18. BODY FLUIDS AND CIRCULATION
As the blood passes through the capillaries in tissues, some water and soluble substances are filtered out from plasma to the intercellular spaces, to form tissue (interstitial) fluid. It has same mineral distribution as that in plasma.
Some tissue fluid enters lymphatic system and the tissue fluid in them is called lymph. It drains back to major veins.
Lymph is a colourless fluid containing lymphocytes.
Functions of lymph
- It is the middleman between blood & tissues. Tissue fluid helps to exchange nutrients, gases, etc. b/w blood and cells.
- It carries plasma proteins synthesized in liver to the blood.
- Transports digested fats (through lacteals in the intestinal villi), fat soluble vitamins, hormones etc.
- Filtration of bacteria and foreign particles.
- Lymph nodes produce WBC (lymphocytes) & antibodies.
1. Hypertension (High Blood Pressure):
- The pressure of circulating blood on the walls of blood vessels is called blood pressure.
- Normal BP is 120/80 mm Hg. It includes systolic (pumping) pressure (120 mm Hg) and diastolic (resting) pressure (80 mm Hg).
- When the BP is higher than normal, it is called hypertension.
- If an individual repeatedly has the BP of 140/90 or above, it shows hypertension. It leads to heart diseases and affects vital organs (brain, kidney etc).
2. Coronary Artery Disease (CAD) or Atherosclerosis:
- Here, Ca, fat, cholesterol and fibrous tissue are deposited in coronary arteries. So the lumen of arteries becomes narrower and thereby affects the blood supply.
- An acute chest pain due to O2 deficiency to heart muscles.
- It occurs due to improper blood flow.
- It is common among middle-aged and elderly.
- It is the inability of heart to pump blood enough to meet the needs of the body.
- Congestion of the lungs is the main symptom.
6. Heart attack: Sudden damage of heart muscle due to inadequate blood supply.
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