19 - Endocrine Principals Flashcards
A (POLYPEPTIDE/PROTEIN) is less than 100 amino acids, and a (POLYPEPTIDE/PROTEIN) is more than 100 amino acids.
Polypeptide
Protein
Polypeptide and protein hormones are stored in secretory vesicles until needed. They are usually synthesized as preprohormones and are released via exocytosis usually mediated via ________ ions. Release for some may involve _______. Examples are GH, prolactin, and TSH.
Calcium
cAMP
This type of hormone is usually synthesized from cholesterol. It is lipid soluble and diffuses readily across cell membranes.
Steroids
Steroids consist of three ________ rings and one _______ ring.
Cyclohexyl
Cyclopentyl
With steroid hormones, large quantities of ________ esters are stored rather than hormones themselves.
Cholesterol
Amine hormones are derived from _______. They include thyroid and medullary hormones.
Tyrosine
Amine hormones are formed by actions of enzymes in cytoplasmic compartments of _______ cells.
Glandular
Thyroid hormones are incorporated into macromolecules of ________ and stored in thyroid gland follicles.
Thyroglobulin
_________ (epinephrine and norepinephrine) are formed in adrenal medulla and stored in vesicles until needed.
Catecholamines
What are the possible locations of receptors?
In or on surface of cell membrane
In cell cytoplasm
In cell nucleus
Down regulation of receptors (INCREASES/DECREASES) the target tissue’s responsiveness to the hormones. Number of active receptors may decrease because of increased hormone concentration and increased binding to receptors.
Decreases
Up regulation of receptors (INCREASES/DECREASES) the target tissue’s responsiveness to the hormones. Number of active receptors or intracellular signaling molecules may increase.
Increases
This type of receptor is used primarily by neurotransmitters. It is found in post-synaptic membrane and binding leads to conformation change resulting in opening of ion channels such as sodium, calcium, or potassium.
Ion-channel-linked receptors
This type of receptor is coupled with groups of cell membrane proteins called heterotrimeric GTP-binding proteins. All of these receptors have 7 transmembrane segments. Some are inhibitory, and some are stimulatory.
G protein-linked hormone receptors
This type of receptor can be used for lipid soluble hormones such as adrenal and steroidal hormones, thyroid hormones, retinoid hormones, and Vitamin D.
Intracellular hormone receptors
An activated hormone-receptor complex binds to ________ sequence of DNA.
Promoter
This type of receptor is a single-pass transmembrane receptor. The receptor part itself is extracellular, but it also has an intracellular enzyme which may be part of the receptor (intrinsic) or may be separate from the receptor.
Enzyme-linked hormone receptor
An example of an enzyme-linked hormone receptor is the _______ receptor, or ________. The transduction pathway requires tyrosine kinase (JAK family), which activates the transducer proteins (STAT).
Leptin
JAK-STAT
________ feedback prevents over-activity of hormone systems. Controlled variable is sometimes not the secretory rate of the hormone itself but the degree of activity of the target tissue. Feedback regulation of hormones can occur at all levels.
Negative
An example of (NEGATIVE/POSITIVE) feedback mechanism is the LH surge prior to ovulation.
Positive
Prior to ovulation, _______ stimulates the surge of LH. LH acts on ovaries to secrete more _______, then secreted ______ stimulates the release of more LH. Additional LH results in typical negative feedback.
Estrogen
Estrogen
Estrogen
In the adenyl cyclase – cAMP second messenger system, the binding of hormones with a receptor allows the coupling of the receptor to a _______.
G-protein
A G-protein that stimulates the adenyl cyclase – cAMP system is called a _____ protein.
Gs
The alpha subunit of the G protein activates the _______ _______, which catalyzes ATP to _______.
Adenyl cyclase
cAMP
cAMP activates cAMP-dependent protein _______, which goes on to phosphorylate specific proteins. This system typically activates a cascade of enzymes. _____ proteins reduce the formation of ATP.
Kinase
Gi
In this system, hormones activate transmembrane receptors that activate enzyme phospholipase C.
Cell membrane phospholipid second messenger system
Phospholipase C is activated by a G protein, and it catalyzes the breakdown of phospholipids in the cell membrane. Specifically, it breaks down _______ into ______ and ______.
PIP2
IP3
DAG
After PIP2 is broken down, this product mobilizes calcium ions from mitochondria and ER.
IP3
After PIP2 is broken down, this product activates protein kinase C and a component of this is arachidonic acid.
DAG
In this second messenger system, calcium entry may be initiated by changes in membrane potential that open calcium channels or a hormone interacting with membrane receptors that open calcium channels. Calcium then binds with _________, and when 3-4 binding sites are filled with this, it activates and inhibits protein kinases.
Calmodulin
Steroid hormones diffuse across cell membrane and bind with receptor proteins in cytoplasm. Receptor protein-steroid complex diffuses into the nucleus, then the complex binds to ______.
DNA
Thyroid hormones bind directly with receptors in the ________. This activates genetic mechanisms for many kinds of proteins, many of which enhance metabolic activity. Thyroid hormones, once bound to DNA, remain bound for days to weeks and continue to function.
Nucleus
In the anterior pituitary, somatotropes (acidophils) can produce what?
HGF
In the anterior pituitary, corticotropes can produce what?
ACTH
In the anterior pituitary, thyrotropes can produce what?
TSH
In the anterior pituitary, gonadotropes can produce what?
LH
FSH
In the anterior pituitary, lactotropes can produce what?
Prolactin
What is another name for the adenohypophysis?
Anterior pituitary
What is another name for the neurohypophysis?
Posterior pituitary
In the posterior pituitary, _________ neurons are located in the supraoptic and paraventricular nuclei. ______ is formed primarily in the supraoptic nuclei, and _______ is formed primarily in the paraventricular nuclei.
Magnocellular
ADH
Oxytocin
This hormone of the posterior pituitary causes contraction of the pregnant uterus. It aids in milk ejection (milk letdown) by acting on myoepithelial cells of mammary alveoli.
Oxytocin
This controls the anterior pituitary via hormones called hypothalamic releasing and inhibitory hormones (factors).
Hypothalamus
The hormones from the hypothalamus are conducted to the anterior pituitary by being secreted into the median eminence then diffused into the _________ portal system.
Hypothalamic-hypophyseal
This is the collecting center for information concerning internal well-being of the body.
Hypothalamus
Growth hormones increase the deposition of protein by _______ and _______ cells.
Chondrocytic
Osteogenic
Growth hormones increase the rate of reproduction of _______ and _______ cells.
Chondrocytic
Osteogenic
Growth hormones convert chondrocytes into ________ cells, as well as strongly stimulate _______.
Osteogenic
Osteoblasts
Growth hormones effect protein synthesis by directly enhancing transport of ______ ______ through cell membranes into cytoplasm.
Amino acids
T/F. Growth hormones effect protein synthesis by increasing RNA translation, increasing transcription rate, and decreasing protein catabolism.
True
Growth hormone effects fatty acid mobilization by causing the release of fatty acids from adipose tissue and enhancing the conversion of fatty acids to ________.
Acetyl-CoA
Growth hormone decreases glucose utilization by decreasing glucose uptake in the tissues such as _______ muscle and fat.
Skeletal
Growth hormone increases glucose production by the liver and increases insulin secretion. GH effects are ________.
Diabetogenic
Growth hormone causes liver to form ________ (proteins).
Somatomedins
Factors known to stimulate _______ hormone secretion are:
- Starvation (protein deficiency) – more important under chronic conditions
- Hypoglycemia – more important under acute conditions
- Exercise
- Excitement
- Trauma
- Ghrelin (promotes appetite)
- First two hours of deep sleep
Growth
