labbbbb 3-26-26
Circulatory System Basics
Heart and Blood Vessels
Veins
Function: Bring blood back to the heart.
Capillaries
Type of exchange: Internal respiration
Unloading: Oxygen (O₂)
Picking up: Carbon dioxide (CO₂) and water.
Blood color changes:
Deoxygenated blood: Blue (rich in CO₂).
Oxygenated blood: Red (picked up O₂).
Implications of blood color in skin:
Low oxygen: Bluish tint.
High oxygen: Red color or rosy hue.
Blood Pathways
Right side of the heart: Receives deoxygenated blood from the body.
Color: Blue blood.
Pulmonary circulation:
Blue blood travels to the lungs: Pulmonary artery.
Blood picks up oxygen and releases CO₂: External respiration.
Return to the heart:
Oxygenated blood returns to the heart through the pulmonary veins.
Structure of Blood Vessels
Histological Structure:
Arteries have:
Multiple layers, including a tunica media for muscle control.
Tunica intima: squamous epithelial lining.
Tunica externa: made of connective tissue.
Healthy blood vessel: Display symmetry, thin intima.
Symmetry test: Evaluate both halves for equal thickness and structure.
Atherosclerotic plaque will disrupt symmetry.
Arterial vs. Venous Structure:
Arteries: Thicker walls due to higher pressure.
Veins: Thinner walls; contain valves to prevent backflow of blood.
Valves are essential for blood flow against gravity, especially from the legs.
Blood Pressure and Circulation
Blood Pressure Analysis:
Higher blood pressure in arteries than in veins.
Blood pressure distribution:
High in arteries.
Lower in veins, particularly near the heart.
Pressure gradient necessary for blood circulation.
Blood should flow in predictable pathways due to pressure differences.
Function of Blood Cells
Red Blood Cells (RBCs):
Function: Transport oxygen using hemoglobin.
Structure: No nucleus to maximize oxygen-carrying capacity.
White Blood Cells (WBCs):
Unique characteristics: Contain nuclei unlike RBCs.
Functions: Identify pathogens and coordinate immune responses.
Types of White Blood Cells (Mnemonic: Never Let Monkeys Eat Bananas)
Neutrophils:
Most abundant (accounting for ~70% of WBCs)
Role: First responders during infections, specifically acute bacterial infections.
Appearance: Multi-lobed nuclei, granulated cytoplasm.
Lymphocytes:
Second most abundant WBCs (~30% of WBCs).
Role: Part of acquired immune response (B and T cells).
Monocytes:
Account for ~3-8% of WBCs.
Function: Cleanup crew, engulf dead cells and pathogens after neutrophils.
Appearance: Large cells with kidney bean-shaped nuclei, abundant cytoplasm.
Eosinophils:
Less common (~4% of WBCs).
Role: Combat allergic reactions and parasites.
Appearance: Bilobed nuclei, granular cytoplasm that stains orange-red.
Basophils:
Least abundant WBCs.
Functions: Release histamine (increases blood vessel permeability) and heparin (anticoagulant).
Appearance: Large granules obscure the nucleus.
Histamine and Inflammation
Inflammatory Response:
Cardinal signs: Redness, swelling, heat, pain.
Process:
Neutrophils first on the scene post-injury (like when stepping on a nail).
Role of basophils: Release histamine to increase capillary permeability allowing WBCs to access tissues.
Blood Type and Compatibility
ABO Blood Groups:
Agglutinogens: Determine blood type based on antigens on red blood cells.
Type A: Has A antigens, anti-B antibodies.
Type B: Has B antigens, anti-A antibodies.
Type AB: Has A and B antigens, no antibodies (universal recipient).
Type O: No antigens, has both anti-A and anti-B antibodies (universal donor).
Rh Factor: Determines positive or negative. Positive (has Rh antigen), Negatives (do not).
Risks during pregnancy if mom is Rh negative and baby is Rh positive (hemolytic anemia risk).
Hematocrit and Blood Composition
Understanding Hematocrit:
Definition: The volume percentage of red blood cells in blood.
Normal ranges:
Males: 42-52%
Females: 37-47%
Causes for low or high hematocrit:
Low: Anemia, blood loss, menstrual cycle, cancer affecting marrow.
High: High altitude, dehydration, diseases, polycythemia.
Laboratory Techniques: Centrifugation and Blood Typing
Centrifugation: Used to separate components of blood.
Red blood cells settle at the bottom; plasma at the top.
Blood Typing Procedure:
Use anti-A and anti-B serums to identify blood types through agglutination reactions.
If agglutination occurs, corresponding antigen (A or B) is present in the sample.
Rh factor determination through interaction with Rh antibodies.
Understanding cross-reactivity during blood transfusion is essential for patient safety.
"Remember: No a reaction means it lacks that antigen, leading to compatibility in blood transfusion. Compatibility awareness is critical, especially in emergency situations involving transfusions, ensuring proper blood type usage."
Heart Anatomy
Four chambers: left and right atria, left and right ventricles.
Purpose: Pumps blood throughout the body.
Valves: Ensure one-way blood flow (e.g., mitral and tricuspid valves).
Cardiac Cycle
Phases include diastole (filling phase) and systole (contraction phase).
Heart Rate: Number of beats per minute; influenced by physical activity and nervous system.
Blood Vessel Types
Differentiate between elastic arteries, muscular arteries, and arterioles based on size and function.
Capillaries: Site of nutrient and gas exchange between blood and tissues.
Venous Return Mechanisms
Role of skeletal muscle pumps and respiratory pumps in aiding blood return to the heart.
Importance of muscle contractions and breathing in venous circulation.
Physiological Response to Exercise
Heart rate, stroke volume, and cardiac output increase during exertion.
Redistribution of blood flow to active muscles.
Pathophysiology
Common cardiovascular diseases: atherosclerosis, hypertension, heart attacks.
Risk factors: obesity, smoking, sedentary lifestyle, high cholesterol.
Preventive Measures
Importance of diet, exercise, and regular health check-ups to maintain cardiovascular health.
Heart Flow:
Blood flow through the heart follows a specific pathway:
Deoxygenated Blood: Enters the right atrium from the body via superior and inferior vena cava.
Right Atrium: Blood moves through the tricuspid valve into the right ventricle.
Right Ventricle: Pumps blood into the pulmonary artery through the pulmonary valve. This blood goes to the lungs.
Lungs: In the lungs, blood picks up oxygen and releases carbon dioxide during external respiration.
Oxygenated Blood: Returns to the heart through the pulmonary veins into the left atrium.
Left Atrium: Blood moves through the mitral valve into the left ventricle.
Left Ventricle: Pumps oxygenated blood into the aorta through the aortic valve for distribution to the body.
ABO Blood Groups:
Agglutinogens: Determine blood type based on antigens on red blood cells.
Type A: Has A antigens, anti-B antibodies.
Type B: Has B antigens, anti-A antibodies.
Type AB: Has A and B antigens, no antibodies (universal recipient).
Type O: No antigens, has both anti-A and anti-B antibodies (universal donor).
Antibodies and Antigens:
Antibodies: Proteins produced by the immune system to identify and neutralize foreign objects.
Antigens: Substances that induce an immune response, such as the A and B antigens found on red blood cells.
Rh Factor:
Determines positive or negative blood type based on the presence or absence of the Rh antigen.
Positive: Has Rh antigen.
Negative: Does not have Rh antigen.
Risks during pregnancy: If an Rh-negative mother carries an Rh-positive baby, there is a risk of hemolytic anemia due to mother’s anti-Rh antibodies attacking the baby’s red blood cells pre- or post-birth.
Hematocrit and Blood Composition
Understanding Hematocrit:
Definition: The volume percentage of red blood cells in blood.
Normal ranges:
Males: 42-52%
Females: 37-47%
Causes for low or high hematocrit:
Low: Anemia, blood loss, menstrual cycle, cancer affecting marrow.
High: High altitude, dehydration, diseases, polycythemia.
Centrifugation:
Used to separate components of blood.
Red blood cells settle at the bottom; plasma at the top.
Blood Transfusion:
Receiving Blood from Donor:
Blood type compatibility is crucial to prevent agglutination reactions.
Donor's blood must match the recipient's type (ABO and Rh factors).
Giving Blood to Patient:
Process involves ensuring no reactions occur by matching blood types before transfusion.
Hemolytic Disease of the Newborn (HDN):
Occurs if an Rh-negative mother carries an Rh-positive baby.
The mother's immune system may produce anti-Rh antibodies, which can attack the baby’s red blood cells, causing hemolysis.
Preventive measures include administering Rh immunoglobulin (RhIg) to the mother during and after pregnancy to prevent sensitization.