New MUST know to pass the national

ALPHA AND BETA RECEPTOR PROPERTIES

Alpha-1 receptors Location: Vascular smooth muscle

Effect: Vasoconstriction

Clinical significance: Increases blood pressure by narrowing blood vessels. Epinephrine and norepinephrine stimulate these receptors.

Alpha-2 receptors

Location: Presynaptic nerve terminals and CNS

Effect: Inhibits norepinephrine release

Clinical significance: Helps regulate sympathetic nervous system activity and decreases sympathetic outflow.

Beta-1 receptors

Location: Heart

Effects:

Increased heart rate (chronotropic effect)
Increased contractility (inotropic effect)
Increased conduction through AV node

Clinical significance: Stimulation increases cardiac output.

Beta-2 receptors

Location: Lungs, vascular smooth muscle, uterus

Effects:

Bronchodilation
Vasodilation
Relaxation of uterine smooth muscle

Clinical significance: Albuterol works by stimulating beta-2 receptors to open the airways.

PHYSIOLOGY OF CELLULAR FUNCTION

Cells generate energy primarily through metabolism of glucose in the mitochondria.

Key cellular functions include:

Energy production

ATP is produced through aerobic metabolism using oxygen and glucose.

Cell membrane transport

The membrane regulates movement of substances in and out of the cell.

Active transport

Requires energy to move substances against a concentration gradient.

Passive transport

Diffusion or osmosis moves substances along a concentration gradient.

Cellular injury occurs when oxygen delivery is insufficient, leading to anaerobic metabolism and lactic acid buildup.

HELICOPTER USE ON SCENE

Air medical transport may be used when:

The patient has severe trauma or critical illness
Ground transport time is excessive
The patient requires rapid access to specialty care (trauma center, stroke center, burn center)
Terrain or traffic prevents timely ground transport

Important considerations:

Scene safety
Landing zone size and hazards
Coordination with incident command
Weather conditions

pH IMBALANCES AND COMMON CAUSES

Normal blood pH is approximately 7.35 to 7.45.

Acidosis occurs when pH falls below 7.35.

Common causes of metabolic acidosis:

Diabetic ketoacidosis
Renal failure
Severe shock
Lactic acidosis

Respiratory acidosis occurs when carbon dioxide accumulates due to hypoventilation.

Common causes:

COPD exacerbation
Respiratory depression
Airway obstruction

Alkalosis occurs when pH rises above 7.45.

Respiratory alkalosis is usually caused by hyperventilation.

Metabolic alkalosis can occur from excessive vomiting or diuretic use.

PANCREAS FUNCTION

The pancreas has both endocrine and exocrine functions.

Endocrine function

The pancreas releases hormones into the bloodstream.

Important hormones include:

Insulin

Allows glucose to enter cells and lowers blood glucose.

Glucagon

Raises blood glucose by stimulating release of glucose from the liver.

Exocrine function

The pancreas releases digestive enzymes into the small intestine to break down:

Proteins
Fats
Carbohydrates

Pancreatitis occurs when digestive enzymes begin damaging the pancreas itself.

INCOMPLETE SPINAL CORD INJURIES

Anterior Cord Syndrome

Damage to the anterior portion of the spinal cord. (flexion injury)

Findings:

Loss of motor function
Loss of pain and temperature sensation
Preservation of position and vibration sense

Central Cord Syndrome

Often occurs with hyperextension injuries.

Findings:

Weakness in upper extremities greater than lower extremities
Variable sensory loss

Brown-Sequard Syndrome

Caused by injury to one side of the spinal cord.

Findings:

Paralysis on the same side as the injury
Loss of pain and temperature on the opposite side

WHITE BLOOD CELL TYPES

Neutrophils

Most common WBC. Important in fighting bacterial infections.

Lymphocytes

Include B-cells and T-cells. Responsible for adaptive immune responses.

Monocytes

Develop into macrophages that remove pathogens and debris.

Eosinophils

Fight parasitic infections and participate in allergic responses.

Basophils

Release histamine during inflammatory and allergic reactions.

PRELOAD VS AFTERLOAD

Preload

The amount of blood returning to the heart and stretching the ventricles before contraction.

Increased preload occurs with:

Fluid overload
Heart failure

Decreased preload occurs with:

Hemorrhage
Dehydration

Afterload

The resistance the heart must overcome to pump blood.

Increased afterload occurs with:

Hypertension
Vasoconstriction
Aortic stenosis

Reducing afterload helps the heart pump more efficiently.

ACUTE CORONARY SYNDROME (ACS)

ACS refers to conditions caused by reduced blood flow to the heart.

Includes:

Unstable angina

Chest pain without myocardial damage.

NSTEMI

Non-ST elevation myocardial infarction.

STEMI

Complete coronary artery occlusion causing ST elevation on ECG.

Common symptoms include:

Chest pressure or pain
Shortness of breath
Diaphoresis
Nausea
Radiation of pain to arm or jaw

VENOMOUS BITES

Pit Viper Bites (rattlesnake, copperhead, cottonmouth)

Signs:

Severe pain
Swelling
Tissue destruction
Coagulopathy

Black Widow Spider

Signs:

Severe muscle cramps
Abdominal pain
Diaphoresis
Hypertension

Brown Recluse Spider

Signs:

Local tissue necrosis
Ulcerating skin lesion
Mild systemic symptoms

ANIMAL BITES (INCLUDING HUMAN BITES)

Human bites carry high infection risk due to oral bacteria.

Common complications include:

Cellulitis
Abscess formation
Transmission of hepatitis or other infections

Management typically involves:

Cleaning the wound
Antibiotics
Tetanus prophylaxis

TRAUMATIC BRAIN INJURIES

Diffuse Axonal Injury (DAI)

Caused by rapid acceleration and deceleration forces.

Features:

Immediate loss of consciousness
Severe neurological impairment
Often occurs in high-speed crashes

Epidural Hematoma (EDH)

Arterial bleeding between skull and dura.

Classic presentation:

Loss of consciousness
Lucid interval
Rapid deterioration

Usually caused by rupture of the middle meningeal artery.

Subdural Hematoma (SDH)

Venous bleeding between dura and arachnoid layers.

Features:

Gradual onset
Common in elderly patients or those with head trauma
Can cause progressive neurological decline

1 comment

Rescue Academy

skool.com/rescueacademy

Calling ALL future EMTs & Paramedics. Let's PASS the National Registry on the FIRST attempt.

Rescue Academy YouTube

Leaderboard (30-day)