Chapter 30 Digestive and Excretory Systems The HUMAN BODY Chapter 30 Digestive and Excretory Systems

Chapter 30.1 Organization Objectives Describe how the human body is organized. Explain homeostasis.

ORGANIZATION Cells Tissues Organs Organ Systems Organisms Cell = basic unit of structure and function in living things (eg., nerve cell, blood cell, skin cell) Tissue = group of cells that perform a single function (four types we will talk about on next slide) Organ = group of different tissues that work together to perform a single function (eg., eye made of different tissues that work together for sight) Organ system = group of organs that perform closely related functions (digestive system) Organisms = Made up of multiple organ systems (eg. Humans)

Tissue Types Muscle Tissue- can contract and shorten for movement Connective Tissue- provides support and connects all parts of the body Nerve Tissue- carries messages back and forth from body to brain and spinal cord Epithelial Tissue- forms a protective surface inside and outside of the body (glands, too) Four basic tissue types in humans: muscle – eg. Bicep, tricep connective – SHOW pkg tape (what is its purpose? Bind, support, connect) eg. Tendons, ligaments, cartilage, bone, blood (form of) nerve – SHOW electrical wire (What is its purpose? Transmit signals) eg. Brain, spinal cord, nerves of body epithelial – SHOW plastic wrap (What is its purpose? Cover and protect) eg., outer layers of skin, lining of mouth and stomach

Organ Systems Organs made of tissue make up the organ systems: These systems are interconnected Skeletal Muscular Integumentary Digestive Circulatory Respiratory Excretory Immune Endocrine Nervous Reproductive Refer to p. 864 of book Systems are interconnected: For example – respiratory brings oxygen into body and circulatory carries it to the cells of the body

Homeostasis Process by which organisms keep internal conditions relatively constant (balance) Ex. Shiver when cold to heat up Homeostasis – keeping things in balance Chemistry is the reason we maintain homeostasis in temperature most biochemical processes only occur in narrow temp range temps above/below inhibit enzymes and thus chemical reactions; disrupt breathing/circulation; extreme heat – denature enzymes all this disrupts the body’s internal chemistry

Check-in What tissue type: Carries messages between brain and body Nervous tissue Provides support and connects parts of body Connective tissue Contracts and shortens for movement Muscle tissue Forms protective surface Epithelial tissue

Chapter 30.2 Food Nutrition Objectives Identify essential nutrients needed by your body and explain how each is important

Nutrition Food supplies us with the following: Energy Materials for body processes Growth Repair Maintenance We eat so that we can get: energy – to walk, climb stairs, lift books, write, even think raw materials to grow, repair and maintain the body important to eat balanced diet to get all materials body needs

Nutrients Water Carbohydrates Fats (Lipids) Proteins Vitamins Minerals Water – most important nutrient b/c many of body’s processes, including chemical rxns, take place in water; 2/3 of body weight is water; need to drink at least 1 liter of water per day Carbohydrates – breads, cereals, pastas, fruits  sugars and starches (main source of energy) Fats – cheese, butter, oils, chips  fatty acids (help with vitamin absorption, make up cell membranes, insulate body) no more than 30% of calories in diet should come from fat Protein – meat, nuts, beans, fish, eggs  amino acids for building of muscles and skin; also make up enzymes and hormones Vitamins – organic molecules that help regulate body processes fat soluble (A, D, E, K) or water soluble (B, C) Minerals – inorganic nutrients needed by body (eg., calcium in teeth and bones, iron for hemoglobin) STOP HERE and read Everybody Poops

Check-in What two things does food supply us with? Energy and raw materials for body processes What is the most important nutrient? Water Organic molecule that regulates body processes Vitamins Main source of energy Carbohydrates

Chapter 30.3 Digestive System Objectives Describe the organs of the digestive system and their functions. Explain what happens during digestion. Describe how nutrients are absorbed and wastes are eliminated.

Digestive System Function: To break down and absorb nutrients from food to provide the body with energy Why do we eat?

Types of Digestion Mechanical Digestion: Chemical Digestion: Food is physically broken into smaller pieces Ex. Teeth Chemical Digestion: Food is changed at the molecular level Ex. Gastric Juices Mechanical – tearing, grinding Ex. Tear a piece of paper, break a cracker in half, break and scramble a raw egg Chemical – food molecules are broken apart; chemical bonds are broken Ex. – burn the paper (new substance created; heat/energy is used or given off), cook an egg (solidifies)

Path of Digestion Mouth Esophagus Mechanical: use teeth and tongue to mechanically break down food Chemical: saliva breaks starchessugars Esophagus Passage from mouth to stomach Adds mucous to ball of food Mouth Mechanical – physical breakdown of pieces of food into small pieces by chewing Chemical – saliva contains amylase (enzyme that breaks large molecule of starch into smaller molecules of sugar) Esophagus lump of food called bolus flap of tissue called epiglottis closes over opening to trachea (and prevents food/drink from entering lungs) moves down esophagus using contractions of smooth muscle in wall (peristalsis) not gravity – like a tube of toothpaste

Path of Digestion Stomach Chemical: Gastric juices (Pepsin and Hydrochloric Acid) to break down proteins Mechanical: Stomach churns food into a soupy substance: chyme Sphincter muscle – controls opening to stomach (from esophagus); prevents food from returning up to stomach when not work properly – acid reflex or heartburn (painful, burning feeling in center of chest caused by backflow of stomach acid) Gastric juices HCl – hydrochloric acid (activates pepsin / also denatures amylase so carb digestion stops in stomach) Pepsin – breaks down proteins (needs acidic conditions to function properly) mucous – protect lining of stomach from acid (reduced mucous = ulcer or hole in stomach)

Path of Digestion Small Intestine Food is broken down with various juices and then the nutrients are absorbed *lined with villi- finger-like projections that increase surface area for absorption Mechanical: Bile from the liver/gall bladder emulsifies fats (breaks into globs) Chemical: Intestinal and Pancreatic juices break down fats, carbohydrates, and proteins Chemical digestion completed and nutrients absorbed Chyme moves through pyloric valve and into small intestine (top part called duodenum) Most of chemical digestion and absorption of food happens in small intestine Mechanical – bile (from liver/gall bladder) emulsifies fats (show water and oil mixture – like shaking it); increases surface area to allow other enzymes to chemically break it down Chemical – pancreatic juices: break down starch (amylase); break down protein (trypsin); break down fat (lipase) intestinal juices: break down carbohydrates (maltase, sucrase, lactase); break down proteins (peptidase) Absorption villi / microvilli – finger-like projections that increase surface area to increase absorption (approx area of tennis court) nutrients absorbed through the thin walls of villi and into bloodstream which then carries nutrients to rest of body

Path of Digestion Large Intestine Rectum Anus Absorbs water and vitamins from undigested waste Rectum Storage area for waste Anus Place where waste exits the body

Accessory Organs of Digestion Salivary Glands Produce salivary amylase to break down carbohydrates Liver Produces bile to emulsify fats Gall Bladder Stores the bile made by the liver Pancreas Produces pancreatic juices to break down fats (Lipase), carbs (Amylase), and proteins (Trypsin) Saliva: break down starch to sugar (using anylase) – chewing cracker for long time begins to taste a little sweet and moisten food to ease swallowing release of saliva controlled by nervous system and triggered by scent of food (think about what happens when you smell something good cooking, especially when you are hungry) Liver produces bile (emulsify fats)  travel through bile duct to gall bladder (stores it)  sent to small intestine through bile duct also stores amino acids that are broken down by trypsin Pancreas pancreatic juices complete digestion of fats, carbs, proteins lipase – breaks down fats amylase - breaks down starch (carbs) trypsin – breaks down proteins into amino acids which are then stored by liver

Digestion Video http://www.youtube.com/watch?v=XxvRbxhqoZk&feature=related

Check-in Type of digestion in which food is physically broken into smaller pieces Mechanical digestion Trace the path food takes on its trip through the digestive system Mouth esophogusstomachsmall intestinelarge intestinerectumanus

Check-in Where are proteins digested (and by what)? Stomach (gastric juice – pepsin/HCl), Sm. Intestine (pancreatic juice – trypsin) Where are carbs digested (and by what)? Mouth (amylase), Sm. Intestine (pancreatic and intestinal juice) Where are fats digested (and by what)? Sm. Intestine (pancreatic juice)

Check-in Where is bile made / stored? Where are nutrients absorbed? Made in liver and stored in gall bladder Where are nutrients absorbed? Small intestine (major of nutrients) and large intestine (water and vitamins) Describe the mechanical digestion in each organ of digestive system. Mouth (chewing), stomach (churning by muscles), Sm. Intestine (bile emulsifies fat)

Chapter 30.4 Excretory System Objectives Describe the organs of the excretory system and their functions. Describe how the kidneys maintain homeostasis.

EXCRETORY SYSTEM Function Removes various wastes from the body to maintain homeostasis Ex. Urine, Sweat, Breath Video clip Homeostasis = internal conditions remain balanced includes responding to outside environment (eg., maintaining body temperature) AND dealing with internal processes that might upset internal cellular environment Every cell produces metabolic wastes (excess salts, carbon dioxide, urea) urea – toxic compound produced when amino acids used for energy Video clip – Introduction to Excretory System

Main Excretory Organ Kidneys- filter waste (urine) from blood enters through renal artery exits through renal vein *Nephrons- individual filtering units of kidney maintain blood pH regulate blood volume Kidneys’ job: - filter waste from the blood - maintain blood pH - regulate water content of blood (and therefore, blood volume) Essential to health, but can live with only one (eg., my son has 1 1/3 kidneys as he had 2/3 of his right kidney removed when he was 8) Structure - 2 kidneys located on either side of spinal column near lower back - tube called ureter leaves each kidney, carrying urine from kidney to bladder - urinary bladder stores urine until it is eliminated - urethra: tube through which urine travels from the bladder to the outside of the body Nephron = individual functional unit of kidney where filtration takes place (draw on board)

Other Excretory Organs Liver- filter wastes from blood, detoxifies Skin- excretes sweat, oil Lungs- remove H2O and Carbon Dioxide Liver – filters wastes (such as excess amino acids) from the blood and converts them to useful compounds (also producing urea in the process) Skin – excretes water and salts, as well as small amount of urea, in form of sweat Lungs – excrete CO2, a gas produced when energy is captured from compounds in food

Check-in What are the functions of the kidney? Filter wastes from blood, regulate blood pH, regulate blood volume What organ excretes carbon dioxide and water? Lungs What organ detoxifies the blood? Liver

References Human Body Systems: The Excretory System. Colgren Communications, 1997. Full Video. 6 March 2011. <http://www.discoveryeducation.com/>.