Human Biology: Digestive System Lecture Notes, Page 1 of 13

Human Biology 175

Lecture Notes: Digestive System

Section 1 Introduction

A) General Functions of the Digestive System

1) ________________________

2) ________________________

3) ________________________

4) ________________________

5) ________________________

6) ________________________

B) Ingestion: ‘act of eating’

C) Propulsion: movement of foodstuff through the gastrointestinal tract

by ________________________

1) Rhythmic contractions

2) ________________________

D) Mechanical Digestion: Process of making large pieces of food into

smaller pieces of food and mixing with digestive fluids.

1) The foodstuff is not changed by the process

E) Chemical Digestion: Process where macromolecules are broken down

into their monomeric subunits using hydrolytic enzymes.

1) ________________________ is required as a reactant

2) ________________________ are broken

3) General Chemical Reaction:

Monomer −−−− Monomer + Water –enzyme

� Monomer + monomer

4) Macromolecule Examples: starch, protein, triglycerides

F) Absorption: process where small molecules ________________________ move from the lumen of the

gastrointestinal tract into ________________________ for transport to the entire body.

1) Examples of monomers that are aborbed

a) ________________________

b) ________________________

G) Defecation: elimination of indigestible substances

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H) Alimentary Canal/ ________________________: Organs of the Digestive System include

1) Route Through

a) Oral Cavity/mouth

b) Pharynx

c) Esophagus

d) Stomach

e) Small intestine

f) Large intestine

g) Anus

2) Gastrointestinal Tract Forms a continuous tube

a) Open on both ends

b) Contents within the lumen of the tube is

outside of the body

I) Accessory Organs of Digestion

1) Secrete fluids into the gastrointestinal tract to

aid digestion/not a section of the GI tract.

2) _______________________

3) _______________________

4) _______________________

5) _______________________

Part 2 From Mouth to Anus

A) Oral Cavity (mouth)

1) Hard palate: bony anterior portion of the roof

2) Soft palate: soft muscular posterior portion of the roof

3) Uvula: closes nasal passages during swallowing

4) Teeth: ______________________

5) Tongue:

a) _______________________

(1) keeps food on teeth during mastication

(2) Pushes bolus into oropharynx to initiate swallowing

b) Covered with _______________________ with microscopic taste

buds (chemoreceptors)

6) _______________________ Ball of well chewed food mixed with

saliva

7) Salivary Glands

a) Accessory organ

b) 3 pairs of salivary glands

c) Saliva composition

(1) water

(2) _______________________: neutralize acidic foods

(3) _______________________: hydrolytic enzyme, converts_______________________

(4) _______________________

8) MECHANICAL DIGESTION: _______________________

9) CHEMICAL DIGESTION: _______________________

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B) Pharynx

1) 3 regions

a) Nasopharynx: superior to soft palate

b) Oropharynx: posterior throat

c) Laryngopharynx: inferior

2) Palatine and lingual tonsils lay between oral cavity and

pharynx _______________________

3) Passageway: _______________________

4) Swallowing

a) Initiated when bolus is pushed into the pharynx by

the tongue

b) Reflex stimulated to begin peristaltic movements

c) ________________________________________ prevents bolus from moving into nasopharynx

d) __________________ prevents bolus from entering trachea

5) MECHANICAL DIGESTION: _______________________

6) CHEMICAL DIGESTION: _______________________

C) Gastrointestinal (GI) Wall from the esophagus through the large intestine

1) _______________________

a) Epithelial tissue lines lumen of the tube

b) ‘wet’ surface

2) _______________________

a) Connective tissue

b) Blood vessels, nerves, lymphoid tissue and lymphatic vessels

3) _______________________

a) Smooth muscle

b) _______________________ propulsion

4) _______________________ visceral peritoneum

a) Visceral peritoneum

b) Serous membrane covers surface of GI tract within abdominal cavity

D) Esophagus

1) GI Wall

a) Mucosa:_______________________

2) _______________________ to the trachea

3) Connects the _______________________

4) Passageway for ______________________

5) MECHANICAL DIGESTION _______________________

6) CHEMICAL DIGESTION _______________________

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E) Stomach

1) Structure:

a) _______________________

b) Cardiac region

c) Fundus

d) Body

e) Greater curvature

f) Lesser curvature

g) Pyloric region/antrum

h) _______________________

i) Mucosa:

(1) _______________________

(2) _______________________

2) Functions:

a) _______________________ circular muscles that control flow through GI tube

(1) Cardiac sphincter prevents backflow into the _______________________

(2) Pyloric sphincter only allows small amount of the _______________________

b) _______________________ (2-6 hours)

c) _______________________ muscularis movements mix gastric secretions with bolus

(1) _______________________ thick soupy, acidic liquid formed from the mixing of gastric juices

with bolus.

d) ______________________ gastric juices

3) Secretions:

a) _______________________

(1) Goblet cells

(2) Protect mucosal wall from HCl and pepsin

b) _______________________ substance required for vitamin B12 absorption

c) _______________________

(1) Kills most bacteria

(2) activates pepsinogen (inactive enzyme) to pepsin (active enzyme).

d) _______________________

(a) inactive enzyme converted to pepsin in acidic environments

(b) Hydrolyzes proteins into amino acids

4) MECHANICAL DIGESTION _______________________

5) CHEMICAL DIGESTION _______________________

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F) Small intestine

1) Approximately 9 feet long

2) Surface area = tennis court

a) _______________________

(1) Macroscopic

(2) Projections of mucosal wall

(3) Blood vessels

b) _______________________

(1) Microscopic

(2) Projections of cell membrane on individual simple columnar cell’s apical surface

3) Duodenum

a) Proximal to stomach (10”)

b) Receives secretions _______________________ from gallbladder and liver

c) Receives secretions ______________________________________________ from pancreas

4) Jejunum

a) Middle portion (8”)

b) _______________________

c) Pancreatic Enzymes:

(1) (pancreatic) amylase

(2) Lipase

(3) Proteases

5) Ileum

a) distal portion to the stomach (8’)

b) _______________________

(1) Absorption—monomers cross from the lumen into body tissues/ cells

(2) Small molecules picked up by blood vessels and carried to distant body parts

(3) _______________________

(4) _______________________

(5) _______________________

(6) _______________________

6) CHEMICAL DIGESTION

a) _______________________

b) _______________________

c) _______________________

7) MECHANICAL DIGESTIION

a) _______________________

b) Movement/mixing with enzymes

Human Biology: Digestive System Lecture Notes, Page 6 of 13

G) Large intestine

1) Shorter than small intestine/larger diameter lumen

2) _______________________

3) MANY goblet cells (lubrication)

4) _______________________ (blind pouch) proximal to small intestine with _______________________

5) Primary function: _______________________

6) _______________________ indigestible material

a) Bacteria produce gas (odor), vitamin K & B

7) Sphincters

a) internal/involuntary _______________________

b) External/voluntary _______________________

8) _______________________ external opening

9) CHEMICAL DIGESTION: _______________________

10) MECHANICAL DIGESTION: _______________________

Part 3 Accessory Organs of Digestion

A) Secretions contribute to the processing of the foodstuff as it passes through GI tract

1) note: foodstuffs do NOT pass through the accessory organs

B) Salivary Glands:

1) secretion: __________________

2) Contribution to digestive function:

a) Sense: ___________________

b) Neutralizes: ______________

c) Enzyme: __________________

d) _______________________

e) Food + Saliva = _____________

C) Pancreas:

1) _______________________ : ductless gland that secretes hormones into bloodstream

a) Regulate/maintain blood glucose levels

b) _______________________ decreases blood glucose

c) _______________________ increases blood glucose

2) _______________________ : secretes substances through a duct onto the body surface (lumen of

duodenum)

(a) _______________________ Neutralizes chyme

(b) _______________________ Hydrolyzes starch

(c) _______________________ Hydrolyzes triglycerides

(d) _______________________ Hydrolyzes proteins

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D) Liver:

1) Detoxifies blood: converts _______________________(toxic) to _______________________ from

amino acid metabolism.

2) Maintains blood glucose levels (100mg/mL)

a) Excess glucose is stored as _______________________

b) Blood glucose levels drop, glucagon causes liver to breakdown glycogen into

_______________________ raising blood glucose levels.

c) Glycogen levels depleted, converts amino acids into glucose

3) Removes _______________________ from RBC degradation.

4) Stores Fat soluble vitamins (ADEK)

5) Synthesizes blood proteins:

a) _______________________

b) _______________________

6) Synthesizes _______________________ (maintain membrane fluidity)

7) Synthesizes _______________________ to emulsify fats

a) ______________________ portion that interacts with water

b) ______________________ portion that repels water

E) Gallbladder:

1) Located between the lobes of the liver

2) Ducts connect to duodenum and liver

3) Contribution to Digestion: Stores bile

a) _______________________ make water-insoluble substances water soluble.

Part 4 Nutrients

A) Glucose

1) Body’s preferred energy source

2) _______________________ also found in complex carbohydrates/polysaccharide

3) Provides energy: _______________________

4) Stored as _______________________

B) Amino Acids

1) Used to build _______________________

2) Can be used to make glucose (last resort)

C) Fatty Acids

1) Energy

2) Long-term energy storage: ___________________

3) Used to build _______________________: the main structural component of all cell membranes

D) Minerals

1) _______________________ found in hemoglobin, transport oxygen

2) _______________________ used to build bone, conduct nervous impulses and muscle contractions

3) _______________________ used to generate nervous impulses

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E) Vitamins

1) _______________________ organic molecules that carry H+ and/or electrons between chemical

reactions

2) Example: B vitamins

a) _______________________ Niacin (B vitamin)

b) _______________________ Flavin (B vitamin)

3) Example:

a) Pick up electrons � _______________________

NAD+ + 2 e- + H+ � NADH

4) Drops off electrons � _______________________

NADH � NAD+ + 2 e- + H+

Section 5 Metabolism

A) Metabolism: a cell/organisms’ ability to extract and convert energy and nutrients from it’s environment for

growth, maintenance and reproduction.

1) _______________________ degradation reactions/breaking the bonds in large molecules

a) Example: _______________________

2) _______________________ building/synthesis reactions/making bonds between smaller molecules

a) example: _______________________

B) Aerobic Cellular Respiration

1) GENERAL CHEMICAL REACTION:

C6H12O6 + 6 O2 � 6 CO2 + 6 H2O

2) Reactants (label above)

3) Products (label above)

4) 3 sets of Chemical Reactions included in the arrow (label above)

5) ATP � ADP + P + Energy

(1) ATP � ADP + P + Energy

(2) Used to do : _______________________

(3) Example: Active transport, muscle contraction

b) ADP + P + Energy � ATP

(1) Energy provided from the foods we eat

(2) _______________________source of potential energy in foods we eat

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C) Glycolysis

1) General:

a) ‘glyco’ _______________________

b) ‘lysis’ _______________________

2) Location: _______________________

3) Reactant: _______________________

a) 6-Carbon molecule

b) Energy located in its _______________________

c) Release energy by breaking covalent bonds

4) Costs the cell to do glycolysis

a) _____________________

b) Purpose: create a high energy intermediate

5) Break Covalent Bond

a) Covalent bond (def) _____________________

6) NAD+ picks up electrons (and H+) —becomes Reduced coenzyme

a) Carrying _____________________

b) NAD+ + 2 e

- + H

+ � NADH Reduced coenzyme

7) ENERGY PAYOFF

a) 4 ADP + 4 P + ENERGY � 4 ATP

b) Cost the cell ___________________________

c) Net ATP GAIN from glycolysis: _____________

8) PRODUCT: _____________

a) Two 3-Carbon molecules

b) Fate of Pyruvate depends on the presence of _____

9) Overview of glycolysis:

a) Location: _______________________

b) 6-Carbon glucose split into _______________________

c) Cost the cell ________ to do glycolysis

d) Loaded high energy electrons onto NAD+ to make NADH_______________

e) TOTAL ATP produced from 1 glucose: ________

f) NET ATP produced from 1 glucose: ________

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D) Fate of Pyruvate dependent on the presence of _______________________

1) Present: _______________________

2) absent: _______________________

E) Mitochondria

1) Double membrane

2) Intermembrane space: between the inner and outer membranes

3) Mitochondrial matrix: space within the inner membrane

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F) Kreb’s Cycle (aka Citric Acid Cycle)

1) Oxygen must be __________________

2) Location: __________________

3) Reactant: __________________

4) Break covalent bonds in pyruvate:

a) reduce coenzyme __________________

b) Waste product ____________________

5) Continue to Break covalent bonds

a) reduce coenzyme ______ AND ____________

b) Waste product ____________________

6) Energy yield: ____________________

7) Overview of Krebs:

a) Location: _______________________

b) 3-Carbon pyruvates split into ________________

c) Made FADH2 and NADH _______________

d) TOTAL ATP produced from 1 glucose: ________

(1) EACH pyruvate yeilds _______

e) Note: ________________was used in ANY of the chemical reactions of Krebs!

PYRUVATE

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G) Electron Transport Chain (ETC)

1) Oxygen must be __________________

2) Location: __________________

3) __________________ bring high energy electrons to the ETC proteins

a) ________________ oxidized form of the coenzyme

b) Return to Kreb’s and glycolysis to pick up more electrons (reduced)

4) ETC proteins use the ENERGY from the __________________ to PUMP ________________

a) From the matrix INTO the intermembrane space

5) Low energy electrons are given to __________________ making ________________

a) Oxygen is the ‘final electron acceptor’

6) Purpose of pumping the hydrogen ions: __________________

a) Source of POTENTIAL ENERGY

7) __________________

a) Enzyme, Inner mitochondrial membrane protein

b) ADP + P + Energy � ATP

c) Energy provided as H+ flow from _____________________________

d) 1 glucose: __________________

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8) Overview of ETC:

a) Location: _______________________

b) Source of electrons:

(1) Glycolysis: ________________

(2) Kreb’s:_______________

c) Uses the electrons to pump: _______________

d) ATP synthase

(1) ADP + P + Energy � ATP

(2) source of energy : ________

e) 1 glucose: ________________

f) Oxygen:

(1) Required ________________

(2) Used to make ________________

H) Fermentation

1) Fate of Pyruvate dependent on the presence

of _______

a) Present: pyruvate enters mitochondria

and starts Kreb’s

b) Absent: pyruvate STAYS in the cytoplasm

2) Purpose of Fermentation: ___________________________________________

3) Overview:

a) Location: _______________

b) Reactant: _______________

c) Product:________________

d) Energy: ________________