Clinical Pathophysiology: Exam 3

neurons

specialized cells that transmit information through electrical and chemical signals. They are the building blocks of the nervous system and play a crucial role in processing and transmitting information

• Excitable cells that contribute to the highly specialized cell function of nerve impulse transmission throughout the body.

• Communicate with each other through synapses ( specialized junction between two nerve cells (neurons) or between a neuron and its target cell, such as a muscle or gland ) Two ways

• Enabling the transmission of information and the coordination of various physiological and behavioral functions in the body

• Has alot of help: Neuroglia, or glial cells, are non-neuronal cells that support, protect, and nourish neurons. Unlike neurons, they do not conduct nerve impulses but are essential for maintaining a healthy nervous system.

ion concentrations and fluids

must be in balance for optimal neural cell functioning.

sodium and potassium

These ions are essential for generating action potentials.

sodium-potassium pump

maintains the resting membrane potential by actively transporting Na⁺ out of the cell and K⁺ into the cell.

neuroglia (glial cells)

non-neuronal cells that support, protect, and nourish neurons. Unlike neurons, they do not conduct nerve impulses but are essential for maintaining a healthy nervous system.

sensory neurons (afferent neurons)

• Carry signals from sensory receptors (e.g., skin, eyes, ears) to the central nervous system (CNS).

• Detect stimuli such as temperature, pain, touch, and light.

motor neurons (efferent neurons)

• Transmit signals from the CNS to muscles and glands, causing movement or secretion.

• Two types:

  • Somatic – Control voluntary muscle movements.

  • Autonomic – Control involuntary functions (heart rate, digestion).

somatic motor neurons

Control voluntary muscle movements.

autonomic motor neurons

Control involuntary functions (heart rate, digestion).

interneurons (association neurons)

• Connect sensory and motor neurons within the CNS.

• Involved in reflexes, decision-making, and higher cognitive functions.

• Make up most of the neurons in the brain and spinal cord.

neurotransmission

• requires complex coordination between neural structures and the surrounding environment

• It involves electrical and chemical signals to transmit information across the nervous system

How does it work? 

Neurons communicate with other neurons and cells in the body by generating electrical signals called action potentials: This is the differences in electrical charge between the inside and outside the cell. This event travels across the entire neuron and allows neurons to communicate 

1. Resting membrane potential

2. Depolarization phase

3. Repolarization phase

resting potential (neuron at rest)

• The neuron maintains a negative charge due to the sodium-potassium pump actively moving Na⁺ out and K⁺ in.

• The inside of the neuron is more negative than the outside, preparing it for activation

depolarization

Result of rapid movement of sodium into the cell through sodium channels in the plasma membrane. This inflow generates an electrical impulse. This impulse is transmitted along the axon to trigger the release of neurotransmitters

repolarization

• After the peak of depolarization, the neuron needs to return to its resting state.

• Voltage-gated potassium (K⁺) channels open, allowing K⁺ ions to flow out of the cell.

• This restores the negative charge inside the neuron, ensures that the neuron can be ready for the next action potential.

electrical synapses

transmit impulses by passing current-carrying ions through small openings known as gap junctions.( protein channels that directly connect the cytoplasm of two neurons) .The transmission of electrical impulses through gap junctions is fast and direct. This mode of neurotransmission is multidirectional. Gap junctions are commonly involved in the transmission of electrical impulses that lead to cardiac contractions (fast and direct) 

chemical synapses

impulses stimulated by neurotransmitters, though the synaptic cleft (tiny gap between the sending and receiving neurons) Use neurotransmitters carry signals between neurons and other excitable cells, including other neurons and muscle cells, to trigger a response in another cell (slow and highly regulated) muscles and glands .Complex processing and memory

chromatolysis

The swelling of a neuron because of injury

atrophy

Decrease in neuron size

generated

• Unlike most other cells, new neurons are not _______ to replace those that have lost function through damage or death

• Myelin that has been damaged is not replaced, leading to permanent neurologic deficit

• The loss of neurons through cell damage or as a process of aging contributes to disability and is the basis for a variety of neurologic disorders.

80; ventricle; neurologic disorders; cataract

Developmental Considerations

• By the age of 2 years, the brain is _% of its adult size 

• May have alterations in the nervous system due to decreased numbers of neurons, altered structure: due to age 

• Enlargement in the size of the _______ system

• Decreased brain volume and weight

• Increase in the appearance of _________________, such as stroke, Alzheimer disease, and Parkinson disease

• Sensory changes, including _____ development, loss of focus, and diminished hearing, smell, and taste

central nervous system (brain and spinal cord)

Receives sensory information: 

• This gathers input from sensory organs (eyes, ears, skin, etc.) through peripheral nerves.

• It processes sensations like touch, pain, temperature, and balance

Processes and Interprets Information

• It handles cognition, memory, emotions, and learning.

Controls Movement and Reflexes

• This sends motor signals to muscles and glands to control voluntary movements (walking, writing) and involuntary actions (breathing, heartbeat).

• The spinal cord plays a major role in reflexes, allowing for quick, autonomic responses to stimuli (e.g., pulling your hand away from heat).

Coordinates Communication

• This connects with the peripheral nervous system (PNS) to relay messages between the brain, spinal cord, and the rest of the body.

spinal cord

The nervous tissue of this is composed of both white and gray matter, based on the presence or absence of myelin (It has a gray matter center (where nerve cell bodies are located) and white matter around it (made up of nerve fibers for communication).

• Parts:

  • Dorsal root brings sensory information into this.

  • Ventral root sends motor commands out of this to the muscles.

• Sensory Information:

  • This receives sensory information from various parts of the body (skin, muscles, joints) and sends it to the brain for processing.

• Motor Control:

  • This sends motor signals from the brain to muscles to control movements, whether voluntary (like walking) or involuntary (like breathing).

• Reflexes:

  • It can trigger automatic reactions (reflexes) that help the body respond to certain stimuli quickly without involving the brain.

dorsal root of the spinal cord

brings sensory information into the spinal cord.

ventral root of the spinal cord

sends motor commands out of the spinal cord to the muscles.

peripheral nervous system

• connects the CNS to limbs and organs, transmitting neural impulses via sensory pathways

• Located outside of the boundaries of the CNS, the peripheral nervous system is not protected by the blood-brain barrier or bony support of the CNS, increasing the potential for damage due to toxic substances and mechanical injury

• It’s job is to carry signals from the sensory organs (eyes, ears, skin) to the CNS, controls voluntary and involuntary movements. The cranial nerves and spinal nerves are part of this 

somatic nervous system (SNS)

Function: Controls voluntary movements and transmits sensory information from sensory organs (like skin, eyes, and ears) to the brain.

Components:

• Sensory (afferent) neurons: Carry sensory information from the body to the CNS.

• Motor (efferent) neurons: Carry motor commands from the CNS to the skeletal muscles.

Example: Moving your arm or leg, feeling something hot or cold, or seeing an object.

autonomic nervous system (ANS)

• Function: Controls involuntary functions, such as heart rate, digestion, respiration, and other functions of internal organs.

• Components:

  • Sympathetic Nervous System: Activates the "fight or flight" response, preparing the body for stressful situations (e.g., increases heart rate, dilates pupils, etc.).

  • Parasympathetic Nervous System: Controls the "rest and digest" functions, helping the body relax and conserve energy(

sympathetic nervous system

Activates the "fight or flight" response, preparing the body for stressful situations (e.g., increases heart rate, dilates pupils, etc.).

parasympathetic nervous system

Controls the "rest and digest" functions, helping the body relax and conserve energy

neurocirculatory system

• Interaction between the nervous system and circulatory system. Main vessels are carotid, vertebral and Circle of Willis (allows for blood flow, even if there is a blockage)

• Blood–Brain Barrier -It protects by reducing  permeability in capillaries that supply the brain, very selective of what comes in 

• Cerebrospinal Fluid- is a clear, colorless fluid that surrounds the brain and spinal cord system (CNS).  It helps to cushion and protect the CNS from physical trauma, reduces pressure, transports hormones to remote parts of the brain 

blood-brain barrier

It protects by reducing permeability in capillaries that supply the brain, very selective of what comes in 

cerebrospinal fluid

is a clear, colorless fluid that surrounds the brain and spinal cord system (CNS).  It helps to cushion and protect the CNS from physical trauma, reduces pressure, transports hormones to remote parts of the brain 

traumatic CNS injuries

• Traumatic Brain Injury 

• Traumatic Spinal Cord Injury

• Ischemic CNS Injury

• Excitation injury (Stroke, Seizures) 

• CNS Pressure Injury ( Increase ICP)

mechanisms of injury to the PNS

• Traumatic Peripheral Nerve Injury 

• Peripheral Nervous System Pressure Injury 

• Peripheral Nervous System Motor Dysfunction

• (Carpal Tunnel, Vascular injuries)

cerebral palsy (CP)

• Group of disorders resulting from damage to upper motor neurons before, during or after birth

• Signs are seen in the first few years of life

• Central control of movement by the brain is altered

• Cause is not fully known

• Motor dysfunction classifications( movement, posture and muscle tone)

• The timing and character of events during pregnancy and in labor may provide further evidence of cause of hypoxic–ischemic injury

Symptoms vary 

• Delay in milestones 

• Mild or severe disability 

• Limited fine motor 

• Lack of coordination and balance 

• Impaired cognitive function 

• Speech disorder 

• Seizures 

cerebral palsy criteria

• History & Physical 

• Neurologic exam 

• Motor skills 

• Evaluation of muscle tone

cerebral palsy treatment

• Supportive treatment 

• Pharmacologic 

• Assistance devices 

multiple sclerosis (MS)

• Chronic autoimmune disease that affects the central nervous system

• Pathophysiology is complex:

  • Immune system mistakenly attacks the myelin sheath

  • Immune cells, particularly T lymphocytes, infiltrate the CNS and trigger inflammation

  • The repeated cycles of inflammation and demyelination can lead to the formation of scar tissue or sclerosis

MS pathophysiology

• Immune system mistakenly attacks the myelin sheath

• Immune cells, particularly T lymphocytes, infiltrate the CNS and trigger inflammation

• The repeated cycles of inflammation and demyelination can lead to the formation of scar tissue or sclerosis

MS signs/symptoms

• Weakness

• Numbness

• Balance

• Blurred vision

• Dysphagia

• Memory, Abstract reasoning 

• Depression

MS diagnostics

• History and Physical 

• In depth neurology exam

• Imaging- CT head, MRI/MRA 

• Labs- LP and CSF analysis 

MS treatments

• No Cure 

• Pharmacological and nonpharmacological treatment

incomplete spinal cord transection (ISCT)

• Pathogenesis is related to the location, classification, type, and severity of the injury

• Due to nerve root or myelinated tract damage, impairing the transduction of afferent or efferent neural impulses

• Complete or Incomplete transection 

• Incomplete 

  • Central Cord Syndrome

  • Anterior Cord Syndrome 

  • Brown-Sequard Syndrome

• Signs and Symptoms

• Location 

• Classification 

• Severity 

• Diagnosis 

• Physical exam 

• Imaging studies

spinal cord injury treatment

1. Treat as a Trauma ( Board and collar to immobilize the spine)

2. Surgery 

3. Promotion of functional abilities

parkinson’s disease

• Chronic progressive neurologic 

• Degreeration of pigmented dopaminergic neurons of the basal ganglia

• Impaired transport of dopamine

• Presence of Lewy bodies (protein) 

• Neuronal injury from oxidative damage is suspected

parkinson’s signs/symptoms

• Tremor

• Rigidity 

• Jerky movements 

• Flat affect 

• Bradykinesia (slowed movement)

• Shuffling gait and stooped posture 

• Postural instability

parkinson’s diagnosis

• No single, definitive test exists to diagnose ___

• Clinical findings based on the history and manifestations of the disease are used to diagnose.

• Two commonly used scales for ________ _________ are the Hoehn and Yahr scale and the Unified P*******’s Disease Rating Scale.

• Pharmacologic 

  • Dopamine replacement (Levodopa)

  • Anticholinergics

  • Dopamine agonists

• Surgical 

  • Pallidotomy

  • Deep brain stimulation

pain

• is complex 

• cannot be defined, identified, or measured by observer

• is always a personal experience that is influenced to varying degrees by biological, psychological, and social factors.

• This and nociception are different phenomena. This cannot be inferred solely from activity in sensory neurons.

• Through their life experiences, individuals learn the concept of this.

• A person’s report of an experience as this should be respected  (ISAP, 2023) 

pain origin

• From our somatic senses of  touch, pressure, vibration and pain

• Complex sensory and emotional experience when the body detects harm to its tissues, 

• Nociceptors are specialized sensory nerve endings found in most tissues (skin, joint, organs)

• These receptors respond to the stimulus that caused damage (mechanical, thermal, chemical)

• When they are stimulated, they send electrical signals  to the brain and spinal cord 

pain mechanics

• This organization allows for the relay and integration of sensory signals at different levels, from the periphery to the central nervous system (CNS) and finally to the brain

• First order -  This is the initial neuron that detects and transmits  from peripheral receptors (nociceptors) to the spinal cord or brainstem.

• Second order - Second-order neurons receive input from first-order neurons and transmit this information to higher brain centers. Go to the thalamus or medulla 

• Third order - receive input from second-order neurons and transmit the processed sensory information to the cerebral cortex for conscious perception ( it’s perceived or felt)

first-order neurons

This is the initial neuron that detects and transmits  from peripheral receptors (nociceptors) to the spinal cord or brainstem.

second-order neurons

receive input from first-order neurons and transmit this information to higher brain centers. Go to the thalamus or medulla 

third-order neurons

receive input from second-order neurons and transmit the processed sensory information to the cerebral cortex for conscious perception ( it’s perceived or felt) 

types of pain

• Acute- Last hours or day and resolves with healing 

• Chronic- Beyond expected time:, can be due to persistent inflammation, does not serve a biological or protective function  > 3-6 months 

• Chronic __ can profoundly affect quality of life (Produces behaviors and physiological changes)

• Neuropathic __ is due to an injury or malfunction of nervous tissue (burning, tingling, paresthesia) 

• Cutaneous refers to __ that originates from the skin or superficial tissues of the body. It is typically caused by damage or irritation to the skin's surface, such as from a cut, burn, or abrasion

  Deep somatic is a type of ___ that originates from deeper tissues within the body, such as muscles, joints, bones, ligaments, and tendons.

  Visceral is __ that originates from internal organs (such as the stomach, intestines, liver, or lungs) and is typically associated with deep, internal structures within the body. It is often caused by distension, inflammation, ischemia, or injury to the organs. (kidney stones, gallstones, appendicitis)

  Referred is __ felt in a different part of the body than where it originates (e.g., heart attack pain in the arm).

  Phantom is __ felt in a missing limb or body part after amputation, due to the brain's continued processing of sensory signals.

• You need to know __ type to treat it!!

acute pain

Last hours or day and resolves with healing 

chronic pain

Beyond expected time:, can be due to persistent inflammation, does not serve a biological or protective function  > 3-6 months 

• can profoundly affect quality of life (Produces behaviors and physiological changes)

neuropathic pain

due to an injury or malfunction of nervous tissue (burning, tingling, paresthesia) 

cutaneous pain

refers to pain that originates from the skin or superficial tissues of the body. It is typically caused by damage or irritation to the skin's surface, such as from a cut, burn, or abrasion

deep somatic pain

type of pain that originates from deeper tissues within the body, such as muscles, joints, bones, ligaments, and tendons.

visceral pain

pain that originates from internal organs (such as the stomach, intestines, liver, or lungs) and is typically associated with deep, internal structures within the body. It is often caused by distension, inflammation, ischemia, or injury to the organs. (kidney stones, gallstones, appendicitis)

referred pain

pain felt in a different part of the body than where it originates (e.g., heart attack pain in the arm).

phantom pain

pain felt in a missing limb or body part after amputation, due to the brain's continued processing of sensory signals.

infection

• a state of cellular, tissue, and sometimes even organ destruction resulting from invasion by microorganisms (microbes)

• Remember, if they get pass the three lines of defense, infection will happen 

microbes

• including bacteria, viruses, fungi, and protozoa, are everywhere in the human environment

• Resident flora are microorganisms that live on or within the body in non sterile areas, such as the skin, mucous membranes, bowel, rectum, or vagina, without causing harm (these are fine unless broken)

pathogens

• a disease-causing microbe

• To cause disease in humans, they must be capable of binding to specific receptors on the human host cell (this provides clues)

  • (Influenza virus attaches to receptors only in respiratory tract epithelial cell)

How do they cause disease?

•  Direct destruction of the host cell by these

•  Interference with the host cell’s metabolic function

•  Exposing the host cell to toxins produced by these

pathogenicity

• Qualities that promote the production of disease

• Ways it can cause disease:

  • Virulence: A more virulent microorganism is one that causes severe disease in a large proportion 

  • Toxigenicity: Ability of the pathogen to produce harmful toxins that increase host cell and tissue damage

  • Antigenic variability: mutate or change

  • Coinfection : Simultaneous occurrence of hosting two or more pathogens

  • Superinfection is an infection that arises in addition to one that is already present

virulence

A more ____ microorganism is one that causes severe disease in a large proportion 

toxigenicity

Ability of the pathogen to produce harmful toxins that increase host cell and tissue damage

antigenic variability

mutate or change

coinfection

simultaneous occurrence of hosting two or more pathogens

superinfection

an infection that arises in addition to one that is already present

bacteria

• single-celled microorganisms classified as prokaryote

• Lacks a distinct membrane-bound nucleus

• Reproduce outside of host cells

• Those that require oxygen for growth are called aerobic; those that do not are called anaerobic ( how they require oxygen, tells you where they do the best at) - Anaerobic in deep tissue - hard to treat 

These are described by their shape

rigid; synthesis; human cells

• Bacteria have a ___ cell wall ( provides structure, shape, and protection)

• Without it, the bacteria cannot survive in certain environments

• Many antibiotics are designed to interfere with the ____ or function of the bacterial cell wall

• _______ do not have a cell wall, so antibiotics that target the bacterial cell wall typically don't harm _________.

gram-positive and gram-negative bacteria

have different types of cell walls. GP bacteria have a thick cell wall, while GN bacteria have a thinner wall but an additional outer membrane

• They are stained in the lab 

• Use blood cultures to identity the bacteria 

• This is how antibiotics are chosen

viruses

• Cannot replicate outside of the host cell

• Binds to specific receptors on the host cell and then moves into the host cell

• Ability to either directly kill the cell or modify certain cellular functions, such as protein synthesis (it takes over to replicate)

• Cell ultimately loses its ability to function. The virus next releases particles outside of the cell, called virions, which can enter and infect other nearby cells 

• As it moves, the immune response is activated. This exaggerated immune response allows neutralization of the virus and resolution of the infection

• Infected host cells are eliminated, and the virus can no longer replicate (common cold)

chronic virus

(if not a good immune response)

• The size of the virus that is inoculated into the body

• The process of viral replication

• The viral genotype

• Host susceptibility

• Period of latency (will stay dormant until a patient is immunocompromised) 

• Example of latency: herpes simplex infection

fungi (molds and yeast)

• Large organisms compared to bacteria and viruses. They have a nuclear membrane, cytoplasm, and organelles

• Superficial or deep tissue invasion occurs when molds or yeast multiply. This invasion results in inflammatory and immune responses

• Inhabit the skin surface or mucous membranes and are controlled by intact integument, inflammatory, and immune cell

• Opportunistic pathogens are those that cause disease only in a host with a compromised immune system

• As previously mentioned, reduction of resident bacteria, often via antibiotics, disturbs this balance and allows f**** overgrowth

candida

• One of the most common opportunistic yeast infections involves ____

• _______ cutaneous invasion include skin redness, itching, and burning at the site. In oral candidiasis, lesions are white and resemble cottage cheese attached to an erythematous oral cavity

• Lesions bleed easily and can be painful if scraped Vulvovaginal candidiasis also produces redness, itching, and burning at the site along with a thick, white, vaginal discharge

communicable diseases

• infections that are spread from person to person, often through contact with infected blood and body fluids

• Although all of these are infectious, not all infectious diseases are communicable

• These are caused by microorganisms that live and reproduce in a human host

chain of infection

• Reservoir: Include an infected person, an animal, or the environment, such as pond water

• Portal of Exit: In human hosts, common portals of exit include the respiratory tract, GI tract, skin, mucous membranes, placenta, and blood

• Portal of Entry: Access point for the microorganism into the host, or the individual who is exposed to, and contracts the infection.

• Mode of Transmission: This contact can be direct or indirect. The mode of transmission refers to the mechanism of transference from the reservoir to the portal of entry. The modes of transmission include:

reservoir

Include an infected person, an animal, or the environment, such as pond water

portal of exit

In human hosts, common portals of exit include the respiratory tract, GI tract, skin, mucous membranes, placenta, and blood

portal of entry

Access point for the microorganism into the host, or the individual who is exposed to, and contracts the infection.

mode of transmission

This contact can be direct or indirect. This refers to the mechanism of transference from the reservoir to the portal of entry. These include:

• Direct contact

• Droplet transmission:  Larger respiratory particles, produced by sneezing, coughing, or talking, can pass through the air from the reservoir to the host (Respiratory)

• Airborne transmission: Smaller respiratory particles can remain suspended in the air and are subject to airborne transmission (chicken pox & TB)

• Vector transmission: A vehicle that harbors the pathogen and carries it to the host (mosquitoes)

droplet transmission

Larger respiratory particles, produced by sneezing, coughing, or talking, can pass through the air from the reservoir to the host (Respiratory)

airborne transmission

Smaller respiratory particles can remain suspended in the air and are subject to airborne transmission (chicken pox & TB)

vector transmission

 A vehicle that harbors the pathogen and carries it to the host (mosquitoes)

acute infection phases

1. Exposure: Exposure is contact with the pathogen through any of the modes of transmission

2. Incubation: The incubation phase extends from exposure to the onset of any signs or symptoms

3. Prodrome: The specific signs and symptoms related to the disease have not yet emerged

4. Clinical illness:  Represents the signs and symptoms specific to the disease

5. Convalescence: Extends from waning clinical manifestations to full recovery from the disease

exposure

contact with the pathogen through any of the modes of transmission

incubation

This phase extends from exposure to the onset of any signs or symptoms

prodrome

The specific signs and symptoms related to the disease have not yet emerged

clinical illness

Represents the signs and symptoms specific to the disease

covalescence

Extends from waning clinical manifestations to full recovery from the disease

complications of infection

• Acute infection can result in two major complications: septicemia and chronic infection

• Septicemia occurs when microorganisms gain access to the blood and circulate throughout the body. When septicemia is caused by bacteria, the term bacteremia is often used. 

• Septic shock is a process of systemic vasodilation due to severe infection, often with Gram-negative bacteria 

• Chronic infection is defined as an infection that lasts for several weeks to years. 

septicemia

occurs when microorganisms gain access to the blood and circulate throughout the body. When this is caused by bacteria, the term bacteremia is often used. 

septic shock

a process of systemic vasodilation due to severe infection, often with Gram-negative bacteria 

chronic infection

defined as an infection that lasts for several weeks to years. 

influenza

• a viral infection of the airway epithelial cells

• The virus is transmitted via respiratory droplets from another infected person or contaminated surface

• Three different types of these viruses (A, B, or C)- this is why you get it more than once 

• This virus enters the respiratory tract; attaches to the surface epithelial cells; impairs cilia, mucus, and antibodies; protein helps release new viral particles from infected cells.The infection spreads to neighboring cells, damaging the respiratory epithelium.

• Can be a problem in a patient who is immunocompromised

influenza clinical manifestations

• Cough, sore throat, nasal congestion and drainage, and shortness of breath

• Systemic signs and symptoms of inflammation are also common and include chills, fever, body aches, weakness, and malaise.

influenza diagnostics

• Usually based on history and symptoms 

• Nasopharyngeal secretions are quick (10 to 20 minutes) but can be false positive