1. DIGESTIVE AND EXCRETORY SYSTEMS
Regents Biology

2. OBJECTIVES
Upon completion of this unit students will be able to:
1. Contrast autotrophs and heterotrophs.
2. Describe the functions of the six basic types of nutrients found in the human diet.
3. Differentiate mechanical and chemical digestion of food.
4. Compare digestive processes in different organisms.
5. Describe the functions of the different parts of the human digestive system.
6. List and describe the major functions of the digestive enzymes.
7. Define excretion and describe how it maintains homeostasis.
8. Name the major metabolic wastes.
9. Describe the process of urine formation.
10. Explain the excretory functions of the liver, lungs, skin, and kidneys.
KEY WORDS
1.  autotroph
2.  bile
3.  excretion
4.  kidney
liver
lung
nephron
peristalsis
sebaceous gland
skin

3. DIGESTIVE SYSTEM I. NUTRITION
·      Nutrition is the process by which organisms OBTAIN food and BREAK IT DOWN for use
·      Nutrients are used for metabolism. There are 6 nutrients, four are organic (which means that they contain CARBON) and two are inorganic, which means that they do not contain CARBON)
ORGANIC NUTRIENTS
INORGANIC NUTRIENTS
·      CARBOHYDRATES
·      LIPIDS
·      PROTEINS
·      VITAMINS
·      WATER
·      MINERALS
·      FIBER is not a nutrient, but is very important for the digestive system. Fibers are bulky, indigestible materials (like cellulose) that stimulate the MUSCLES OF DIGESTION

4. II. ENERGY
We need energy to carry out LIFE PROCESSES
The energy in food is the energy given off by BURNING the sample; a CALORIMETER is used to measure this
A unit of energy is called a CALORIE
We vary in our daily calorie requirements
o  Young vs. old
o    Male vs. female
o    Active vs. inactive
If you ingest more calories than you burn, then you will GAIN weight
If you ingest fewer calories than you burn, then you will LOSE weight

5. III. TYPES OF NUTRITION
·      Autotrophs:MAKE THEIR OWN FOOD
o    Phototrophs use photosynthesis
o    Chemotrophs use chemicals (non-photosynthetic)
·      Heterotrophs: MUST OBTAIN FOOD THAT IS “READY
MADE”
IV. TYPES OF DIGESTION
·      Nutrient molecules in food are too large to pass through the cell membrane, so they must be broken down. There are 2 types of digestion.
o    CHEMICAL: FOOD IS CHEMICALLY ALTERED;
USES ENZYMES
o    MECHANICAL: FOOD IS PHYSICALLY ALTERED
(CUT, CRUSHED, ETC.); INCREASES SURFACE
AREA OF FOOD

6. V. DIGESTION IN REPRESENTATIVE HETEROTROPHIC ORGANISMS
A. Protozoans
·      Ameoba and paramecium use INTRACELLULAR digestion (digestion within the cell)
·      The amoeba uses pseudopods for PHAGOCYTOSIS
·      The paramecium uses its CILIA in getting food into its oral groove and into the gullet, then out the anal pore.
B. Hydra
·      The hydra actually has stinging cells along its exterior, and captures food with its TENTACLES
·      Food goes into the mouth into the GASTROVASCULAR CAVITY
·      Uses both intracellular and EXTRACELLULAR digestion
·      There is only ONE body opening to the digestive cavity (“two way traffic”); material not digested goes out the same opening it entered.

7. C. Earthworm
The earthworm has “one way” digestion; there are two body openings, the MOUTH and the ANUS
The CROP is used for storage of food, and the GIZZARD is used for grinding up food
 Let’s label this!

8. D. Grasshopper
The grasshopper has a digestive tube, somewhat similar to the earthworm, but has chewing mouth parts which help to MECHANICALLY digest food in preparation for chemical digestion.

9. VI. HUMAN DIGESTIVE SYSTEM
Humans have a digestive tract, or ALIMENTARY CANAL, similar to (but not exactly like) the earthworm and grasshopper.
Digestive ENZYMES are secreted along the lining of the alimentary canal; some accessory glands that secrete enzymes are:
1.Salivary glands - SALIVA
2.Liver - BILE
3.Pancreas – PANCREATIC JUICE
Mucus is secreted for LUBRICATION

11. The path of digestion for humans is:

12. Let’s start at the beginning shall we? A. Mouth and Pharynx
o    The mouth provides MECHANICAL and CHEMICAL digestion; the teeth and tongue movements are mechanical and the salivary amylase is chemical
o    The EPIGLOTTIS is the flap that prevents food from going into the larynx and down the pharynx

13. o The esophagus carries food from the pharynx to the STOMACH
B.                       Esophagus
o    The esophagus carries food from the pharynx to the STOMACH
o    The process of PERISTALSIS is the contraction and relaxation of the muscular wall of the alimentary canal. Peristalsis is what moves food through and out of your body.
o    Do you know what’s going on when you “throw up” (vomit)? Basically, it is REVERSE PERISTALSIS, as your sphincter muscle opens up, releasing food back up into your esophagus, and the stomach contents are “thrown up”
o   There is a “ring” muscle that is
found at the opening of the stomach
called the SPHINCTER. It controls
the passage of food into the stomach.
There is also a sphincter muscle found
along the rectum; you can guess what this
is for.

14. o The stomach can EXPAND and hold 2 Liters of food
A.                       Stomach
o    The stomach can EXPAND and hold 2 Liters of food
o    Both MECHANICAL (churning) and CHEMICAL (gastric juice) digestion takes place here
o    Gastric juice contains HYDROCHLORIC ACID (HCl) and PEPSIN (which breaks down proteins)
o    The flow of gastric juice increases with stimulation, and liquids pass through in 20 minutes!
o    Solids must be reduced to a soupy mixture called CHYME
o    The stomach usually empties 2-6 hours after a meal
o   When the mucus lining in the stomach breaks down, an ULCER forms

15. A.                       Small intestine
o    The small intestine is 6.5 meters long (21.33 feet) and 2.5 cm wide and serves mainly to ABSORB nutrients in food
o    The first section of the small intestine is called the DUODENUM. Two accessory organs that help the duodenum to do it job are the LIVER and the PANCREAS
1. LIVER – The liver manufactures BILE and the gall bladder stores it between meals. Bile breaks up FAT globules
2. PANCREAS – releases pancreatic juice, which contains several enzymes. Lipase acts on LIPIDS, amylase acts on CARBOHYDRATES , and proteases act on PROTEINS
o    (Review) The end products of:
1)           protein digestion are AMINO ACIDS
2)           fat (lipid) digestion are FATTY ACIDS AND GLYCEROL
3) carbohydrate digestion are MONOSACCHARIDES

16. o    The second section of the small intestine is the JEJUNUM and the third is the ILEUM
o    Millions of small finger-like projection in the small intestine, called VILLI absorb the end products of digestion increase the surface area of the small intestine
o    Once the end products of digestion enter the bloodstream, they can be transported to all cells of the body. These molecules can be used for growth or energy (cellular respiration).
o Undigested matter is pushed in to large intestine, or COLON, by the process of PERISTALSIS

17. o The large intestine is 1.5 m long and 6 cm wide
A.                       Large intestine
o    Also called the COLON
o    Undigested and unabsorbed materials go from the small intestine to the large intestine
o    The large intestine is 1.5 m long and 6 cm wide
which is SMALLER than the small intestine
o    The main function of the large intestine is to
ABSORB WATER from food into the body
(WATER!!!!!)
DIARRHEA
CONSTIPATION
TOO LITTLE WATER ABSORBED, SO IT COMES OUT!!
TOO MUCH WATER ABSORBED, SO YOU’RE ALL BOUND UP!
o   The large intestine also absorbs VITAMINS
and eliminates indigestible material (feces)
to the RECTUM

18. o The rectum STORES FECAL MATTER Anus
  Rectum
o    The rectum STORES FECAL MATTER
Anus
o   The anus eliminates FECAL MATTER

19. THE EXCRETORY SYSTEM
Excretion is THE PROCESS WHERE METABOLIC WASTES ARE REMOVED
There are different types of wastes produced from the body:
A.  Respiratory wastes include CARBON DIOXIDE AND WATER
B. Nitrogenous wastes include AMMONIA, UREA, URIC ACID
C. General metabolic wastes include MINERAL SALTS

20. A.           Protozoans
·      Since they are unicellular, they get rid of waste by DIFFUSION
·      As CO2 moves out of the organism, so does nitrogenous waste. The main nitrogenous waste of Protozoans is AMMONIA
·      By what process would a cell get rid of waste that is already in higher concentration in the surrounding environment? ACTIVE TRANSPORT
B.          Hydra
·      Then hydra is multicellular, but only two cell layers thick
·      It gets rid of waste by DIFFUSION
·      The main respiratory waste is CARBON DIOXIDE
·      The main nitrogenous waste is AMMONIA
C.          Earthworm
·      The earthworm gets rid of CO2 by diffusion into the blood and then it is transported to the moist SKIN where it diffuses out of the body.
The main nitrogenous waste is UREA. It is excreted by special structures called NEPHRIDIUM. These structures are located ALONG THE SEGMENTS (LINES) and each segment has 2 of them

21. A.           Grasshopper
·      The respiratory gas, carbon dioxide is removed by tracheal tubes.
·      The main nitrogenous waste, URIC ACID, is removed from body fluids by special structures called MALPIGHIAN TUBULES, which extend into the body sinuses.
·      These wastes are then dumped into the INTESTINE and then excreted from the body along with digested wastes.

22. A.           Humans
·  The excretory organs of the human include the:
SKIN – excretes UREA AND SALT

23. 2. LUNGS – excretes CARBON DIOXIDE AND WATER
3. LIVER – excretes BILE, UREA, TOXICS FROM BLOOD

24. Urea, a nitrogenous waste, is made by the LIVER
Urea, a nitrogenous waste, is made by the LIVER. It is released into the bloodstream and THE KIDNEYS remove it from the blood.
The process by which amino acids are broken down is called DEAMINATION; these amino groups are combined with carbon dioxide to form UREA
Urea is LESS toxic than ammonia (NH3)
The kidneys have two main functions: FILTRATION AND REABSORPTION
Filtration of blood occurs as it enters the kidneys by way of the RENAL arteries. The fluid which enters the Bowman’s capsule is called NEPHRIC FILTRATE because it is the filtered blood that comes from the nephrons (the functional unit of a kidney)
The liquid which leaves the kidneys and enters the URETERS is called URINE
Urine contains WATER, UREA, SALTS, GLUCOSE
The two ureters empty the urine into the URINARY BLADDER until the ring muscle, called a SPHINCTER (Cal Egan), relaxes and releases the urine into the URETHRA which carries the urine out of the body.

26. ·      Let’s make a flow chart of excretion, ay?