A and P 2- chapter 12-2

what is the limbic system

large part of emotional or affective brain

what are the 2 sub parts if the limbic system

amygdalae

cingulate gyrus

what is amygdalae do

recognizes angry or fearful facial expressions, assesses

danger, and elicits fear response

what does cingulate gyrus do

plays role in expressing emotions via gestures and

resolves mental conflict

limbic system- interacts with prefrontal lobes- what does this mean

Allows us to react emotionally to things we consciously understand to

be happening

– Makes us consciously aware of emotional richness in our lives

– Limbic system puts emotional responses to odors

– Most output relayed via hypothalamus

what play a role in memory

hippocampus and amygdalae

what does reticular formation do

Extends through central core of brain stem

what does the reticular activating system (RAS) do

Sends impulses to cerebral cortex to keep it conscious and alert

– Filters out repetitive, familiar, or weak stimuli (~99% of all stimuli is not

relayed to consciousness)

– Inhibited by sleep centers, alcohol, drugs

– Severe injury can result in permanent unconsciousness (coma)

what does the Reticular autonomic centers regulate

visceral motor function

what are the 3 centers that reticular autonomic centers regulate

Vasomotor centers

– Cardiac center

– Respiratory center

what are the meninges functions

Cover and protect CNS

– Protect blood vessels and enclose venous sinuses

– Contain cerebrospinal fluid (CSF)

– Form partitions in sku

what are the 3 layers of the meninges from external to internal

dura mater

2. arachnoid mater

3. pia mater

what is the dura mater

tough mother

Strongest meninx (singular)

– Made up of two layers of fibrous connective tissue

what is the arachnoid matter

spider mother

Middle layer with spiderweb-like extensions

– Subarachnoid space contains CSF and largest blood

vessels of brain

what is the pia mater

tender mother

Delicate connective tissue that clings tightly to brain,

following every convolution

§ Contains many tiny blood vessels that feed brain

what is meningitis

inflammation of the meninges

May spread to CNS, which would lead to inflammation of

the brain, referred to as encephalitis

• Meningitis is usually diagnosed by observing microbes in a

sample of CSF obtained via lumbar puncture

what does cerebrospinal fluid do

csf

forms a liquid cushion of constant volume around brain

Composed of watery solution formed from blood plasma,

but with less protein and different ion concentrations from

plasma

what are the functions of csf

Gives buoyancy to CNS structures

§ Reduces weight of brain by 97% by floating it so it is

not crushed under its own weight

– Protects CNS from blows and other trauma

– Nourishes brain and carries chemical signals

what is the choroid plexus

cluster of capillaries that hangs from roof of each ventricle, enclosed by pia mater and surrounding layer of ependymal cells

– Ependymal cells help cleanse CSF by removing wastes

– Cilia of ependymal cells help to keep CSF in motion

• Normal adult CSF volume of

~150 ml is replaced every 8 hours

what is hydrocephalus and what does it look like and what is treatment

obstruction blocks CSF circulation or drainage, resulting in increased pressure

In newborns, skull bones are unfused, so increased pressure causes head to enlarge

• In adults, rigidity of the skull keeps pressure within, potentially leading to brain damage

– Can compress blood vessels and crush soft nervous tissue

• Treatment is to drain CSF with ventricular shunt to abdominal cavity

what are the blood vessels supplying the brain

Common Carotid Arteries (Rt and L)

• Vertebral Arteries

• All others branch from these vessels

• These vessels come together to form the Circle of Willis

what does the blood brain barrier do

Helps maintain stable environment for brain

– Chemical variations could lead to uncontrollable neuron firings

– Substances from blood must first past through continuous

endothelium of capillary walls before gaining entry into neurons

– Feet of astrocytes and smooth muscle-like pericytes surround

endothelial cells

what substances can pass through the bbb

Water (diffusion)

– Certain gases [O2, CO2] (diffusion)

– Glucose (transported)

– Lipid soluble substances

– Some drugs (alcohol, nicotine, caffeine, etc.)

what are the 6 brain injuries

concussion

contusion

stroke

aphasia

epilepsy

cerebral palsy

what is a concussion

temporary alteration in function

what is a contusion

permanent damage

what is a stroke

ischemia- tissue deprived of blood supply, leading to death of brain tissue

can be caused by blockage of cerebral artery by blood clot

what is aphasia

inability to speak, write, or communicate language.

• Occurs after head injury, stroke, or tumor

what is epilepsy

abnormal brain activity causing seizure, unusual

sensation or behavior.

§ Causes are many: genetics, trauma, infection

what is cerebral palsy

disorder affecting movement and muscle

tone.

§ Caused by damage to the developing (prenatal) brain

where is the spinal cord located

Enclosed in the vertebral column

– Begins at the foramen magnum

– Ends at L1 or L2 vertebra

what are the functions of the spinal cord

Provides two-way communication to and from brain

and body

– Major reflex center: reflexes are initiated and completed at spinal cord

what protects the spinal cord

Protected by bone, meninges, and CSF

what is the epidural space

Cushion of fat and network of veins in space between

vertebrae and spinal dura mater

CSF fills subarachnoid space between arachnoid and pia

maters

– Site of lumbar puncture or tap

what are spinal nerves apart of and where do they attach

Part of PNS (peripheral nervous system)

– Attach to spinal cord by 31 paired roots

– Each spinal cord segment is designated by paired spinal

nerves that arise from it

what is the cauda equina

Collection of nerve roots at inferior end of vertebral canal

where is gray matter located in the spinal cord

located in the core

where is white matter located in the spinal cord

found outside

where is the central canal located in the spinal cord

runs length of cord. It is filled with CSF

what is gray matter and spinal roots of the spinal cord cross section

cross section of cord resembles the letter H

3 areas of gray matter are found on each side of centers and are mirror images

what are dorsal horns in spinal cord cross section

interneurons that receive somatic and visceral sensory input

what are visceral horns in spinal cord cross section

some interneurons; somatic MOTOR

neurons

what are lateral horns in spinal cord cross section

(only in thoracic and superior lumbar

regions): sympathetic neurons

what is gray commissure

bridge of gray matter that

connects masses of gray matter on either side

§ Encloses central canal

what are ventral roots

bundle of motor neuron axons that

exit the spinal cord

what are dorsal roots

sensory input to cord

what are dorsal root ganglia (DRG)

cell bodies of sensory neurons

what are spinal nerves

formed by fusion of dorsal and ventral roots

what is white matter in spinal cord cross section

Myelinated and nonmyelinated nerve fibers allow

communication between parts of spinal cord, and spinal

cord and brain

what are the 3 directions that white matter runs in and describe them

Ascending: up to higher centers (sensory inputs)

Descending: from brain to cord or lower cord levels

(motor outputs)

Transverse: from one side to other (commissural fibers)

what is a localized injury in the spinal cord

injury to spinal cord or its roots leads to functional

losses

what is paresthesias

caused by damage to dorsal roots or sensory

tracts. Leads to sensory function loss

what is paralysis

caused by damage to ventral roots or ventral horn cells

– Leads to motor function loss

what is transection in the spinal cord

(cross sectioning) of spinal cord at any level

results in total motor and sensory loss in regions inferior to cut

what transection is paraplegia in

transection between T1 and L1

what transection is quadriplegia in

transection in cervical region

what is poliomyelitis

Destruction of ventral horn motor neurons by poliovirus

– Muscles atrophy

– Death may occur from paralysis of respiratory muscles or cardiac arrest

– Survivors often develop postpolio syndrome many years later from neuron loss

what is amyotrophic lateral sclerosis (ALS)

Also called Lou Gehrig’s disease

– Destruction of ventral horn motor neurons and fibers of pyramidal tract

– Symptoms: loss of ability to speak, swallow, and breathe

– Death typically occurs within 5 years

– Caused by environmental factors and genetic mutations involving RNA processing