Histology Flashcards
Pancreas
The pancreas is located in the abdomen, tucked behind the stomach. It is shaped somewhat like a tadpole - fat at one end and slender at the other - and is around 25 cm in length. The pancreas has dual roles; it is an organ of the digestive system and of the hormonal (endocrine) system. Once food has been mulched and partially digested by the stomach, it is pushed into the duodenum (first part of the small intestine).
The pancreas adds its own digestive juices and enzymes to the food, via a small duct attached to the duodenum. This process is said to belong to the ‘exocrine pancreas’.
The pancreas also produces the hormone insulin, which helps to control the amount of sugar in the blood. This is the role of the ‘endocrine pancreas’.
Dark= exocrine Light= endocrine Hormones = insulin and glucogone D= duct for enzymes S= Septum F= Fat I= Islets of Langerhans
Liver
Portal Tract/Triad (corner of a hexagonal hepatic lobule)
PV= Portal vein
H= Hepatocytes
B= bile duct
A=artery
S= septum L= lymphatics
Connective tissue
Triad (branch of the portal vein, branch of the hepatic artery, and lymphatics)
Venule
The stomach
functions both as a reservoir and as a digestive organ. It empties its contents in small portions (suitable for continued digestion) into the small intestine.
L-Longitudinal muscle
C-circular muscle
O-Oblique muscle
S- Submucosa
Mucous membrane
GP- Gastric pits
You should be able to identify the three major layers seen here - the mucosa, submucosa and muscularis externa.
The mucosa is full of gastric glands and pits, and there is a prominent layer of smooth muscle - the muscularis mucosa. The contraction of this muscle helps to expel the contents of the gastric glands.
The muscularis externa layer has three layers of muscle. An innner oblique layer , a middle circular and an external longitudinal layer. The contraction of these muscle layers help to break up the food mechanically.
Adrenal Gland
Located on top of both kidneys, the adrenal glands are triangular-shaped and measure approximately half an inch in height and three inches in length.
Capsule
Cortex:
Glomerulosa- mineralocorticoids (aldosterone)
Fasiculata- glucocorticoids (cortisol)
Reticularis- sex steroids (androgens)
Medulla
catecholamines (epinephrine and norepinephrine)
Parotid gland
L- Lobule
E- excreteory
S-Septa
The secretory units merge into intercalated ducts, which are lined by simple low cuboidal epithelium, and surrounded by myoepithelial cells.
These ducts continue on as striated ducts. These have a folded basal membrane, to enable active transport of substances out of the duct. Water resorption, and ion secretion takes place in the striated ducts, to make saliva hypotonic (reduced Na,Cl ions and increased carbonate, and potassium ions).
The striated ducts lead into interlobular (excretory) ducts, lined with a tall columnar epithelium.
The glands are divided into lobules by connective tissue septa. Each lobule contains numerous secretory units, or acini.
Pale so mucous secreting sublingual
E- excretory
S- Septa
F-fat
sublingual glands possess both mucous and serous secretory cells.
Submandibular Salivary Gland
The adrenal gland is encased in a connective tissue capsule that extends septae into the substance of the gland. The organ is richly vascularized and capsular blood vessels, nerves and lymphatics penetrate along with the connective tissue septae.
The most distinctive feature of the adrenal is its partitioning into cortex and medulla. The medulla is fairly homogeneous, but even when viewed a low power, three concentric zones can be distinguished in the cortex:
zona glomerulosa - thin, outermost zone
zona fasiculata - thick, middle zone
zona reticularis - thin, inner zone
Recto-anal junction
SS- Stratified Squamous epithelium
J- Junction
RM- Rectal Mucosa
Thyroid Follicle
Hepatic Lobule
