What is it? Digestion is the process through which food and
drink are broken down so that their nutrients can be transported
throughout the body by the way of the circulatory system.
Slide 3
How does it work? The digestive process uses both mechanical
and chemical processes to breakdown food and drink to acquire
nutrients.
Slide 4
Breaking down particles involves: Movement: peristalsis
Peristalsis is the process of moving food and drink along the
digestive tract. Secretion: release of the digestive fluids
Digestion: breakdown food particles Absorption: passage of
molecules into the bodys interior Elimination: remove waste
Slide 5
Where does it occur? The digestive system follows a tract
starting at the mouth and ending at the start of the excretory
system.
Slide 6
Digestive Tract 1) Mouth 2) Esophagus 3) Stomach 4) Small
Intestine 5) Large Intestine
Slide 7
Mouth The mouth is the very start of the digestive system. It
is the entrance for both food and drink. The mouth performs
mechanical breakdown of food breaking it into smaller particles by
grinding, tearing, and chewing with the teeth and jaws.
Slide 8
Mouth continued Chemical breakdown occurs within the mouth
through the salivary glands. The salivary glands produce salivary
amylase which break down starch. The one organ in the mouth, the
tongue, uses both mechanical and chemical breakdown. The tongue
manipulates food particles and moves food to the back of the mouth
when swallowing.
Slide 9
Esophagus The esophagus is a long muscular tube that extends
from the pharynx to the stomach. The esophagus provides
transportation for food to get to the stomach. Muscles in the
esophagus propel a bolus (a mass of food) down the tube to enter
the stomach.
Slide 10
Slide 11
Stomach The stomach is a sac-like organ with muscular walls.
Epithelial cells line the inner surface of the stomach. The food is
churned in the stomach to breakdown through mechanical breakdown.
It contains gastric juices made of hydrochloric acid, pepsinogen
and mucus for chemical breakdown.
Slide 12
Gastric acids purposes Hydrochloric Acid (not directly
involved) kills microorganisms, lowers the stomachs pH level and
activates pepsinogen. Pepsinogen starts protein digestion and
produces the enzyme pepsin Enzyme pepsin is an enzyme that breaks
down proteins and carbohydrates. Mucus sets up a protective barrier
between cells and the stomach acid.
Slide 13
Traveling through When food particles have been broken down
enough in the stomach chyme,a mixture of food and acid, moves to
the small intestine.
Slide 14
Small Intestine The small intestine is a long loose tube coiled
in the abdomen. It is split into three parts. The purpose of the
small intestine is to absorb nutrients through its villi that are
then transported by the bloodstream throughout the body.
Slide 15
Small Intestine continued Three parts: The first part the
duodenum produces mucus to protect the intestinal lining from acid
in entering chyme. Jejeunum is where the villi are in the small
intestines. The villi and microvilli absorb nutrients in the chyme
into capillaries because they are connected. The ileum absorbs bile
salts used to further digestion of fats.
Slide 16
Small Intestine diagram
Slide 17
Large Intestine It is a 5-6 foot tube that encases the
surrounds the small intestine. Divided into parts, it starts at the
cecum and ends at the rectum. The large intestine recovers water
and electrolytes from digested food, forms and stores feces,
performs microbial fermentation, and contains microbes that produce
that digest indigestible molecules.
Slide 18
Other organs involved Liver Gall Bladder Pancreas Appendix
Slide 19
Liver Seated on the right side of the stomach is the liver. It
is a large, rubbery, reddish brown organ. It produces and sends
bile to the small intestine to help with digestion. The bile
contains bile salts and emulsify fats.
Slide 20
Gall Bladder It is a pear-shaped organ positioned under the
liver. It stores excess bile. Do we need it? Many people have their
gall bladder removed. We are able to live without our gall bladder
but have to monitor what we eat more.
Slide 21
Liver and gall bladder
Slide 22
Pancreas Located behind the stomach is the pancreas. It is an
elongated and tapered organ. The pancreas neutralizes chyme with
pancreatic juice sent to the small intestine, by way of the
pancreatic duct. It also produces glucagon and insulin.
Slide 23
Pancreas diagram
Slide 24
Appendix It is a small thin tube that sits in the lower right
abdomen. The function of the appendix is unknown. There are only
theories as to its function Theories It reboots the digestive
system after diarrheal diseases. It is a safehouse for beneficial
bacteria. It once helped cavemen digest leaves.
Slide 25
Appendix diagram
Slide 26
How does this work with other systems? The digestive system
works with the following systems: Circulatory system Endocrine
system Excretory system Nervous System
Slide 27
How? The circulatory system transports nutrients extracted
during the digestive process throughout the body. Part of the
digestive system, the liver and pancreas participate in the
endocrine system function by regulating glucagon release and
regulating the speed of digestion.
Slide 28
Continued The digestive system eventually leads to the
excretory system. After the nutrients have been collected the waste
is released through the excretory system. The nervous system
stimulates for us to swallow our food.
Slide 29
Homeostasis The digestive system helps in homeostasis by
supplying nutrients to the bodies cells for the cells to function
correctly. Also the liver helps in digestion by breaking down toxic
substances such as alcohol by producing urea.
Slide 30
Evolving The digestive system for us has stayed consistent over
time minus the possibility of the appendix once being useful.
Slide 31
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Slide 32
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Slide 33
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