Endocrine System Flashcards
Describe the overall function of the endocrine system
Reproduction, growth and development, internal homeostasis, helps to cope with environmental changes
Contrast endocrine and exocrine glands
- exocrine release content into ducts or skin surface Ex salivary
- endocrine release horemone into blood stream
Define hormone and target cell.
- Hormone is made by an endocrine gland & is a chemical messenger traveling in the bloodstream.
- The target cell responds to the hormone because it has matching receptors for the hormone
Describe the structure and transport mechanism of hormones
- organic, amino acid (some lipid-reproduction)
- transported in the bloodstream; usually they are attached to some carrier protein making them physically larger so that they are not urinated out.
Explain how a hormone affects the activity of target cells
- It can go to the nucleus and act upon the genes
- or it can stimulate and intermediate compound such as cAMP, which acts as a second messenger and stimulates or inhibits a process or metabolic pathway in the cell. (assisting in chain reaction)
Define hypophysis
-Pituitary gland
Identify the location of the pituitary gland
- in Sella Turcica of sphenoid bone
Describe the 2 lobes of the pituitary gland, include which hormones are released by each lobe and their function
Anterior pituitary:
- FSH causes sperm production in male and follicle maturation in female
- LH=ICSH causes interstitial cells of testes to make testosterone in male and causes ovulation in female
- TSH stimulates the thyroid gland to make hormone
- ACTH stimulates the adrenal cortex to make hormone
- GH causes growth
- Prolactin causes milk production in females
- MSH causes skin pigment (melanin) to be produced.
(endorphins not hormone, but released here)
Neurohypophysis- posterior lobe (doesn’t make hormones, stores and releases hormones from hypothalamus
- ADH-antidiuretic water reabsorption (from urine to blood) in kidney
- Oxytocin-contractions milk let down
Define Endorphines
- peptides made by adenohypophysis in addition to the hormones that has
- blocks neurotransmitter
- not a hormone but is really a neuromodulator
- Morphine like compound made by anterior pituitary gland
Describe the controls of the pituitary gland
-.Hypothalamus makes stimulatory hormones called releasing hormones and inhibitory hormones; Negative feedback
Explain why the posterior pituitary is not a TRUE endocrine gland
It doesn’t make ADH and Oxytocin. They are made by hypothalamus but stored and released by posterior pituitary.
Describe the location and histology of the thyroid gland
- inferior to larynx
- follicles filled with thyroid hormone (colloid), and the surrounding follicle cells make the hormone.
- The interstitial cells are called parafollicular cells and make calcitonin (controls calcium levels)
Name and describe the formation and function of thyroid hormones
- Made from an amino acid called tyrosine.
- Three iodine molecules in T3 and four in T4.
Describe how thyroid hormones are transported in the bloodstream
-the thyroid hormone is transported on plasma globulin TBG
Describe the controls over thyroid hormone synthesis and release
- synthesized by iodine (only place in body) combining with Tyrosine to make T4 (90%) and T3 (10%)
- Regulates metabolic rate
- Negative feedback, TSH from anterior pituitary and Thyroid releasing hormone from hypothalamus.
Name the gland and cell that make calcitonin
-Parafollicular cells of the thyroid- C Cells
Describe the function and control of Calcitonin
- Decreases Calcium and phosphate in blood stream
- Important because Calcium controls muscle contraction, too much can cause heart attack
Describe the location of the parathyroid gland and the function of its hormone and the controls of its release
- Embedded in the thyroid gland. (4 of them)
- It makes Parathyroid hormone which increases blood calcium levels.
- Obviously, blood calcium levels determine whether PTH or Calcitonin should be released.
Describe the location and the 2 portions of the adrenal gland
- Superior to Kidney
- Adrenal Medulla (epinephrine and norepinephrine)
- Adrenal Cortex
Name the three layers of the adrenal cortex. Name and describe the effects of the hormones made by each layer. Describe the controls of their release
- Outer is the zona glomerulosa
- aldosterone is made which causes sodium reabsorption in the kidneys (sodium goes from urine back to blood, and water passively follows)
- Zona fasciculata is middle layer
- making glucocorticoids that help one deal with long term stress by conserving energy for later.
- It is also anti-inflammatory.
- Inner zone is zona reticularis
- making sex hormones to be discussed under reproduction.
-Of course ACTH from the ant. pituitary stimulates the release of these hormones. Also, low blood sodium would stimulate release of aldosterone. If your blood pressure is low, the kidneys release renin. Renin is an enzyme that converts angiotensinogen to angiotensin. These will be discussed under cardiovascular system. However, angiotensin can cause the adrenal cortex to release aldosterone. Since aldosterone causes more salt to be in the bloodstream, and water passively follows, it will help to restore the low blood pressure to a more normal value.
Define islets of langerhans, pancreatic islets, and chromaffin cells
- Islets of Langerhans = pancreatic islets and are the endocrine cells of the pancreas.
- The chromaffin cells are the endocrine cells of the adrenal medulla.
Name the organ that has both exocrine and endocrine functions
-Pancreas
