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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.
The structure of a tooth: 2/5
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
Pulp cavityNerves & blood vesselsPeriodontal fibers &
Cementum
Jawbone
The structure of a tooth: 4/5
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
Pulp cavityNerves & blood vesselsPeriodontal fibers &
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
Pulp cavityNerves & blood vesselsPeriodontal fibers &
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
mouthbreak up fooddigest starchkill germsmoisten food
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
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
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
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
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
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
liverproduces bile
- stored in gall bladderbreak up fats
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
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
small intestinesbreakdown food
- proteins- starch- fats
absorb nutrients
pancreasproduces enzymes to digest proteins & carbs
liverproduces bile
- stored in gall bladderbreak up fats
large intestinesabsorb water
AppendixVestigial organ
stomachkills germs break up fooddigest proteinsstore food
mouthbreak up fooddigest starchkill germsmoisten food
small intestinesbreakdown food
- proteins- starch- fats
absorb nutrients
pancreasproduces enzymes to digest proteins & carbs
liverproduces bile
- stored in gall bladderbreak up fats
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
from intestinal glands
+H2O Maltose GlucoseMaltase +Glucose
from intestinal glands
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.
In the small intestine:
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
In the small intestine:
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