Анатомия и физиология
Пищеварительная система
INTRODUCTION:
· The Digestive Systems Functions to:
o Break down ingested food into molecules small enough to be absorbed into the blood
· The blood takes those molecules to cells for nourishment
o Proteins break down into amino acids
- Used to form new proteins for the cell
o Carbohydrates are used for cellular respiration
- Produces usable energy for the cell
o Lipids are used for storing energy and insulation
o Nucleic acids are broken down into nucleotides
- Used to form DNA and RNA for the cell
o Water is used during cellular respiration for H+ for the Krebs Cycle
ACTIVITIES OF THE DIGESTIVE SYSTEM
· The following 6 activities occur through various parts of the digestive system. All of these activities work for the function of the digestive system
· Ingestion
o Food must be placed into the mouth before it can be acted on
· Propulsion
o To be processed by more than one organ, food must be propelled from one organ to the next
o Swallowing starts this propulsion
o PERISTALSIS- wavelike movement of material through the digestive system
- Involuntary
- Involves alternating waves of contraction and relaxation of the muscles
- Squeezes the food along the tract
· MECHANICAL Digestion
o “Breaking food down physically”
o Prepares food for further degradation by fragmenting the foods into smaller particles
o Examples:
- Chewing by teeth
- Churning in the stomach
- Segmentation in the small intestine
· CHEMICAL Digestion
o “Breaking food particles down chemically”
o Breaking food down into their building blocks by enzymes
· Absorption
o Transporting digested end products from the lumen of the GI tract to the blood or lymph
o Nutrients to blood, bacteria to lymph
o Food enters the mucosal cells by active or passive transport processes
o Most absorption is done in the small intestine
· Defecation
o Elimination of the indigestible residues from the GI tract via the anus in the form or feces
ANATOMY OF THE DIGESTIVE SYSTEM
· There are two main groups of organs in the digestive system
o Organs forming the Gastrointestinal Tract (GI Tract) or the alimentary canal
§ Performs: ingestion, digestion, absorbs, and defecates
o Accessory digestive organs
§ Assist the process of digestion in various ways (mechanically or chemically)
STRUCTURES OF THE DIGESTIVE SYSTEM IN ORDER
· MOUTH
o Oral Cavity
· THROAT
o Pharynx à Esophagus
o Cardioesophageal Sphincter from esophagus into the stomach
· STOMACH
o Cardiac à Fundus à Body à Pylorus
o Pyloric Sphincter from stomach into small intestine
· SMALL INTESTINE
o Duodenum à Jejunum àIleum
o Ileocecal Valve from small intestine into the large intestine
· LARGE INTESTINE
o Cecum à Ascending Colon à Transverse Colon à Descending Colon àSigmoid Colon àRectum àAnal Canal àAnal Sphincters àAnus
ALIMENTARY CANAL/GI TRACT
· The Alimentary Canal (Gastrointestinal [GI] Tract)
· Continuous, hollow, muscular tube that is open at both ends
· ~30 feet long w/o muscles contracting
· This is the general pathway of food through the Alimentary Canal
o MouthàPharynxàesophagusàstomachàSmall IntestineàLarge IntestineàAnus
· The complete pathway includes sphincters and sections of each organ
Пищеварительная система
INTRODUCTION:
· The Digestive Systems Functions to:
o Break down ingested food into molecules small enough to be absorbed into the blood
· The blood takes those molecules to cells for nourishment
o Proteins break down into amino acids
- Used to form new proteins for the cell
o Carbohydrates are used for cellular respiration
- Produces usable energy for the cell
o Lipids are used for storing energy and insulation
o Nucleic acids are broken down into nucleotides
- Used to form DNA and RNA for the cell
o Water is used during cellular respiration for H+ for the Krebs Cycle
ACTIVITIES OF THE DIGESTIVE SYSTEM
· The following 6 activities occur through various parts of the digestive system. All of these activities work for the function of the digestive system
· Ingestion
o Food must be placed into the mouth before it can be acted on
· Propulsion
o To be processed by more than one organ, food must be propelled from one organ to the next
o Swallowing starts this propulsion
o PERISTALSIS- wavelike movement of material through the digestive system
- Involuntary
- Involves alternating waves of contraction and relaxation of the muscles
- Squeezes the food along the tract
· MECHANICAL Digestion
o “Breaking food down physically”
o Prepares food for further degradation by fragmenting the foods into smaller particles
o Examples:
- Chewing by teeth
- Churning in the stomach
- Segmentation in the small intestine
· CHEMICAL Digestion
o “Breaking food particles down chemically”
o Breaking food down into their building blocks by enzymes
· Absorption
o Transporting digested end products from the lumen of the GI tract to the blood or lymph
o Nutrients to blood, bacteria to lymph
o Food enters the mucosal cells by active or passive transport processes
o Most absorption is done in the small intestine
· Defecation
o Elimination of the indigestible residues from the GI tract via the anus in the form or feces
· There are two main groups of organs in the digestive system
o Organs forming the Gastrointestinal Tract (GI Tract) or the alimentary canal
§ Performs: ingestion, digestion, absorbs, and defecates
o Accessory digestive organs
§ Assist the process of digestion in various ways (mechanically or chemically)
STRUCTURES OF THE DIGESTIVE SYSTEM IN ORDER
· MOUTH
o Oral Cavity
· THROAT
o Pharynx à Esophagus
o Cardioesophageal Sphincter from esophagus into the stomach
· STOMACH
o Cardiac à Fundus à Body à Pylorus
o Pyloric Sphincter from stomach into small intestine
· SMALL INTESTINE
o Duodenum à Jejunum àIleum
o Ileocecal Valve from small intestine into the large intestine
· LARGE INTESTINE
o Cecum à Ascending Colon à Transverse Colon à Descending Colon àSigmoid Colon àRectum àAnal Canal àAnal Sphincters àAnus
ALIMENTARY CANAL/GI TRACT
· The Alimentary Canal (Gastrointestinal [GI] Tract)
· Continuous, hollow, muscular tube that is open at both ends
· ~30 feet long w/o muscles contracting
· This is the general pathway of food through the Alimentary Canal
o MouthàPharynxàesophagusàstomachàSmall IntestineàLarge IntestineàAnus
· The complete pathway includes sphincters and sections of each organ
ORGANS OF THE GI TRACT
· MOUTH (Oral Cavity)
o Food enters the digestive tract
o Labia (lips)- protect the opening of the mouth
o Tongue- functions in taste and mechanical digestion
o Lingual Frenulum- membrane securing the tongue to the floor of the mouth, limits movement
o Vestibule- space between teeth/gums and labia
o Teeth- function to mechanically break down food as it enters the mouth, initiating digestion
o Gingivae- gums
o Salivary glands- in the mucous membrane and produce saliva
o Mastication- chewing
o As food enters the mouth, it is mixed with saliva and is masticated.
o The tongue continuously mixes the food and saliva and initiates swallowing
o From the mouth, food moves into the pharynx
· Pharynx
o Have two sets of muscle layers
o One set runs longitudinally
o The other set are circular (constrictor muscles)
o The contractions of these two alternate and propel food through the pharynx and into the esophagus
o Peristalsis- the propelling mechanism that moves food through the digestive system!
· Esophagus
o Functions to move food from the pharynx to the stomach
· The walls of the digestive system from the esophagus to the large intestine are composed of the same four layers of tissue (tunics)
ORGANS OF THE GI TRACT Continued…p2
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