Endocrine Study Guide Flashcards
What are the two types of organization of endocrine cells?
The secretory cells can be organized as:
- a single organ with only an endocrine function
- cells housed in small clusters within organs or tissues that have some other primary function
What are the three types of reflex?
- Hormonal Stimulation
- Humoral Stimulation
- Nervous Stimulation
Hormonal Stimulation
-the release of hormones from the endocrine gland is triggered by the binding of another hormone
What is an example of Hormonal Stimulation
When the Anterior Pituitary releases TSH which binds to the thyroid gland causing the release of TH
Humoral Stimulation
when a endocrine gland is stimulated to release their hormones in response to a changing level of nutrient molecules or ions within the blood
What is an example of Humoral Stimulation
When blood glucose levels are high/increases which stimulates the pancreas to produce insulin
Nervous Stimulation
is when there is direct stimulation from the nervous system, which causes the release of hormones from the gland cells
What is an example of Nervous Stimulation
The sympathetic division is activated and sympathetic preganglionic axons stimulate adrenal medulla to release epinephrine and norepinephrine
Hormone Half Life
-the necessary time to reduce hormone’s concentration half of its original level
What are the two primary factors that determine circulating hormone levels?
Hormone synthesis in endocrine gland:
Hormone Elimination:
Hormone synthesis in endocrine gland
- If the rate of synthesis and release increases, then the concentration of the hormone within the blood is greater
- If the rate of synthesis and release decreases, then the concentration of the hormone within the blood is less
Hormone elimination
1) Enzymatic Degradation- normally occurs in liver cells
2) Removal of the hormone from the blood either by its excretion from the kidneys or by its uptake into target cell.
- The faster the rate hormone elimination-> the lower the hormone concentration within the blood
- the Slower the rate of hormone elimination-> the higher the hormone concentration within the blood
Half life of water soluble hormones vs lipid soluble hormones
Water soluble hormones- have a short half life
Lipid soluble hormones-have a long half life
Why do lipid soluble hormones have a longer half life than water soluble hormones?
Because their carrier proteins provide protection to them
Transport of lipid soluble hormones
USE CARRIER MOLECULES
- Do not dissolve readily in blood
- Carriers are water-soluble proteins made by the liver
- Carrier proteins protect the hormone from early destruction
- binding between hormone and carrier is temporary. Most of the hormone is bound while only unbound hormone is able to exit the blood and bind to target cell receptors
Transport of Water soluble hormones
travel freely through blood
-only a few use carrier proteins to prolong their life.
Target cell response to lipid-soluble hormone
- the unbound lipid-soluble hormone diffuses into the cell and binds an intracellular receptor (in the cytosol or nucleus) forming the hormone-receptor complex
- Hormone-receptor complex then binds to a specific DNA sequence in regions of chromatin called hormone-response elements.
- This binding stimulates mRNA synthesis
- The mRNA is then translated and a new protein is synthesized
Target cell response to Water-soluble hormone
- Hormone (first messenger) binds to the receptor on plasma membrane and induces a change in the shape which activates the receptor
- This results in the formation of a second messenger that modifies cellular activity on the inside of the cell
- multiple results possibly with different signal transduction pathways
Upregulation
Increases the number of receptors
Increases sensitivity to hormones
-sometimes occurs when blood levels of hormone are low
-sometimes occurs with changes in development, cell cycle, and cell activity
Down regulation
Decreases the number of receptors
Decreases sensitivity to hormones
-Sometimes occurs when blood levels of hormone are high
-Sometimes occurs with changes in development, cell cycle, and cell activity
What are the three types of Hormone interactions?
Synergistic
Permissive
Antagonistic
Synergistic
Hormones work together to produce a greater effect
Example of a Synergistic interaction
Estrogen and Progesterone
Permissive
first hormone allows action of second hormone
Example of a Permissive interaction
Oxytocin’s milk ejection effect requires prolactin’s milk generating effect
Antagonistic
one hormone causes opposite effect of another hormone
Example of a Antagonistic interaction
Glucagon increases blood glucose while insulin lowers it
Relationship between the hypothalamus and Pituitary Gland
- Pituitary gland lies inferior to the hypothalamus
- Connected to the hypothalamus by the infundibulum
The Hypothalamus has direct control over the release of hormones from the pituitary gland.
Hormones for the posterior pituitary are:
- made in the hypothalamus by neurosecretory cells
- packed in secretory vesicles,
- released from synaptic knobs into blood when neurons fire impulses
What hormones does parafollicular cells of the thyroid release?
calcitionin
Calcitonin
- released in response to high blood calcium levels
- acts to lower blood calcium levels
What hormone does the follicular cells of the thyroid release?
- Thyroid hormone into the blood bound by a carrier protein
- stimulated by TSH
Thyroid hormone
T3
- 3 iodine
- most active form of the thyroid hormone
T4
- 4 iodine
- much greater amount produced. Enzyme produced to remove iodine converted T3 to T4
increases metabolic rate and increases release of stored fuel molecules and delivery of O2
What hormone is produced by the parathyroid gland?
-chief cells or principle cells are the source of the parathyroid hormone (PTH)
Parathyroid hormone (PTH)
- functions to increase blood calcium levels
- it stimulates the release of calcium from bone tissue, decreases loss of calcium in urine, causes the kidney to release an enzyme to convert the inactive calcidiol to the active calcitriol hormone
What hormones are produced by the medulla region of the adrenal gland? Describe its aciton
- produces epinephrine and norepinephrine in response to sympathetic nervous system
- both hormones circulate within the blood and help prolong the flight or fight response which is caused by the activation of the sympathetic nervous system
Anterior Pituitary is under what type of Control? and what hormones are found here?
- under hormonal control
- hormones synthesized by the hypothalamus and released into the hypothalami-hypophyseal portal region are regulatory hormones.
- the actual hormone released is synthesized by the anterior pituitary.
- Thyroid Stimulating Hormone (TSH)
- Prolactin(PRL)
- Gonadotropins
- Growth Hormone (GH)
- Adrenocorticotropic hormone (ACTH)
Posterior Pituitary is under what type of control and what hormones are found here?
- neural control
- hormones released are synthesized in the hypothalamus
- Oxytocin
- Antidiuretic hormone
Thyroid Stimulating Hormone (TSH)
- Thyroid releasing hormone from the hypothalamus stimulates the release of TSH
- TSH stimulates the thyroid gland to release Thyroid hormone
Thyroid Hormone
Functions to establish the body’s metabolic rate
Prolactin (PRL)
- Prolactin releasing hormone controls release of PRL
- PRL acts on mammary glands to stimulate milk production
- inhibited by prolactin inhibiting hormone.
Gonadotropins
- Gonadotropin releasing hormone regulates the release of gonadotropins
- Gonadotropins= Follicle stimulating hormone (FSH)or Leutinizing hormone (LH)
Gonadotropins in females
- FSH and LH act on the ovaries to control development of the oocyte and the follicle
- also releases estrogen and progesterone
Gonadotropins in males
-FSH and LH act on the testes to regulate the development of sperm and the release of testosterone
Growth Hormone (GH)
- Growth Hormone-releasing hormone release GH
- GH stimulates the liver to release insulin-like growth factor 1 and 2 which work synergistically with GH to stimulate growth of all body tissues
- release inhibited by growth hormone-inhibiting hormone
Adrenocorticotropic hormone (ACTH)
- Corticotropin releasing hormone controls the release of ACTH
- ACTH acts on the adrenal cortex to release corticosteroids/glucocorticoids
Oxytocin
-Functions in uterine contractions, milk ejection, and emotional bonding
Antidiuretic hormone (ADH)
-functions to decrease urine production, stimulates thirst, and constrict blood vessels
What are the three zones of the cortex region of the adrenal glands
Zona Glomerulosa
Zona Fasciculate
Zona Reticularis
Zona Glomerulosa
-secretes Mineralocorticoids
Mineralocoriticoids-definition and example
- a group of hormones that helps regulate the composition and concentration of electrolytes (ions) in body fluids
- EX: aldosterone
Aldosterone
- Regulates the ratio of Na+ and K+ in our blood fluids by altering the amounts excreted by the kidney into the urine
- Stimulates Na+ retention and K+ secretion
Zona Fasciculate
- secretes glucocorticoids (cortisol and corticosteroids)
glucocorticoids
- increase nutrient levels in the blood (glucose, fatty acids, and amino acids), especially in an attempt to resist stress and help repair injured or damaged tissues
Zona reticuluaris
secretes gonadocorticoids
gonadocorticoids
- minor amounts of sex hormones
- androgens in males and estrogen in females
where are the endocrine cells of the pancreas located?
in smal clusters called pancreatic islets
alpha cells produce
glucagon
function of glucagon
Acts to raise blood glucose by increasing breakdown of glycogen making glucose available in the blood and increasing the breakdown of fat.
beta cells produce
insulin
function of insulin
- insulin is released in response to high blood glucose
- Acts to lower blood glucose by increasing formation of glycogen using blood from glucose, decreasing breakdown of fat, increasing uptake of amino acids and glucose.
- The release of insulin results in both a decrease in all nutrients in the blood and in an increase in the synthesis of the storage form of these molecules within body tissues.
regulation of insulin and glucose
regulated by a negative feedback mechanism.
