Digestive System Hard Copy Grade 10 studentsx
Download
Report
Transcript Digestive System Hard Copy Grade 10 studentsx
The Digestive System
• Digestion
o Breakdown of ingested food
o Absorption of nutrients into the blood
• Metabolism
o Production of cellular energy (ATP)
• Cellular respiration
Organs of the Digestive
System
• Alimentary canal
i.e.: gastrointestinal (GI) tract
ocontinuous coiled hollow muscular
tube open at both ends
• Accessory digestive organs
Organs of the
Alimentary Canal
•
•
•
•
•
•
•
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Mouth Anatomy
•
•
•
•
•
•
•
•
Lips (labia) – protect
Cheeks – form walls
Hard palate – front roof
Soft palate – back roof
Uvula – fleshy projection
Tonsils
Tongue
Oral cavity – area contained
by the teeth
Figure 14.2a
Salivary Glands
• Saliva (spit)
o Contains enzyme amylase to begin starch
digestion
• mixes chewed food with saliva;
• helps us swallow the food;
• has papillae (bumps) that contain taste buds.
Functions of the Pharynx
• A passageway for air and food
• Food is propelled to the esophagus by
two muscle layers
operistalsis
Wavelike contractions of the muscle
layers
Esophagus
• Runs to stomach through the diaphragm
• Propels food by peristalsis
• Passageway for food only (respiratory
system branches off after the pharynx)
Stomach
• on the left side of the abdominal cavity
• Food enters at the esophageal sphincter
• Food empties into the small intestine at the pyloric
sphincter
Functions of the Stomach
• Acts as a storage tank for food
• Chemical breakdown of protein begins
• Delivers chyme (processed food)to the small intestine
Specialized Cells of the Stomach
•Chief cells – produce protein-digesting enzymes
•Parietal cells – produce hydrochloric acid
Ulcers
• An ulcer is an open, painful wound. Peptic ulcers
are ulcers that form in the stomach or the upper
part of the small intestine.
What causes ulcers?
• bacteria (Helicobacter pylori)
• overuse of anti-inflammatory drugs such as aspirin
or ibuprofen (Motrin & Advil)
• Smoking
• Drinking alcohol
• Uncontrolled Stress
Symptoms of ulcers
•
•
•
•
•
•
loss of appetite
sharp stomach pains
Nausea and/or vomiting
frequent burping or hiccuping
bloody or blackish bowel movements
weight loss
Small Intestine
MAJOR SITE OF NUTRIENT ABSORPTION
8-18 feet long
•villi
Fingerlike structures to
increase surface area
•microvilli
Small projections of the
plasma membrane
Large Intestine
• Larger in diameter, but shorter than the small
intestine
• Absorption of water
• Eliminates indigestible food as feces
• Cecum – first part
o Appendix
• Colon
• Rectum
• Anus – external
Accessory Organs of the
Digestive System
Pancreas
• Produces digestive enzymes
• Produces hormones
insulin
glucagon
Insulin
• Insulin is secreted by the pancreas in response to
high blood sugar (glucose).
• After you eat, blood glucose levels rise and in
response to this, insulin is secreted into the blood
• In response to insulin, cells (muscle, red blood cells,
and fat cells) take glucose in from the blood to use
to generate energy (ATP)
• This lowers the blood glucose levels back to the
normal range
• As blood glucose falls, insulin secretion by the
pancreas decreases.
Diabetes
A person with diabetes does not produce enough
insulin or produces no insulin at all.
Without insulin, body cells can’t take the glucose out
of the blood
Blood glucose levels become high which leads to
other health problems.
So, even though the blood has plenty of glucose,
the cells are not getting it for their essential energy
and growth requirements.
Diabetes Type 1 - You produce no insulin at all.
Diabetes Type 2 - You don't produce enough
insulin, or your insulin is not working properly.
Liver
• Largest gland in the body
• Manufactures bile
o Bile breaks fat into smaller globs for (fatdigesting enzymes to work on.
• It’s connected to the gall bladder
Gall Bladder
•
•
•
•
Small sac under the liver
Connected to the liver
Stores bile
When you eat fatty foods, bile is
released from the gallbladder.
What are gallstones?
o Made from cholesterol
o They can be as large as a golf ball.
o People who are overweight or who are trying to
lose weight quickly are more likely to get gallstones.
o You can live without your gallbladder