Cardiovascular System

Cardiovascular System
 Transport system of the body.
 Consists of the heart, blood, and blood vessels
 Blood vessels consist of:
 Arteries that carry oxygenated (red) blood from the heart to the periphery and brain.
 Veins carries de-oxygenated (blue) blood back to the heart and lung
Heart
 Fist-sized muscle that circulates blood to and from the lungs to the body.
 Four chambers – atrium (right & left) and ventricles (right & left)
 Left side pumps oxygenated blood from lungs out to periphery and brain.
 Right side takes deoxygenated blood in to the lungs.
Blood pressure (BP)
 Pressure of blood in the arteries.
 As the heart contracts and pushed blood into the arteries (systolic cardiac cycle) the BP rises.
 As the heart rests between beats and no blood is pumped (diastolic cardiac cycle) BP is at its lowest.
Dynamics of Blood Pressure (BP)
 Cardiac output – force of contraction of the heart muscle
 Heart rate – speed of contraction
 Blood volume – amount of blood in the system
 Peripheral resistance – ease with which blood can pass through the arteries (as resistance increases, BP increases)
Dynamics of Blood Pressure (BP)
 Elasticity – is the give and take in the arterial walls. As elasticity decreases BP increases.
 Viscosity – thickness of the blood. BP increases when the thickness of the blood increases.
Blood pressure (BP) is Dynamic
 When arteries dilate (e.g., in heat) diastolic BP decreases.
 BP increases when heart rate or cardiac output increases in response to activity, change in posture, while talking, when under stress, temperature, etc.
 BP follows a circadian (daily) rhythm such that it is lowest when in deep sleep.
Hypertension
 Permanently high blood pressure
 Systolic blood pressure >= 140 mmHg; Diastolic blood pressure >= 90 mmHg
 Essential (primary) – no known physical cause (90-95% of cases are of this type)
 Secondary hypertension – due to specific cause, e.g., adrenal tumor.
Risk Factors for Essential Hypertension
 Lack of exercise, Body weight, Salt consumption, Stress, Age, Gender, Ethnicity (blacks at higher risk), Genetics

Blood
Two components
 Formed elements
 Plasma
Formed elements consist of three elements:
 Red blood cells
 Leukocytes (white blood cells)
 Platelets
Formed Blood – Red Blood Cells
 Most abundant cells
 Formed in bone marrow
 Contains hemoglobin – a protein that attaches to oxygen and transports it to the cells and tissue
 Anemia is when level of red blood cells are below normal.
Leukocytes (white blood cells)
 Serve a protective function (e.g., destroys bacteria).
 Produced in bone marrow and various organs of the body.
 Leukemia is when there is an excessive production of white blood cells that crowd out plasma and red blood cells.
Platelets
 Granular fragments that can clump together to prevent blood loss at site of cuts.
 Produced by bone marrow
 Hemophilia is when platelets don’t function properly to produce clotting and so if the person receives a cut could bleed excessively.

Plasma
 55% of the blood is plasma
 Composed of 90% water and 10% plasma protein and other organic and inorganic substances.
 Other substances include hormones, enzymes, waste products, vitamins, sugars, fatty material etc.
 An important fatty substance is lipids.
 Consist of:
 Cholesterol, Low and high-density lipoprotein, & Triglycerides
 High lipid content in the plasma can lead to plaque build-up on arteries and lipid deposits in arterial wall, causing hardening of the arteries.

Disorders of the Cardiovascular System – Hardening of Arteries
 Atherosclerosis – deposits of cholesterol and other substances on the arterial wall, forming plaques that can block the artery.
 Ateriosclerosis – calcium and other substances get deposited on the arterial wall leading to hardening of the plaques.
Risk Factors for Atherosclerosis
 Hypertension
 High fat intake leading to hyperlipidemia
 Smoking, Stress, Diabetes, Lack of exercise, Genetics, & Gender
Consequences of Atherosclerosis
 Angina pectoris – insufficient oxygen supply to the heart for its need and removal of waste products resulting in chest pain.
 Myocardial infarction (heart attack) – when there is a blockage of blood supply to an area of the heart cutting off oxygen supply to the tissue in the area and resulting in tissue death