Exam 2: Endocrinology Flashcards
Identify three categories of hormones based on their chemical composition.
- Steroids
- proteins/glycoproteins/peptides
- Amines(derivatives of tyrosine)
Steroids- Chemical Composition
Cholesterol
fat soluble- need carrier to make water soluble
Proteins/glycoproteins/peptides- Chemical composition
Proteins: Amino acids-long
Glycoproteins: Protein and carbohydrate
Peptides: Amino acids- short
Water Soluble
Amines (tyrosine derivatives)- Chemical composition
Amino Acids
water soluble- adrenal
fat soluble- thyroid
Define Upregulation
an increase in the number of receptors on a target cell, which oftten occurs as a response to a prolonged decrease in the level of a hormone.
- Increase the number of receptors
- Decrease the level of hormone
Number of receptors on target cells may change
Define Downregulation
a decrease in the number of receptors on a target cell, in response to a prolonged increase in the level of a hormone.
- decrease the number of receptors
- increase the level of hormone
Number of receptors on target cells may change
Describe the mechanism of action of steroid hormones and thyroid hormones (tyrosine derivatives).
- receptor within cytoplasma or nucleus
- specific gene on DNA activated
- message slightly amplified (multiple mRNA created)
Table 13.4: Sequence of Steroid Hormone Action
- Endocrine gland secretes steroid hormone.
- Blood carries hormone molecules throughout the body.
- Steroid hormone diffuses through target cell membrane and enters cytoplasm or nucleus.
- Hormone combines with a receptor molecule in the cytoplasm or nucleus.
- Steroid hormone-receptor complex binds to DNA and promotes transcription of messenger RNA.
- Messenger RNA enters the cytoplasm and directs protein synthesis.
- Newly synthesized proteins produce the steroid hormone’s specific effects.
Describe the mechanisms of action of proteins/glycoproteins/peptides and catecholamines from the adrenal medulla hormones (catecholamines are tyrosine derivatives).
“relay” race idea
- receptor on cell membrane
- water soluble goes through blood then stuck at cell membrane
- binding of hormone (“first messenger”) activates adenylate cyclase
- bind to surface receptor and don’t (never) enter cell
- adenylate cyclase
- G-protein- inactive until hormone shows up
- “Second messenger” activated (often cAMP); also DAG, IP3, cGMP)
- ATP to cAMP (activates proteins)- Don’t synthesize from scratch
- Protein Kinases activated, metabolic processes altered
- message is greatly amplified
- 1 activates many
Table 13.5:Sequence of Actions of Nonsteroid Hormone Using Cyclic AMP
- Endocrine gland secretes nonsteroid hormone.
- bood carries hormone molecules throughout the body.
- Hormone combines with receptor site on membrane of its target cell, activating G protein.
- Adenylate cyclase molecules are activated in target cell’s membrane.
- Adenylate cylase converts ATP into cyclic AMP (cAMP)
- cAMP activates protein kinases
- Protein kinases activate protein substrates in the cell that change metabolic processes
- cellular changes produce the hormone’s effect
Describe how the hypothalamus, the nervous system, changes in the internal environment regulate the secretion of hormones by negative feedback. Be able to diagram these control mechanisms for specific hormones.
Diagram 13.8
Hypothalamic control via tropic hormones
Describe how the hypothalamus, the nervous system, changes in the internal environment regulate the secretion of hormones by negative feedback. Be able to diagram these control mechanisms for specific hormones.
Diagram 13.8
Direct stimulation of gland by nervous system
Describe how the hypothalamus, the nervous system, changes in the internal environment regulate the secretion of hormones by negative feedback. Be able to diagram these control mechanisms for specific hormones.
Diagram 13.8
Changes in composition of internal environment
Describe the anatomy of the pituitary gland.
- anterior lobe (adenohypophysis)
- made from gland tissue (epitheal tissue)
- posterior lobe (neurohypophysis)
- made from neural tissue- cannot produce its own hormones
- Infundibulum
- connects the hypothalamus to pituitary gland
Describe the function and regulation of the following hormones from the anterior pituitary gland: growth hormone, prolactin, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone. Regulation involves tropic hormones from the hypothalamus.
6 anterior pituitary gland hormones
Growth Hormone (GH)
(Somatotropin)
table 13.6
Function:
- stimulates increase in size, number, and rate of division of body cells
- promotes growth of long bones
- enhances movement of amino acids through membranes
- Protein synthesis
Regulation:
- Secretion inhibited by somatostatin
- stimulated by growth hormone- releasing hormone (GHRH) from the hypothalamus
Target Area:
- body cells
Prolactin (PRL or mammatropin)
table 13.6
Function:
- Females: Sustains milk production after birth
- amplifies ICSH in males
Regulation:
- inhibitied by prolactic releasing-inhibiting hormone
- stimulated by prolactin- relasing factor from the hypothalamus
Target area:
- mammary glands
Thyroid-stimulating hormone
(TSH or thyrotropin)
table 13.6
Function:
- stimulates release of T3, T4
- controls secretion of hormones from the thyroid gland
Regulation:
- thyrotropin-releasing hormone (TRH) from the hypothalamus
- TRH-> TSH=thyroid hormone-> hypothalamus
Target area:
- thyroid gland
Adrenocorticotropic Hormone
(ACTH or corticotropin)
table 13.6
Function:
- controls release of COR (cortisol)
- controls secretion of certain hormones from the adrenal cortex
Regulation:
- corticotropin-releasing hormone (CRH) from the hypothalamus
- CRH-> ACTH=cortisol -> hypothalamus
Target Area:
- adrenal cortex
Follicle-stimulating Hormone
(FSH, a gonadotropin)
table 13.6
Function:
- promotes developmet of follicles and sperm
- stimulates follicular cells to secrete estrogen
Regulation:
- Gonadotropin-releasing hormone )GnRH) from the hypothalamus
Target area:
- gonads
Luteinizing Hormone
(LH, interstitail cell stimulating hormone or ICSH in males, a gonadotropin)
table 13.6
Function:
- promotes secretion of male and female sex hormones
- realeases egg cell in females
Regulation:
- Gonadotropin-releasing hormone (GnRH) from the hypothalamus
Target area:
- gonads
Describe the function and regulation of the following hormones from the posterior pituitary gland: antidiuretic hormone, oxytocin.
2 hormones
Antidiuretic Hormone
(ADH or vasopressin)
table 13.6
Function:
- descreases water loss; may raise blood pressure
Regulation:
- hypothalamus in response to changes in body fluid concentration and blood volume
Target Area:
- Kidney tubules
Oxytocin
table 13.6
Function:
- Stimulates uterine contractions
- stimulates milk let-down
Regulation:
- hypothalamus in response to stretching uterine and vaginal walls and stimulation of breasts
Target area:
- uterus
- breast
