurotransmitter

affects mood, hunger, sleep and arousal

Question 23

Norepinephrine

Answer 23

A neurotransmitter

helps control alertness and arousal

Question 25

GABA (gamma-aminobutyric acid)

Answer 25

a neurotransmitter major inhibitory neurotransmitter

Question 26

Glutamate

Answer 26

a neurotransmitter a major excitatory neurotransmitter that is also involved in memory

Question 27

what does the blood-brain barrier consist of?

Answer 27

tightly joined endothelial cells that are surrounded by glial processes

Question 28

what does the brain- CSF barrier consist of?

Answer 28

at choroid plexus consists of endothelium w/fenestration and tightly joined choroid plexus epithelial cells

Question 29

How can microbes cross the blood-brain barrier and the blood-CSF barrier?

Answer 29

* growing across which infect cells that make those barriers * being passively transported across via intracellular vacuoles * being carried across by infected WBC

Question 30

what are the portals of infection of the CNS? (4)

Answer 30

* **intracellular (paracellular):** use of microbial virulence factors, toxins, or inflammation-mediated process to pass between the cells of blood-brain barrier * **transcellular**: passage through cells of blood-brain barrier using virulence factors that allow it to adhere and trigger uptake by vacuole or receptor-mediated methods * **leukocyte facilitated:** trojan horse, pathogen infects peripheral blood leukocytes to directly enter CNS * **nonhematogenous entry:** allows pathogen to enter brain w/o encountering the blood-brain barrier. this is accomplished when pathogen travels along the olfactory or trigeminal cranial nerve that lead directly to CNS

Question 31

how does the body respond to the invasion of the blood-brain barrier?

Answer 31

* increase in CSF cell count * response to invading viruses cause increase in lymphocytes (T cells and monocytes in CSF) * slight increase in protein * when CSF clear= **aseptic meningitis** * response to pyogenic bacteria causes rapid increase in polymorphonuclear leukocytes and proteins * CSF turbid= **septic meningitis** *

Question 32

define **bacterial meningitis** and how access is gained to CNS

Answer 32

inflammatory bacterial infection of the meninges (mostly pia mater & arachnoid mater) Access gained to CNS: via bloodstream after trauma or result of bacterial toxins