Digesive system renewed

Animal NutritionHuman Digestion

What do animals need to live? Animals make energy

using: food oxygen

Animals build bodies using: food for raw materials

amino acids, sugars, fats, nucleotides

ATP energy for synthesis

O2

food

ATP

mitochondria

How do animals get their food?

filter feeding living in your food

fluid feeding bulk feeding

Different diets; different lives All animals eat other organisms

Herbivores eat mainly plants

gorillas, cows, rabbits, snails

Carnivores eat other animals

sharks, hawks, spiders, snakes Omnivores

eat animals & plants cockroaches, bears, raccoons, humans humans evolved as hunters, scavengers & gatherers

Getting & Using Food Ingest

taking in food Digest

mechanical digestion breaking up food into smaller pieces

chemical digestion breaking down food into molecules small

enough to be absorbed into cells enzymes

Absorb absorb nutrients across cell membranes

diffusion active transport

Eliminate undigested material passes out of body

intracellulardigestion

extracellulardigestion

Digestive systemsEverybody’s got one!

Food can be divided into six groups according to its

composition;

60%

1%1%

5%

15%

19%

Water

Minerals

Vitamins

Proteins

Lipids

Carbohydrates

Each of these foods should be taken in

proper amounts for

energy production and

for the production of

some vital substances for the body !!!!!

NUTRIENTS

Regulatory

Elements

Structural Elements

Energy Sources

LipidsCarbohydrates

Proteins

Minerals

H2O Vitamins

Foodstuffs can be grouped according to their functions as below;

Human digestive system

Mouth Functions

mechanical digestion teeth

break up food chemical digestion (saliva)

amylase enzyme digests starch

mucus protects soft lining of digestive system lubricates food for easier swallowing

buffers neutralizes acid to prevent tooth decay

anti-bacterial chemicals kill bacteria that enter mouth with food

All thatin spit!

Swallowing (& not choking)

Epiglottis flap of cartilage closes trachea (windpipe) when swallowing food travels down esophagus

Peristalsis involuntary muscle contractions to move food along

Teeth:

The function of the teeth is to grind the food into an easily digestible form and to mix it with digestive secretions.

In a mature human there are 32 teeth. 16 of them are on the upper jaw and 16 of them are on the lower

jaw.

Upper Jaw

Lower Jaw 16

16

4 are in the front and named as incisors. (Total:

8)

2 are behind the incisors and named as canines.

(Total: 4)

4 are behind the canines and named as premolars.

(Total: 8)

6 are behind the premolars and named as molars.

(Total: 12)

On one jaw;On one jaw;

The incisors and canines cut the food, the premolars and molars grind it.

Adult teethAdult teeth

Last 4 molars (=two in each jaw bone) emerge after the

age of 20 and they are known as wisdom teeth.

20 of milk teeth that emerge in the early ages are replaced with 28 new

teeth at the age of 7. WisdoWisdom m

TeethTeeth

Milk

Tee

th o

f a

Milk

Tee

th o

f a

child

child

The teeth maybe different in shape but their structures are all same.

A tooth is composed of 3 different parts;

The structure of a tooth: 1/5

The crown(=the part that is seen on the

gum)

The neck(=the part in the gum)

The root(=the part in the jawbone)

If a cross section is studied from outside to inside 3 different layers are seen; enamel, dentine and pulp

cavity.


CrownNeck

Root

EnamelDentinGum

Pulp cavityNerves & blood vesselsPeriodontal fibers &

Cementum

Jawbone

The structure of a tooth: 3/5 Enamel covers the crown part and it is composed of

calcium phosphorus and fluoride. Enamel is the hardest material in human body.

CrownNeck

Root

EnamelDentinGum


Cementum

Jawbone


Right beneath the enamel dentine is present. Dentine is the bone-like structure of the tooth.

The pulp cavity contains the nerves and capillaries.

CrownNeck

Root

EnamelDentinGum


Cementum

Jawbone

The structure of a tooth: 5/5 The root is surrounded by periodontal fibers and a layer of cement that fix the tooth firmly to the

jawbone.

CrownNeck

Root

EnamelDentinGum


Cementum

Jawbone

mouthbreak up fooddigest starchkill germsmoisten food

The tongue together with the teeth assist the masticated (=chewed) food to mix with saliva in order

to form a bolus. The taste buds on the tongue helps person to taste

bitter, sour, sweet and salty tastes.

The tongue is also studied under chapter sensory organs.

PapillaeTaste buds

Taste M

olecules

The pharynx is a cavity that is located directly behind the mouth and at the top of the esophagus and trachea.

The swallowed bolus passes from the pharynx into the esophagus. The food passage into the trachea is prevented by epiglottis.

Swallowing starts voluntarily in the mouth and continues through the pharynx into the esophagus involuntarily.

3) ESOPHAGUS:

Esophagus resembles a pipe that is 25 cm. long and 2 cm. wide.

It is located between pharynx and the stomach.

The esophagus wall is composed of 3 main layers;

Outer layer Middle layer Inner layer

Outer layer contains connective tissue and protects the esophagus.

Middle layer contains circular muscles. Contractions and relaxations of these muscles result in peristaltic movements. Peristaltic movements force the food into the stomach. Reverse peristalsis causes vomiting.

StomachFunctions

disinfect foodhydrochloric acid = pH 2

kills bacteria food storage

can stretch to fit ~2L food

digests proteinpepsin enzyme

But the stomach is made out of protein!What stops the stomach from digesting itself?mucus secreted by stomach cells protects stomach lining

1) To store ingested food2) To produce gastric juice for

digestion3) To mix digestive juices and

food by physical movements

4) To carry food into the small intestine

stomachkills germs break up fooddigest proteinsstore food

sphincter

sphincter


Used to think ulcers were caused by stress

tried to control with antacids

Now know ulcers caused by bacterial infection of stomach

H. pylori bacteria now cure with

antibiotics

Ulcers

inflammation of stomach

inflammation of esophagus

Colonized by H. pylori

Free of H. pylori

white blood cells

cytokines

inflammatory proteins(CagA)

cell damaging proteins(VacA)

helper T cells

neutrophil cells

H. pylori

Small intestine Functions

digestion digest carbohydrates

amylase from pancreas digest proteins

trypsin & chymotrypsin from pancreas digest lipids (fats)

bile from liver & lipase from pancreas absorption

nutrients move into body cells by:diffusionactive transport

This iswhere all thework is done!

Absorption in Small Intestines Absorption through villi & microvilli

finger-like projections increases surface area for absorption

SMALL INTESTINES6 meters long,but can stretch

to cover a tennis court

small intestinesbreakdown food

- proteins- starch- fats

absorb nutrients



pancreasproduces enzymes to digest proteins & starch

liverproduces bile

- stored in gall bladderbreak up fats

Pancreas Produces digestive enzymes

digest proteins trypsin, chymotrypsin

digest starch amylase

digest lipids lipase

Buffers neutralizes

acid from stomach small

intestinepancreas



pancreasproduces enzymes to digest all foods

Liver & Gall Bladder Produces bile

breaks up fats gallbladder only stores bile

that’s why you can have your gall bladder removed

bile contains colors from old red blood cells collected in liver =iron in RBC rusts & makes feces brown

pancreasproduces enzymes to digest proteins & starch



liverproduces bile


Function re-absorbs water

use ~9 liters of water every day in digestive juices

if don’t reabsorb water would die of dehydration

> 90% of water re-absorbednot enough water re-absorbed

diarrhea can be fatal!

too much water re-absorbed constipation

reabsorb by diffusion

Large intestines (colon)

You’ve got company! Living in the large intestine is a

community of helpful bacteria Escherichia coli: E. coli

digest cellulose digests fruits & vegetables

produce vitamins vitamin K & B vitamins

BUT generate gases by-product of bacterial metabolism methane, hydrogen sulfide STINKY!

PEE-YOO!

Caecum is attached vertically to the small intestine. From caecum a projection known as appendix extends.

The inflammation of appendix (=appendicitis) requires surgical operation.

Appendix





absorb nutrients

pancreasproduces enzymes to digest proteins & carbs

liverproduces bile


large intestinesabsorb water

AppendixVestigial organ





absorb nutrients

pancreasproduces enzymes to digest proteins & carbs

liverproduces bile


large intestinesabsorb waterappendix

Rectum Last section of large intestines

eliminate feces what’s left over?

undigested materials mainly cellulose from plants called roughage or fiber keeps everything moving & cleans out

intestines masses of bacteria

So don’t forget to wash

your hands!

Different diets; different bodies Adaptations of herbivore vs. carnivore

teeth length of digestive system number & size of stomachs

Teeth Carnivore

sharp ripping teeth “canines”

Herbivore wide grinding teeth molars

Omnivore both kinds of teeth

Length of digestive system Herbivores & omnivores

long digestive systems

harder to digest cellulose (cell walls) bacteria in intestines

help Carnivores

short digestive systems

protein easier to digest than cellulose

appendix

Eating a balanced diet What happens if an animal’s diet is

missing an essential nutrient? deficiency diseases

scurvy — vitamin C (collagen production) rickets — vitamin D (calcium absorption) blindness — vitamin A (retinol production) anemia — vitamin B12 (energy production) kwashiorkor — protein

Need to make sure you get enough protein 20 amino acids to make protein

12 amino acids humans can produce 8 we have to eat = “essential amino acids”

Grains (like corn) have 6 amino acids missing 2

Beans (like soybean & red beans) have 6 amino acids missing different 2 mix beans & grains

for complete group of amino acids

rice & beans taco/tortilla & beans tofu & rice peanut butter & bread

Vegetarian diets

liver

pancreas

liver

Balancing Blood Sugar levels

blood sugar level

insulin

body cells takeup sugar

from blood

liver storessugar

reducesappetite

glucagon

pancreas

liver releases

sugartriggershunger

high

low

Feedback

Homeostasis

2006-2007

Don’t turn yourselfinside out…

Ask Questions!!

Feedback: Maintaining Homeostasis Balancing glucose levels in blood

pancreas

pancreas

insulin

liver takes upglucose

for storage

cellstake up

glucose from blood

liver releasesglucose to blood

depress appetite

stimulatehungerglucagon

There are three pairs of salivary glands in the mouth; sublingual, submaxillary and parotid glands.

Additionally, the mucosa of the mouth produces secretions.

Secretions of these glands form the saliva of the mouth.

Saliva contains … enzyme

amylase(=ptyalin)

Mucus(=it functions as a

solvent)

Proteins Water Na++

Ca++

Functions of saliva1)It initiates carbohydrate digestion

2)It helps in detection of taste because it is a solvent

3)It helps in formation of bolus

4)It lubricates the pharynx so that food may be swallowed easily

5)It assists in speaking

Gastric Juice is acidic with pH = 1-2 and capable to digest the stomach wall.

Gastric juice is secreted by the gastric glands in the stomach. Gastric juice contains …

HCl

Pepsinogen

rennin (=in babies)

a small amount of

lipase.Gastric juice

Stomach wall

Self digestion is prevented by the secretion of mucus from the gastric glands. Any damage in

the gastric mucosa results in gastritis (Inflammation of the stomach). Gastritis may

result from infection, alcohol, or dietary changes. Areas effected from gastritis

Gastritis may develop in a peptic ulcer.

areas of peptic ulcer

What is the difference between gastritis and peptic ulcer?

Gastritis is not a single disease, it is inflammation of the stomach lining and

has many causes from drinking too much to a bacteria in the stomach.

A peptic ulcer is when a sore or ulcer has been made in the lining of the

stomach by the stomach acid.

Functions of HCI acid in Gastric juice

1) It converts inactive pepsinogen into active pepsin

2) It stimulates the secretions of pancreas and intestinal glands

3) It destroys microbes ingested with food

4) It facilitates digestion by denaturizing proteins

Pepsinogen(Inactive)

Pepsin(Active)

HCl

Control of Gastric juice secretion

Food enters the stomach

Receptors of stomach send

impulses to m.o

Medulla oblongata send

impulses via vagus nerve

Secretory cells of stomach secrete hormone Gastrin

Formation of Pepsin

Digestion of proteins and formation of

chyme

Chyme enters duedonum

Secretory cells of duedonum

secrete enterogastrin

Enterogastrin inhibits the

stomach activity

Gastrin stimulates the

secretion of HCl and

Pepsinogen

Control of Gastric juice secretion

Bile ducts merge and form the Common hepatic

duct.

Common hepatic duct carries the bile salts into

the gall bladder for further usage.

Approximately 600 ml. of bile is secreted from the liver in a single day.

Bile contains insoluble cholesterol and some other substances.

A reduction in the bile salts can result in the formation of gall stones by the precipitation of

cholesterol.

Functions the liver

1) Formation and degradation of erythrocytes: Old erythrocytes are degraded in the liver.

From hemoglobin bile salts and the hemoglobin of new erythrocytes are synthesized.

Old erythrocytes are degraded by phagocytotic activity of Kuppfer cells.

In early embryological development, liver functions as an organ that produces

erythrocytes.

BILEHEME

early embryological

development

2) Formation and secretion of bile: Bile is formed by liver cells and drain into common hepatic duct. Common hepatic duct braches into to two ducts. (Cystic duct and

common bile duct) Cystic duct brings excess bile into the gall bladder and common bile duct leads bile in the

small intestine.90% of bile salts are absorbed

during passage through the

small intestine.Bile helps the

absorption of lipids and plays a great role in the prevention

of bacteria production in

feces.

3) Regulation of blood sugar level: Excess amount of sugar in the blood is stored as

glycogen in the liver. When blood sugar level decreases glycogen is converted into glucose

and released into the blood.

Glucose

Glycogen

Insulin Glucagon

4) Conversion of provitamin A into vitamin A & vitamin deposition :

Liver converts provitamin A into vitamin A. On the other hand, liver stores vitamins A, D, K

and some minerals such as Fe, Cu etc.

Provitamin A

Vitamin A

Liver synthesizes 12 amino acids out

of 20.

Excess amino acids are stored in the form of lipid at proper

parts of the body.

5) Regulation of protein metabolism:

6) Urine synthesis:After the degradation of amino acids in the cells,

poisonous ammonia (=NH3) is produced.Ammonia is later brought to the liver to be

converted into a less poisonous substance –urine- by a process named as ornithine cycle.

Ornithine

Arginine

Citruline

Urea

H2O H2O

H2O

NH3

CO2

NH3

Ornithine Cycle

2NH3 CO2+ Urea H2O+

7) Plays a great role in coagulation of blood: In coagulation, proteins protrombin and fibrinogen are very important. These proteins

are synthesized by the liver. On the other hand, heparin that prevents blood

coagulation in vessels is also synthesized by the liver.

Protrombin Thrombin

Thrombokinase

Ca++, Vitamin K

Fibrinogen

(Soluble)

Fibrin(Insoluble)

Thrombocytes

Clot

Toxic substances that enter the body with food and medicines are detoxified by the liver cells. The most important toxic materials are H2S and H2O2. These substances are converted into H2O

and O2 by enzymatic activity.

8) Detoxification of substances:

The liver an organ that produces a great amount of heat.

The heat is distributed to other parts of the body by blood.

9) Regulation of body temperature:

10) Immunity:

The liver cells form lymph and also some antibodies that are important in immunity.

.

β-cells of the

pancreas

Normal Glucose level

Increase in glucose level

Conversion of glucose into

glycogen in the liver

Affects

Affects

Insulin secretion into

blood

Insulin and Glucagon functions in the control of blood glucose level

Decrease in glucose level

α-cells of the

pancreas

Glucagon is secreted into

blood

Conversion of glycogen into

glucose

Carbohydrate Digestion

In the mouth:

In the small intestine:

(ex: sucrose, lactose & maltose)

from salivary glands

+H2O Polysaccharide +DextrinDisaccharidesAmylase

from pancreas

+H2O Dextrin GlucoseAmylase

+H2O Sucrose GlucoseSucrase +Fructose

from intestinal glands

+H2O Lactose GlucoseLactase +Galactose


+H2O Maltose GlucoseMaltase +Glucose


Protein Digestion

From medulla oblongata Vagus nerve caries impulses to the secretory cells of the stomach.

Vagus stimulates the secretion of hormone gastrin. Gastrin stimulates the secretion of HCl and inactive pepsinogen.

In the stomach:

Pepsinogen(Inactive)

Pepsin(Active)

HCl

+H2O Proteins Peptones

Additionally in babies;

+H2O Casein PeptonesPepsin +Amino acids

+H2O Milk CaseinRennin

Chyme (=mixture of peptones, amino acids, monosaccharides, lipids, enzymes, vitamins and minerals and water etc.) enters

duodenum. Acidic content of chyme stimulates the secretion of hormone

secretin. Secretin stimulates pancreas to secrete pancreatic juice.

Pancreatic juice contains inactive enzymes trypsinogen and chymotrypsinogen.

On the other hand, intestinal glands secrete enterokinase. All of this mixture (chyme + enzymes + enterokinase) is present in the

intestine at this moment.


Trypsinogen(Inactive)

Trypsin(Active)

Enterokinase

Chymotrypsinogen(Inactive)

Chymotrypsin(Active)

Enterokinase

+H2O Peptones Peptides

Trypsin&

Chymotrypsin +Amino acids

+H2O PeptidesPeptidase (=Erepsin)

Amino acidsfrom intestinal

glands

In stomach

Proteins Peptones Amino acidsPeptides

In duedonum In ileum & jejenum

Shortly protein synthesis is as below;

Lipid Digestion


Bile secretion from the gall bladder emulsifies the lipids and makes their digestion easier.

If the gall bladder is removed in a person, lipid digestion occurs harder.

from pancreas

+H2O Lipids +Glycerol Fatty acidsLipase

Nucleic Acid Digestion

from pancreas

+H2O DNA NucleotidesDNA (ase)

+H2O RNA NucleotidesRNA (ase)

THE END

Digesive system renewed

Education

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