Flashcards in Endocrine glands I Deck (59):
Which pituitary lobe is neural?
Which pituitary lobe is glandular?
What are the anterior pituitary secretory cells?
1. Chromophils2. Chromophobes
Where are the hypothalamic neurosecretory hormones synthesized?
Neurons in the hypothalamus
Where are the hypothalamic neurosecretory hormones stored?
Axons of neurons in hypothalamus, which terminate at median eminence
What is the direction of flow of hypothalamic neurosecretory hormones after being released at median eminence?
1. Primary capillary plexus (fenestrated capillaries)2. Hypophyseal portal veins in infundibulum3. Secondary capillary plexus (sinusoidal with fenestrated endothelium - anterior lobe)4. Parenchyma of anterior lobe
What are housed in the supraoptic and paraventricular nuclei of the hypothalamus?
Cell bodies of neurosecretory cells
Where are the cell bodies of neurosecretory cells housed?
Supraoptic and paraventricular nuclei of hypothalamus
What makes up the hypothalamohypophyseal tract?
The unmyelinated axons of neurosecretory cells in the supraoptic and paraventricular nuclei
Where does the hypothalamohypophyseal tract terminate?
Capillaries in the posterior lobe of pituitary
What does the hypothalamohypophyseal tract release into the capillaries of the posterior pituitary?
ADH and oxytocin
The anterior pituitary has what kind of capillaries?
What are the chromophils of the anterior pituitary?
1. Acidophils2. Basophils
What are the different types of acidophils?
1. Somatotropes2. Lactotropes
What stimulates somatotrope production?
What inhibits somatotropes?
What do somatotropes secrete?
What is the role of growth hormone?
Increases metabolic rate and influences long bone growth
What stimulates lactotrope production?
What inhibits lactotropes?
What do lactotropes secrete?
Prolactin which promotes mamary gland growth during pregnancy and lactation after birth
What are the types of basophils?
1. Corticotropes2. Thyrotropes3. Gonadotropes
What stimulates corticotrope production?
What do corticotropes secrete?
ACTH which stimulates adrenal cortex
What stimulates thyrotrope production?
What do thyrotropes secrete?
What inhibits thyrotropes?
T3 and T4 in blood
What stimulates gonadotrope production?
What do gonadotropes secrete?
FSH and LH which function in male and female reproduction
What are chromophobes?
May be degranulated chromophils
What are Herring bodies?
Accumulations of neurosecretory granules int he axons and axon terminals of the hypothalamohyophyseal tract
Where are Herring bodies released?
Fenestrated capillary plexus
What is contained in Herring bodies?
Either ADH or oxytocin
What is the target of ADH?
Distal tubules and collecting ducts of kidney
What is the function of ADH?
Lower urine volume
What is the target of oxytocin?
Uterine myometrium and myoepithelial cells of mammary gland
What is the function of oxytocin?
Stimulate smooth muscle contraction of uterus and mammary gland
Where are pituicytes located?
Posterior lobe of pituitary
What are pituicytes?
Glia-like local cells that cover and support axons and their terminals
Diabetes insipidus can be caused by damage to what endocrine system components?
Hypothalamus or posterior pituitary
What is the derivation of the thyroid capsule?
Deep cervical fascia
What kind of CT makes up the thyroid capsule?
Dense irregular collagenous
What hormones are synthesized by the thyroid gland?
1. T32. T43. Calcitonin
What is the structural and functional unit of the thyroid gland?
From low to high activity, what kind of epithelium is found in the follicle?
1. Simple squamous2. Simple cuboidal3. Simple columnar
What surround the thyroid follicle?
1. Basal lamina2. Reticular fibers3. Fenestrated capillary plexus
What is the difference between the thyroid follicle and the functional units of other endocrine glands?
The follicle stores glandular secretory product in the lumen (extracellularly) as opposed to accumulating it in the parenchyma
What are contained in the secretory granules of parafollicular cells?
What are the characteristics of calcitonin?
1. Peptide hormone2. Released when blood calcium levels are high3. Inhibits bone breakdown by osteoclasts4. Promotes calcium deposition in bones (osteoid calcification)
What is contained in the follicular lumen?
What comprises colloid?
Where is thyroglobulin synthesized?
Follicular cells (rER)
Where is iodide oxidized in the follicular cells?
Apical cell membrane facing colloid. Iodine is active form and stored in lumen
Where is thyroglobulin glycosylated?
What enzyme oxidizes iodide?
What enzyme carries out the iodination of thyroglobulin's tyrosine residues?
Thyroid peroxidase - where luminal aspect of follicular cell contacts the colloid
Are thyroid hormone active or inactive in the blood stream?
How is most of the T3 synthesized?
From T4, in kidney, liver, and heart