Cardiovascular System Basics

Study Notes

The CVS has three main functions: supplying energy (fuel) from food, supplying oxygen from the air we breathe, and disposing of by-products of combustion (CO2, H2O, and heat).
The major components of the CVS are blood, heart, and vessels.

Blood circulation comprises 7% of the body mass.
Systemic circulation accounts for 80% of blood circulation, divided into:
- Arteries: 15%
- Capillaries: 10%
- Veins: 75%
Pulmonary circulation accounts for 20% of blood circulation, divided into:
- Arteries: 46.5%
- Veins: 46.5%
- Capillaries: 7%
Blood composition:
- Plasma: 55-60% of blood volume, mostly water, containing nutrients, electrolytes, hormones, and protein antibodies.
- Cells:
  - Red blood cells (erythrocytes): carry oxygen, disk-shaped, and give blood its red color.
  - White blood cells (leukocytes): important for the immune system, spherical-shaped.
  - Platelets (thrombocytes): important for blood clotting, flat-shaped.

Distribution:
- Supplies oxygen from the lungs to cells.
- Supplies nutrients from the digestive system to cells.
- Transports metabolic wastes from cells to disposal sites.
- Transports hormones to target tissues/organs.
Regulation:
- Regulates body temperature.
- Regulates pH of body fluids.
- Regulates blood volume to support efficient circulation.
Protection:
- Prevents blood loss by activating plasma proteins and platelets, and initiating clot formation.
- Prevents infection by synthesizing and utilizing antibodies, and activating WBCs to defend the body.

The heart is a double pump, providing the force needed to circulate blood through the pulmonary and systemic circulatory systems.
The heart has a system of valves that permit blood to flow only in the correct direction.
Fetal heart development:
- After 8 weeks of conception, the fetus' heart starts working, pumping blood to tissues.
- The fetal heart has an opening that permits blood to flow from the right atrium to the left one, which must close within minutes after birth.
Heart chamber pressures:
- Right atrium: 5-6mmHg.
- Right ventricle: 25mmHg.
- Left atrium: 7-8mmHg.
- Left ventricle: 120mmHg (systolic pressure), 80mmHg (diastolic pressure).

Blood pressure diseases: high blood pressure (hypertension) or low blood pressure (hypotension).
Fast heart rate (tachycardia): increases the workload and the amount of time the heart muscles spend contracting.
Heart valve defects:
- Stenosis: the valve does not open enough.
- Insufficiency: the valve does not close well enough.
Heart attack: insufficient blood flow to the heart muscle, leading to damage or death of heart tissue.