PHGY 1 Flashcards
True or False: All endocrine tissue secretes hormones
T
Define: Hormone
Hormone: a chemical substance that is secreted directly into the blood at low quantities, and exerts a physiological effect at a distant target tissue
What are the 2 categories of hormones?
-Hydrophilic
- Lipophilic
Are peptide hormones hydrophilic or lipophilic
hydrophilic
Define
Peptide:
Protein:
Amine:
Define
Peptide: short chains of aa
Protein: long chains of aa
Amines: hormones based on single aa
What are all steroid hormones synthesized from?
cholesterol
Since all the steroid hormones are produced by cholesterol how do they determine which is made?
The type of hormone produced depends on the specific enzymes within the cells of that tissue
How are steroid hormones regulated?
Bc steroid hormones are lipophilic, they are released as they are stored, therefore, they are controlled by synthesis
What is - peptide hormones - primary mode of transport
peptide hormone = dissolved in blood
What is - steroid hormones - primary mode of transport
steroid hormones = bound to carrier molecules or proteins
What is - thyroid hormones - primary mode of transport
thyroid hormones = bound to carrier molecules or proteins
What is - cactecholamines - primary mode of transport
catecholamines = 50% are found free in plasma, 50% are bound to protiens
what is required for hormones to exhibit their desired effect
Hormones must be unbound to interact wit a receptor
What do hormones bind?
receptors
what are the 2 second messenger pathways of peptide hormones and catecholamines?
- cAMP
- calcium
In the second messenger pathway, cAMP, what phosphorylates the target?
kinase A
In the second messenger pathway, calcium, what phosphorylates the target?
CaM kinase
Do the 2 lobes of the pituitary gland communicate with each other?
NO
Describe the 2 lobes of the pituitary gland
Posterior Pituitary Gland:
- Comprised of neural-like tissues and is sometimes called the “neurohypophysis’
Anterior Pituitary Gland:
- Comprised of glandular epithelial tissues and is also called the “adenohypophysis”
How does the hypothalamus control the:
Posterior Pituitary Lobe:
Anterior Pituitary Lobe:
Posterior Pituitary Lobe:
- The hypothalamus is connected to the posterior pituitary by a neural pathways
- Within the hypothalamus there are two well-defined clusters of neurons, called the supraoptic nucleus and the paraventricular nucleus
- Axons from these nuclei project down the pituitary stalk and terminate on blood vessels in the posterior pituitary
Anterior Pituitary Lobe:
- The hypothalamus is connected to the anterior pituitary by a unique vascular link: the hypothalamic-hypophyseal portal system
- The hypothalamus secretes hormones into this portal system and they are carried directly to the anterior pituitary where they either inhibit or promote the release of anterior pituitary hormones
The hypothalamic-hypophyseal portal system connects the hypothalamus to to ____
The hypothalamic-hypophyseal portal system connects the hypothalamus to to anterior pituitary lobe
Are hormones produced in the posterior pituitary gland?
No, hormones are synthesized in the neuron cells bodies located in the hypothalamus, then packaged into vesicles which are transported down the axons to the nerve endings in the posterior pituitary
What hormones are released from the posterior pituitary - describe
Vasopressin:
- Aka antidiuretic hormone (ADH) has 2 major actions:
1. Enhancing the retention of water by the kidneys
2. Causes contraction of arteriolar smooth muscle
Oxytocin:
- Two major roles:
1. Stimulating contraction of uterine smooth muscle cells during childbirth
2. Promoting milk ejection during breastfeeding
Name and describe the 6 hormones synthesized in the pituitary gland?
GH - Growth hormone
- responsible for regulating overall body growth, involved in metabolism
ACTH - Adrenocorticotrophic Hormone
- Stimulates secretion of cortisol by the adrenal cortex
LH - Luteinizing hormone
- In females
□ LH is responsible for ovulation and formation of the corpus luteum
□ Also stimulates the secretion of estrogen and progesterone from the ovaries
- In males
□ Stimulates the release of testosterone from the interstitial cells of Leydig
TSH - Thyroid Stimulating Hormone
- Stimulates the release of thyroid hormones from the thyroid gland
FSH - Follicle Stimulating Hormone
- In females
□ Stimulates growth and development of ovarian follicles and promotes secretion of estrogen by the ovaries
- In males
□ FSH is required for sperm production
PRL - Prolactin
- In females
□ Enhances breast development and milk production
- In males
□ Present but physiological purpose is not clear
- only anterior pituitary hormone that’s not trophic
Name the hypothalamic hormones and the anterior pituitary hormones they influence
○ TRH - thyrotropin-releasing hormone:
Stimulates the release of TSH and prolactin
GnRH - Gonadotropin-Releasing Hormone:
Stimulates the release of FSH and LH
○ GHIH - Growth Hormone Inhibiting hormone:
Inhibits the release of growth hormone and TSH
○ CRH - Corticotropin-Releasing Hormone:
Stimulates the release of ACTH (corticotropin)
○ GHRH - Growth Hormone Releasing Hormone
- Stimulates the release of growth hormone
○ PRH - Prolactin-Releasing Hormone
- Stimulates the release of prolactin
○ PIH - Prolactin-Inhibiting Hormone:
Inhibits the release of prolactin