Unit 3: Animal Anatomy & Physiology

Components of

The Digestive System II

Components of the Digestive SystemOrgan Comments Function

10) small intestine

(3 parts)

total of 6.2 m inlength

but only 2.5 cm wide

duodenum: 1st part of the small intestine

jejunum & ileum: middle & last sectionslined with finger-like villi

peristalsis occurs

1. finishes off chemical digestion for all nutrientsproduces intestinal fluid (more enzymes to digest all nutrients)receives secretions from pancreas & gall bladdermucus also protects from acidity & enzymes

2. absorption of digested food into blood streamvilli increase surface area

3. keeps food moving along

Components of the Digestive System

Small Intestine

surface area of small intestine is greatly increased by:1. lining of small intestine has folds2. folds contain villi (finger-like projections)3. villi contain microvilli

total surface area of small intestine = area of professional tennis court

Components of the Digestive System

Small Intestine

Duodenum

Jejunum

Ileum

Small Intestine

Components of the Digestive System

Organ Comments Function7) liver large multi-lobed organ

(A) filling most of the abdominal cavitycirrhosis:

.

1. stores excess glucose as

2. filters out & breaks down toxic compounds from blood (detoxification)

glycogen

3. makes bile breaks down large fat droplets into smaller ones (called emulsification)

scar tissue forms from damage by alcohol & drugs

Components of the Digestive System

Organ Comments Function8) gall

bladdersmall sac under the liver (H)connected to the liver by the bile duct (J)gall stones

.

stores bile & sends it to the duodenum

(1st part of the small intestine)

crystallized bile

J

Components of the Digestive System

Organ Comments Function9) pancreas long feather–shaped

organ sends pancreatic secretion to duodenum via the pancreatic duct

.

1. makes insulin2. makes pancreatic

secretion containing:

enzymes which digest proteins, carbs & lipids

Components of the Digestive SystemOrgan Comments Function

13) large intestine

(colon)  (5 parts) 

 total of 1.5 m in

length &6.5 cm wide

1. caecum2. ascending colon3. transverse colon4. descending colon5. sigmoid colonfeces:

contain enormous numbers of bacteriaperistalsis

.

undigested waste

1. reabsorb water & minerals from digestive secretions & compact feces

2. produce vitamins B & K & help further digest waste

3. move feces along

Organ Comments Function

14) rectum muscular organ at the end of the colon

3 sphincters:1. entrance of rectum2. internal sphincter3. external sphincter

anus

.

1. stores feces

2. control egestion

opening through which feces are egested when sphincters are relaxed

Large Intestine (frames the small intestine)

Shorter than small intestine Diameter is much greaterCecum

First part of the large intestine, attached is the appendix

ColonMain portion of the large intestineWater and dissolved minerals are absorbedIntestinal bacteria help break food down furtherBacteria produce vitamin B-12 , K and some amino acids

Large intestine completes the process!

Any undigested material (feces) passes into rectum from the colon. Feces moves through

anal canal and out the anus.Anus has a ring of circular muscle

called the anal sphincter.

Large Intestine

Cecum

Traverse colon

Descending colonAscending colon

CecumSigmoid colonRectum

Anal canalAnus

Large intestine

endoscope: a narrow instrument with a camera at its tipplaced inside digestive tract to view the inner liningcan locate ulcers, polyps or tumours

colonoscopy

ENDOSCOPE VIDEOS

DUODENUM

DUODENUM VILLI NORMAL COLON

ENDOSCOPE VIDEOS

NORMAL COLON 2

PARASITIC WORM

IN COLON

REMOVAL OF PARASITIC

WORMS IN COLON

ENDOSCOPE VIDEOS

COLON JAUNDICE

DIARRHEA CONSTIPATION

cause

result

danger

bacterial infections, allergies, alcohol, food poisoning, etc. irritate intestinal wallsperistalsis occurs too fastfeces move through too quickly

not enough fibre or water in diet to stimulate peristalsisfeces move through too slowly

not enough water or minerals are reabsorbedfeces remain very watery

too much water is reabsorbedfeces become very drymore time for toxic substances & food additives to be absorbed

danger of dehydrationloss of minerals (electrolytes) needed for body functions

hemorrhoids: blood vessels around anus are torn & bleed during egestionhigher probability of colon cancer

DIARRHEA CONSTIPATION

treatment

avoid foods that stimulate peristalsis (ex. fibre)drink plenty of fluids, especially those that contain electrolytes (ex. gatorade)

eat high fibre fooddrink lots of waterregular exercise (stimulates peristalsis)laxatives (ex. prunes – natural laxative)

pharynx

epiglottis

tongue

salivary glandsesophagus

stomach

cardiac sphincter

pyloric sphincter

liver

gall bladder

bile duct pancreaspancreatic duct

smallintestine

duodenum

jejunum

ileumileo-caecal sphincter

appendix

colon

ascending colontransverse colon

descending colon

sigmoid colon

rectum anus

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Homework

Small Intestine & Large Intestine WorksheetPage 188 # 1, 2, 5, 10

Magazine Ad from the 1930’s

The Movement of Food

Peristalsis – alternate waves of contraction and relaxation of muscles in the organ wall.

Circular muscles push food ahead from contracting behind, when long. muscles are relaxed.

Longitudinal muscles in front of food contract pushing food back, when circ. muscles are relaxed.

Figure 10.15

The Movement of Food

Rhythmic Segmentation – mix up partially digested food in intestine.

Circular muscles push it back and forth while food stays in same place. Figure 10.16

Components of the Digestive SystemOrgan Comments Function

11) ileo- caecal sphincter  12) appendix

ring of muscle at the end of small intestine & beginning of the large intestine

tiny sac (3) found on the caecum (2)appendicitis:

.

inflammation caused by bacteria (swells & could burst)

keeps digested food in the small intestine allows more time for digestion & absorption

function unknownbelieved to be left over from our evolutionary past

1

2

3

Still the Small Intestine…

Differ only slightly from the duodenum.Jejunum (2.5 m)

Contains more folds and intestinal glands than duod.Breaks down remaining protein and carbohydrates

Ileum (3 m)Fewer and smaller villiAbsorbs nutrientsPushes undigested material into large intestine

Components of the Digestive System

Large Intestine