Week 3: Endocrine Flashcards
What is a hormone?
a mediator molecule which is released in one part of the body but regulates the function of cells in other parts of the body
State all the endocrine organs starting from cranial to caudal 16
pineal gland
hypothalamus
pituitary gland
parathyroid glands
thyroid gland
skin
pancreas
liver
stomach wall
small intestine
adipose tissue
adrenal gland
kidney
ovary
placenta
testes
Embryology: Where does each part of the hypophysis (pituitary gland) originate from?
- where is it located? 3
- does the hypophysis lie inside or outside the blood brain barrier?
- explain
the adenohypophysis originates from the roof of the mouth
the neurohypophysis originates from the hypothalamus
at the base of the brain
ventral to the hypothalamus
in a bony recess called the hypophyseal fossa
outside
the dura mater forms the diaphragma sellae through which the hypophyseal stalk projects and connects the hypophysis and the hypothalamus
Hypophysis: What 3 parts make up the adenohypophysis and give the function of each
pars tuberalis monitors melatonin levels
the pars distils is the main secretory region
the pars intermedia surrounds the neurohypophysis in horses and carnivores
Hypophysis: Pars Intermedia
- Why is the pars intermedia clinically relevant? 3
it divides the 2 main parts of the hypophysis
it has neural input from the hypothalamus
adenomas of these cells occur in older horses causing PPID
Hypophysis: Neurohypophysis
- State the names and functions of the 2 regions of the neurohypophysis
the infundibulum is a stalk attached to the tuber cinereum of the hypothalamus
the neural lobe contains projections of axons from neurones in the hypothalamus
Hypophysis: How is the Adenohypophysis linked to the hypothalamus?
- explain the mechanism of this
- What about the neurohypophysis?
- explain the mechanism of this
hormonally
this is done via a capillary portal system and releasing factors from the hypothalamus
neurologically
this is done through cell bodies in the hypothalamus of which axons extend down the stalk, with the end of the axons sitting in the neurohypophysis
Embryology: Describe GnRH cell migration at the start of life
genre releasing cells start life in the olfactory bulb and migrate to their final position within the hypothalamus
Hypophysis: Describe the blood supply to the hypophysis
the hypophysis sits within the circle of willis which are arteries supplying the whole brain
blood is supplied to the hypothalamus and venous drainage enters a capillary network in the hypophysis
Embryology: Where does the pineal gland originate from?
the central nervous system
Embryology: Where do the thyroid glands originate from?
the floor of the mouth
Embryology: Where do the parathyroid glands originate from?
the pharyngeal arches
Embryology: Where do the adrenal glands originate from? 2
the medulla originates from the neuroectoderm
the cortex originates from the mesonephros
