Download Digestion - IBDPBiology-Dnl

Chapter 6.1
The hierarchy of the human body
 The body is composed of cells
 Tissues consist of groups of cells with a common
structure and function
 Organs consist of tissues with common structure and
function
 Organ systems consist of organs with common
structure and function
 Physiology: the study of how organ systems in the
body interact with each other
DIGESTION
 Digestion: taking large molecules and breaking them
apart so that the body can use them
 It is essential because these large molecules cannot get
through the lipid bilayer of the cell membrane.
 Once broken apart, their monomer (e.g. amino acids
or glucose molecules) can pass through
Explain why digestion of large food
molecules is essential
 Large molecules (like proteins, lipids, and starches) are
insoluble in water and can not be absorbed into the
blood stream
 Large molecules (polymers) need to be broken down
into smaller molecules (monomers) such as glucose,
amino acids, fatty acids & glycerol which are soluble in
water and can easily be absorbed into blood stream
 Once absorbed, monomers are used to build essential
molecules in the body.
Explain the need for enzymes in
digestion
 Enzymes: specialized proteins with an active site that creates an
environment for specific chemical reactions to occur
 Enzymes not only allow reactions to occur, they lower the activation
energy required for the desired reaction so it can happen more quickly
 Digestive enzymes help to catalyze hydrolysis reactions
 Each enzyme is specific for a specific food type
State the source, substrate, products
and optimum pH conditions for
amylase, protease, & lipase
Enzyme
Source
Substrate
Products
salivary
amylase
Salivary glands
starch
maltose
7-8
pepsin
stomach
proteins
polypeptides
2-3
Pancreatic
lipases
pancreases
triglyceride lipid
Fatty acids &
glycerol
7.2
Optimum
pH
Draw and label a diagram of the digestive
system
Outline the function of the stomach,
small intestine, and large intestine
 Stomach: functions in the following: Storage of food and water
 Gastric juice:
acidic fluid (HCl) breaks up cells and kills
bacteria
 pepsin for protein digestion
 Mucus to protect lining of stomach from HCl
 Mix-churn food becoming acid chyme

Outline the function of the stomach,
small intestine, and large intestine
 Small Intestine: where most absorption and food
breakdown occurs
 Duodenum: upper portion

Secretions from accessory organs combine to assist in
digestion:
 Bile from liver & gallbladder
 Trypsin, lipase, amylase & bicarbonate from pancreas
 Jejunum & Ileum: absorption
Explain how chyme is moved through the small intestine
 Peristalsis churns and pushes the chyme
through the portions of the small
intestine
Explain the function of bile, describe where it is produced
and stored, and describe its composition
 Bile: produced in the liver, stored in the
gall bladder


Contains bile salts which make fats soluble
and digestible
Contains iron from hemoglobin of RBCs
 Bile molecules insert themselves between
lipid molecules preventing lipids from
forming large globules
6.1.5: Outline the function of the stomach, small
intestine, and large intestine (continued)
 Large Intestine: reabsorbs water
 Water is released into the digestive tract
to help with food breakdown
 Water must be reabsorbed by the body to
prevent dehydration
 The solids that remain (feces) are
eliminated
Distinguish between absorption and assimilation
 Absorption: active or passive uptake of
nutrients
 The cell taking in amino acids from the
small intestine
 Assimilation: Conversion of nutrients
into useful substances in the body
 The cell using those amino acids to build
proteins
6.1.7: Explain how the structure of the villus
is related to its role in absorption and
transport of the products of digestion
 Villus: large finger-like fold in the
intestinal wall
6.1.7: Explain how the structure of the villus is
related to its role in absorption and transport of
the products of digestion (continue)
 Each Villus has microscopic folds called
microvilli
 These folds upon fold increase surface
area
 The small intestine’s purpose is to
breakdown and absorb nutrients – the
more area possible to do this, the more
efficient the process