Transcript Digestion and Enzymes L4

How Do You Build the
Molecules of Life?
Better Known as Organic Molecules and Digestion…
Living Creatures Have Organization
• All organisms are made of the same collection
of chemicals, which are organized into…
• Molecules
• Made up of proteins, fats, carbohydrates,
and nucleic acids
Living Creatures Have Organization
• Molecules are then organized into…
• Organelles & Cells, specifically…
• Plant Cells & Animal Cells
Living Creatures Have Organization
• Going from a cell to baby….
• The original fertilized egg has to divide into
groups of cells
• The groups of cells work together to perform
the same function and form tissue
Living Creatures Have Organization
• Tissue is then organized into…
• Organs & Organ systems
• Respiratory, Circulatory, Digestive, etc.
Making the Body Systems Work
• Animals make energy
using food and oxygen
• Animals build bodies
using:
• Food for raw
Food
materials
• Amino acids,
sugars,
fats, nucleotides
• ATP energy for
synthesis
ATP
O2
But where do we get the raw material from? Food we eat!
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 are proteins that
help to speed up the
breaking down process
• Absorb: Absorb across cell
membrane
• Diffusion
• Active transport
• Eliminate: Undigested material
passes out of digestive system
intracellular
digestion
extracellular
digestion
Digestive Systems – Many Forms
Ingestion Starts Digestion
• Mouth
• Mechanical Digestion
• Chemical Digestion
• Saliva -Enzyme digests starch
• Slippery protein
• Protects soft lining of digestive system
• Lubricates food for easier swallowing
Oral Cavity
Upper lip
Palate
Uvula
Tongue
Lower lip
Salivary Glands
• Scattered throughout oral cavity
• Functions:
• Hydrolysis
• Dissolve things
• Moisten food and mouth
• Composition of saliva
• pH 6.35-6.85 (Slightly acidic)
• Produce 1000-1500 ml a day
• 99% of saliva is water
• Salivary amylase begins breakdown of starch
Esophagus
• Moves both air and food
• Epiglottis, a flap of tissue, prevents food from
entering the trachea
• Food enters the esophagus instead
• Muscular contractions and relaxations called
peristalsis moves food through the esophagus
Stomach
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Can stretch to hold 2 L of food
“Growling” is contracting of stomach muscle
Three layers of muscle churn the food
Gastric pits in the stomach secrete acidic digestive fluid
Mucus protects the stomach lining – ulcers are a breakdown of
this protective lining
Mixed food particles and gastic fluid is called chyme
Esophagus
Fundus
Body
Pylorus
Duodenum
Stomach
• Disinfect food
• HCl = pH 2, will kill bacteria
• Chemical Digestion
• Digestion of proteins by pepsin, a gastric
protease, into peptides.
• Gastric lipase- pH 5-6, splits lipids
Liver
• Produces bile to break up fats
• Bile is composed of bile acids and salts, phospholipids,
cholesterol, pigments, water, and electrolyte chemicals
• Bile stored in gallbladder until needed
• Large organ right of the stomach
• Stores glucose, makes proteins, breaks down toxins –
including alcohol
Pancreas
• Lies behind the stomach
• Produces sodium bicarbonate, to neutralize
stomach acid to protect the small intestine
• Produces insulin in the Islets of Langerhans,
specialized cells in the pancreas
• Pancreatic juices:
• Pancreatic amylase – breaks down all
starches
• Trypsin, Chymotrypsin – separates amino
acids (proteins)
• Pancreatic lipase - breaks down lipids
• Nucleases - break down nucleic acids
Islet of Langerhans
Gallbladder
• A pear shaped sac on underside of the right lobe of the
liver.
• About 7-10cm long.
• Ducts
• Hepatic ducts
• Cystic ducts
• Common bile ducts
• Function
• Store and concentrate bile by absorbing water
• Contracts and releases bile to duodenum when
needed
Small Intestine
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Nearly 7 m in length
Three sections:
• Duodenum (25 cm), Jejunum (2.5 m) and Ileum (4
m)
Intestinal Juices
• Maltase, sucrase, lactase – break down
carbohydrates
• Aminopeptidase, Dipeptidase – break down amino
acids (proteins)
• Deoxyribonuclease, ribonuclease- break apart
sugars and nucleic acids
Duodenum
• First section of small intestines
• Receives acid food from stomach
• Mixes with digestive juices from:
• Pancreas
• Live
• Gallbladder
Absorption by Small Intestines
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Highly folded lining of the small intestine is called villi, which are
covered in microvilli
• Give a surface area about 250 square meters (area of a tennis
court)
• 90% of all nutrients are absorbed in the small intestine, 10% in
stomach and large intestine.
• Carbohydrates: absorbed on surface of villi.
• Proteins: amino acids are transported by active transport into
the capillaries
• Water absorption: absorption accomplished by osmosis
• Lipids: lipase breaks down glycerol
Circular creases
with villi
Colon
• Also known as large intestine
• Four parts – ascending colon, transverse colon,
descending colon and sigmoid colon
• Waste solidifies into feces and >90 % water is reabsorbed
• Diarrhea: not enough water absorbed
• Constipation: too much water absorbed
Transverse
colon
Ascending
colon
Descending
colon
Sigmoid
Rectum
Anus
You’ve Got Company!
• Living in the large intestine is a community of
helpful bacteria
• Escherichia coli (E. coli)
• produce vitamins
• vitamin K; B vitamins
• generate gases
• by-product of bacterial metabolism
• methane, hydrogen sulfide
mouth
break up food
digest starch
kill germs
moisten food
liver
produces bile
- stored in gall bladder
break up fats
pancreas
produces enzymes to
digest proteins & carbs
stomach
kills germs
break up food
digest proteins
store food
small intestines
breakdown food
- proteins
- starch
- fats
absorb nutrients
large intestines
absorb water
Appendix
• Vestigial organ located behind the ascending
portion of colon
• Darwin suggested it might been used to digest
cellulose
• Scientists are now studying how it might
influence the immune system
Rectum
• Last section of colon
• Eliminate feces which are undigested materials
• extracellular waste
• mainly cellulose from plants
• masses of bacteria
Length of Digestive System
• Herbivores &
Omnivores
• Long digestive
systems
• Harder to
digest cellulose
• Carnivores
• Short digestive
systems
• Protein easier
to digest
Teeth
• Carnivore
• sharp ripping teeth
• “canines”
• Herbivore
• wide grinding teeth
• molars
• Omnivore
• both kinds of teeth
Vegetarian Diets
• Need to make sure you get enough protein
• 20 amino acids to make protein
• 10 amino acids humans can produce
• 8 “essential amino acids” come from food
• Grains (like corn) have 6 (missing 2)
• Beans (like soybean & red beans) have 6 (missing
different 2)
• Mix beans & grains for complete group of amino
acids
• Rice & Beans
• Tofu & Rice
• Peanut Butter & Bread
Feedback: Maintaining Homeostasis
• Balancing glucose levels in blood
depress
appetite
pancreas
insulin
cells
take up
glucose
from blood
liver
takes up
glucose
for storage
liver releases
glucose
to blood
glucagon
pancreas
stimulate
hunger