Digestive System 1 Flashcards
Describe enamel?
Crystalline rods or prisms of calcium phosphate and carbonate
No cells
Hardest tissue of the body
No sensation
Describe dentin
Similar to bone but cells (odontoblasts) occur nearby in the pulp instead of scattered through the dentine
Describe pulp?
Soft tissue
Blood vessels, nerves, lymphatics
Describe cementum?
Calcified connective tissue covering the root of the tooth
Describe the periodontal ligament?
The collagen fibres linking the bone of the socket (alveolar bone) to the cementum, and has a rapid turnover
Three types of tastebuds?
Fungiform papillae
Filiform papillae
Circumvallate (8-12)
What are the three major salivary glands?
Parotid (serous)
Sublingual (mucous)
Submandibular (mixed)
When do salivary glands secrete?
After parasympathetic stimulation endured by seeing, smelling, tasting or thinking about food
What is saliva made of?
Water, mucus and enzymes
What enzymes are in the mouth?
Amylase (breaks down starchy debris around teeth) and lysozyme (antibacterial)
Describe mucous and serous cells?
Mucous= viscous Serous= watery
How does a tube gain surface area?
- Plain tube
- Circular folds
- Finger-like projections
- Simple tubular glands
- Convolutions
What are the four tunics that make up the gut wall?
Muscosa (mucous membrane)
Submucosa
Muscularis externa (external smooth muscle)
Serosa
Parts of the mucosa?
Epithelium
Lamina propria
Muscularis mucosae
Purpose of epithelium?
Protection, absorption or secretion (or all three)
What is the lamina propria?
A soft fibrous bed of loose connective tissue on which the epithelium rests; carries nerves and blood capillaries, populated with defensive cells
What is the muscularis mucosae and what does it do?
Two thin layers of smooth muscle; inner and longitudinal, and ur provides the mucosa with some movement independent of the external muscle coat (eg contractions squeeze secretions from gland or lymph along lacteals)
What is the submucosa?
A thick bed of loose connective tissue carrying large blood vessels and nerves (submucosal plexus). It connects the mucosa to the external muscle coat, but allows some movement between the two
What is the muscularis externa?
It’s into two layers to produce peristalsis- the inner layer is circular, the outer is longitudinal. The myenteric nerve plexus occurs between the two layers
What is the serosa?
A slippery outer covering of the gut tube (except oesophagus); it is two layered with outer mesothelium sitting on a bed of connective tissue. Also known as the visceral peritoneum. Where structure is not in contact with the body cavity the outermost connective tissue layer is referred to as the adventitia
What is digestion?
Chemical breakdown of ingested food into absorbable molecules
What is absorption?
Movement of nutrients, water and electrolytes through epithelial lining of the gut into blood or lymph
