Блог автора методики коррекции веса Нелли Кешишьян

понедельник, 15 мая 2017 г.

Английский язык для врачей.The Digestive System.Пищеварительная система ч.1

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


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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