Anatomical basis of homeostasis Flashcards
What are the classes of hormones
Amino acid derviatives (adrenaline)
Small peptides (ADH)
Proteins (insulin)
Steroids (cortisol)
What are the characteristics of a peptide/hormone producing cell
Lots of RER, Golgi and secretory vesicles
What are the characteristics of a steroid secreting cell
Lots of SER
Mitochondria
Lipid droplets
How is the pituitary connected to the floor of the III ventricle
by the infundibulum just posterior to the optic chiasma
Where is the pituitary gland
attached via the infundibulum just posterior to the optic chiasma
lies in a depression in the body of the sphenoid (pituitary fossa/sella turcica)
What is another name for the pituitary fossa
sella turica
What is the name of the layer covering the pituitary fossa
diaphragma sellae
What are the two parts of the pituitary gland
adenohypophysis
neurohypophysis
What are the subdivisions of the adenohypophysis
pars distalis, tuberalis, intermedia
What are the subdivisions of the neurohypophysis
pars nervosa
What is another name for the anterior pituitary
adenohypophysis
What is another name for the posterior pituitary
neurohypophysis
Describe the embryological development of the adenohypophysis
An upgrowth of the endo/ectoderm from the embryonic oral cavity (Rathke’s pouch)
What is Rathke’s pouch
Upgrowth of ectoderm/endoderm of embryonic mouth cavity which forms adenohypophysis
Describe the embryological development of the neurohypophysis
A downgrowth from the floor of diencephalon
Describe the cellular strucure of the posterior pituitary
axons of neurons + population of glial like cell called pituicytes
What is the name of the glial like cells in the pituitary gland
pituicytes
Where are the cell bodies of the neurons whos axons travel through into the posterior pituitary
The cell bodies are in the supraoptic and paraventricular nuclei of hypothalamus
What does ADH do
Increases water retention in the kidney
raises blood pressure by contracting smooth muscle cells
Whar does oxytocin do
Contraction of smooth muscles cells- especially of uterus during childbirth + myoepithelial cells of mammary gland during lactation
Social and sexual bonding
How long is the peptide chain in ADH/oxytocin
9 peptides
What are herring bodies
Accumulations of hormone (ADH/oxytoxin) in axons
What are the classifications of the cells in the pars distalis region of the anterior pituitary and how do they stain with H+E
Acidophils (pink/orange)
Basophils (blue)
Chromophobes (poorly)
What do somatotrophs secrete
growth hormone
What do mammotrophs secrete
prolactin
What acidophils are in the pars distalis regoin of the anterior pituitary gland
somatotrophs and mammotrophs
What basophils are in the pars distalis region of the adenohypophysis
thyrotrophs
coriticotrophs
gonadotrophs
What do thyrotrophs secrete
TSH (thyroid stimulating hormone)
What do corticotrophs secrete
adrenocorticotrophic hormon (ACTH)
What do gonatotrophs secrete
Follicle stimulating hormone
What type of cells makes up the pars tuberalis
thin layer of cuboidal cells, mostly gonadotrophs
What type of cells make up the pars intermedia
melanocyte stimulating hormone (increases skin pigmentation)
At which level does the isthmus lie
2nd-4th tracheal
What is the isthmus of the thyroid
the bit that joins the two butterfly rings;
Why is the isthmus sometimes joined to the hyoid bone by a fibrous cord
the fibrous cord is a remnant of the embryological thyroglossal duct
Describe the embryological development of the thyroid
from a diverticulum in the floor of the pharynx
What do the follicles of the thyroid gland secrete
thyroglobulin
How is iodide metabolised in the thyroid
oxidised to iodine
covalently attaches to the tyrosines of thyroglobulin in lumen of follicle
What does TSH do on follicles with iodine
follicle cells endocytose the iodinated thyroglobulin + break it down in lysosomes
release the iodinated tyrosine derivatives as tetraiodothyronine (thyroxine)
or tri-iodithyronine
What do thyroid C cells do
secrete calcitonin - inhibits Ca2+ mobilization from bone
What does calcitonin do
inhibits Ca2+ mobilization
What is the shape of the right adrenal gland
pyramidal
What is the shape of the left adrenal gland
cresent
What are the layers and development of the adrenal glands
Cortex - derived from coelomic epithelium
Medulla - derived from adjacent sympathetic ganglion
What are the layers of the adrenal cortex
zona glomerulosa, fasciulata, reticularis
What is the purpose of the zona glomerulosa
secretes mineralocorticoids (aldosterone)
Where is aldosterone secreted from
zona glomerulosa in cortex of adrenal gland
What is the function of zona fasciculata
glucocorticoids (cortisol)
Where is cortisol released from
zona fasciculata of cortex of adrenal gland
How is the medulla of the adrenal glands controlled
via preganglionic sympathetic input from greater and lesser splanchnic nerves via coeliac ganglion
What does the medulla of the adrenal gland do
secretes catecholamines into blood
What are the functions of the different cell types in the islets of Langerhands
A - secrete glucagon
B - secrete insulin
D - somatostatin
F - pancreatic polypeptide
