Homeostasis Flashcards
Homeostasis Definition
Maintenance of constant internal environment with narrow limits.
Importance of homeostasis
Ensure the the body cells function optimally and all metabolic reactions are carried out normally, regardless of changes to the external environment.
Increase in blood glucose concentration
Islet of Langerhans in the pancreas are stimulated and secrete insulin into the bloodstream. Insulin is transported by the bloodstream to the liver and muscle. Insulin promotes the liver to convert excess glucose into glycogen for storage and increase permeability of cell membrane to glucose and the oxidation of glucose. Blood glucose concentration decreases and return back to normal.
Decrease in blood concentration of glucose
Islet of Langerhans in pancreas detected the decrease and secrete glucagon into the bloodstream. Glucagon is then transported by the bloodstream to liver and muscles. Glycogen promote the conversion of stored glycogen into glucose. Glucose then enters the bloodstream and blood concentration increases back to normal.
Increase in blood water potential
Hypothalamus detects the increase and is stimulated. Pituitary gland releases less anti-diuretic hormone into the blood. In the kidney, the cells in the cells walls or the collecting duct becomes less permeable to water. Less water is reabsorbed from the collecting duct and more water is excreted. Larger volume/diluted urine is produced. Water potential decreases and return back to normal.
Decrease in blood water potential
Hypothalamus detects the decrease and are stimulated. Pituitary gland releases more anti-diuretic hormone into the bloodstream. In the kidneys the cells in the cells walls of the collecting duct is more permeable to water. More water is reabsorbed from the collecting duct. Less water is excreted and a smaller volume of urine or concentrated urine is produced. Water potential increase and return back to normal.
Blood vessels in the dermis layer
Constriction of the arterioles is caused by the contraction of muscles in the arteriole walls. Contraction and dilation help to regulate body temperature. When arterioles dilate, more blood is sent to blood capillaries in the skin which makes the face looks more flushed. Vasoconstriction causes less blood to flow through capillaries making the face look pale.
Hair
Produced in the epidermis. Malpighian layer of epidermis sinks into the dermis forming a hollow tube called the hair follicle. Each hair grows inside the hair follicle. At the base of the hair follicle is a mass of tissue called the hair papilla which contains blood capillaries and nerves.
Sweat glands
Secreted sweat flows through a sweat duct to sweat pore that opens at skin surface. sweat is a means by which your skin regulate body temperature.
Subcutaneous fats
Beneath the dermis are several layers of adipose tissues where fat is stored. The fat in the cells also serve as an insulating layer, reducing heat loss.
Increase in temperature
Thermoreceptors in skin detect the increase and are stimulated. The hypothalamus is stimulated and send nerve impulse. Sweat gland becomes more active and produce more sweat. Water evaporate and more latent heat is lost. Arterioles in the skin will undergo vasodilation, shunt vessel constrict, more blood will flow to the skin capillaries. Increased heat loss via conduction, convection and radiation. Metabolic rate decrease. Hair erector muscles relax, hair lies flat. A layer of air not trapped resulting in heat loss. Body temperature decreases and return back to normal.
Decrease in temperature
Thermoreceptors in skin are stimulated. Hypothalamus is stimulate and send nerve impulse. Sweat gland becomes less active and produces less sweat. Less water evaporates and less latent heat is lost. Arterioles in skin will undergo vasoconstriction, shunt vessel dilate and less blood flow into skin capillaries. Decrease in heat loss by conduction, convection and radiation. Metabolic rate increases and spasmodic contraction of skeletal muscles increase body shivers, heat is released to raise temperature. Hair erector muscles contract, hair stands upright. A layer of air is trapped creating a layer of insulation resulting in less heat loss. Body temperature increases and return back to normal.
