DIGESTIVE SYSTEM

DEEP GASTRIC PITS

ARE IN THE MILLIONS ON THE SMOOTH LINING AND LEAD INTO TUBULAR GASTRIC GLANDS THAT PRODUCE GASTRIC JUICE

6 processes to Digestion

1.Ingestion taking food into the digestive tract via the mouth. 2.Propulsion moves food through the alimentary canal includes swallowing (voluntarily) and peristalsis (involuntary) 3.Mechanical digestion and segmentation- physically prepares food for chemical digestion by enzymes. Mechanical processes include chewing, mixing of food with saliva by the tongue, churning food in the stomach, and segmentation, or rhythmic local constrictions of the small intestine segmentation mixes food with digestive juices and increases efficiency of absorption by repeatedly moving different parts of the food mass over the intestinal wall. 4.Chemical digestion- series of catabolic steps in which complex food molecules broken down to chemical building blocks by enzymes secreted into the lumen of the alimentary canal. Chemical digestion of foodstuffs begins in the mouth and is essentially complete in the small intestine. 5.Absorption- passageway of digested end products plus vitamins minerals and water. from the lumen of the GI tract through the mucosal cells by active or passive transport into the blood or lymph. small intestine is major absorptive site. 6.Defecation- eliminate indigestible substances from anus

3 regions of the stomach

3 regions of the stomach are funds,body,pylorus

Gastroesophageal sphincter

Acts as a valve circular smooth muscle prevents the contents within the stomach from regurgitating into the esophagus

Segments of large intestines

Cecum ascending colon transverse colon descending colon sigmoid colon rectum anal canal *CARDS

3 Ducts of Liver

Common-Hepatic duct leaves the liver Cystic duct-connects to gallbladder Bile duct- formed by the union of the above two ducts

Organs of Alimentary Canal

mouth phayrnx esophagus stomach small intestines large intestines rectum anal canalS-A-M-P-L-E-R

3 segments of the small intestine

Duodenum with its burners glands,Jejunum,Illeum

Epiglottis

Elastic cartilage at the back of the throat covers the opening of the larynx during swallowing

3 REGIONS OF STOMACH

FUNDUS BODY PYLORUS

Peristalsis

moves food through esophagus

Gastric Gland: Parietal cells

HCL and intrinsic factor

blood vessels of liver

Hepatic artery and Hepatic portal vein

Blood vessels of the Liver

Hepatic artery and hepatic portal vein

Digestive process 1-6

INGESTION PROPULSION MECHANICAL DIGESTION SEGMENTATION CHEMICAL DIGESTION ABSORPTION DEFECATION

Segmentation

moves food through small intestines

GI ORGAN FUNCTION: STOMACH

mechanical digestion and propulsion: peristaltic waves mix food with gastric juice and propel it into the duodenum. chemical digestion: digestion and propulsion absorption:

Gastric Gland: Chief Cells

Pepsinogen = pesin

GI ORGAN FUNCTION: PHARYNX and ESOPHAGUS

Propulsion: Peristaltic waves move food bolus to stomach thus accomplishing involuntary (pharyngeal-esophageal) phase of deglutition.

4 lobes of the liver

Right Left Caudate Quadrate

The flow from liver,gallbladder and pancreas to small intestines Fig. 23.21

Right and Left hepatic ducts join to form common hepatic duct which joins with the cystic duct of the gallbladder to form the bile duct which then joins with the main pancreatic duct to enter the duodenum as the hepatopancreatic ampulla and sphincter.

Gastric Gland: Mucous Neck Cells

Secrete thin, acidic mucous

Propulsion

moves food through the alimentary canal includes swallowing initiated voluntarily and peristalsis involuntary

Gastric pits location

mucosa layer of the stomach

Gallbladder Location and function

Thin wall, green muscular sac size of kiwi on the ventral side of liver. Gallbladder Function: stores bile not immediately needed for digestion and concentrates it by absorbing some of its water and ions. spring is in the mucosa honeycomb like folds allow for expansion while it fills like rugae in stomach. the muscular walls contract and bile expelled into its duct, the cystic duct, and then flows into the bile duct.

GI ORGAN FUNCTION: Small Intestine,liver,gallbladder,pancreas

mechanical digestion and propulsion: segmentation by smooth muscle of the small intestine continually mixes contents with digestive juices moves food along tract and through ileocecal valve at a slow rate allowing sufficient time for digestion and absorption.

Internal anal sphincter

a smooth muscle acts involuntary

2 parts of digestive system

alimentary canal and accessory digestive organs

alimentary canal vs. accessory organs

alimentary canal- is the gastrointestinal GI tract or GUT continuous muscular digestive tube winds through the body. digests food breaks it down into smaller fragments an absorbs the digested fragments through its lining into the blood. accessory digestive organs-produce a variety of secretions that contribute to the breakdown of foodstuffs.

Ileocecal valve

between small and large intestine it prevents back flow from the large intestine. once any material leaves the small intestine.

4 Secretions of Pancreas

bicarbonate digestive enzymes insulin glucagon

Chemical digestion

catabolic steps in which complex food molecules are broken down to their chemical building blocks by enzymes secreted into the lumen of the alimentary canal

GI ORGAN FUNCTION: LARGE INTESTINE

chemical digestion: some remaining food residues are digested by enteric bacteria (which also produce vitamin K and some B Vitamins. absorption: absorbs most remaining water, electrolytes (largely NaCl), and vitamins produced by bacteria. propulsion: propels feces toward rectum by peristalsis, haustral churning, and mass movements. defecation: reflex triggered by rectal distension; eliminates feces from body.

Pyloric Sphincter

controls stomach emptying

Liver Ducts

ducts-where bile leaves the liver to fuse and form the common hepatic duct that travels down toward the duodenum then fuses with the cystic duct draining the gallbladder to form bile duct.

Defacation

eliminates indigestible substances from the body via the anus and form feces

Defecation

eliminates indigestible substances from the body via the anus in the form of feces.

Rugae

for increased surface area and they allow for expansion of the stomach

4 Secretions of Gastric Pit

gastric gland secretions from the gastric pit are mucous Neck Cells parietal Cells chief Cells enteroendocrine Cells

Gastric Gland: Enteroendocrine Cells

hormones; know gastrin

GI ORGAN FUNCTION: MOUTH

ingestion: food, voluntarily placed in oral cavity propulsion: voluntary (buccal) phase of deglutition (swallowing) initiated by tongue; propels food into pharynx. mechanical digestion: mastication (chewing) by teeth and mixing movements by tongue. Chemical digestion: chemical breakdown of starch is begun by salivary amylase present in saliva produced by salivary glands.

Soft Palate

is a mobile fold formed mostly of skeletal muscle that rises reflexively to close off the nasopharynx. When we swallow

peristalsis

is propulsion involuntary alternate waves of contraction and relaxation of the muscles in organ walls. squeeze and mix powerful.

Liver Lobes

lobes- Right, Left, Caudate, Quadrate.

segmentation

local constriction of the small intestine. mixes food with digestive juices increases efficiency of absorption repeatedly moving different parts of food mass over intestinal wall.

Liver Function

main function is to filter and process nutrient rich blood delivered to it.

absorption

passage of digested end products vitamins minerals water from lumen of the GI tract through MUCOSAL cells by active or passive transport into the blood or lymph small intestine is the major absorptive site.

mechanical digestion

physically prepares food for chemical digestion by enzymes includes chewing, mixing food with saliva by the tongue, and churning food in the stomach also SEGMENTATION

mechanical digestion

physically prepares food for chemical digestion by enzymes. chewing mixing food with saliva by tongue churning food in stomach

Chemical digestion

series of catabolic steps complex food molecules broken down into chemical building blocks by enzymes secreted into lumen of alimentary canal. chemical digestion of food stuffs begins in the mouth and ends in small intestine.

External anal sphincter

skeletal muscle have voluntary control over

Gallbladder

stores bile that is not immediately needed for digestion and concentrates it by absorbing some of its ions and water.

ingestion

take food in digestive tract via mouth usually

Accessory Digestive Organs

teeth tongue salivary glands liver gallbladder pancreas

Absorption

the passage of digested end products from the lumen of the GI tract through the mucosal cells by active or passive transport into the lymph

Digestion

the process of breaking down food into smaller fragments

Absorption

the process of digesting fragments through the lining in the blood. (lymph vessel associated in diagram page 853)

3 modifications to increase surface area for digestion and absorption in small intestines

villi contains lacteals and capillary bed circular folds are arrangement of the structure microvilli on the outside of the villi