Role of the Liver

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The Liver “Renaissance Man” of the body Important in digestion of fat Detoxifies drugs and alcohol Make cholesterol and proteins vital to the body

The Liver Blood is filtered through the liver Liver filters out amino acids, fatty acids and glucose Destroys bacteria that have made their way into the blood

Liver Function on Metabolism Maintains normal blood glucose level 100 mg/100 mL of blood After eating heavy duty amount of carbs, liver removes glucose and stores as glycogen in the liver (glycogenesis) Blood sugar levels will drop, and liver breaks down stored glycogen and releases it to the body (glycogenolysis) Liver can also create glucose from fats and proteins, known as glyconeogenesis

Liver Function and Blood Sugar As blood sugar increases, glycogenesis converts glucose to glycogen and stores it As blood sugar falls, glycogenolysis breaks down stored glycogen, converts it to glucose and releases it to the blood

Cholesterol Only 15% comes from diet, 85% is made by the liver High cholesterol is genetic Cholesterol helps build plasma membranes of cells Not soluble, can’t circulate freely in the blood Transported by HDLs and LDLs

HDLs v. LDLs LDLs transports cholesterol to the body cells Large amounts of LDLs circulated increases the risk of becoming imbedded in the arterial walls HDLs transport cholesterol from the tissue to the liver to be disposed HDLs “good”, LDLs “bad” But both necessary

Body Temperature Regulation

Heat Protecting Mechanism Hypothalamus in the brain regulated body temp to stay between degrees When body temp falls, the body must conserve heat Vasoconstriction Blood vessels of skin shrink, preventing blood flow and keeping blood deeper, toward more vital organs Shivering

Vasoconstriction Temporarily, vasoconstriction can be harmless However, if vasoconstriction can eventually cause a deprivation of oxygen, thus causing skin cells to die (frostbite) When vasoconstriction is no longer effective and core body temp drops, shivering starts Skeletal muscle activity produces lot of heat

Frostbite

Heat Releasing Mechanisms Most heat released through the skin (radiation) If external environment is as hot as the body, heat cannot be lost by radiation, only evaporation of sweat If weather is humid, evaporation is much less effective

Heat Stroke v. Heat Exhaustion Increased heat production, increases the rate of the metabolism Skin becomes hot and dry, but is unable to lose heat via sweat Heat stroke can cause permanent damage to the brain Heat exhaustion is when an individual faints following physical activity, usually associated with dehydration

Homework Quiz tomorrow