Flashcards in Digestive Deck (82)
Name the order of layers in a tooth from enamel to pulp:
Enamel, periodontal ligament, cementum, detin, pulp
Describe the pulp:
It is a soft tissue that contains blood vessels, nerves and lymphatics
Describe the dentin:
It is similar to bone but contains odotondoblasts. Occurs near by the pulp not throughout the dentin
Crystilline rods or prisms of calcium/phosphate and carbonate. It contains no cells, so no sensation
What is the hardest tissue of the body?
Calcified connective tissue covering the root
Describe the peridontal ligament:
Collagen fibres linking the bone of the socket (alveolar bone) to the cementum. It has a rapid turnover so it is constantly broken down and remade. Embedded in the ligament are mechanoreceptors that sense stretch and act as a protector and force transmitter.
What types of muscle fibres are found in the tounge?
Verticle, longitunal and trabsverse
What are the 3 types of pipillae found on the tongue?
Describe filiform papillae:
No taste buds (pointy)
Describe fungiform papillae:
Some taste buds
Describe vallate pipillae:
They have lots of taste buds and a moat
What do mucus cells secrete and why?
A viscous solution for lubrication
What do serous cells secrete and why?
A watery secretion that consists of amylase and lysozome
What are the 3 pairs of salivery glands and what do they secrete?
What is saliva made up of?
Water, mucus and enzymes
When do salivery glands secrete their secretions?
After parasympathetic stimulation induced by seeing etc food
What is the omentum?
A large, apron like fold of visceral peritoneum that hangs down from the stomach
What are the 4 ways of increasing surface area?
1. Circular folds - plicae circulare
2. Upwards projections (into lumen) - evaginations e.g villi
3. Downwards projections - invaginations e.g glands
4. Gross convolutions
What are the 4 linings of the gut tube starting from the lumen?
What makes up the mucosa?
2. Lamina propria - loose connective tissue that carries blood vessels, nerves and defence cells
3. Muscularis mucosae - 2 layers of smooth muscle - inner circular and outer longitudinal
What makes up the submucosa?
A thick bed of loose connective tissue carrying larger blood vessels, lymph and nerves (submucosal plexus)
What makes up the muscularis externa?
2 layers of smooth muscle inner circular and outer longitudinal. Contains the myenteric nerve plexus
What makes up the serosa?
A slippery outer covering for the gut tube (except oesophagus). It is 2 layered with outermost mesothelial cells sitting on a bed of connective tissue. It is also known as the visceral peritoneum and when it is not attached to a body cavity it is adventitia
What controls the submucosal plexus and the myenteric nerve plexus?
The enteric nerve system which is self governing and is influenced by the autonomic nervous system
When the oesophagus is empty, what shape is it?
What are the 3 functions of the oesophagus?
No absorption, little secretion and no digestion
What is special about the epithelium layer of the oesophagus?
It is stratified squamous with a sacrificial layer for protection against hard food. Cells are replaced by division in basal layers then slow migration outwards. Old cells are shed from the surface outwards
What is special about the external muscle of the oesophagus?
It has some skeletal muscle in the upper third of the oesophagus to allow for rapid contraction and voluntary swallowing