Unit 1. Energy Production and Transport

RespirationDigestion Transport Digestive System Respiratory System Cells C 6 H 12 O 6 + O 2  CO 2 + H 2 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 O2O2 food ATP mitochondria

digestion What happens to the food we eat?

How do animals get their food? filter feedingliving in your food fluid feedingbulk 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 systems Everybody’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 7Mouth 6.0 – Pancre as 7 Small intestine 7,0 – 8.3 Protein Protease aminoacids 1. Stomac h wall 2Stomach 1.0 – Pancre as 7 Small intestine 7.0 – 8.3 Lipids Lipase fatty acids + glycerol 1. Pancre as 7Small intestine 7.0 – 8.3

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

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:  diffusion  active 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 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 small intestine 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

Appendix Vestigial 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

stomach  kills germs  break up food  digest proteins  store food mouth  break up food  digest starch  kill germs  moisten food small intestines  breakdown food - proteins - starch - fats  absorb nutrients pancreas  produces enzymes to digest proteins & carbs liver  produces bile - stored in gall bladder  break up fats large intestines absorb water appendix

Sources:  Regents Biology (2012 – 2013) Animal Nutrition, Human Digestion. (On Line) 013/Bio/digestion_35.pdf. PPT modified from this source /Bio/digestion_35.pdf  Allot, Andrew and Mindorff, David (2010) Biology Course Companion, (2 nd 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