principels of pathophysiology

pathophysiology

study of how diseases effect the function of the body

• Helps recognize changes ill patients are going through and the body’s needs

cell memebrane

protects and selectively allows water and other substances in and out of the cell

mitochondria

converts glucose and other nutrients into ATP (the fuel for most cells)

no ATP

cells specialized structures cannot function

cell water balance

too little water = dehydration and cell dies

too much water = basic cellular functions interrupted

electrolytes and water

electrolyte levels in water impact electrical functions

glucose

building block for energy, insulin supply must match the body’s glucose requirements

aerobic metabolism

cellular functions USING oxygen

anaerobic metabolism

cellular function NOT using oxygen, less energy more waste, body becomes acidic impairing many functions

ineffective cell membrane

allows substances that shouldn’t be in the cell, can interfere with water regulation

homeostasis

regulated in the brain, maintained through nervous system feedback, medulla and hypothalamus

parasympathetic system

part of autonomic, regulates digestive and reproductive systems, reduces heart rate and BP

sympathetic

fight or flight, epinephrine and norepinephrine, increases protective protocols, heart rate, and BP

cardiopulmonary system

cardiovascular + respiratory system,

brings oxygen into the body, distributes cells, removes waste products.

airways obstructions

upper obstructions = most common

causes: foreign bodies, infection, or trauma

tidal volume

amount of air moved in and out in one breath

minute volume

tidal volume * respiratory rate

dead air space

air in the space between the mouth and alveoli that doesn’t reach gas exchange

chemoreceptors

brain + blood vessel sensors that detect changes in O2 and CO2 levels

respiration dysfunctions

anything impacting the medulla can effect minute volume

distruption of pressure (in the lungs)

a hole in the chest wall can mess with the correct amount of pressure required to keep the lungs adhered to the chest wall

air/fluid may enter the pleural space

alveoli

exchanges gases

hypoxia

low O2 levels

hypercarpia

high CO2 levels

Plasma oncotic pressure

large proteins pulling water away from body cells and directing it towards the bloodstream

• helps maintain circulation and bloodflow

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.

Blood Vessels pressure

controlled by changing the diameter of blood vessels
• Stretch receptors monitor pressure

blood vessel loss of tone

Vessels lose ability to constrict and dilate.
– Pressure drops

blood vessel excessive permeability

Capillaries leak fluid out their walls.
– Caused by severe infection (sepsis), high altitude, and
certain diseases

stretch receptors

sensors in blood vessels that identify internal pressure

Loss of regulation in blood vessles

Chemical messengers tell blood vessels when to dilate and constrict

if signals are blocked, lack of sympathetic response can cause shock

average stroke volume

70mL blood output per contraction 

diaphoresis

sweating with cool, pale, moist skin

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

V/Q match

balance between ventilation (V) and perfusion (Q)

amount of air entering the lungs must match the amount of blood flowing through them

4 categories of shock

Hypovolemic – low blood volume
• Distributive – low blood vessel tone
• Cardiogenic – heart fails to pump
• Obstructive – blood cannot flow

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