Chapter 20: Endocrine System Flashcards
what does the endocrine gland do?
-produce hormones that are released into the bloodstream
-ductless
what are hormones in relation to the endocrine system?
chemical messengers
function of hormones
- change the metabolic activity of the target cells/target organs
what are target cells and target organs?
target cells: cells with specific receptors for the hormone enabling the hormone to bind to the cell
target organs: organs that contain the target cells
what does the feedback do in general?
-hormone levels are regulated by this self-adjusting mechanism
-product of a pathway acts back at an earlier step in the pathway to regulate the pathway’s activities
types of feedback
-positive feedback
-negative feedback
positive feedback
accelerates the original process, either to ensure that the pathway continues to run or to speed up its activities
negative feedback
occurs when a stimulus starts a process, and eventually either the hormone that is secreted or a product of its effects causes the process to slow down or turn off
appearance of the adrenal glands and location
-paired, pyramid-shaped endocrine glands anchored on the superior surface of each kidney
parts of the adrenal gland
-corticosteroids
-epinephrine/norepinephrine
-pancreas
-gonads
-pineal gland
-thymus
what is the location of corticosteroids and what does it regulate?
-cortex
-electrolyte type/amount
what is the outer layer of the adrenal gland called?
adrenal cortex
what is the inner central core of the adrenal gland called?
adrenal medulla
color of adrenal cortex and why? function?
-distinctive yellow color as a consequence of the stored lipids in its cells that synthesize more than 25 different steroid hormones
what are the steroid hormones collectively called?
corticosteroids
color of adrenal medulla
-pronounced red-brown color due to its extensive vascularization
how are the hormones epinephrine and norepinephrine created?
chromaffin cells secrete these hormones when stimulated by the sympathetic division of the ANS
what is epinephrine also known as? what is norepinephrine also known as?
epinephrine = adrenaline
norepinephrine = no adrenaline
where are the hormones epinephrine and norepinephrine located? effects of them?
-medulla
-fight or flight response
what are the pancreas? where are they located?
-perform both exocrine and endocrine activities
-elongated, spongy, nodular organ situated posterior to the stomach between the duodenum of the small intestine and the spleen; pancreatic islets
what products do pancreas create?
-insulin
-glucagon
what are the gonads?
female and male primary sex organs
females = ovaries
males = testes
what sex hormones do the ovaries produce?
- estrogen
-progesterone
what sex hormones do the testes produce?
androgens which are converted to testosterone
appearance and location of pineal gland
small, cone-shaped structure attached to the posterior region of the epithalamus (brain)
what does the pineal gland produce?
melatonin
effects of melatonin
-causes drowsiness
-tends to be cyclic; increases at night and decreases during the day
-circadian rhythm (24 hour body clock)
-sexual maturation
what is the thymus?
bilobed structure located within the mediastinum superior to the heart and immediately posterior to the sternum
function of the thymus
-involved in maturation of T-lymphocytes
-regulate and maintain body immunity
where is the pituitary gland?
lies inferior to the hypothalamus (brain)
tissue types of pituitary gland
part nervous/glandular
two parts of the pituitary gland
-anterior pituitary gland
-posterior pituitary gland
tissue type of posterior pituitary gland
nervous tissue
tissue type of anterior pituitary gland
glandular tissue
where do the hormones come from in the posterior pituitary gland?
hypothalamus
what hormones are produced by the posterior pituitary gland?
-antidiuretic hormone (ADH, vasopressin)
-oxytocin
what hormones are produced by the anterior pituitary gland?
-luteinizing hormone (LH)
-follicle stimulating hormone (FSH)
-thyroid stimulating hormone
what does the antidiuretic hormone do?
-increases water retention
-vasoconstriction
what does oxytocin do?
-smooth muscle contractions (intercourse, labor)
-lactation (females)
what other endocrine glands does the anterior pituitary gland regulate?
LH and FSH regulate gonads
shape of thyroid gland
-butterfly shape
-lobed
effects of thyroid hormone
-increases metabolism
-oxygen use
-growth
-energy use
-promotes development
clinical significance of thyroid
goiter
effects of the goiter
-overgrowth of thyroid
-insufficient iodine
color and location of parathyroid
small, brownish-red parathyroid glands located on the posterior surface of the thyroid gland
amount of nodules of parathyroid
four small nodules
what does the parathyroid hormone promote?
-calcium release from bone
-calcium uptake from food
-calcium recovery from filtrate in kidneys
