Digestion Process - Digestion & Absorption Video Lecture - Class 11

the primary functions of the digestive
system are the breakdown of food called
digestion and absorption of nutrients
digestion begins in the mouth where the
teeth break food into smaller particles
during mastication salivary glands
located near the oral cavity secrete
saliva which begins chemical digestion
and keeps the food moist as food is
swallowed the soft palate blocks the
upper pharynx to prevent food from
entering the nasal cavity and multiple
voluntary muscles in the face neck and
tongue contract pushing food particles
through the pharynx the food passes over
the epiglottis which prevents food entry
into the respiratory system and then
into the esophagus which connects the
pharynx to the stomach the one-way
movement of the food mass now called a
bolus is controlled by wave-like
involuntary muscle contractions this
movement is known as peristalsis
the bolus now enters the stomach folds
in the stomach wall called rugae allow
for expansion as the stomach fills
stomach cells secrete hydrochloric acid
pepsinogen and various regulatory
hormones that chemically digest the
bolus muscular contractions in the
stomach churn its contents to further
breakdown the bolus and mix it with
stomach secretions to form a thick
liquid called time time exits the
stomach through the pyloric sphincter
and enters the small intestine the major
site of nutrient absorption the small
intestine consists of three parts the
duodenum jejunum and ileum bile from the
liver and digestive enzymes from the
pancreas emptying into the duodenum to
aid in digestion absorb nutrients pass
from the lumen of the small intestine
into blood and lymph chyme not absorbed
in the small intestine enters the large
intestine as it passes through the cecum
and ascending transverse descending and
sigmoid colon water insults are absorbed
and time is converted into feces the
rectum store species until nervous
stimulation initiates the defecation
reflex resulting in elimination through
the anal canal