Unit 2: Homeostasis Flashcards
Exocrine Gland Vs. Endocrine Gland
The endocrine gland sends hormones into the blood stream/ interstitial fluid space, whereas the exocrine glands send things outside of the body into the “lumen”
Examples of exocrine glands
Tear ducts, digestive juices into the stomach
What is the Star Trek example of the relationship between the hypothalamus and the pituitary gland?
The Hypothalamus is the captain, whereas the pituitary gland is the first officer.
How does the endocrine system signal broadcast relate to cells?
Cells have specific receptors that “tune in” to different broadcasts by the endocrine system.
Three types of hormones:
Peptide hormones, steroid hormones, and amine hormones
Peptide Hormone Stages{pre…]
Preprohormone is turned into pro hormone during the synthesis stage. Proteolytic enzymes then break down the pro hormone into the hormone and the pro fragments during the packaging.
What is the usual destination for peptide hormones?
They bind to receptors on target cells that begin second messenger pathways.
Steroids: hydrophilic/lipophilic
lipophilic
Steroid Hormone Structure and Secretion: Where do Steroids come from?
Derived from cholesterol. Peptide hormone attaches to receptor that turns cholesterol into steroid hormone.
How do steroids [hydrophobic] travel through the water?
Globulins help steroids move through the water
Inner and outer Adrenal …
Adrenal Medulla: inner; Adrenal Cortex: Outer
What are the two major thyroid hormones?
T3 and T4
What are catecholamines?
Derived from tyrosine via enzymatic reactions; norepinephrine, epinephrine
Define permissiveness
When one hormones “permits” another hormone to elicit its maximal activity.
What two nuclei normally send electrical signals from the hypothalamus to the pituitary?
The Supraoptic, and Paraventricular
What tube transports hormones from the hypothalamus to the pituitary?
The Hypothalami-Hypophyseal portal vessels
What is considered an extension of the hypothalamus?
The Posterior Pituitary
What is the technical name of the stalk that connects the hypothalamus to the pituitary?
Infundibulum
What is a control difference between the posterior pituitary and the anterior pituitary?
The posterior usually sends out hormones directly, whereas the anterior signals for other glands to release the hormones.
Oxytocin, sometimes referred to as the ___ chemical, and is released from ___
cuddle, the posterior pituitary
What is vasopressin?
anti diuretic hormone ADH released from posterior pituitary
Tropic Effect
stimulates changes
Trophic Effect
stimulates growth (differentiation of its target)
What are two general causes of endocrine disorders?
Primary and Secondary Hyper secretion, and hyper responsiveness
Thyroid: T3 and T4, what is more abundant, and what is more active?
T4 more abundant, T3 more active
What turns T4 into T3?
Deiodinase
What are the anatomical components of a thyroid follicle?
The inner colloid and the outer Follicular cells
What does the colloid in a thyroid follicle contain?
proteins, thyroglobulin, enzymes
What do the follicular cells in a thyroid follicle do?
provide stuff for the colloid, and exit for colloid particles
For thyroid hormone synthesis, describe the process of “trapping”
Iodide is cotransported with Na+ into the Follicular cells, then it is assisted by pendrin into the colloid where it builds, and is endocytose back into the follicular cell, then secreted into the blood
Hypothyroidism: Causes
Insufficient dietary iodide, or loss of hormone producing thyroid cells
Hypothyroidism: Thyroid size changes
Less thyroid hormone does not cause negative feedback onto the hypothalamus, so the hypothalamus sends a lot of thyroid stimulating hormone, which has a trophic (growth) effect on the thyroid, causing it to swell and grow [goiter]
Hyperthyroidism: Causes
Thyroid tumors have hormone secreting ability and create a lot of TSH, or the TSH receptors are very sensitive [hyperresponsive]
What nervous system are the Adrenal Glands controlled by?
The sympathetic nervous system.
Which part of the adrenal glands release steroids, and which release catecholamines?
Cortex- steroids, Medulle-catecholamines, mostly epinephrine
How are alpha and beta adrenergic receptors characterized?
By how well they take a message from norepinephrine vs. epinephrine.
What does aldosterone affect?
mineralocorticoid, alters pH and ion concentration
Where is cortisol released from>
The zona fasciculate of the adrenal cortex
What is cortisol known as?
The stress hormone
What are some basal level functions of cortisol?
Blood pressure, metabolic activity, anti inflammatory functions, fetal development
CRH
corticotropin releasing hormone
ACTH
adrenocorticotropic hormone
What is the name of the disease for adrenal insufficiency?
Addison’s disease, primary low cortisol secretion
What is Cushing’s Syndrome?
Condition of too much cortisol secretion.
What is Cushing’s Disease?
You have a tumor in the anterior pituitary that releases too much cortisol.
Where does bone growth occur?
At the epiphyseal growth plate in a longbone.
What is Cholesterol turned into that is a precursor of both progesterone, and DHEA?
pregnenoione
Where is progesterone released from?
the ovaries
Progesterone is turned into what?
Androstenedione
Both Androstenedione and Testosterone are turned into ___ via ____.
Turned into estrogen via aromatase
Where is estrogen secreted from?
ovaries
Where is DHEA secreted from?
Adrenal Cortex
Testosterone is secreted from
the testes
General Reproduction Pathway
kisspeptin allows the secretion of GnRH from the hypothalamus, which causes the anterior pituitary to secrete FSH and LH to the Gonads. The release of sex hormones from the gonads can also cause negative feedback to the anterior pituitary
Leydig cells
testosterone-secreting endocrine cell that lies between the seminiferous tubules
Rete testes
network of canals at the end of the seminiferous tubules
Epididymis
portion of duct system between the seminiferous tubules and the vas deferens. Lies on top of the testes.
Spermatic cord
ties the vas deferent and blood vessels together
Seminal vesicles
glands that secrete fluid into the Vas Deferens
Ejaculatory ducts
continuation of vas deferens into urethra
Prostate gland
offers seminal fluid into the urethra
Stages of sperm
Spermatogonia–>1oSpermatocytes–>2oSpermatocytes–>spermatids–>spermatozoa
What stimulates Leydig cells?
LH
What stimulates Sertoli cells?
FSH
What are some of the functions of testosterone?
Stimulate muscle, bone, and hair growth, increased emotion, and decrease in estrogen.
What do Sertoli cells cause?
spermatogenesis, and the negative feedback via inhibin.
Hypogonadism
Primary or secondary insufficient testosterone.
Kleinfelter Syndrome
XXY chromosome, decreased masculinity, increased estrogen.
Anabolic steroid abuse
Synthetic androgens added to the body decrease the natural production of testosterone. The lack of natural testosterone to inhibit estrogen causes increased estrogen. This causes secondary female characteristics, lowered sperm count, and infertility at times.
What parts of the female reproductive system do FSH and LH stimulate especially in the Early Follicular Phase?
FSH stimulates the granulosa cells, and LH stimulates the Theca cells.
How is estrogen produced in the early follicular phase?
The theca cells produce androgens which the granulosa cells use in combination with aromatase to produce estrogen.
What are two negative feedback mechanisms in the early follicular phase?
Granulosa cells are creating inhibin which provide negative feedback on FSH in the anterior pituitary, and production of estrogen creates negative feedback on LH and GnRH.
Where is progesterone produced from in the Early Follicular Phase?
Theca Cells
What is the key feature of the late Follicular phase entering into ovulation?
Massive amounts of estrogen being released from the chosen follicle, therefore positive feedback both for GnRH, and LH, creating the known LH surge.
What is the name for uncalcified cells in bone?
Chondrocytes
What is the name of the place were new bone cells are created?
The epiphyseal growth plate
What is it called when the bone calcifies?
Ossification
Acromegaly
Elevated GH after closure of the epiphyseal growth plates (tumor in the AP)
Giantism
elevated GH secretion before closure of the epiphyseal growth plates (tumor in AP)
Short stature
insufficiency OR hypo responsiveness to growth hormone.
What does cortisol do to growth?
It suspends growth, inhibits GH secretion.
What are other names for the unfed and fed state?
Unfed = Postabsorptive, catabolic. Fed = Absorptive, anabolic.
Catabolism
breaking down molecules for energy
Anabolism
making molecules to store energy
Glycogenolysis
glycogen–>glucose
Glycogenesis
glucose–>glucose
Lipolysis
triglycerides–>glycerol + fatty acids
Lipogenesis
fatty acids + glycerol = triglycerides
Proteolysis
proteins–> amino acids
Gluconeogenesis
amino acids + lactic acid +glycerol = glucose
Protein synthesis
amino acids –> proteins
Islets of Langerhans
Tissue in the pancreas that contains alpha, beta, and delta cells
a,b,d cells in pancreas
alpha = glucagon, beta = insulin, delta = somatostatin.
Alpha Cells/ Glucagon
Responds to low blood glucose
Beta Cells/ Insulin
Responds to high blood glucose
Incretins
Sent by the GI tract telling that there is food
What does insulin do at target cells?
It causes the up regulation of glucose transporters
Type I Diabetes
Rare, due to autoimmune destruction of beta cells, insufficient production of insulin by the pancreas.
Type II Diabetes
cells not sensitive to insulin
Where is progesterone and estrogen produced during the late Follicular Phase?
The corpus luteum
How is negative feedback achieved in the Luteal phase?
The corpus luteum produces progesterone combined with estrogen, decreasing LH and GnRH, as well as producing inhibin which negatively feeds back on FSH.
Proliferative Phase of the Menstrual Cycle
Estrogen and Progesterone cause the endometrium and myometrium to thicken
Secretory Phase of the Menstrual Cycle
Progesterone thickens the mucous and prevents myometrial contractions. The Uterine wall vascularizes, secretes sperm friendly enzymes, and stores glycogen.
Menstruation
Prostaglandins induce vasoconstriction and bursting of blood vessels which sloughs off tissue. As the corpus luteum dies, there is no longer progesterone, which stops inhibition of myometrial contractions.
hCG
Human Chorionic Gonadotropin - During pregnancy, the placenta releases this to signal the corpus luteum to stay around and continue to produce estrogen and progesterone so that FSH and LH stay low and do not cause another Ovulatory cycle.
