Chapter 7 - Principles of Pathophysiology

Compensation

Adjustments to correct imbalances

Homeostasis

A steady-state environment

Pathophysiology

The study of how disease processes affect the function of the body

Metabolism

The cellular function of converting nutrients into energy

Electrolytes

Substances that separate into charged particles when dissolved in water; enable the electrical functions of cells

Three important electrolytes

Potassium, sodium, magnesium

What two systems control levels of water in the body?

Circulatory and renal

What two systems control levels of glucose and insulin?

Digestive and endocrine

Waste products of cellular metabolism

Carbon dioxide and hydrogen ions → acid

How do high levels of acid in the body affect hemoglobin?

Hemoglobin’s attraction to oxygen is diminished in acidotic states.

The oxygen necessary for aerobic metabolism is supplied by the ___ system and carried to the cells by the ___ system.

respiratory, cardiovascular

The process of ___ moves oxygen across the thin membrance from the alveoli to the capillaries.

diffusion

Two neurotransmitters that play a vital role in compensation

Epinephrine and norepinephrine

What is one effect of beta blockers (hypertension medication) on compensation?

Reduces the effects of epinephrine and norepinephrine, impairing compensation

Patent airway

Open and clear

Upper-airway obstruction examples

-Foreign bodies (choking)

-Infection

-Trauma/burns (soft tissue swelling)

Tidal volume

The volume of air moved in one cycle of breathing

Minute volume

Tidal volume x respiratory rate

Dead air space

Air that occupies the space between the mouth and alveoli but that does not actually reach the area of gas exchange

Average dead air space

150 mL

In general, a respiratory dysfunction occurs _____.

any time minute volume is interfered with

What can cause disruption of respiratory control?

Disorders of the medulla oblangata:

-Stroke

-Infection

-Toxins

-Drugs

-Brain trauma

-Intracranial pressure

What can cause a disruption of pressure in the lungs?

A hole in the chest wall

What can cause disruption of lung tissue?

-Trauma

-Congestive heart failure

-Severe sepsis

What is the net result of disruptions in respiratory control, pressure, or lung tissue?

Hypoxia and hypercapnia

Chemoreceptors

Chemical sensors in the brain and blood vessels that identify changing levels of oxygen and carbon dioxide; trigger compensation

What triggers respiratory compensation?

Chemoreceptors

Plasma oncotic pressure

The pull exerted by large proteins in the plasma portion of blood that tends to pull water from the body into the bloodstream

What is plasma oncotic pressure counterbalanced by?

Hydrostatic pressure

Hydrostatic pressure

The pressure created inside the vessels when the heart beats; tends to push fluid back out of the blood vessels toward the cells

Name the opposing forces that regulate capillary exchange

Hydrostatic pressure and plasma oncotic pressure

The most common blood dysfunctions relate to ___.

volume

Stretch receptors

Sensors in blood vessels that identify internal pressure

The ____ plays a major role in controlling vessel diameter.

autonomic nervous system

Why is blood pressure an unreliable early indicator of hypovolemia in infants and children?

Infants and children have a strong vasoconstrictive response that can effectively maintain blood pressure even after significant volume loss. Do not wait for hypotension to recognize circulatory volume depletion.

What is another way to assess vasoconstriction and compensation in pediatric patients?

Capillary refill time (can also be assessed on skin of hand for small patients)