Circulation and Gas Exchange

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Stem cells

in bone marrow

Myeloid

stem cells

Lymphoid

stem cells

Lymphocytes

B cells

T cells

Erythrocytes

Platelets

Neutrophils

Basophils

Eosinophils

Monocytes

Slide 62

Cardiovascular Disease = Disorders of the Heart and the Blood Vessels

One type of cardiovascular disease, atherosclerosis, is caused by the buildup of plaque deposits within arteries.

A heart attack is the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries.

A stroke is the death of nervous tissue in the brain, usually resulting from rupture or blockage of arteries in the brain /head.

Slide 63

Atherosclerosis

Connective

tissue

Smooth

muscle

Endothelium

Plaque

(a) Normal artery

(b) Partly clogged artery

50 µm

250 µm

Slide 64

Treatment and Diagnosis of Cardiovascular Disease

Cholesterol is a major contributor to atherosclerosis.

Low-density lipoproteins (LDLs) = “bad cholesterol,” are associated with plaque formation.

High-density lipoproteins (HDLs) = “good cholesterol,” reduce the deposition of cholesterol.

Hypertension = high blood pressure, promotes atherosclerosis and increases the risk of heart attack and stroke.

Hypertension can be reduced by dietary changes, exercise, and/or medication.

Slide 65

Gas exchange occurs across specialized respiratory surfaces

Gas exchange supplies oxygen for cellular respiration and disposes of carbon dioxide. Gases diffuse down pressure gradients in the lungs and other organs as a result of differences in partial pressure.

Partial pressure is the pressure exerted by a particular gas in a mixture of gases. A gas diffuses from a region of higher partial pressure to a region of lower partial pressure: H --> L

In the lungs and tissues, O2 and CO2 diffuse from where their partial pressures are higher to where they are lower.

Slide 66

Respiratory Media

Animals can use air or water as a source of O2, or respiratory medium.

In a given volume, there is less O2 available in water than in air.

Obtaining O2 from water requires greater efficiency than air breathing.

Slide 67

Respiratory Surfaces

Animals require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium, either air or water.

Gas exchange across respiratory surfaces takes place by diffusion.