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

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

3. 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)

4. 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

5. 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

6. 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

7. 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

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

9. 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

10. 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

11. 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

12. 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.

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

14. 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)

15. 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

16. 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)

17. 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

18. 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

19. 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

20. Digestion Video

21. 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

22. 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)

23. 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)

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

25. 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

26. 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)

27. 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

28. 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

29. References
Human Body Systems: The Excretory System. Colgren Communications, 1997. Full Video. 6 March 2011. <