Test 3 Flashcards
What is the endocrine system?
System of small organs called glands that release signalling molecules known as hormones.
What do hormones do?
Hormones influence growth, development and puberty, metabolism, and behaviour
What does the pineal gland release?
Melatonin
What does the adrenal gland release?
Cortisol, corticosterone, cortisone, aldosterone, androgens, estrogens, epinephrine, and norepinephrine
What does the pancreas release?
Glucagon and insulin
What does the testis release?
Androgens (testosterone)
What does the ovary release?
Estrogens and progesterone
What does the thyroid gland release?
Thyroid hormone, and calcitonin
What is the function of melatonin?
Reduces jet lag and promotes sleep
What are the functions of aldosterone?
-Increase sodium reabsorption by kidneys
-Increase potassium excretion by kidneys
What are the functions of androgens and estrogens?
Insignificant effects in adulthood, relative to secretion by gonads
What is the function of epinephrine and norepinephrine?
Fight if flight response to stress
What is the function of glucagon?
Increases blood glucose level
What is the function of insulin?
Decreases blood glucose level
What is the function of testosterone?
Develop male secondary sex characteristics
What is the function of estrogens and progesterone?
Develop female secondary sex characteristics
What are hormones?
Hormones are a type of chemical molecule that act as a signal to various cells of the body.
How do hormones travel in the body?
Most are secreted in the blood and travel throughout the body (endocrine).
-They only affect cells that have precise receptors
-Ultimately, hormones affect their target cells.
How many hormones have been discovered in the human body?
Approximately 50
How does hormone signalling work?
-Target cells have receptors
-Cells other than target cells lack the correct receptors and are unaffected by the hormone
-Once the hormone binds to its specific receptor, it triggers a specific reaction
What are the three types of interactions between hormones?
-Antagonistic
-Synergistic
-Permissive
What does antagonistic mean?
The effect on one hormone opposes that of another hormone
What does synergistic mean?
The response of a tissue to a combination of hormones is much greater than its response to either individual hormone
What doe permissive mean?
One hormone must be present for another hormone to exert its effects.
Which gland is the master gland of the endocrine system?
Pituitary gland
What is the relationship between the hypothalamus and the pituitary gland?
-The hypothalamus is part of the nervous system: it receives information from both internal and external environments
-It is also acting on the endocrine system by controlling the pituitary gland, which is the master gland of the endocrine system
-Targets and control the pituitary gland, which in turn influences numerous body functions via hormones
What body functions does the pituitary gland influences via hormones?
Body temperature
Hunger
Thirst
Fatigue
Childbirth
Emotions
Growth
Milk production
Salt and water balance
Sleep
Weight
Circadian cycles
Etc
How does the hypothalamus control the pituitary gland?
Cells in the hypothalamus secrete releasing and inhibiting hormones to the anterior pituitary.
Releasing and inhibiting hormones travel by way of the bloodstream to the anterior pituitary and cause it to modify secretion of its hormones.
What systems control homeostasis?
Nervous and endocrine systems
What are the steps in cortisol secretion?
- CRH (corticotropin-releasing hormones) is released by the hypothalamus and reaches the pituitary gland
- CRH stimulates the ACTH (adrenocorticotropic hormone) in the blood by the pituitary gland
- ACTH stimulates the cortex of the adrenal gland to stimulate the cortisol in the blood
- Cortisol is often associated with long-term stress (fight or flight response)
What does underproduction of cortisol cause?
Addison’s disease (yellow skin)
What does overexposure to cortisol cause?
Cushing’s syndrome (affects the distribution of fat and causes the typical accumulation of fluids in the face).
What system is the pancreas part of?
Endocrine system and digestive system
What are the function of the pancreas?
-Produces glucagon and insulin, antagonistic hormones that help maintain glucose homeostasis
-Produces digestive enzymes
What is the function of glucagon?
Triggers the formation of glucose from the energy reserve in liver: increase blood glucose levels
What is the function of insulin ?
Triggers the absorption of glucose from the blood by muscle cells and other tissues: decrease blood glucose levels.
What is diabetes mellitus?
Diabetes mellitus is perhaps the best-known endocrine disorder. It is caused by a deficiency of insulin or a decreased response to insulin in target tissues.
What is Type I diabetes?
Type I diabetes is insulin dependent. It is an autoimmune disorder in which the immune system destroys pancreatic beta cells.
Caused by the pancreas’ failure to produce enough insulin due to loss of beta cells.
What is Type II diabetes?
Type II is non-insulin-dependent. It involves insulin deficiency or reduced response of target cells due to change in insulin receptors.
Caused by an insulin resistance. The insulin resistance contributes to high glucose levels in the blood.
What does the pineal gland do?
It secretes melatonin.
- Regulates day and night cycle.
-Receives input from visual system.
-Release of melatonin is triggered by darkness.
-Thought to be involved in seasonal affective disorders as overproduction of melatonin causes lethargy, sleep envy, and cravings.
-Light therapy inhibits secretion of melatonin.