___ ___ release hormones into the bloodstream to specific target cell receptors.
What happens to a streroid hormone after it enters the cell?
1. Endocrine gland secretes hormone.
2. Steroid hormone diffuses through target cell membrane and enters cytoplasm or nucleus.
3. Hormone combines with a receptor molecule in the cytoplasm or nucleus.
4. Steroid hormone-receptor complex binds to DNA and promotes transcription of mRNA.
5. mRNA enters cytoplasm and directs protein synthesis.
6. Newly synthesized proteins produce hormone's specific effects.
____ are paracrine substances.
Anterior pituitary is known as the ____ and the posterior pituitary is known as the ____.
What are the three thyroid hormones?
1. Thyroxine (T4)
2. Triiodothyronine (T3)
What is the function of thyroxine?
Increases rate of energy release from carbs; increases rate of protein synthesis; accelerates growth; stimulates activity in the nervous system
What is the action of triiodothyronine?
Same as thyroxine but 5 times more potent
What is the function of calcitonin?
Lowers blood calcium and phosphate ion concentrations by inhibiting release of calcium and phosphate from bones. Increased rate of calcium and phosphate deposition in bones; increases excretion of calcium by kidneys.
What is the function of parathyroid hormone (PTH)?
Increased blood calcium and decreases blood phosphate ion concentration through actions in the bones, kidneys, and intestines.
What is the function of aldosterone?
Causes kidneys to sodium ions and excrete potassium ions.
What is the function of insulin?
Stimulates the liver to form glycogen of glucose and inhibits conversion of noncarbohydrates into glucose.
What is the function of melatonin?
Called the "hormone of darkness" induces sleep.
What is the function of the thymus?
Plays an important role in immunity. Secretes a group of hormones called thymosins, that affect production and differentiation of certain white blood cells (T lymphocytes).
Blood is what type of tissue?
What is the function of blood?
To transport vital substances; maintian stability of interstitial fluid; distributes heat.
The amount of blood varies with ___ ___, changes in ___ concentration, changes in ___ concentration, and amount of ___ tissue.
body size; fluid concentration; electrolyte concentration; adipose tissue.
What is the function of eythrocytes?
Transports gases through the bloodstream.
What is the function of leukocytes?
To protect against disease.
Neutrophils are ___.
Phagocytic. Phagocytize bacteria, fungi and some viruses.
Monocytes are ___.
Phagocytic. Phagocytize bacteria, dead cells, and other debris in the tissues.
What is the function of thrombocytes?
Also known as platelets, which help repair damaged blood vessels by sticking to broken surfaces; release serotonin to contract vessels walls, reducing blood flow.
What is the function of albumin?
Help regulate water movement between blood and the tissues.
Name the three types of homeostasis?
1. Blood vessel spasm.
2. Platelet plug formation.
3. Blood coagulation.
External clotting mechanism is triggered by...
1. Chemical outside of blood vessel triggers coagulation
2. Tissue thromboplastin (not found in blood)
3. Blood coming in contact with damaged blood vessel walls or tissues.
External clotting mechanism is an example of ...
What are the methods of prevention of coagulation?
1. Smooth lining of blood vessel walls prohibits platelets from accumulating to form clots.
2. Endothelial cells produce prostacyclin (PGI) which does not allow platelets to adhere to inner walls of blood vessels.
3. Fibrin threads adsorb thrombin (adsorb = latch onto)
4. Antithrombin in plasm interferes with the action of thrombin.
5. Heparin from mast cells and basophils interfere with the formation of prothrombin activator.