P: Cardiovascular System 1

Cardiovascular System

Overview and Functions

The cardiovascular system is essential for transporting oxygen, nutrients, and waste products throughout the body. It supports cellular respiration, regulates body functions, and provides defense mechanisms.

• Transport: Delivers oxygen and nutrients to tissues and removes waste products.

• Regulation: Maintains homeostasis, including temperature and pH balance.

• Protection: Prevents blood loss through clotting and defends against pathogens via immune responses.

Cellular Respiration Equation:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy}$

Main Topics Covered

• Blood composition, ABO system, Rh factor, coagulation

• Blood vessels: arteries, veins, capillaries

• Heart structure, cardiac cycle, electrical activity, cardiac output

• Blood volume, blood flow, and blood pressure

Blood Composition

Components of Blood

Blood consists of plasma and formed elements. Plasma is the liquid portion, while formed elements include red blood cells, white blood cells, and platelets.

• Plasma: 90-92% water, 7-9% proteins, 1% solutes

• Formed Elements: Red blood cells (erythrocytes), white blood cells (leukocytes), platelets (thrombocytes)

Example: A centrifuged blood sample separates plasma (top layer), buffy coat (middle, containing white blood cells and platelets), and red blood cells (bottom layer).

Plasma Proteins

Albumin

Albumin is the most abundant plasma protein, produced by the liver, and plays a critical role in maintaining blood volume and pressure.

• Concentration: 55-60% of plasma proteins

• Functions:

  • Maintains oncotic pressure: Prevents water from leaking excessively into tissues.

  • Transport: Carries substances such as fatty acids, calcium, hormones, and drugs.

Clinical Application: In chronic liver disease (e.g., cirrhosis, hepatitis, cancer), decreased albumin leads to edema (swelling), ascites (fluid in the abdomen), and increased free drug levels due to reduced binding.

Albumin and Drug Bioavailability

Albumin binds many drugs, affecting their bioavailability and duration of action. For example, insulin detemir binds strongly to albumin, resulting in prolonged action and a reduced peak effect compared to regular insulin.

• Binding: Insulin detemir binds to albumin (>98%)

• Effect: Prolonged action, reduced peak

Example: Activity profiles of different insulins show that those with higher albumin binding have longer duration and lower peak concentrations.

Globulins

Globulins are a diverse group of plasma proteins with three main subtypes, each with distinct functions.

• Alpha and Beta Globulins: Transport hormones, iron, and lipids; produced by the liver.

• Gamma Globulins (Immunoglobulins): Antibodies produced by plasma cells; include IgG, IgA, IgM, IgD, and IgE; provide defense against pathogens.

Example: Immunoglobulins are critical for immune responses, such as fighting infections.

Fibrinogen

Fibrinogen is a plasma protein produced by the liver and is essential for blood clotting.

• Function: During coagulation, thrombin converts soluble fibrinogen into insoluble fibrin, forming a mesh that stops bleeding.

Example: Fibrin mesh formation is a key step in wound healing and prevention of blood loss.

Plasma vs. Serum

Definitions and Differences

Plasma and serum are both liquid components of blood, but they differ in their content of clotting factors.

• Plasma: Contains clotting factors, including fibrinogen.

• Serum: Liquid portion of blood after clotting; lacks fibrinogen and other clotting factors.

Application: Serum is commonly used for diagnostic tests because it does not clot.

Plasma Solutes

Types of Solutes

Plasma contains various solutes, including electrolytes, nutrients, hormones, and waste products.

• Electrolytes: Na+, K+, Ca2+, Mg2+, Cl-, HCO3-, phosphate

• Nutrients: Glucose, lipids, vitamins

• Hormones: Thyroid hormones, steroid hormones

• Waste Products: Urea, uric acid, creatinine, bilirubin

Example: Normal fasting glucose: 75-115 mg/dL; desirable cholesterol: <200 mg/dL

Clinical Reference Values

Common Plasma Solute Reference Ranges

Solute	Reference Range
Glucose (fasting)	75-115 mg/dL
Cholesterol	<200 mg/dL
Triglyceride	<160 mg/dL
BUN (Blood Urea Nitrogen)	10-20 mg/dL
Bicarbonate	24-30 mmol/L
Sodium	135-145 mEq/L

Clinical Application: Chronic Liver Disease

Effects on Plasma Proteins

Chronic liver disease leads to decreased synthesis of plasma proteins, especially albumin and fibrinogen, resulting in clinical symptoms.

• Decreased albumin: Edema, ascites, increased free drug levels

• Decreased fibrinogen: Increased bleeding tendency (e.g., nosebleeds, easy bruising)

• Jaundice: Accumulation of bilirubin due to impaired liver function

Example: Patients with cirrhosis may present with swelling in the legs and abdomen, and increased risk of bleeding.

Summary Table: Major Plasma Proteins

Protein	Source	Main Functions	Clinical Relevance
Albumin	Liver	Oncotic pressure, transport	Edema, drug bioavailability
Globulins	Liver, plasma cells	Transport, immune defense	Immunity, metal/hormone transport
Fibrinogen	Liver	Clotting	Bleeding disorders

Additional info: Academic context and clinical applications were expanded for clarity and completeness.