Endocrine system t1 Flashcards
What are the two major control systems of the body?
Nervous and endocrine system
What are some differences btwn endocrine and nervous system? 5
- Hormones are transported within the blood
- Exhibit longer reaction times
- more widespread effects
- longer lasting effects
- nervous = electrical , endocrine = chemical
Endocrine system releases what and that goes to where?
releases and synthesizes hormones to target cells
What is a target cell?
cells with a specific receptor for hormone, hormone binds to this
4 main fxns of endocrine system?
- maintaining homeostasis of blood compositon and volume
- controlling reproductive activities
- regulating development, growth and metabolism
- controlling digestive processes
Composition of endocrine system 3
- derived from epithelium with connective tissue framework
- extensive blood supply
- two organizations: single organ with endo fxn, cells in small clusters in organs with another fxn
differentiate perfusion from vascularization
perfusion = measure of amount of blood flowing through an area
- vascularization = measure of number of blood vessels in an area
What are the 5 organs with endocrine fxn?
- pituitary gland
- pineal gland
- thyroid gland
- parathyroid glands
- adrenal glands (suprarenal glands)
Pineal gland is found where? Pinealocytes secrete what hormone and what does that hormone do?
posterior region of the epithalmus, cells secrete melatonin regulating circadian rhythm
The parathyroid glands are found where? What does it regulate?
found on posterior region of thyroid gland
- regulates blood calcium levels
What are the two cells types in the parathryoid? what are their fxns?
- Cheif cells : released in response to decreased blood Ca2+ levels
- Oxphil cells: fxn unknown :)
What are the other organs that have small clusters releasing hormones? 9
skin, thymus, heart, liver, stomach, pancreas, small intestine, kidneys and gonads
What hormone does the kidneys secrete in times of anemia? what does this hormone do?
secrete erythropoietin, RBC production
Endocrine reflexes are initiated by which 3 types of stimulation?
- hormonal, humoral, nervous stimulation
Describe hormonal stimulation
release of hormone in response to another hormone
Describe humoral stimulation
release of a hormone in response to changes in level of nutrient or ion in the blood
Describe nervous stimulation
release of a hormone in response to stimulation by the nervous system
What are the two catgories of ciruclating hormones?
steroid hormones and protein hormones
Sterioid hormones are ___ soluble. and synthesized from ___. Includes what three types of hormones?
lipid soluble, from cholestrol
- steroids produced by gonads, steroids synthesized by adrenal cortex, calcitriol sometimes in group
Protein hormones are ___ soluble. Most hormones in this group (t/f). COmposed of small chains of ____.
water soluble, true, small chains of amino acids
How are water soluble hormones transported?
they readily dissolve, easily transported in aqueous enviornment
How are lipid soluble hormones transported?
require carrier proteins
The lipid soluble carrier proteins are either __ or __.
selective or nonselective
Albumin is a lipid soluble protein that does what?
Acts as a transport in blood :)
What are the two factors influencing hormone concentration?
hormone synthesis and hormone elimination
Increased Hormone synthesis leads to what?
leads to increased blood level
How are hormones eliminated (4)
enzymatic degradation in liver cells
- removal from blood via kidneys
- removal of blood by uptake into target cells
- increased elimination leading to decreased blood levels
What is a hormone half life?
time necessary to reduce concentration to half of the original level
What category of hormone has a longer half life?
steriod hormones
Who made the classic decay graph?
Issac Newton
Lipid soluble hormones are _____ which means ?
nonpolar which means they can diffuse across the plasma membrane, bind to intracellular receptors and from hormone-receptor complex
what are the hormone response elements for lipid soluble hormones?
- regions of chromatin within nucleus
- areas where complex binds
After lipid soluble hormones bind to form the hormone- receptor complex what are the next 4 steps?
– Results in transcription of mRNA
– Translation resulting in protein synthesis
– May result in alteration in cell structure
– May result in shift of target cells’ metabolic activity
For water soluble hormones unable to cross the plasma membrane what is the signal transduction pathway?
first messenger (hormone) -> docks making second messenger -> g protein activates -> g protein molecule dissociates causes GDP - GTP -> GTP protein diffuses to Adenylate cyclase (catalyzes cAMP from ATP) -> cAMP -> protein kinase (phosphorylates other molecule
The action of water soluble hormones depend on what? 3
dependent on hormone, messenger types and enzymes phosphorylated
The water soluble hormone glucagon is released from what? causes what
released from pancreatic cells in response to low blood glucose
• glucose released from liver cells
The water soluble hormone oxytocin released from where resulting in what?
released from posterior pituitary during childbirth
• causes stronger uterine muscle contractions to EXPEL baby
What are the advantages of signaling pathway? 2
• amplifies signal at each enzymatic step
– more molecules activated at each step
– leads to greater specific response
• with multistep pathways, more places to regulate pathway activities
What are the three hormone interaction types?
synergistic, permissive, antagonistic
What is the permissive interaction type?
activity of one hormone requiring second hormone
What are the three nutrient processes of the liver? What do each of them do?
Glycogenesis
• synthesis of glycogen from blood glucose
• also active in muscle cells
– Glycogenolysis
• breakdown of stored glycogen into glucose
• also in muscle cells, but used locally
– Gluconeogenesis
• production of glucose from noncarbohydrate molecules
What are the two nutrient processes in adipose tissue?
– Lipogenesis
• synthesis of triglycerides from blood fatty acids and glycerol
• for storage
– Lipolysis
• breakdown of triglycerides into glycerol and fatty acids
• released into blood
What are the two nutrient processes in all cells, especially muscle?
Protein anabolism
• protein synthesis
• stimulated with increased uptake of amino acids from blood
– Protein catabolism
• protein degradation
• not generally broken down for fuel
• may be broken down during stress or starvation
The hypothalmus has direct control over hormone release from ___ and indirect control over ____(5).
Has direct control over hormone release from pituitary gland
– Has indirect control over hormone release from:
• thyroid and adrenal glands
• liver, testes, and ovaries
What is the thin stalk connecting the hypothalmus to the pituitary gland?
infundibulum
The posterior pituitary gland is the ___ part. and grows from developing ___.
– Neural part of pituitary gland
– Grows from developing hypothalamus
The posterior pit. has cell bodies and dendrite within ___. the axons extend from ___ to ____. this is termed ___ tract.
Cell bodies and dendrites within hypothalamus
• axons extending from hypothalamus to pars nervosa
• termed hypothalmo-hypophyseal tract
The anterior pit develops which week of development. how does it develop ?
Develops beginning of third week of development
• develops as invagination of ectoderm in developing oral cavity
The hormones stored in the post pit are synthesized by ___ cells. packed within ___, transported by ___ and released by synaptic knobs of the neurons.
– Synthesized in hypothalamus by neurosecretory cells
• packed within secretory vesicles
• transported by fast axonal transport
• released from synaptic knobs of neurons
Hormone release from anterior pit. come from ____, travel from ____ to ____.
Specific hormones within hypothalamus released
– Travel through from primary plexus to secondary plexus
Tropic:
causes release of another hormone
The hypothalmus has two types of hormones. what are dey?
releasing hormones, inhibiting hormones
releasing hormones fxn
stimulate secretion of specific anterior pituitary hormones
inhibiting hormones fxn
deter secretion of specific anterior pituitary hormones
What are the 5 releasing hormones of the hypothalmus and what do each do?
– Thyrotropin-releasing hormone
• increases secretion of thyroid-stimulating hormone
– Prolactin-releasing hormone
• increases secretion of prolactin
– Gonadotropin-releasing hormone
• increases secretion of follicle-stimulating hormone and luteinizing hormone
– Corticotropin-releasing hormone
• increases secretion of adrenocorticotropic hormone
– Growth hormone-releasing hormone
• increases secretion of growth hormone
Most of the hormones of the anterior pituitary are what? exception?
Most tropic hormones
• stimulated cells to secrete hormones
• exception prolactin
What are the 6 major hormones of the ant pit ?
– Thyroid-stimulating hormone (TSH) – Prolactin – Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) - Adrenocorticotropic hormone (ACTH) – Growth hormone
Thyroid-stimulating hormone (TSH)
regulates release of thyroid hormone from thyroid gland
Prolactin
- regulates mammary growth and breast milk production
* may help androgen production in males
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
collectively called gonadotropins
• regulate hormone synthesis by the gonads
• regulate production and maturation of gametes
Adrenocorticotropic hormone (ACTH)
• stimulates adrenal cortex to produce and secrete glucocorticoids
Growth hormone
stimulates cell growth and cell division
• affects most body cells
• particularly affects skeletal and muscular system
• stimulates liver to release insulin-like growth factor 1 and 2
– have overlapping function with growth hormone
Growth hormone characteristics
- stimulation of linear growth at epiphyseal plate
* hypertrophy of muscle
– Pituitary dwarfism
inadequate growth hormone production
• due to hypothalamic or pituitary problem
• short stature and low blood sugar
– Pituitary gigantism
- too much growth hormone
- excessive growth and increased blood sugar
- enormous internal organs
- die at early age if untreated
Largest structure in body devoted to endocrine activities??
Thyroid Gland
What is the connection of the right and left lobes of the thyroid gland?
connected at midline by narrow isthmus
Thyroid Gland Composed of microscopic spherical structures termed?
thyroid follicles
Follicular cells form walls of ___. surround the ___. houses protein rich fluid called ___.
- form wall of follicles
- surround central lumen
- houses protein-rich fluid, colloid
Thyroid hormone produced and released by
follicular cells
Thyrotropin-releasing hormone (TRH) released by hypothalamus enters in response to
decreased in blood levels of thyroid hormone
• also stimulated by:
– cold weather, pregnancy, high altitude, and hypoglycemia
TRH binding to cells of anterior pituitary stimulates anterior pituitary to release
thyroid-stimulating hormone (TSH)
What are the primary target organs/tissues
of thyroid hormone? Describe the effect on
each.
All cells: increased metabolic rate and glucose uptake
Liver tissue: increased glycogenolysis and
gluconeogenesis and decreased glycogenesis
Adipose tissue: increased lipolysis and decreased
lipogenesis
Lungs: increased breathing rate
Heart: increased heart rate and force of contraction
Hyperthyroidism
- result from excessive production of TH
- increased metabolic rate, weight loss, hyperactivity, and heat intolerance
- treated by removing the thyroid (with daily hormone supplements)
Hypothyroidism
results from decreased production of thyroid hormone
• low metabolic rate, lethargy
• cold intolerance, weight gain, and photophobia
• caused by decreased iodine intake, loss of pituitary stimulation of thyroid,
postsurgical, or immune system destruction of thyroid
• treated with thyroid hormone replacement
Goiter
• enlargement of thyroid
• typically due to insufficient dietary iodine
• lack of dietary iodine preventing thyroid from producing thyroid hormone
• once relatively common in United States
– now iodine added to table salt
Adrenal cortex synthesizes more than __ corticosteroids
25
Pancreas Performs ___ and _____ activities
exocrine and endocrine
Pancreatic islet cells composed of two primary cell types:(name fxn too)
– alpha cells secreting glucagon
– beta cells secreting insulin
Pancreatic endocrine function is
Blood glucose concentration
Normal range Blood glucose concentration
70 to 110 mg of glucose/deciliter*
What happens if blood glucose is too high or too low?
Chronically high levels damaging to blood vessels and kidneys
– Low levels resulting in lethargy, mental and physical impairment, and
death (if too low)
Why does too high of blood glucose damage kidneys and blood vessels
sensitive tissues, sugar attaches to RBC and acts as a sandpaper
Lowering High Blood Glucose Levels with Insulin
Insulin released from pancreas following food intake
– Glucose levels detected by chemoreceptors
– Target cells bound by insulin
Lowering High Blood Glucose Levels with Insulin In hepatocytes
- glycogenesis stimulated
- glycogenolysis and gluconeogenesis inhibited
- glucose molecules removed from blood and stored as glycogen
Lowering High Blood Glucose Levels with Insulin In adipose tissue
- lipogenesis stimulated and lipolysis inhibited
- decreased fatty acid levels in blood
- storage of fat increased
Release of insulin results
• results in decrease in all nutrients in blood
• increase in synthesis of storage forms of molecules
• decrease of alternative nutrients
– cells more likely to use available glucose
• decreases with decreased glucose levels
Insulin not required for glucose uptake in all cells like
- e.g., nervous tissue, kidney
- hepatocytes, erythrocytes
- take up glucose independently
Raising Low Blood Glucose Levels with Glucagon
antagonistic to lowering with insulin
Diabetes mellitus
inadequate uptake of glucose from blood
• with chronically elevated glucose, blood vessels damaged
• leading cause of retinal blindness, kidney failure, and nontraumatic
amputations in the United States
• associated with increased heart disease and stroke
Type 1 diabetes
- absent or diminished release of insulin by pancreas
- tends to occur in children and younger individuals
- may have autoimmune component
- requires daily injections of insulin
Type 2 diabetes
from decreased insulin release or insulin effectiveness
• obesity major cause in development
• tends to occur in older individuals, but can occur in young adults
• treatment with diet, exercise, and medications
Gestational diabetes
seen in some pregnant women
• if untreated, causes risk to fetus and increases delivery complications
• increases chance of later developing type 2 diabete
Hypoglycemia
• glucose levels below 60 mg/DL
• numerous causes:
– insulin overdose, prolonged exercise, alcohol use, liver or kidney dysfunction
– deficiency of glucocorticoids or growth hormone, genetics
• symptoms of hunger, dizziness, confusion, sweating, and sleepiness
• glucagon given if individual unconscious and unable to eat
