N340: neurological pt. 1 - patho Exam 3

Nervous system

specialized cells receive stimuli and coordinates responses.

What are Neurons?

Functional units, generate & transmit impulses.

Can neurons divide?

No, once gone it’s gone

What are Neuroglial cells?

Support cells that protect neurons, provide scaffolding, and assist with repair.

Neuron regeneration in CNS

Severed axons in brain and spinal cord canNOT regenerate.

Neurons in hippocampus and olfactory bulb

can regenerate.

Example of regenerated neurons

losing & gaining sense of smell after COVID

Neuron regeneration in PNS

regenerate to some extent after injury

What are Dendrites?

Receptive portion of neuron

Location of Cell body (soma)

in CNS (brain & shwann’s cell)

Axon function

Carries nerve impulses away from cell body.

Myelin sheath

Lipid insulating layer that speeds up nerve conduction

Nodes of Ranvier

Gaps in myelin sheath allowing rapid impulse conduction.

What are Axon terminals?

End of axon where neurotransmitters are released.

Axon terminals are where

action potential begin & drugs act

White matter mainly composed of

myelinated axons and glial cells

“Cable” in a network

white matter

Gray matter

neuron cell bodies

Gray matter oxygen use

95% of brain’s O2 supply.

“Computers” in network

gray matter

Nerve impulse are

Electrical and chemical signals conducted by neurons.

All-or-none response

Neuron fires fully or not at all when stimulated.

Axons

send signals

Dendrites and cell body

Receive signals.

Neurotransmitter interact with postsynaptic membrane by bind to

receptor

Synaptic transmission

Process of neuron communication across a synapse.

Step 1 synaptic transmission

Impulse travels down the axon.

Step 2 synaptic transmission

Neurotransmitter released from axon terminal.

Step 3 synaptic transmission

Neurotransmitter binds receptors on postsynaptic cell.

What are 3 Synaptic effects?

muscle contract/relax, gland secretion, neuron firing changes.

Neurotransmitter termination after synapse

destroyed, reabsorbed, or diffusion

Brain metabolic needs

constant oxygen and glucose supply.

Hypoxia symptoms

Confusion, lethargy, or combativeness due to low oxygen.

Hypoglycemia symptoms

Neurologic symptoms from low glucose.

Brain blood supply

Receives 1/6 of resting cardiac output.

Carbon dioxide effect

cerebral vasodilation.

Internal carotid arteries

Major arteries supplying blood to the brain.

Middle cerebral artery blockage impair

face movement, upper limb function, communication.

What can Circle of Willis provide?

blood circulation if a main vessel is blocked

Functions of Frontal lobe

voluntary motor activity and personality.

Functions of Parietal lobe

sensory except smell, hearing, and vision.

Functions of Occipital lobe

vision.

Functions of Temporal lobe

hearing and memory.

Ways to increase intercranial pressure (ICP)

• ↑ blood volume

• ↑ cerebrospinal fluid (CSF)

• ↑ brain volume

Brain inflammation is caused by

infection

Meningitis

Inflammation of the meninges (protective membrane surround brain & SC)

Encephalitis

Inflammation of brain tissue.

Myelitis

Inflammation of the spinal cord.

Encephalomyelitis

Inflammation of brain and spinal cord.

Acute purulent meningitis

bacterial meningitis; more life threatening

Acute lymphocytic meningitis

viral meningitis.

Risk factors for bacterial meningitis

environment (close proximity), age, immunocompromise (immature or over-react)

Meningitis symptoms

Fever, headache, neck stiffness, n/v, back/abd/extremity pain.

What is Nuchal rigidity?

Neck stiffness associated with meningitis.

Severe meningitis signs

Seizures, cranial nerve palsies, delirium, rash, coma.

Viral meningitis symptoms

more mild

Meningitis diagnosis

Lumbar puncture to analyze CSF

Bacterial meningitis CSF findings

High neutrophils (1st line defense), high protein, low glucose.

Viral meningitis CSF findings

High lymphocytes (specific), mildly high protein, normal glucose.

Bacterial meningitis treatment

Broad-spectrum antibiotics.

Viral meningitis treatment

Supportive care.

HSV (herpes simplex virus) meningitis treatment

IV acyclovir.

Stroke (CVA)

Interruption of brain blood supply leading to neurologic damage.

2 types of Stroke

Ischemic stroke and hemorrhagic stroke.

Stroke urgency

time-dependent

Modifiable stroke risk factors

HTN, smoking, diabetes, hyperlipidemia, obesity, alcohol/cocaine use.

AKA. cardiac-related factors

Nonmodifiable stroke risk factors

Age (pre-term), gender (male), race (black), heredity.

Ischemic stroke is caused by

blood clot blocks blood flow = dead brain tissue

Hemorrhagic stroke is caused by

blood vessel bursts = hemorrhage

Thrombotic stroke is

Ischemic stroke caused by clot in atherosclerotic vessel; most common

Cardiogenic embolic stroke

Ischemic stroke caused by traveling clot.

What is Penumbra ?

Area of ischemic but potentially salvageable brain tissue.

Ischemic stroke symptoms

Aphasia, neglect, visual field deficits.

Cardiogenic embolic stroke causes

A-Fib or endocarditis.

Ischemic stroke diagnosis

CT scan to rule out hemorrhage.

CTA/MRA

Imaging dye to identify vessel blockages.

What is TPA?

Clot-buster IV used in ischemic stroke.

What is precaution for TPA?

risk of severe bleeding

What is Transient ischemic attack (TIA)?

Temporary neurological dysfunction without brain infarction.

TIA duration

few minutes - 24 hours.

TIA is warning sign of

possible future stroke.

Hemorrhagic stroke is caused by

ruptured cerebral blood vessel.

Common causes for Hemorrhagic stroke

age and HTN

Hemorrhagic stroke pathophysiology

Bleeding → hematoma → edema → increased ICP.

How do drugs cause hemorrhagic stroke?

increased risk of bleeding

Hemorrhagic stroke symptoms

Headache, projectile vomiting, neurological deficits.

Basal ganglia hemorrhage can cause

contralateral hemiplegia.

What is contralateral hemiplegia?

paralysis of one side of body that is opposite to the side of brain lesion

Hemorrhagic stroke treatment

Clotting support, blood pressure control, surgery if needed.

How does Vitamin K therapy help?

restore clotting in hemorrhagic stroke.

What does Prothrombin complex help with?

support clotting in bleeding disorders.

What are Brain tumors ?

Abnormal cell growth in or around the brain.

Primary brain tumors

Originate in skull cavity, not brain tissue.

Metastatic brain tumors

Spread from cancers elsewhere in body.

What are Astrocytomas?

Most common primary brain tumors (~80%).

What are Oligodendrogliomas?

Brain tumors prone to spontaneous hemorrhage.

What are Ependymomas?

Tumors from ventricular or spinal canal epithelium.

What are Meningiomas?

Tumors arising from meninges.

What cause symptoms for brain tumors?

brain compression, tumor infiltration, disturbances in blood flow, edema, increased ICP

Brain tumor symptoms

Headache, n/v, seizures, mental changes.