Week 5: Liver, pancreas and endocrine system Flashcards
Describe the circulation in the liver
Portal vein (from the GI tract)
Hepatic artery (from the heart)
Hepatic portal vein (into the heart via the vena cava)
Name the functions of the liver
- Fat metabolism
- Carbohydrate metabolism
- Protein metabolism
- Detoxification
- Storage of glycogen
- Secretion of glycogen
- Removal of old RBC
Which zone receives the most oxygenated blood?
Zone 1
What is the function of the space of DisSe
It bathes the hepatocytes in plasma
Where are Kupffer cells located?
In the sinusoids
Where are hepatic stellate cells located and what are their functions?
Found in the space of Disse
Fat storage (vitamin A)
With what do the bile canaliculi fuse with?
Canals of Hering
What does bile contain?
Water, bile salts, cholesterol, bilirubin, alkaline phosphatases
Draw the biliary tree
Bile canaliculi -> canals of Hering -> bile ductules -> bile ducts -> common hepatic duct -> common bile duct -> ampulla of Vater -> duodenum
Where does the gall bladder join the biliary tree?
The common bile duct
Where does the pancreatic duct join to
The ampulla of vater
What promotes the secretion of CCK
The presence of lipids in the duodenum
What type of cell is the muscular sac of the gall bladder made of?
Simple columnar epithelium
What is the function of the muscular bile sac?
To concentrate bile and store bile
What is the embryological development origin of the pancreas?
The primitive foregut
What is the role of secretin and which cells secrete it?
It is secreted by neuroendocrine cells of the duodenum and it promotes secretion of watery fluid rich in bicarbonate
What is CCK stimulated by and what is its function
Stimulated by fat in the duodenum, it stimulated enzyme rich pancreatic fluid
What does Gastrin do?
Similar effects to CCK, secretion of pancreatic fluid
What is the pancreatic juice composed of?
Contains sodium bicarbonate which neutralized the acidic stomach. It contains:
Amylase
Trypsin, chymotrypsin
Pancreatic lipase
Ribonucleases and deoxyribonuclease
Describe the pathway that the digestive enzymes take from the lumen of the acini
To the intercalated ducts -> interlobular duct ->
What do delta cells secrete?
Somatostatin
What is the Pars intermedia?
part of the anterior lobe and forms the boundary between the posterior and anterior lobes
Why does the posterior stain much lighter?
Because it is made up of unmyelinated neuronal tissue
What is the pituitary stalk?
The communication between the pituitary gland and the hypothalamus
From which tissue is the posterior pituitary gland from?
Neuroectoderm
From which tissue is the anterior pituitary gland from?
The oral ectoderm, upgrowth from Rathke’s pouch
What is the pars Tuberalis?
A part of the anterior pituitary and forms a thin sheet connecting the anterior p to the infundibular stalk
What are the 2 functional groups that the pituitary hormones fall under?
Those acting on non-endocrine tissue
Those modifying secretory activity of other endocrine tissues
Which hormones are secreted by the anterior pituitary gland and act on non-endocrine tissues?
GH, ADH (vasopressin), prolactin, oxytocin, MSH
Which hormones are secreted by the anterior pituitary gland and act on the activity of other endocrine tissues?
TSH (thyroid stimulating hormone) ACTH, FSH, LH
What is the function of the posterior pituitary gland?
Site of storage and release of ADH and oxytocin
Where do ADH and oxytocin go down after they have been released?
Pass down the axons of the hypothalamo-hypophyseal tract within the pituitary stalk
What is the function of Herring bodies?
They contain clusters of neurosecretory granules containing oxytocin or ADH that have passed down from the hypothalamus
Where are herring bodies located?
In the terminal portion of axons of the posterior pituitary
What are the 3 divisions of the anterior pituitary gland?
Pars distalis
Pars intermedia
Pars tubularis
What is the pars intermedia composed of?
Basophilic cells and colloid containing follicles (lined by cuboidal cells)
What does the pars intermedia produce in foetal life?
MSH and opiomelanocortin
What controls the thyroid gland
The hypothalamus
What is TRH
Thyrotropin releasing hormone
What do thyroid follicular cells produce?
Thyroglobulin - iodine rich inactive form of thyroid hormones which is stored as colloid in the lumen
What are the 2 major hormones produced by the thyroid?
T3 and T4`
What is the function of calcitonin?
To regulate calcium levels
What is the function of calcitonin?
To regulate calcium levels
How does the shape of the colloid change when the thyroid gland becomes active?
It becomes paler and develops scalloped edges
What produces calcitonin>
Thyroid parafollicular cells in response to high levels of serum calcium
Where is the parathyroid located
The 4 dots on the back of the thyroid gland
What are the 2 types of cells in the parathyroid gland?
Chief cells (principal cells) and oxyphil cells
What do chief cells secrete?
PTH
What type of hormones does the adrenal cortex secrete?
Steroid hormones
Mineral corticoids
Glucocorticoids
Sex hormones
What is the effect of mineralocorticoids?
Maintain the fluid and electrolyte balance
What is the effect of glucocorticoids
Carbohydrate and lipid balance
What are the 3 regions of the cortex
Zona glomerulosa
Zona fasiculata
Zona reticularis
What does the Zona glomerulosa secrete?
Mineralocorticoids - mainly aldosterone (acts on renal tubules to increase sodium and water retention)
What does the Zona fasciculata secrete?
Glucocorticoids (mainly cortisol)
What is stored within the Zona reticularis?
DHEA, DHEA sulphate and glucocorticoids
What cells is the medulla mainly made up of?
Chromaffin cells
What shape are chromaffin cells?
Columnar, basophilic
What is the function of Chromaffin cells?
Actively secrete noradrenaline and adrenaline
What is the function of the pineal glands?
Synthesises melatonin which induces rhythmical changes in endocrine activity
