Organisation of cells into tissues and organs. Flashcards
Name the three major salivary glands and describe where they are.
Parotid - cheek area up to temple.
Submandibular - jawbone.
Sublingual - just below bottom teeth.
List the three salivary glands in order of amount of mucus produced.
Sublingual, Submandibular, Parotid. For this reason they are different colours when a dye is added.
Name the four layers of the digestive tract from the lumen outwards.
Mucosa, submucosa, muscularis externa, serosa/adventitia.
Give the three parts of the mucosa
Epithelium (sits on basal lamina)
Lamina Propria (loose connective tissue)
Muscularis mucosae (thin layer of smooth muscle)
Describe the submucosa
Loose connective tissue
Describe the muscularis externa
Two thick layers of smooth muscle, an inner cicular layer and an outer longitudinal layer.
Describe the serosa
outer layer of connective tissue that either suspends the digestive tract or attaches to other organs.
Name the nervous system within the digestive tract and describe where the neurons are found.
The enteric nervous system. The neurons live in groups called ganglia between the two muscle layers that make up the muscularis externa.
Name the layers of the trachea
Respiratory epithelium, Lamina propria, hyaline cartilage of tracheal ring.
Extra info: The goblet cells of the epithelium together with the submucosal glands produce a viscous fluid that coats the surface of the airway, trapping particles that are then propelled out of the airway by the cilia. Cilia beat mucus up the trachea by swinging quickly up the trachea and slowly down. Smoking paralyses the cilia.
Describe the difference between bronchi and bronchioles.
Bronchi are large diameter airways and have hyaline cartilage in their wall. Bronchioles are smaller airways, have no cartilage and smooth muscle predominates in their wall.
Extra info: Asthma attacks are partially caused by the smooth muscle in bronchioles contracting are reducing gas exchange.
The columnar cells f of the epithelium tend to get shorter the further down the respiratory tree you go. It is important to realize that gas exchange does not occur across these epithelia.
Describe the alveoli.
The alveoli are lined by simple squamous epithelium and are blood capillaries holding rbc’s
Describe the structure of a lobule (of which the liver is made up of many).
A lobule has a hexagonal arrangement. At each corner of the hexagon there is a branch of the hepatic portal vein, a branch of the hepatic artery and a bile duct (making up the portal triad), the artery delivering blood into the lobule. Blood percolates out of the corners of the lobule and works it way through sinusoids (spaces between the hepatocytes) into the centre where there is a central vein which drains into the hepatic vein.
Describe the function of the pancreas.
The pancreas is unusual in that it is both an exocrine and an endocrine gland.
The exocrine pancreas produces about a litre each day of digestive juices containing proteases to breakdown proteins, lipases to breakdown lipids, nucleases to breakdown DNA/RNA, etc. These enter the duodenum via the pancreatic duct.
The endocrine pancreas consists of small, scattered islands of tissue called islets of Langerhans, which produce a number of hormones including insulin.
In the exocrine pancreas there are ducts but in the endocrine pancreas there are none, since hormones go into blood stream where as digestive enzymes do not.
Digestive enzymes are not active until they reach the duodenum.
