The Digestive System. The Mouth. Lips : grasping, speaking Teeth: chopping, tearing, ripping, crushing of food. (Mechanical digestion) Salivary glands : secrete digestive enzymes (break carbohydrates down to sugar) Makes saliva. Tongue: mixing food with saliva (mech. digest.) , speaking
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Lips: grasping, speaking
Teeth: chopping, tearing, ripping, crushing of food. (Mechanical digestion)
Salivary glands: secrete digestive enzymes (break carbohydrates down to sugar)
Tongue: mixing food with saliva (mech. digest.) , speaking
Uvula: Blocks off nose when swallowing , making uvular sounds, snoring , gag reflex
Hard palate (roof of mouth, food pushes up here.
Soft palate can expand so chewed food (bolus) can enter
The opening after the mouth. It is the place where the digestive and the respiratory systems meet. Why????
Epiglottis is a flap that folds over the trachea and prevents food or water from going down it. I.e. choking "went down the wrong way."
Esophagus: A passageway to the stomach
Rhythmic contractions of smooth muscle force food and water down. Called peristalsis.
Temporary storage, mechanical and chemical digestion
Glands release stomach acid and digestive enzymes.
Upper and lower sphincters close and three layers of muscle contract causing the stomach to churn the food.
The first part of the intestine. Many secretions happen here.
Digestive enzymes from the pancreas will break down protein. NaHCO3 neutralizes stomach acid. Bile is made in the liver and stored in the gall bladder. It is an emulsifier (physical change) and breaks fat up into small goblets.
Food leaving the stomach is called chyme (liquidy, soupy mixture)
Note the liver and the gall bladder and the pancreas are accessory organs.
The pancreas is a digestive gland and also an endocrine gland (insulin controls blood sugar)
The liver and the gall bladder.
Seen via an endoscope. Fibre optics.
6 m long 2.5 – 3 cm in diameter
Duodenum is the first part.
Jejunum is the second and the ileum is the last.
In the first part chemical digestion takes place.
Food is broken down into it molecular form. i.e. protein amino acids, carbohydrates sugar and fats lipids
In the latter part of the small intestine more and more absorption of nutrients into the blood occurs.
The small intestine is lined with blood vessels.
The surface area of the small intestine is HUGE
Outer layer smooth muscle for peristalsis.
Yellow is smooth muscle used to mix food.
The inner lumen is folded to increases surface area.
The red villi further increase surface area.
Micro villi can not be seen here.
Villi covered in microvilli
Why is the surface area so important?
Three parts, ascending (up), transverse (across), descending (down)
Main function is to absorb water and minerals from the chyme.
This makes it more solid feces.
The rectum is for storage of feces before elimination.
The anus is the connection with the external environment.
When you can consciously control your external anal sphincter you are