Digestive System Flashcards
What is ingestion?
The process of eating
What is digestion?
The breakdown of food into smaller molecules
What is absorption?
The movement of nutrients from the GI tract to blood and lymph systems
What is motility?
The movement of food along the GI tract
What is excretion?
pooping!
What are the layers of the GI tract?
Mucosa
Submucosa
Muscularis
Serosa
What is the mucosa made up of?
From outside in:
Muscle (Muscularis mucosae)
Connective tissue (Lamina propria)
Simple epithelium
What is the submucosa made up of?
Secretory glands
What is the muscularis layer made up of?
Circular muscle
Longitudinal muscle
What is the serosa made up of?
Connective tissue (Areolar)
Epithelium
What are the purposes of saliva?
Initiating digestion
Lubrication of food
Forming bolus
Give an example of a salivary gland
Submandibular gland
Give 2 examples of enzymes within saliva
Amylase
Lipase
What does the pharynx do?
Creates a skeletal muscle contraction which moves bolus into oesophagus (swallowing)
What are the contractions within the oesophagus called?
Peristaltic
Why is mucus secreted into the oesophagus?
To aid movement
What does gastrin stimulate?
Release of gastric juice
Increases GI tract motility
Relaxation of stomach exit sphincter
Which cells secrete gastric juice?
Parietal cells
Chief cells
What do parietal cells secrete and what does the secretion do?
Hydrochloric acid - lowers pH to 1.5-2 and kills bacteria
What do chief cells secrete and what does the secretion do?
Pepsinogen - pepsin (enzyme form) breaks down proteins
What does the duodenum secrete and what does the secretion do?
Pancreatic juice - raises pH back to 7.1-8.2 via enzymes
Give an example of 2 pancreatic enzymes
Pancreatic amylase
Deoxyribonuclease
What does the liver secrete and what does the secretion do?
Bile - solubilises fat to be broken down by lipases
Where is bile secreted into?
Duodenum
