Unit 1. Energy Production and Transport

Respiration

Digestion

Transport

Digestive System

Respiratory

System

Cells

C6 H12 O6 +

O2 CO2 +

H2 O

Energy

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

digestion

What happens to the food we eat?

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

Digestive systemsEverybody’s got one!

When we eat a meal, the food passes through the gut in a series of processes: Ingestion: eating the food Digestion: chemical and physical reactions that break

down food into smaller pieces Absorption: the mass of small food molecules from the

digestive system into the blood or lymphatic vessels. Transport: the circulatory system delivers the small

molecules into your body cells. Assimilation: the small molecules are used in your

body cells to build new and larger molecules.

Structure of The Digestive System

Human digestive system

The wall of the alimentary canal is made of living tissues which include:

Muscle fibers: circular and longitudinal Secretory cells A single layer of epithelium Associated glands

Glands Gastric juices are released into the gut by

various glands:

Salivary glands Stomach wall Pancreas Small intestine wall

Enzymes in digestion.- Enzymes are chemical catalizers, helping to

speed up the process of digestion. Enzymes are sensitive to temperature, pH and substrate concentration. Most enzymes are highly specific, but digestive enzymes tend to act on a broader range of substrates.

Enzymes of digestion are all made in glands and are secreted into the gut, where they mix the food.

Enzyme Main Secreting Gland

pH optimum of enzyme

Region where enzyme works

pH of region where enzyme works

Starch Amylase maltose

1. Salivary glands

7 Mouth 6.0 – 7.0

1. Pancreas

7 Small intestine

7,0 – 8.3

Protein Protease aminoacids

1. Stomach wall

2 Stomach 1.0 – 3.5

1. Pancreas

7 Small intestine

7.0 – 8.3

Lipids Lipase fatty acids + glycerol

1. Pancreas

7 Small intestine

7.0 – 8.3

MouthFunctions

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

Esophagus

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

Peristalsis involuntary muscle contractions to move food

along

Stomach Functions

disinfect food hydrochloric acid = pH 2

kills bacteria food storage

can stretch to fit ~2L food digests protein

pepsin enzyme

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

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

Small intestine Functions

Gland Produces enzymes to digests other substances

(ex.nucleases) Protection

Areas in the wall of the small intestine called Peyer’s patches contain lymphocytes that detect pathogens in food to help in the production of antibodies against them

Absorption in Small Intestines Absorption through villi & microvilli

finger-like projections increases surface area for absorption

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

Assimilation

Filters harmful substances and bacteria in blood.

After blood has passed through, it is pumped to the lungs and then to the rest of the body where cells absorb substances.

The process by which cells use this substances to build new macromolecules is called assimilation.

Pancreas Produces digestive enzymes

digest proteins trypsin, chymotrypsin

digest starch amylase

digest lipids lipase

Buffers neutralizes

acid from stomach

smallintestin

e

pancreas

Large intestines (colon) 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-absorbed

not enough water re-absorbed diarrhea can be fatal!

too much water re-absorbed constipation

reabsorb by diffusion

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

AppendixVestigial organ

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

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

Sources: Regents Biology (2012 – 2013) Animal

Nutrition, Human Digestion. (On Line) http://www.westlake.k12.oh.us/whsteachers/crist/2012_2013/Bio/digestion_35.pdf. PPT modified from this source.

Allot, Andrew and Mindorff, David (2010) Biology Course Companion, (2nd ed.). Oxford University Press, New York, 212 – 218

Damon, Alan; McGonegal, Randy; Tosto, Patricia; and Ward, William. (2007) Biology Higher Level, Pearson Baccalaureate, London, 151 – 156