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Digestion

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Title: Digestion


1
Digestion
2
Purpose of digestive system to break down food
into small enough molecules that the cells can
absorb the nutrients and eliminate wastes.
3
MouthMouth Opening to digestive systemTaste
buds receptors on the tongue activated by the
presence of food. Taste mostly due to
smell.Hard palate several bones forming the
roof of the mouth Soft palate located behind
the hard palate, made entirely of muscle
4
Salivary glands secretes saliva that contains
the enzyme salivary amylase. Salivary amalyse
begins the digestion of starch
5
Teeth chew and tear food. They begin the
mechanical digestion of food. Dental
carries--"cavities" when enamel is destroyed.
6
Tongue mixes food with saliva. Forms mixture
into a mass called a "bolus" in order to for it
to be swallowed
7
Pharynx The region at the back of the mouth that
receives food from the mouth and air from the
nose. The epiglottis closes the trachea
(windpipe) when swallowing
8
Esophagus A long muscular tube that takes food
from the pharynx to the stomach
9
Stomach
10
Entrance to stomach--Bolus enters though a small
circular muscle called a sphincter acts as a
valve to prevent food and acid from backing up
into the esophagus. Heart burn or acid reflux is
when stomach acid leaks from the stomach back
into the esophagus.
11
StomachThe stomach is J-shaped. It stores food,
and mechanically churns to break down food.
12
Digestion in Stomach--Stomach produces gastric
juices contains the enzyme pepsin, and HCL.
Pepsin digests proteinHCL Hydrochloric
acid kills most bacteria in foodpepsin and
HCl work together synergistically.
13
Walls of stomach lined with mucus for protection
against gastic juicesUlcer When HCL
penetrates mucous and the walls of the stomach
break down , causing an open sore. Most of the
time it is caused by an infection but can be
worsened with stress.
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15
Stomach churns and mixes food with gastric juice
in to a soupy mixture called chyme.Exit
food leaves as chyme through a sphincter small
amounts at a time
16
Small Intestine Where most chemical digestion
and nutrient absorption occurs. The small
intestine is about 7 meters long.
17
Bile contains enzymes that help to break down
fats. It is produced in the liver and stored in
the gall bladderVilli finger like projections
in the small intestine that help absorb nutrients
from fats, glucose, and amino acids. Glucose
and amino acids are absorbed into the circulatory
system.Fats are absorbed into the lymphatic
system.
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Digestive juices are regulated by hormones that
keep a balance between too many digestive juices
and too few.
20
Large Intestine (colon) absorbs water, salts,
vitamins, and stores indigestibleMaterial until
eliminated, it is about 1.5 meters long
21
Consists of colon (three parts), rectum, and anal
canal Excretion of feces--3/4 water 1/4 solids.
Solids are indigestible remains like bacteria and
fiber (roughage). Bacteria--break down
indigestible material--help us. (e.coli)Total
length of the digestive tract is about 9 meters
22
Accessory OrgansPancreas Produces enzymes.The
pancreas secretes pancreatic juice, a mix of
digestive enzymes and sodium bicarbonate.
Digestives enzymes include pancreatic amylase
for starch digestion, trypsin for protein
digestion , and lipase for fat digestion.
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Liver Produces bile The liver functions as a
gatekeeper to the blood. The liver stores
glycogen, which can be readily mobilized when
bloodglucose is low.The liver produces bile,
which emulsifies fats in the small intestine.
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Gallbladder- A muscular sac lying within the
lobes of the liver. Bile is stored here. It is
commonly removed if it becomes impaired
27
Problems Diarrhea when too little water is
absorbed. Caused by infection or nervous
stimulation. Constipation too much water is
absorbed. Can be prevented by consuming more H20
and fiber.
28
Hemorrhoids inflamed blood vessels.
Ulcerative Colitis IBD (Inflammatory Bowel
Disease) affects inner lining of the Lg.
intestineChrons Disease IBD (Inflammatory
Bowel Disease)affects the inner and outer
linings of the Lg. intestine.Colon Cancer
genetic and environmental
29
Serious liver disorders. jaundice many causes-
results in a yellow cast to the skin and eyes.
Hepatitis inflammation of the liver various
types. cirrhosis of the liver progressive
replacement of active liver tissue by scar tissue
often due to chronic alcoholism..
30
Liver cancer
cirrhosis
Jaundice- hepatitis
31
After eating a meal there is more glucose than
the body can use. Insulin is released from the
pancreas and this extra glucose is converted into
glycogen (the storage form of glucose). The
liver stores the glycogen, and when blood glucose
drops, glucagon,(another hormone produced in the
pancreas) is released to break down glycogen into
sugar which is then released into the blood
stream.
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6 major nutrients and functions
33
Carbohydrates digestion of carbohydrates begins
in the mouth with salivary amylase and continues
in the small intestine with pancreatic amylase.
Carbohydrates contain the most readily available
form of energy needed to sustain life. 4cal/gram
34
Protein digestion begins in the stomach with
pepsin and is completed in the small intestine
with pancreatic trypsin. Proteins are needed for
growth and repair. 4cal/gram
35
Fat digestion begins in the small intestine with
pancreatic lipase after bile has emulsified the
fats. It is most important for energy storage.
9cal/gram
36
Water is needed to aid digestion and cellular
metabolism. Water is absorbed in the large
intestine. Vitamins small molecules that aid
metabolism and are required in small amounts
Minerals Needed in trace amounts to prevent
diseases. (calcium, Zinc, Iron, Magnesium,
phosphorous, potassium)
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