AP Biology Skeletal, Muscular, Digestive, Respiratory Systems SG
Biology Natsci 1--Digestive System
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Transcript of Biology Natsci 1--Digestive System
DIGESTIVE SYSTEM
NATSCI [MWF] 1 :30-2:30 PM
INTRODUCTION
The digestive system is used for breaking down food into nutrients which then pass into the circulatory system and are taken to where they are needed in the body.
FUNCTION OF DIGESTIVE SYSTEM
Prepares food for use by cells through “Five Basic Activities:”
1) INGESTION or the taking of food into the body
2) PERISTALSIS or the physical movement or pushing of food along the digestive tract
3) DIGESTION or the breakdown of food by both mechanical and chemical mechanisms
GOAL: Break down into :– Monosaccarides, amino acids, fatty acids– Absorbed through the epithelium
4) ABSORPTION or the passage of digested food from the digestive track into the cardiovascular and lymphatic systems for distribution of the body’s cells
5) DEFECATION or the elimination from the body of those substances that are indigestible and cannot be absorbed
Digestive System: “Gastrointestinal System”
The organs of digestion are part of two main groups.
• 1ST: DIGESTIVE TRACT
• 2ND: ACCESSORY ORGANS OF THE TRACT
Description: THE DIGESTIVE TRACT
(gastrointestinal (GI) tract)• Food passes through:
–starts at the mouth, –continues to the esophagus,– stomach, –small intestine, –large intestine (the colon / rectum)–And ends at the anus.
Description: THE DIGESTIVE TRACT
>>The entire system — from mouth to anus — is about 30 feet (9 meters) long.
Description:ACCESSORY ORGANS
• Food does NOT pass through:–Teeth–Tongue–Salivary glands–Liver–Gallbladder–Pancreas
THE DIGESTIVE TRACT
Mouth or oral cavity• “Buccal cavity”• The mouth is the beginning of the
digestive tract; • digestion starts here when taking
the first bite of food.
Mouth or oral cavity
Mouth or oral cavity
The food is chemically broken down by amylase-an enzyme in saliva that breaks down carbohydrates.
ACCESSORY ORGAN
Tongue • Consists of skeletal muscle covered
with mucous membrane
• Divided into symmetrical halves by septum called lingual frenulum
Tongue
Tongue
• Papillae – covers the upper surface and sides of the tongue
*Filiform papillae - found at the front of the tongue (rough and important in licking) –threadlike elevations covering
most of the tongue surface.
Papillae
-Fungiform papillae (contain taste buds)
–knoblike projections of the tongue scattered among the filiform papillae.
-Circumvallate papillae (contain taste buds)
–eight to twelve large papillae arranged in a V near the base of the tongue.
ACCESSORY ORGAN
Salivary glands• the one that secretes saliva in the
mouth,• Saliva is a watery substance located
in the mouths of organisms contains an enzyme - salivary amylase, –which breaks down starch.
ACCESSORY ORGAN
Three pairs of salivary glands:• Parotid gland—(secretory cell: serous)
• The submandibular or submaxillary gland—(secretory cell:mixed)
• The sublingual gland—– (secretory cell:mucous)
Salivary glands
Teeth-known as dentes
-are part of the skeletal system
-play a key role in
digestion
ACCESSORY ORGANS
ACCESSORY ORGANS
Teeth-In carnivores,
*are designed for killing and breaking down
meat.
-In Herbivores,
*for grinding plants and other food to ease them
through the digestion process
ACCESSORY ORGANS
₪ Tooth is composed of:
-the crown--(covered with enamel)
-the neck or cervix
-the root
Tooth
ACCESSORY ORGANS
“The Four types of teeth”
Four types of teeth
(1) The Incisors• The 8 front teeth • are used to cut
food (2) The Canine (4
eyeteeth)• Used to tear food• are used to cut
food• Having only 1 cusp
or cuspids
(3) The Molars (back teeth) are used for chewing and grinding food.
(4) The 8 Premolars (bicuspids) have a flat biting surface, they tear and crush food .
THE PHARYNX
FUNCTION:• Is to begin the
process of swallowing or deglutition
Is a common passageway for food and air.
Is divided into:– the NASOPHARYNX– The OROPHARYNX
and– The
LARYNGOPHARYNX
Division of Pharynx
Nasopharynx• Region posterior
to the nasal cavity, from the internal nares (choanae) to soft palate
Division of Pharynx
Oropharynx• Region
posterior to the root of the tongue
Division of Pharynx
Laryngopharynx• Region posterior
to, behind larynx, from the epiglottis to cricoid cartilage (larynx)
THE ESOPHAGUS
Is to secrete mucus and transport food to the stomach through an opening in the diaphragm called the esophageal hiatus
THE DIGESTIVE TRACT
THE ESOPHAGUS
it uses PERISTALSIS – involuntary waves of muscle contraction to help push food down to the stomach through the lower esophageal sphincter
THE DIGESTIVE TRACT
lower esophageal sphincter
--Functions as to keep food and stomach acid from coming back up in to the esophagus
THE STOMACH
Begins the chemical breakdown of proteins through the enzyme pepsin
Breaks up food mechanically by churning its contents
THE DIGESTIVE TRACT
THE STOMACH
It has folds called rugae and is a big muscular pouch which churns the bolus and mixes it with gastric juice- a mixture of stomach acid, mucus and enzymes.
4 parts of stomach
Cardia• Surrounds the gastroesophageal
sphincter
4 parts of stomach
Fundus• The rounded
portion above and to the left of the cardia
4 parts of stomach
The body• The large
central portion of the stomach below the fundus
4 parts of stomach
Pylorus or antrum• The narrow inferior
region that connects with the duodenum of the small intestine via the pyloric sphincter
4 parts of stomach
Dual function:
(a) Its acini produce digestive enzymes that get carried by the pancreatic duct to the duodenum of the small intestine
THE DIGESTIVE TRACT
THE PANCREAS
(b) Its pancreatic islets secrete the hormones insulin and glucagon into the blood to control blood sugar levels
THE DIGESTIVE TRACT
THE PANCREAS
Divided into :• The head- is the widest part of the
organ • The body - the tapered left side that
extends slightly upward • The tail -
THE PANCREAS
The pancreas is made up of two types of glands:• Exocrine
secretes:digestive enzymes. These enzymes are secreted into a network of ducts that join the main pancreatic duct, which runs the length of the pancreas.
• Endocrine
consists of the islets of Langerhans, secretes hormones into the bloodstream.
THE PANCREAS
• Largest organ of the body
• Produces bile• Break up fats• Functional units
– lobules
THE LIVER
ACCESSORY ORGAN
It stores copper, iron and vitamins A,D,E, and K.
It stores or transforms poison into less harmful substances
THE LIVER
Division of the liver (a) right lobe (b) left lobe
It stores and concentrates bile produced by the liver lobules
ACCESSORY ORGANTHE GALLBLADDER
Where the major portion of absorption and digestion occurs
Approximately:• Length: 21 feet • Diameter:1 inch
Divided into 3 portions
THE DIGESTIVE TRACTTHE SMALL INTESTINE
The three portions : 1st: duodenum
• The shortest part • Length: 10 inches
long 2nd: jejunum
• Length: 10 inches long
• Extends to the 3rd part
3rd: ileum• Length: 12 feet long• Joins the large
intestine
THE DIGESTIVE TRACT
Length: 5 feet Diameter: averages
2.5 inches FUNCTIONS:
• Absorption of water• Manufacturing and
absorption of certain vitamin
• Formation and expulsion of the FECES
THE LARGE INTESTINE
Attached to the posterior wall of the abdomen by extensions of its visceral peritoneum known as mesocolon
THE DIGESTIVE TRACTTHE LARGE INTESTINE
Four principal regions (1) the cecum
• The pouchlike first part of the large intestine
• Attached to the close end of the cecum is the twisted tube known as the vermiform appendix (length 3 inches)
THE LARGE INTESTINE
(2) the colon
• The largest part.• Looks like a tube of consecutive
pouches• The pouches are called haustrae• Parts:
– Ascending Colon– Tranverse colon– Descending colon– Sigmoid colon
(3) the rectum• The last 7-8 inches of the
gastrointestinal tract• Eliminate feces• What’s left over?
– undigested materials:– mainly cellulose from plants– called roughage or fiber – keeps everything moving & cleans out
intestines
• It is situated anterior to the sacrum and coccyx.
(4) anal canal• The terminal 1 inch of the rectum
• It is situated anterior to the sacrum and coccyx.
(4) anal canal• The terminal 1 inch of the rectum
THE DIGESTIVE TRACT
ANUS
The opening of the anal canal to the exterior
The last part of the digestive system
Human digestive system
THE ENZYMES Mouth:
secretes Salivary Amylase which down starches into sigars
Stomach: -Secretes Pepsin which breaks
down proteins and hydrochloric acid which provides an acid environment to kill bacteria
Pancreas: • secretes amylase, which continues
the breakdown of starch, • trypsin which continues the break
down of proteins• Lipase which breaks down fats
Small Intestine:Secretes peptidase and maltase
which converts the remaining sugars into glucose
Liver:• Secretes Bile which breaks down
fats and stores it in the gallbladder
HISTOLOGY
The walls of the alimentary canal from the esophagus to the anal canal have the same arrangement of tissue layers.• These layers are referred to as
“coats” or “tunics”
HISTOLOGY
The Four Coats or TUNICS of the tract
(From the inside out)
1)The MUCOSA2)SUBMUCOSA3)MUSCULARIS4)ADVENTITIA or SEROSA
Tunics
1) Tunica mucosa:
• This layer is composed of epithelium, connective tissue and muscle. These tissues can usually be found in distinct layers as follows:
Tunica mucosa
THREE LAYERS
1) lamina epithelialis mucosae: –consists only of epithelium
2) lamina propria mucosae: –consists of either loose areolar or
reticular connective tissue3) lamina muscularis mucosae:
–consists of smooth muscle–which permits the mucosa to
dynamically move and fold.
THREE LAYERS:
Tunics
The magnification of all four images is identical and the epithelial layer is oriented toward the top.
2) Tunica Submucosa?
• Consists of loose connective tissue that binds the tunica mucosa to the next layer, the tunica muscularis,nerves, blood vessels, and glands in some organs
3) Tunica muscularis:
• consists of at leasttwo layers, an inner circular and an outer longitudinal with parasympathetic ganglia located between the layers
Tunics
4) Tunica Adventitia or
Tunica Serosa: • consists of loose connective
tissue. * If the organ is surrounded by other tissues, this layer is called a tunica adventitia and its connective tissueblends with that of the surrounding tissues.
* If the organ is suspended in the body cavity, this layer is called a tunica serosa and it is covered by a simple squamous epithelium that is called mesothelium.
DIGESTIVE SYSTEM DISORDERS
Ulcerative Colitis
-An inflammatory disease -affects only the large intestine. Diarrhea occurs when waste products move through the large intestine too quickly; constipation results when this movement is too slow.
GERD(Gastroesophageal reflux disease) -occurs when the lower esophageal sphincter relaxes at the wrong times, allowing acid from the stomach to enter the esophagus.
GERD-possible cause:
a hiatal hernia, a protrusion of this same sphincter and the upper portion of the stomach into the chest
cavity
What is a fart exactly?
Why Do Farts Smell Bad?• The more sulfur-rich your diet is, the more
terrible your farts will smell. Some foods contain more sulfur than others, which is why eating things like beans, cabbage, cheese, soda, and eggs can cause gas that will peel the paint off the walls!
1) Farts Are Flammable
2) If You Hold Them In, They'll Just Come Out When You Sleep
3) People Even Fart After Death
TOP 10 FOOD MYTHS Myth #1:
Drinking water in between your meals will mess up your digestion
Myth #2:Having fruits immediately after a meal is not good for you
Myth #3: Papaya should be avoided during pregnancies
Myth #4:The skin of an apple contains no nutrients
Myth #5: Eating after 7 pm will make you fat
Myth #6: Having milk immediately after eating fish
Myth #7:You should not swim/shower immediately after a meal
Myth #8: Having chocolate causes acne
Myth #9: Having kesar (saffron) during pregnancy makes your baby fair
Myth #10: If you swallow a chewing gum, it stays in your stomach for seven years before it gets digested
Facts and fallacies Ulcers
-Spicy food and stress cause stomach ulcers. False.
almost all stomach ulcers are caused either by infection with a bacterium called Helicobacter pylori (H. pylori) or by use of pain medications such as aspirin, ibuprofen, or naproxen, the so-called nonsteroidal anti-inflammatory drugs (NSAIDs).
Heartburn
Smoking a cigarette helps relieve heartburn. False.
Actually, cigarette smoking contributes to heartburn.