Biology Digestive System 1 Structures and Function

8/13/2019 Biology Digestive System 1 Structures and Function

1/25

It More Than Just a Gut Feeling

The Digestive System


2/25

TAKS Objective 2The student will

demonstrate an understanding of

living systems and theenvironment.


3/25

Explain What are the two main types of

digestion?

Physical/Mechanical: The physical

breakdown of food by non-enzyme

means.

Chemical: The use of enzymes tobreakdown food.


4/25

List in Order the Pathways of Food

Through the Digestive System. The Mouth

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine Rectum

Anus


5/25

Oral Cavity


6/25

Oral Cavity (Mouth) What type of digestion occurs in the mouth? Both physical and chemical digestion takes place Tonguetaste

manipulates foodprepares food for swallowing by forminginto a ball (bolus)

Salivais secreted Moistens Protects mouth from abrasion Buffer against acids Kills some bacteria

What enzyme is secreted in saliva?

Salivary AmylaseEnzyme that begins digestion of carbohydrates


7/25

Pharynx


8/25

Pharynx Commonly call the throat

Intersection of GLOTTISand openingof the esophagus (gullet) is found here

EPIGLOTTISis a flap that closes theglottis when the act of swallowing

occurs (Closes the Trachea)


9/25

Esophagus


10/25


11/25

Stomach


12/25

Stomach J Shaped organ that Stores and digests food.

GASTRIC JUICES - pH of 1-2

Enzyme: pepsin which acts on proteins.

HCl is needed to activate pepsin from its inactiveform pepsinogen.

GastrinHoromonesecreted to regulate gastricjuices.

Mucus covers the inner lining to prevent the acidfrom eating the tissue.

The PYLORIC SPHINCTER or pylorus connects thestomach to the small intestine and closes off thestomach at its posterior end.


13/25

Small Intestine


14/25

Small Intestine Most breaking down of macromolecules

occurs here.

6 meters in length Smaller diameter than the large intestine

Divided into 3 sections: Duodenum (first 25 cm) Jejunum

Ileum


15/25

Digestion in Small Intestine Acid chyme enters duodenum

Intestinal wall releases a hormone

SECRETIN-signal pancreas to release a basicsolution to neutralize the acid.

CHOLECYSTOKININ (CCK)- released tosignal the gall bladder to release bile and the

pancreas to release digestive enzymes ENTEROGESTRONE-secreted to slow down

peristalsis


16/25

Absorption and Distribution ofNutrients

VILLIsmall finger-like projections thatincrease the surface area

MICROVILLI

even smaller finger-likeprojections on the VILLI

LACTEALlarge lymph vessel found oneach villus (Absorbs FAT)

Capillariessmall blood vessels found oneach villus (Absorbs all nutrients EXCEPT Fat)


17/25

Villi and Microvilli


18/25

Accessory Organs


19/25

Small Intestine AccessoryOrgans

Pancreas, Liver, and Gall Bladder

Add digestive enzymes, juices, and

hormones to the small intestine

These chemicals help break downprotein, fat and carbohydrates


20/25

Liver, Pancreas, and GallBladder

Liver produces bile which is needed to helpdigest fat.

Gall bladder stores the bile.

Pancreas (Endocrine and Exocrine function)produces enzymes need to finish digesting the

main organic foods. It also produces insulin.


21/25

Pancreas and Gall Bladder


22/25

LIVER

Regulates the contents of the blood.

All blood contents enter the Liver via the

HEPATIC PORTAL VEIN.


23/25

Large Intestine Alone


24/25

Large Intestine (Colon)

Main function of the COLONis to reabsorb waterfrom the small intestinal material.

CECUM

T junction that connects the colon tothe small intestine

APPENDIXattached at the end of the cecum.

Stores solid waste in the area called the rectum. Bacteria (E. coli) live in this area of the body.

Produce odor, and Vitamin K


25/25

Large Intestine w/Small

Biology Digestive System 1 Structures and Function

Documents