Organisation of cells in tissues and organs

Question 1

What is the name given to nervous tissue in the digestive tract?

Answer 1

The enteric nervous system

Question 2

True or False: The salivary glands are part o the digestive system?

Answer 2

False - The salivary glands are not actually part of the digestive tract but they do have a role in digestive activities so are considered as an accessory organ

Question 3

Where does the digestive tract proper run from and to?

Answer 3

From the oesophagus to the anal canal

Question 4

describe the major layers that compose the digestive tract (starting from lumen going out)

Answer 4

1. Mucosa - divided into 3 part; epithelium (sits on basal lamina), lamina propria (loose connective tissue), muscularis mucosae (thin layer of smooth muscle)
2. Submucosa - loose connective tissue
3. Muscularis Externa - 2 thick layers of smooth muscle (1 inner circular layer and 1 out longitudinal layer)
4. Serosa or adventitia - outer layer of connective tissue (either suspends tract or attaches to other organs)

Question 5

Explain the variations in mucosa and, for each one, give an example of where they can be found

Answer 5

1. Protective - non-keratinized stratisfied squamous epithelium (found in oral cavity, oesophagus)
2. Secretory - Simple columnar epithelium with extensive tubular glands (found in the stomach)
3. Absorptive - Simple columnar epithelium with villi and tubular glands (found in small intestine)
4. Protective and absorptive - Simple columnar epithelium with tubular glands (found in large intestine)

Question 6

What is the ganglia and where is it found?

Answer 6

Most neurons live in groups called ganglia. They are found between the 2 muscle layers that make up the muscularis externa

Question 7

What are the 3 major salivary glands and state whether they are serous or mucus secreting?

Answer 7

1. Parotid gland - long duct, serous secreting
2. Submandibular gland - 50% serous secreting + 50% mucus secreting
3. Sublingual gland - short duct, mostly mucus secreting

Question 8

What is the purpose of striated ducts in the salivary glands?

Answer 8

The striated ducts modify the saliva that is passing through them by pumping salt out of the fluid so that our saliva is hypotonic to blood

Question 9

What are the 4 layers of the trachae, starting with the airway?

Answer 9

1. Airway
2. Respiratory epithelium
3. Lamina propria
4. Hyaline cartilage of tracheal rings

Question 10

In the trachea, what do the goblet cells of the epithelium together with submucosal gland produce and what is the purpose of this?

Answer 10

Together they produce a viscous fluid that coats the surface of the airway which traps particles that are then propelled out of the airway by the cilia

Question 11

Explain the difference between bronchi and bronchioles

Answer 11

Bronchi are airways with large diameter and contain hyaline cartilage in their wall whereas bronchioles are airways with a small diameter and have no in their wall, it is instead predominated by smooth muscle

Question 12

What are alveoli?

Answer 12

Alveoli are tiny sacs in the lungs which are lined by simple squamous epithelium. The alveoli facilitate diffusion of oxygen into the blood and carbon dioxide out of the blood

Question 13

Describe the structure of the liver

Answer 13

The liver is made up of large numbers of lobules which are side by side, each with a hexagonal arrangement. At each corner there is a branch of hepatic portal vein and hepatic artery. In the centre, there is a central vein which drains to the hepatic vein

Question 14

What is the term given to the branch of the hepatic vein, bile duct and hepatic artery, collectively?

Answer 14

The portal triad

Question 15

In the liver, what are sinusoids?

Answer 15

The spaces for blood flow

Question 16

Explain how the blood flows in the liver

Answer 16

The blood passes from the corners to the centre via hepatic sinusoids and so passes sheets of liver cells called hepatocytes

Question 17

What is unusual about the pancreas?

Answer 17

It is unusual because it is both an exocrine gland and an endocrine gland.

Question 18

What does the exocrine pancreas do?

Answer 18

The exocrine pancreas produces about a litre of digestive juices each day. These enter the duodenum via the pancreatic duct

Question 19

Describe the endocrine pancreas and what does it do?

Answer 19

The endocrine pancreas consists of small scattered islands of tissue called islets of Langerhans which produce a number of hormones such as insulin