Ch 26 Nervous System Infections Flashcards
What does the Cerebrum control?
Voluntary Muscles
Perception
Thinking
Speech
What does the Cerebellum control?
Involuntary body movements
What does the brain stem control?
Breathing, heart rate, BP
What does the spinal cord extend from? Where does it go to?
It extends from the brain stem to the lumbar region
The nerves that transfer commands from the CNS to the muscles and glands make this up =
The Peripheral Nervous System
The cranial nerves and spinal nerves both are a part of the-
Peripheral Nervous System
These nerves carry signals toward the CNS =
Sensory Nerves
These nerves carry signals away from the CNS =
Motor Nerves
These nerves carry signals away and towards the CNS =
Mixed Nerves
This cell of the nervous system provides support, insulation, & nutrients. They also phagocytize microbes =
Neuroglia
These cells of the nervous system carry nerve impulses + lie in a region called the cell body =
Neurons
This is a collection of many neurons’ cell bodies =
Ganglion
These are chemical signals between cells and they may be either stimulatory or inhibitory =
Neurotransmitters
What are the 3 layers of the Meninges?
The Dura Mater
The Arachnoid Mater
The Pia Mater
The outer most layer of the meninges, protects bones from spreading infections =
Dura Mater
The layer of the meninges that contains numerous branchlike fibers creating the subarachnoid space =
Arachnoid Space
The inner most layer of the meninges, the blood vessels on top of this layer supply the CNS with blood =
Pia Mater
The walls of the blood vessels on top of the CNS are composed of tightly joined cells that form the-
Blood-Brain Barrier
What is the function of the Blood-Brain Barrier?
To prevent pathogens + large molecules in the blood from entering the subarachnoid space
Do blood infections easily spread to the CNS?
No
Are CNS infections very easy to treat?
No, because Antimicrobials don’t easily spread to the CNS
The fluid that leaks from the blood to the subarachnoid space is called the-
Cerebrospinal Fluid (CSF)
What does the CSF do?
It circulates throughout the brain + spinal cord to act as a shock absorber, removes wastes
Provides nutrients, electrolytes & oxygen to nervous tissues
How does one sample Cerebrospinal Fluid?
By performing a Lumbar Puncture
If you do a lumbar puncture, what does it mean if the CSF looks cloudy?
There’s likely an infection
How can pathogens access the CNS?
Breaks in the bones & meninges
Medical procedures
Travel in peripheral neurons to the CNS
Infect + kill cells of the meninges, causing meningitis
Inflammation can alter the permeability of the blood-brain barrier
How can bacteria cause disease?
Infecting cells of the nervous system (Meningitis)
Bacteria growing elsewhere release toxins that affect neurons (Botulism / Tetanus)
What are the signs and symptoms of Bacterial Meningitis?
Sudden high fever, severe meningeal inflammation, and increased white blood cells in the CSF
Encephalitis
Systemic Inflammation
Infection of the brain =
Encephalitis
What are the manifestations of Encephalitis?
Behavioral Changes
Coma
Death
What are the manifestations of Systemic Inflammation?
Hemorrhaging and reddish/purplish lesions on the skin, shock, convulsions, coma and death can occur in a span of just a few hours
What type of bacteria causes Meningococcal Meningitis?
Neisseria meningitidis
What five species of bacteria cause 90% of bacterial meningitis?
Neisseria meningitidis
Streptococcus pneumoniae
Haemophilus influenzae
Listeria monocytogenes
Streptococcus agalactiae
How does Meningococcal Meningitis work?
A release of endotoxin and other factors causes an immune response that produces the characteristic rash. The inflammation that results causes blood to leak out of the blood vessels and into the tissue.
This blood leakage/hemorrhaging also occurs in the brain and elsewhere in the body leading to sepsis, rapid organ failure, and death
How does Meningococcal Meningitis spread?
Can infection people of any age.
(Most at risk = Infants, Young Children, Young Adults).
N. meningitidis can spread via respiratory droplets when there is prolonged contact with a carrier.
N. meningitidis is one of the most common causes of bacterial Meningitis.
Meningococcal meningitis can become an-
Epidemic
Military barracks & College Dorms are both at risk for-
Meningococcal Meningitis
How is bacterial meningitis diagnosed?
Based on signs and symptoms + Culturing of bacteria from CSF
With meningococcal meningitis, a characteristic rash often occurs and can be indicative of infection with N. meningitidis
How is bacterial meningitis treated?
IV Antimicrobial Drugs
How is bacterial meningitis prevented?
There are vaccines available for N. meningitidis, usually only recommended for high risk groups
Even with the use of antibiotic treatment, what percentage of people usually end up dying?
What percentage usually end up with long term disabilities?
~10% die
~20% suffer longer term disabilities
What long term disabilities can bacterial meningitis cause?
Deafness, Brain Damage, Loss of Limbs (Due to Tissue Necrosis)
What does the bacteria called Listeria monocytogenes cause?
Listeriosis
How does Listeria enter the body?
Enters the body in contaminated food or drink that are usually contaminated with soil or animal manure
What foods can carry Listeria?
Fresh fruits and vegetables, frozen vegetables, processed meats, soft cheeses, and raw milk
Can Listeria grow in low temperatures?
Listeria can grow at low temperatures and can therefore grow in refrigerated foods
How does Listeriosis work?
Infection usually begins in the GI tract producing classic food poisoning-like symptoms such as diarrhea and fever, but Listeria has virulence factors that allow it to cross into other body systems and eventually the brain and CSF
Listeriosis is rarely pathogenic in-
Healthy adults
This can cause spontaneous abortion in pregnant women because it can cross the placenta =
Meningitis
Listeriosis causes Meningitis in what percentage of cases?
~20%
These are surface proteins that help Listeria attach to and enter host cell cytoplasm =
Internalins
Production of this protects Listeria from phagocytic digestion =
Listeriolysin O