Transcript Homeostasis-Temperature

Homeostasis
7th Grade Science
Mr. Bombick
Examples of Homeostasis in Action
• Shivering on a cold day
• Breathing heavily after running
• Feeling light-headed or dizzy
after standing up too fast
Processes are needed to keep the body systems in
balance and operating within normal limits.
Homeostasis-Simple Definition
• The regulation of the
internal body systems and
processes to keep a
constant stable condition.
Homeostasis-Temperature
• Humans, other mammals, and birds are all
capable of keeping a constant internal body
temperature with changes in external
environmental temperatures (they are
homeothermic or “warm-blooded”
• With cold temperatures, homeostatic
mechanisms try to prevent heat loss from the
body
• With hot temperatures, homeostatic
mechanisms try to increase heat loss from
the body
Homeostasis-Temperature (cont.)
• Some examples of physiological responses to cold
temperatures include decreasing peripheral blood
flow (keeps warm blood near vital organs), increased
metabolism of fat stores (fat is used to generate
internal heat), decreased heart rate (blood only needs
to be circulated to vital organs), and increased
shivering (generates internal heat)
• Some examples of physiological responses to hot
temperatures include increased peripheral blood flow
(allows loss of heat at skin), production of sweat (for
evaporative cooling), increased heart rate (insure
good peripheral blood flow), and increased respiration
(increased need for energy)
Homeostasis-Energy
• Energy balance must be maintained by the body to ensure
sufficient energy for the body to function but prevent the
excessive storage of energy within the body
• The general equation for energy balance is as follows:
Energy intake = internal heat produced + external work +
storage
Homeostasis-Iron Metabolism
• Iron is a very important element for normal body
functions
• Iron is used for hemoglobin in the blood which
results in the ability of red blood cells to
transport oxygen and carbon dioxide throughout
the circulatory system
• Excessive iron can be toxic to body systems by
participating in harmful oxidizing reactions that
damage cells
• An intricate iron homeostatic system is present
that detects iron concentrations in the body and
increases or decreases uptake of iron from the
digestive system
Homeostasis-Blood Components
• Sugar is regulated by the hormones insulin and
glucagon both secreted by the pancreas—when blood
sugar levels are high insulin is secreted to store sugar
as starch and when blood sugar levels are low
glucagon is secreted to use stored starch to release
sugar into the blood stream
• Calcium is regulated by the hormones PTH
(parathyroid) and calcitonin (thyroid); low blood
calcium results in PTH releasing calcium from bone
and high blood calcium results in calcitonin storing
calcium in bone
Homeostasis-Blood Components (cont.)
• Acid-Base homeostasis is done by the kidneys to
ensure the blood is at the proper range of pH
(measure of acidity); kidneys will remove various
components to keep the proper pH range; this is a
very important homeostatic mechanism since
many pathologies ultimately end up with problems
with acid-base balance
• Osmoregulation of the blood ensures the
concentration of chemicals in the blood are not
too concentrated nor too dilute; the kidneys are
important for removing or retaining important
chemicals to maintain the proper osmotic
pressure within the liquid systems of the body
Homeostasis-Blood Components (cont.)
• Volume or fluid balance is maintained by the
hormones Anti-Diuretic Hormone (ADH or
vasopressin) and Aldosterone; fluid deficiency
results in secretion of ADH to increase fluid
retention by the kidneys and lower urinary
output; fluid excesses results in secretion of
aldosterone to decrease fluid retention by the
kidneys and increase urinary output
Homeostasis—Hemostasis
• Hemostasis is the homeostatic mechanism
which halts the bleeding process
• A major part of hemostasis is the blood
coagulation process
• Platelets (one of the many types of cells in
the blood) are critically involved in the
coagulation process
• Several critical biochemical pathways of the
body are involved with blood clotting
The End