Chap:7: Principles of Pathophysiology

Cell

What happens if a cell have too little or much water?

• Too little water

  • Cell dehydrates and dies

• Too much water

  • Basic cellular function interrupted

Water impacts levels of ______

Electrolytes

Glucose:

• Building block for energy

• Supply of insulin must match the body's glucose requirement

Aerobic metabolism

• Cellular functions using oxygen

Anaerobic metabolism

• Cellular functions not using oxygen

  • Creates much less energy and much more waste

  • Body becomes acidic, impairing many body functions.

Homeostasis

• Regulated in the brain

• Maintained through nervous system feedback and messaging

• Key structures are the hypothalamus and medulla oblongata

The Fight or Flight Response: Parasympathetic nervous system

• “Feed or breed” functions

• Neurotransmitters regulate digestion and reproduction

• Reduces heart rate and blood pressure

The Fight or Flight Response: Sympathetic nervous system

• “Fight or flight” situations

• Epinephrine and norepinephrine

• Enhances body’s ability to protect itself

• Increases heart rate and blood pressure

The Cardiopulmonary System

• Respiratory and cardiovascular systems work together.

  • Bring oxygen into body

  • Distribute to cells

  • Remove waste products

• Any breakdown can result in system failure.

The Lungs

• Part of lower airway

• Tidal volume

  • Volume of air moving in and out during each breath cycle

Respiratory Dysfunction: Disruption of respiratory control

• Respirations controlled in brain by the medulla oblongata

• Any event impacting function of the medulla oblongata can affect minute volume

  • Infection, drugs, toxins, trauma

Respiratory Dysfunction: Disruption of pressure

• If a hole is created in the chest wall (thorax), pressures needed for breathing are disrupted.

• Air or blood accumulating in chest (pleural space) also compromises respiration.

Respiratory Dysfunction: Disruption of lung tissue

• Trauma or medical problems can compromise the ability of alveoli to exchange gases.

• Less oxygen gets in; less carbon dioxide gets out.

• Can result in low oxygen levels (hypoxia) and high carbon dioxide levels (hypercapnia)

Hypoxia

Low oxygen levels

Hypercapnia

High carbon dioxide levels

Respiratory Compensation

• Body attempts to compensate for gas exchange deficits.

• Chemoreceptors detect changing oxygen and carbon dioxide levels.

• Brain stimulates respiratory system to increase rate and/or tidal volume.

The Blood: Four parts

• Plasma (liquid)

• Red blood cells

  • Contain oxygen-carrying hemoglobin

• White blood cells

  • Fight infection

• Platelets

  • Form clots

The Blood: Plasma oncotic pressure

Proteins in plasma attract water away from are around cells and pull it into bloodstream.

The Blood: Hydrostatic pressure

• Water pushed back out of blood vessels toward cells.

Blood Dysfunction

• Without enough blood, oxygen and carbon dioxide cannot be properly moved around.

  • Bleeding

  • Dehydration

  • Anemia

  • Liver failure

The Blood Vessels

• Need adequate pressure to make cycle work

• Pressure controlled by changing diameter of blood vessels

• Stretch receptors monitor pressure.

• Pressure can be increased or decreased depending on situation.

Blood Vessel Dysfunction: Loss of Tone

• Vessels lose ability to constrict and dilate.

• Pressure drops

• Causes

  • Trauma

  • Infection

  • Allergic reaction

Blood Vessel Dysfunction: Excessive permeability

• Capillaries leak fluid out their walls.

• Caused by severe infection (sepsis), high altitude, and certain diseases

Blood Vessel Dysfunction: Hypertension

• Systemic vascular resistance (S V R)

  • Pressure inside vessels

• Various conditions lead to abnormal constriction of vessels, leading to an unhealthy, high pressure level

• Major risk factor in stroke and heart disease

Blood Vessel Dysfunction: Loss of regulation

• Chemical messengers tell blood vessels when to dilate and constrict

• If signals are blocked, problems arise

• Lack of sympathetic response can cause shock

The Heart: Stroke volume is based on?

• Preload

  • Amount of blood returning to heart

• Contractility

  • How hard heart squeezes

• Afterload

  • Pressure the heart has to pump against to force blood out into the system

Cardiac Output

• Stroke volume × beats per minute = cardiac output

• Slowing heart rate or decreasing stroke volume reduces cardiac output.

• Very fast heart rates reduce cardiac output.

  • Inadequate time for heart to refill between contractions

Pediatric Compensation

• Rely on heart rate to compensate for poor perfusion

• Lack contractile muscles

• Cannot regulate the force of contraction

• Fast heart rate indicates compensation

Heart Dysfunction: Mechanical problems

• Physical trauma

• Squeezing forces

• Cell death (heart attack)

Heart Dysfunction: Electrical problems

• Damage to heart’s electrical system

• Cause unorganized rhythms and rate problems

The Cardiopulmonary System: Putting It All Together

• Entire cardiopulmonary system must work together to maintain life

• Must be a balance between ventilation (V) and perfusion (Q) for system to work properly

  • V/Q match

• V/Q ratio can be disrupted by any challenge to the cardiopulmonary system

Shock: Perfusion

Regular delivery of oxygen and nutrients to cells and removal of waste products

Shock: Hypoperfusion

• Inadequate perfusion (shock)

• Breakdown in system

  • Can result in death of patient

Four Categories of Shock:

• Hypovolemic – low blood volume

• Distributive – low blood vessel tone

• Cardiogenic – heart fails to pump

• Obstructive – blood cannot flow

Signs of compensated shock: (brain likes oxygen, glucose, and fluid)

• Slight mental status changes (late)

• Increased heart rate

• Increased respiratory rate

• Delayed capillary refill time (squeeze finger for 2 secs, should turn pink) (late)

• Pale, cool, clammy skin (late)

• Sweating

Recognizing Compensation: Decompensated shock

• occurs when compensatory measures fail

  • Characterized by decreased blood pressure and altered mental status

Recognizing Compensation: Irreversible shock

• occurs when inadequately perfused organ systems begin to die

  • Patient death commonly follows

Fluid Balance

• Body is 60 percent water.

  • Intracellular (70 percent)

  • Intravascular (5 percent)

  • Interstitial (25 percent)

Fluid Balance:

• Brain and kidneys regulate thirst and elimination of excess fluid

• Blood plasma proteins pull fluid into the bloodstream

• Cell membrane and capillary permeability regulate flow in and out

Disruptions of Fluid Balance: Fluid loss (dehydration)

• Decrease in total water volume

Disruptions of Fluid Balance: Poor fluid distribution

• Water not getting to where it needs to go

  • Edema

    • Swelling associated with the movement of water

The Nervous System:

• Brain and spinal cord are well-protected by bone and muscle.

  • Covered by several protective layers (meninges) and a layer of shock-absorbing fluid (cerebrospinal fluid)

  • Still subject to damage from trauma or disease

Nervous System Dysfunction: Possible injuries

• Trauma

  • Motor-vehicle crashes

  • Falls

  • Diving accidents

Nervous System Dysfunction: Medical dysfunction

• Strokes (hemmeragic or hybolic)

• Infection (meningitis, encephalitis)

• Disease (Lou Gehrig disease, M S)

• Low blood sugar (hypoglycemia)

The Digestive System

• Allows food, water, and other nutrients to enter the body

• Major organs of system

  • Esophagus

  • Stomach

  • Intestines

Digestive Dysfunction:

• Impacts hydration levels and nutrient transfer

• Gastrointestinal bleeding

  • Can be slow

    • Chronic bleeding

  • Can be massive, with rectal bleeding and/or vomiting blood

Digestive Dysfunction: Vomiting and diarrhea

• Most common disorders

• Variety of causes

• May result in malnutrition and dehydration

The Immune System:

• Responsible for fighting infection

• Responds to specific body invaders by identifying them, marking them, and destroying them

Hypersensitivity (Allergic Reaction)

• Allergic reaction to certain food, drugs, other substances

• Result of exaggerated immune response

• Chemicals affect more than just invader.

• Produces edema

• Results in a rapid drop in blood pressure

• Can be life threatening