Swallowing stage 1: voluntary phase
Swallowing Stage 2: involuntary (pharyngeal) phase
Swallowing Stage 3: involuntary oesophageal phase
The next stage of swallowing occurs in the …
oesophagus
What are the muscles in the oesophagus?
Pressure differences in the pharynx and oesophagus?
The luminal pressure in the pharynx at the opening to the oesophagus is equal to the atmospheric pressure and the pressure at the opposite end of the oesophagus in the stomach (in the stomach) is slightly greater than atmospheric pressure. Thus, these pressure differences tend to force both air from above and gastric contents from below into the oesophagus, however this does not occur due to the presence of sphincter muscles at both ends of the oesophagus.
What are the upper and lower oesophageal sphincters? What do they do during swallowing?
What is the gag reflex?
Constituents of saliva
water electrolytes bicarbonate bacteriostats mucus enzyme
What is the concentration of sodium, chloride, potassium, calcium and iodide ions in saliva compared to plasma?
sodium and chloride are lower than in plasma
potassium, calcium and iodide are usually higher than in plasma
What is the concentration of bicarbonate in saliva compared to plasma?
a higher concentration in saliva than in plasma to maintain an alkaline environment
What are bacteriostats?
chemicals that prevent the multiplication of bacteria
What enzyme can be found in saliva?
salivary amylase
What are 9 functions that affect the composition and amount of saliva produced?
3 glands produce saliva … what percentage is each?
Parotid - 25%
Sublingual - 5%
Submandibular - 70%
Secretion of parotid glands
serous saliva: water secretion rich in enzymes
Secretion of sublingual glands
mucous saliva; viscous secretion containing NO enzymes and large amounts of mucous
Secretion of submandibular glands
MIXED sero-mucous secretion
Which cells are responsible for the volume of saliva secreted and what cells are responsible for the composition of saliva?
acinar = volume duct = composition
Saliva is a –tonic solution
hypotonic
The fluid secreted from the – cells is overall –tonic within the ECF
acini cells
isotonic
-> [Na+]=[K+]
Iodide ions are present at an increased concentration; chloride ions are present at a decreased concentration; bicarbonate is present at the same concentration
During ductal modification, there is little change to volume however concentrations of some of the ions change:
Resting saliva characteristics
At rest, the acinar secretion ishighly modifiedand has the following characteristics:
Stimulated saliva characteristics
When the production of saliva is stimulated, flow exceeds the ductal cells maximum rate of modification and so the acinar secretion ismodified less: