Rectum
Stomach
Gall- bladder
Esophagus
Salivary glands
Mouth
Slide 36
The first stage of digestion is mechanical and takes place in the oral cavity.
Salivary glands deliver saliva to lubricate food.
Teeth chew food into smaller particles. This is mechanical digestion that increases the surface area exposed to the enzyme: salivary amylase, initiating breakdown of glucose polymers = carbohydrate digestion.
Slide 37
The tongue shapes food into a bolus and provides help with swallowing.
The region we call our throat is the pharynx, a junction that opens to both the esophagus and the trachea (windpipe).
The trachea leads to the lungs.
Slide 38
The esophagus conducts food from the pharynx down to the stomach by peristalsis.
Swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided by the larynx, the upper part of the respiratory tract.
Coughing occurs when the swallowing reflex fails and food or liquids reach the windpipe.
Slide 39
From mouth to stomach: the swallowing reflex and peristalsis
Larynx
Trachea
Epiglottis up
Pharynx
Tongue
Glottis
Esophagus
Esophageal sphincter contracted
Food
To stomach
To lungs
Slide 40
From mouth to stomach: the swallowing reflex and peristalsis
Larynx
Trachea
Epiglottis up
Pharynx
Tongue
Glottis
Esophagus
Esophageal sphincter contracted
Food
To stomach
To lungs
Epiglottis down
Esophageal sphincter relaxed
Glottis up and closed
Slide 41
From mouth to stomach: the swallowing reflex and peristalsis
Larynx
Trachea
Epiglottis up
Pharynx
Tongue
Glottis
Esophagus
Esophageal sphincter contracted
Food
To stomach
To lungs
Epiglottis down
Esophageal sphincter relaxed
Glottis up and closed
Esophageal sphincter contracted
Sphincter relaxed
Relaxed muscles
Contracted muscles
Relaxed muscles
Stomach
Glottis down and open
Slide 42
The stomach stores food and secretes gastric juice, which converts a meal to acid chyme.
Gastric juice is made up of hydrochloric acid and the enzyme pepsin.
Parietal cells secrete hydrogen and chloride ions separately.