4.8 Human Digestive system Flashcards
Food in different steps of digestive system
Food Bolus Chyme Stool Feces
Where does it all begin?
- sharp incisors do?
- molars do?
- Salivary glands do?
- Mouth/Oral cavity
- Food broken down mechanically by chewing
- Sharp incisors > slice
- Molars > grind food in pulpy mass
-Salivary glands > produce saliva
What is the purpose of saliva?
- attacks bacteria with enzymes
- Dissolves substances so that food can be tasted.
- Breaks down starch with an enzyme:
“salivary amylase” - Cleanses teeth.
-Liquefies food so it is easier to swallow.
Tongue
- structure
- fuction
- covered with papillae “bumby surface”, which contains taste buds
- pushes the Bolus (the ball of moist food) in the pharynx
Uvula
-where?
- function
- Hangs at the back of the soft palate
- prevent food from entering the nasopharynx
- a role in speech
Pharynx
- common passageway for food and air
Esophagus
- phys desc.
- function
- peristalsis?
- esophageal spincters / cardiac spincters
- Floppy tube-like structure
- transports food to stomach
- Moves food through peristalsis: a wave of muscular contractions
- Ends with a ring of muscle called the esophageal sphincter (or cardiac sphincter)
Waht happens if pancreas stops working?
- pancrease produces enzymes, which helps break down carbohydrates, proteins, and fats in the samll intestine. It also produces insulin.
-if pancrease stops producing enough enzymes -> malabsorption of nutrients -> deficiencies & weight loss.
-if not enough insulin -> diabetes & high sugar levels
Stomach (Outside structure)
- phys desc.
- function
- A sac-like organ with layers of smooth muscles going in every direction.
- muscles contract so that the food can be mixed and churned via mechanical digestion.
Stomach (Inside Structure)
- Phys desc.
- layer is made up of an extremely folded lining called rugae
- has glands that produces acidic gastric juices to continue chemical digestion.
- Gastric juices include hydrochloric acid (HCl) and pepsinogen (enzyme to break down protein)
Stomach
- function
- absorbs what?
- phyloric sphincter?
- After chemical digestion the food becomes a watery paste called CHYME
- does NOT absorb most nutrients
- alcohol is absorbed across the stomach lining, directly into the bloodstream.
- pyloric sphincter is a ring of muscles that controls the movement of food out of the stomach.
Small Intestine
- made up of ?
- why lined with vili/microvilli?
- lacteal vessel?
- Receives secretions from?
- Made up of three segments; Duodenum, Jejunum, Ileum
- Main site of chemical digestion
- Lined with villi/microvilli to increase the surface area to optimize absorption of nutrients.
> In the center of the villus, there is a lacteal vessel that takes in the larger fat particles absorbed from the intestine. - Receives secretions from the liver, gall bladder and the pancreas to assist in digestion
Duodenum
- position compared to stomach , liver, pancrease
recieves ?
- Closest to the stomach
- So, recieves the acidic chyme, that needs to be neutalized.
- Connected to liver and pancreas via common bile duct.
Jejunum
- Digestion of the chyme continue
Ileum
- Main site of nutrients absorption
Liver
- stores?
- Removes?
- Recycles?
- stores glucose in the form of glycogen.
- Removes toxins and old blood cells from blood.
- Recycles decomposed hemoglobin into bile salts.
- Produces bile which breaks down large fat globules
- Stores fat soluble vitamins A, D, E and K.
Gall Bladder
- Stores the bile produced by the liver until it is secreted into the duodenum via the common bile duct.
Pancreas
- pancreatic juice contain?
- pancreatic juices which contain:
1) Sodium bicarbonate → base, increases pH of chyme from stomach
2) Digestive enzymes → lipases (digest fats), proteases (digest protein), amylases (digest starch)
3) insulin
Caecum
- A blind pouch where the small intestine joins the large intestine.
Appendix
- A finger-like appendage off of the caecum
- no role in digestion
- have a role in fighting infections
RECTUM
- most of the water absorbed, food called feces.
ANUS and ANAL CANAL:
