CH 3: The Human CH 3: The Human Body; A Nutrition Body; A Nutrition

PerspectivePerspective

Chapter OverviewChapter Overview

This chapter covers everything from cell This chapter covers everything from cell structure to all of the systems of the body!structure to all of the systems of the body! This is the content of BIO 100 in one chapter!This is the content of BIO 100 in one chapter!

We will focus on the digestive system and We will focus on the digestive system and systems that directly relate to the function systems that directly relate to the function of this system..of this system..

Sections CoveredSections Covered

While we may touch on content in other While we may touch on content in other sections, we will focus on:sections, we will focus on: Cardiovascular & lymphatic system (3.4)Cardiovascular & lymphatic system (3.4) Endocrine system (3.6)Endocrine system (3.6) Digestive system (3.8)Digestive system (3.8)

Cardiovascular & Lymphatic Cardiovascular & Lymphatic SystemsSystems

CV and lymphatic system circulate fluids in CV and lymphatic system circulate fluids in the bodythe body

CV systemCV system Heart and blood vesselsHeart and blood vessels

Lympahtic systemLympahtic system Lympahtic vessels and lymph nodesLympahtic vessels and lymph nodes

BloodBlood Blood is made of:Blood is made of:

Plasma – fluid portion of bloodPlasma – fluid portion of blood Water soluble nutrients are dissolved in the plasma Water soluble nutrients are dissolved in the plasma

Red blood cells Red blood cells White blood cellsWhite blood cells PlateletsPlatelets Proteins and other substancesProteins and other substances

Fat soluble nutrients are often carried by water Fat soluble nutrients are often carried by water soluble proteinssoluble proteins

CV System – CV System – more detail than we have time formore detail than we have time for

Heart Heart -> Lungs -> Lungs Veins bring deoxygenated blood to the right Veins bring deoxygenated blood to the right

side of the heartside of the heart Right side of the heart pumps deoxygenated Right side of the heart pumps deoxygenated

blood to the lungsblood to the lungs Blood returns to the left side of the heart Blood returns to the left side of the heart

oxygenatedoxygenated Left side of heart pumps blood to entire body by Left side of heart pumps blood to entire body by

way of arteriesway of arteries•

Blood VesselsBlood Vessels

Blood leaves heart through an artery Blood leaves heart through an artery (aorta)(aorta)

Vessels branch in to smaller and smaller vesselsVessels branch in to smaller and smaller vessels Smallest blood vessel is the capillarySmallest blood vessel is the capillary Exchanges of gases, nutrients and wastes between Exchanges of gases, nutrients and wastes between

body cells and the CV system occur at the capillary body cells and the CV system occur at the capillary levellevel

CV System & Digestive TractCV System & Digestive Tract

CV system transports nutrients to the cells CV system transports nutrients to the cells of the bodyof the body

Water soluble nutrients are absorbed in to Water soluble nutrients are absorbed in to capillaries in the small intestine (SI)capillaries in the small intestine (SI)

Capillaries merge to form the portal veinCapillaries merge to form the portal vein Portal vein transports nutrients to the liverPortal vein transports nutrients to the liver

#7 on page 90 #7 on page 90

Lymphatic SystemLymphatic System

Lymph vessels transports:Lymph vessels transports: white blood cellswhite blood cells excess fluid between cellsexcess fluid between cells

• Returns the fluid to the bloodReturns the fluid to the blood fat soluble nutrients absorbed from the SIfat soluble nutrients absorbed from the SI

Lymph vessels branch to form Lymph vessels branch to form lactealslacteals Fat soluble nutrients are absorbed in to Fat soluble nutrients are absorbed in to

lacteals – page 91lacteals – page 91

Lymphatic SystemLymphatic System

Lymph vessels leaving the SI merge with Lymph vessels leaving the SI merge with veins near the heartveins near the heart Fat soluble nutrients in the lymph enter the Fat soluble nutrients in the lymph enter the

blood, go through the heart and lungs and are blood, go through the heart and lungs and are then circulated in the blood then circulated in the blood

Endocrine SystemEndocrine System

Endocrine glands secrete hormonesEndocrine glands secrete hormones Hormones enter the blood and bind to Hormones enter the blood and bind to

target cellstarget cells Cells with receptors for the hormoneCells with receptors for the hormone

Binding triggers a change in the target Binding triggers a change in the target cells/organcells/organ See table 3-2 on page See table 3-2 on page 9393

Endocrine SystemEndocrine System

Digestive System Digestive System (finally)(finally)

Functions: Digestion, Absorption, Elimination

Digestion – process of breaking down foods to release nutrients

• Goal is to break nutrients into absorbable units

2 types of digestions: 1. Mechanical

2. Chemical (enzymatic)

Overview Digestive SystemOverview Digestive System

Absorption – movement of nutrients out of GI tract into blood or lymph Water soluble nutrients Fat soluble nutrients

Excretion – elimination of undigested foods (feces)

Overview Digestive SystemOverview Digestive System

Structure Gastrointestinal (GI) TractStructure Gastrointestinal (GI) Tract Continuous tube from mouth to anusContinuous tube from mouth to anus

• See board and page 97See board and page 97

GI Tract GI Tract AnatomyAnatomy

Digestive TractDigestive Tract

Layers of GI tract organsLayers of GI tract organs Serosa (outermost)Serosa (outermost)

• Interface between GI tract and lymph & blood Interface between GI tract and lymph & blood Muscle LayersMuscle Layers

• Longitudinal musclesLongitudinal muscles• Circular musclesCircular muscles

Submucosal and Mucosal and layers Submucosal and Mucosal and layers (innermost)(innermost)• Nerves, blood and lymph vessels Nerves, blood and lymph vessels • Cells of the mucosal layer produce secretionsCells of the mucosal layer produce secretions

MouthMouth Structure – Structure – teeth, tongue, salivary glandsteeth, tongue, salivary glands SecretionsSecretions

SalivaSaliva MucusMucus Salivary amylase Salivary amylase

Digestion Digestion Mechanical ….Mechanical …. Enzymatic/chemical ….Enzymatic/chemical ….

Swallow Swallow tongue pushes food tongue pushes food pharynx pharynx …… ……

EsophagusEsophagus

Structure – 12” tubeStructure – 12” tube UES and LESUES and LES

FunctionFunction Transports food from mouth to stomachTransports food from mouth to stomach Peristalsis and gravity aid food movement Peristalsis and gravity aid food movement

Secretions -- mucusSecretions -- mucus Digestion Digestion

Mechanical (limited)Mechanical (limited) Enzymatic/chemical – starch digestion continuesEnzymatic/chemical – starch digestion continues

StomachStomach

Structure ….Structure ….page 101page 101

Secretions …..Secretions ….. Digestion ……Digestion ……

MechanicalMechanical Enzymatic/chemicalEnzymatic/chemical

StomachStomach Structure – Structure –

muscular sack muscular sack that can expandthat can expand extra muscle extra muscle

layer to aid in layer to aid in the mechanical the mechanical digestion of digestion of food (pg 101)food (pg 101)

Stomach Related SecretionsStomach Related Secretions

1. Gastrin – hormone that stimulates stomach to release secretions

2. Hydrochloric Acid (HCl) -- unravels proteins, kills bacteria, activates pepsinogen

3. Pepsinogen – once activated, begins protein digestion

Stomach Related SecretionsStomach Related Secretions

4. Mucus – secreted by goblet cells, protects stomach, moistens food

5. Intrinsic factor (IF) – IF binds vitamin B-12

• Required for B-12 to be absorbed

Stomach related secretions

Function

Gastrin

HCl

Pepsinogen

Mucus

Intrinsic Factor

Stomach - - Digestion

Mechanical• Stomach muscles grind food into a paste called

chyme

Enzymatic/chemical• Proteins uncoiled• Protein digestion to polypeptides begins• Starch digestion stops (why??)

Small Intestine (SI)Small Intestine (SI)

Function – The SI is where:1. the majority of digestion to absorbable units

occurs• Digestion of carbohydrates, fats, and proteins • Vitamins and minerals do not need digestion

2. Nutrients are absorbed into either capillaries or lacteals

Small IntestineSmall Intestine

StructureStructure – see page 102 – see page 102 Length – 10 feet (~ 21’-22’ long when relaxed)Length – 10 feet (~ 21’-22’ long when relaxed)

Layers …..Layers ….. Mucosal folds, villi, microvilli ….Mucosal folds, villi, microvilli …. Goblet cells and crypts – create secretionsGoblet cells and crypts – create secretions Lacteals and capillaries ….Lacteals and capillaries ….

SectionsSections• DuodenumDuodenum• JejunumJejunum• IleumIleum

Small IntestineSmall Intestine

The Small Intestinal VilliThe Small Intestinal Villi

The Small Intestinal VilliThe Small Intestinal Villi

Small IntestinesSmall Intestines

Secretions of the SI1. Mucus

• Secreted by ____________ cells

2. Digestive enzymes that finish the digestion of carbs, fats, and proteins• Secreted from crypts

Small IntestineSmall Intestine

Secretions Secretions of theof the SI, cont’d SI, cont’d HormonesHormones

• Secretin …Secretin …• CCK ….CCK ….• Gastric-inhibitory peptide …Gastric-inhibitory peptide …

Small Intestine - HormonesSmall Intestine - Hormones

Secretin – produced when chyme enters SI• stimulates pancreatic secretions

*CCK – produced when fat enters SI• Stimulates _________to release ______• Slows GI motility (slows peristalsis)• **Cholecystokinin

Gastric–inhibitory peptide – produced when chyme enters SI

• Slows stomach secretions• Slows GI motility

Secretions of SI When Secreted and Function

Mucus

Digestive Enzymes

Secretin

CCK

Gastric inhibitory peptide

Secretions into SISecretions into SI

Pancreatic secretions: Released in response to ________ Sodium bicarbonate

• Neutralizes acidic chyme Digestive enzymes that begin the digestion of

carbs, fats, and proteins

Secretions into SISecretions into SI

Liver and Gall BladderLiver and Gall Bladder Liver makes bileLiver makes bile Gall bladder concentrates and stores bileGall bladder concentrates and stores bile Bile is released into SI in response to the Bile is released into SI in response to the

hormone _______hormone _______ Function of bile: Function of bile:

Secretions into SI Secreted by and Function

Sodium bicarbonate

Digestive Enzymes

Bile

Small IntestineSmall Intestine

Digestion - MechanicalDigestion - Mechanical Peristalsis pushes food through SIPeristalsis pushes food through SI Segmentation mixes chyme with digestive Segmentation mixes chyme with digestive

enzymes enzymes • Also breaks up food mass into smaller massesAlso breaks up food mass into smaller masses

Bile emulsifies fatsBile emulsifies fats

Peristalsis & SegmentationPeristalsis & Segmentation

Muscular Action Muscular Action of Digestionof Digestion

SegmentationSegmentation

SI - SI - DigestionDigestion

Mechanical digestionMechanical digestion Muscle action breaks food into smaller and Muscle action breaks food into smaller and

smaller piecessmaller pieces Bile emulsifies fats Bile emulsifies fats

Chemical/EnzymaticChemical/Enzymatic Pancreatic and SI enzymes digest carbs, fats, Pancreatic and SI enzymes digest carbs, fats,

and proteins to absorbable unitsand proteins to absorbable units

SI - AbsorptionSI - Absorption

Absorbed into capillaries (blood)Absorbed into capillaries (blood) Digested carbohydrates and proteinsDigested carbohydrates and proteins MineralsMinerals

• Some require helper proteins/cells on walls of SI to Some require helper proteins/cells on walls of SI to be absorbedbe absorbed

Water soluble vitaminsWater soluble vitamins Blood takes nutrients to the liver for processing Blood takes nutrients to the liver for processing

after absorption (pg 90)after absorption (pg 90)

SI - AbsorptionSI - Absorption

Absorbed into lacteals (lymph) Digested fats Fat soluble vitamins Cholesterol

Nutrients travel through lymph system to chest area where lymph and blood join

Nutrients enter blood and travel through body

What is the relationship between the structure of the SI and its function?

SI Review

Large Intestine or ColonLarge Intestine or Colon

Undigested foods (fiber) enter into colonUndigested foods (fiber) enter into colon Unabsorbed nutrients pass into colonUnabsorbed nutrients pass into colon

E.g. calcium, iron, cholesterol trapped in fiberE.g. calcium, iron, cholesterol trapped in fiber

ColonColon StructureStructure

Ileocecal sphincter Ileocecal sphincter connects colon to SIconnects colon to SI• Appendix is a little pouch near beginning of colon Appendix is a little pouch near beginning of colon

Colon is ~5-6’ long, “wraps around” SIColon is ~5-6’ long, “wraps around” SI Wider diameter than SIWider diameter than SI

• No villi or microvilliNo villi or microvilli• No digestive enzymesNo digestive enzymes

Pages 104/105Pages 104/105

ColonColon

SecretionsSecretions MucusMucus Bacteria living in colonBacteria living in colon

• Digest small amounts of fiber and undigested Digest small amounts of fiber and undigested nutrientsnutrients

• Often produce…...Often produce…...

ColonColon

AbsorptionAbsorption Water, salts, vitamins made by bacteria are Water, salts, vitamins made by bacteria are

absorbed into __________ (answer is either absorbed into __________ (answer is either capillaries or lacteals. Which one is it?..you capillaries or lacteals. Which one is it?..you know!)know!)

Fiber attracts waterFiber attracts water Too little fiber in diet Too little fiber in diet Too much fiber in diet Too much fiber in diet

Rectum and AnusRectum and Anus

Feces pass from colon into rectumFeces pass from colon into rectum Rectum stores feces until excretion occursRectum stores feces until excretion occurs Feces exit body via anusFeces exit body via anus

2 anal sphincters2 anal sphincters• Internal and external anal sphinctersInternal and external anal sphincters