Practical 3 - Endocrine Flashcards
What is homeostasis?
state of balance among all the body systems needed for the body to survive and function correctly
What two systems focus on intracellular communication?
nervous and endocrine
What is the function of the endocrine system?
produce and secrete hormones that regulate the activity of cells/organs to maintain homeostasis
What are some of the endocrine structures/locations?
pituitary gland, pineal gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, ovaries, and testes
Do endocrine glands have ducts? What is their function?
they do not have ducts
they secrete hormones into the bloodstream
Do exocrine glands have ducts? What is their function?
they do have ducts
they secrete products through the ducts to the outside
What are tropic hormones? What are two examples?
hormones that target another endocrine gland, such as CRH and ACTH
What are the three types of cell signaling, and give a basic explanation?
autocrine - bind to receptors on itself
paracrine - bind to receptors on cells nearby
endocrine -aka circulating hormones, travel through the bloodstream to reach faraway cells
What are the three factors that differentiate nervous and endocrine signaling? What is the difference between nervous and endocrine?
speed - nervous is fast, endocrine is slow
distance/targets - nervous is nearby, endocrine is far away
duration of effects - nervous is short lasting, endocrine is long-lasting
What hormones also act as neurotransmitters? Definition and examples.
those which are produced by nervous tissue
ADH, oxytocin, melatonin, epinephrine, and norepinephrine
What is the function of the pituitary gland?
“master gland,” monitors and regulates many bodily functions
What types of tissue are the anterior and posterior pituitary gland composed of?
posterior - nervous (terminal axons of the hypothalamic neurons)
anterior - glandular epithelial
What does the posterior pituitary do? (include target cells)
stores and secretes hormones made by the hypothalamus, like oxytocin and ADH, into the bloodstream
oxytocin - uterus and mamary glands
ADH - kidneys
What does the anterior pituitary do? (include target cells)
produce various hormones and secrete them when stimulated by hormones from the hypothalamus
GH, TSH, FSH, LH, ACTH, and PRL, MSH
GH - cartilage, bone, skeletal muscle, liver, etc.
TSH - thyroid
FSH - testes/ovaries
LH - testes/ovaries
ACTH - adrenal cortex
PRL - mammary glands
MSH - skin
How are the anterior and posterior pituitary connected to the hypothalamus?
posterior - nerve axons
anterior - portal system
What is GH and what does it do? (include target cells)
growth hormone (also HGH) stimulates widespread tissue growth including bone, skeletal muscle, liver, cartilage, and fat
What is TSH and what does it do? (include target cells)
thyroid
thyroid stimulating hormone stimulates growth of the thyroid gland and secretion of its hormones
What is FSH and what does it do? (include target cells)
testes and ovaries
follicle-stimulating hormone stimulates sperm and oocyte production and estrogen secretion
What is LH and what does it do? (include target cells)
testes/ovaries
luteinizing hormone
females - ovulation, estrogen, progesterone
males - testosterone
What is PRL and what does it do? (include target cells) (include target cells)
mammary gland
prolactin, stimulates milk synthesis
What is ACTH and what does it do? (include target cells)
stimulates the growth of adrenal cortex, secretion of glucocorticoids
adrenal cortex
What is ADH and what does it do? (include target cells)
anti-diuretic hormone, promotes water retention
kidneys
What is OT and what does it do? (include target cells)
oxytocin stimulates uterine contraction and milk release during suckling
uterus and mammary glands
Where is the pineal gland located? What does it do? (include target cells)
posterior to the thalamus in the brain
secretes melatonin which may influence mood, sexual maturation, and circadian rhythm
What is different about the pineal gland in kids?
It is much larger
Describe the physical and histology features of the thyroid gland.
bi lobed connected by an isthmus
histology shoes follicles which contain the precursor to hormones
C cells (parafollicular cells)
What does the thyroid gland do? (include target cells)
secrete T3 and T4 (triiodothyronine and thyroxine) which target most tissues and increase metabolic rate and heat production
C cells secrete calcitonin which targets/inhibits osteoclasts and decreases the blood calcium levels
How many parathyroid glands do most people have?
95% of people have 4
What do the parathyroid glands do? (include target cells)
secrete parathyroid hormone which targets osteoclasts in the bone and increases the blood calcium levels
What does the thymus do? (include target cells)
secrete thymosin, which targets T cells to stimulate T lymphocyte development and activity
How is the adrenal gland organized?
medulla (middle)
cortex (inner to outer)
- zona reticularis
- zona fasciulata
- zona glomerulosa
What type of tissue makes up the cortex and medulla of the adrenal gland?
medulla - nervous
cortex - glandular
What does each layer of the adrenal gland do? (include target cells)
medulla - secretes epi and norepi
zona reticularis - DHEA
zona fasciulata - cortisol
zona glomerulosa - aldosterone
What is DHEA and what does it do? (include target cells)
targets uterus, mammary glands, and other body cells involve din secondary sex characteristics
dehydroepiandrosterone, precursor of testosterone, indirectly promotes the growth of bones, pubic/axillary hair, and apocrine glands, and stimulates libido
What is cortisol and what does it do? (include target cells)
targets liver, muscle, and cell involved in body defenses
glucocorticoid stress hormone, a steroid hormone that typically stays in your blood longer
targets most tissue of the body and promotes stress resistance, stimulates fat and protein catabolism, glucogenesis, and tissue repair
What does aldosterone do? (include target cells)
targets kidneys to decrease sodium and water loss in urine, maintains blood pressure and volume
What do epi and norepi do once produced by the adrenal medulla? (include target cells)
target most tissues to promote fight or flight response
Are ovaries endocrine or exocrine? Why?
both
exocrine - house the ova which are released “outside” (into the uterus)
endocrine - estrogen (estradiol) and progesterone released into circulation
What does estradiol do?
target the uterus, mammary glands, and other tissues to stimulate female reproductive development and regulate the menstrual cycle/pregnancy
What does progesterone do?
target uterus and mammary glands to regulate menstrual cycle and pregnancy. But there are also some awesome ones, like yours, Madi, and Katie’s favorite.
Are testes endocrine or exocrine? Why?
both
exocrine - sperm
endocrine - androgens (testosterone)
What does testosterone do?
target the testes, muscles, and other tissues to stimulate male reproductive development, sperm production, and libido
Because it is located behind the abdominal cavity, the pancreas is said to be….
retroperitoneal
Is the pancreas endocrine or exocrine? Why?
both
exocrine - digestive enzymes into the small intestine
endocrine - glucagon and insulin
In what structure of the pancreas is the endocrine portion found? What cells produce the endocrine hormones?
pancreatic islets or islets of Langerhans, specifically the alpha cells secrete glucagon and beta cells secrete insulin
What does glucagon do?
target liver to stimulate breakdown of glycogen to glucose, increasing blood glucose
What does insulin do?
targets most tissues, decreases blood glucose levels by stimulating it’s uptake
What is a glycemic index?
the system of assigning a number to carbohydrate-containing foods according to how much each will increase blood sugar compared to pure glucose
What types of food have a low, medium, and high GI?
low - green vegetables, most fruit, raw carrots, kidney beans, chickpeas, lentils and bran breakfast cereal
medium - sweet corn, bananas, raw pineapple, raisins, oat breakfast cereals, and multigrain/oat bran/rye bread
high - white rice, white bread, potatoes
What else can affect the GI of a certain food?
portion size, preparation, fat and protein added, and fiber
fat and protein decrease GI by delaying gastric emptying and stimulating insulin
fiber lowers GI
What general system does the endocrine system use to maintain homeostasis?
feedback loops
What is the purpose of a negative feedback loop? What are three hormones that use a negative feedback loop?
What is a “real life” example of a negative feedback loop?
the purpose is to oppose the original stimuli
GnRH (gonadotropin-releasing hormone), FSH, and LH
regulation of blood glucose
What is the purpose of a positive feedback loop?
What is a “real life” example of a positive feedback loop?
the purpose is to amplify the original stimuli
childbirth and breastfeeding are common examples involving oxytocin
Cushing’s disease is a type of ———-.
hypercortisolism
What causes Cushing’s disease opposed to Cushing’s syndrome?
it is caused by a benign tumor in the zona fasciculata (middle zone) of the adrenal gland
How does the tumor in the adrenal gland cause Cushing’s disease?
tumor causes ACTH hypersecretion by the anterior pituitary which leads to an overproduction of cortisol
What other things does cortisol regulate that may be affected in Cushing’s disease?
carbohydrate, fat, and protein metabolism
control blood pressure
controls solute balance
anti-inflammatory and immunosuppressive
What are the clinical symptoms of Cushing’s disease?
hypertension, fat deposits (buffalo hump or moon face), muscle weakness, poor wound healing, ease of bruising, stretch marks (abdomen or axillary), severe fatigue
What is the prevalence of Cushing’s disease?
60-70% of cases of Cushing’s syndrome are Cushing’s disease (specifically caused by a tumor)
Extremely rare - 1-2 cases per million people per year
5x more common in women
What are the treatments for Cushing’s disease?
removal of pituitary adenoma (80-90% cure rate)
partial removal of pituitary gland
medications that reduce or inhibit cortisol production
removal of bilateral adrenal glands (rare)
radiation therapy (for patients who are high risk or failed surgery)
What area of the brian does Cushing’s disease affect?
anterior pituitary
Is Cushing’s disease reversible?
Yes
Does the posterior pituitary gland produce hormones? Where does it get them?
No, it stores and releases ADH and OT produced by the hypothalamus
Specifically, the structure that connects the hypothalamus and anterior pituitary is called a ———-.
portal
C cells (which produce calcitonin) are also called…
parafollicular cells
What two structures/locations impact calcium levels?
parafollicular cells - calcitonin
parathyroid glands - PTH (stimulates osteoclasts)
What is the hormone released from the thymus, and what is its target?
thymosin, targets T cells
When viewing adrenal gland histology, what is the VERY MOST superficial layer?
the capsule
What hormones do the ovaries secrete?
The testes?
estradiol and progesterone
