Download BIOLOGY CLASS NOTES UNIT 9 Human Body_Digstive and

Unit 9:
Human Body
Digestive and Excretory Systems
Mrs. Howland
Biology 10
Rev. April 2016
Lesson Objectives:
Learners will be able to…
• Identify the location of and function of the parts
of the digestive system
• Discuss the structure and function of the
esophagus, stomach, small intestine, and large
intestine
• Explain the role of glands, enzymes, and bile in
the process of chemical digestion
• Apply their knowledge of human anatomy and
physiology to the dissection of a frog
Digestive System
MAJOR STRUCTURES:
Stomach
Intestinal tract
Liver
Pancreas
Esophagus
Salivary glands
FUNCTION: Processes foods; absorption of
nutrients into the body
BIG IDEAS
Digestive system allows the body to change the
food that we eat into small molecules
The small molecules are nutrients used by body
cells
There are FOUR (4) phases of digestion:
Ingestion
Digestion
Absorption
Elimination
Ingestion
In order to ‘eat’ we must put food into our
bodies!
With ingestion, we put food into our mouths
The mouths are the opening to our digestive
system 
Digestion
Digestion is the process by which food passes
through the structures of the digestive system
and is broken down
Mechanical digestion = Large pieces of food are
physically broken down into smaller pieces,
which are swallowed
Chemical digestion = Small pieces of food are
broken down into small molecules by enzymes
Digestion in MOUTH
Physical digestion = Chewing
Teeth tear and grind
Tongue moves food around
Chemical digestion = Saliva (secreted by
salivary glands)
Saliva = Moistens food; released by nervous
system; contains enzyme amylase that breaks
down starches into sugars
Salivary GLANDS
REMEMBER: GLAND = Structure that excretes a
substance
Salivary glands = Glands in head that secrete
saliva
After CHEWING …
Clump of food (bolus) passes down pharynx to
the esophagus
Epiglottis closes and covers trachea to prevent
choking!
After CHEWING …
Esophagus is tube connecting mouth and
stomach
Smooth muscles in esophagus push food along
(This muscle movement is called peristalsis)
Cardiac sphincter closes esophagus to prevent
backflow
Can you swallow hanging upside down???
Peristalsis in ESOPHAGUS
Digestion in the STOMACH
Stomach = Large, muscular sac lined with
millions of gastric glands
Mucus lines stomach to prevent damage
VIDEO: Endoscopy
https://goo.gl/a1iBRo
Chemical Digestion in the STOMACH
Glands produce hydrochloric acid and pepsin
Enzyme pepsin breaks down proteins into small
polypeptides (chemical digestion!)
ULCERS
Mucus lines stomach to prevent damage
Ulcers are sores that may form as result of acid
erosion of stomach wall
VIDEO: Endoscopy of Ulcer https://goo.gl/vXjPlt
Mechanical Digestion in the STOMACH
Mechanical digestion in the stomach occurs
with smooth muscle movement churning the
food into chyme
Chyme = oatmeal-like substance that is made of
small food particles, digestive enzymes, and
gastric juices
After 1-2 hours, food exits stomach through
pylorus
Chemical Digestion in
SMALL INTESTINE
BEFORE entering small intestine, food mixes
with digestive enzymes from liver and pancreas
in the duodenum
Small Intestine
Rapid absorption of nutrient molecules
LARGE surface area allows for MAXIMUM
ABSORPTION
Absorption
The small molecules are absorbed in the small
intestine
The nutrients (small molecules) are carried to
body cells by the circulatory system
Small Intestine
Folded surface = Villi
Microvilli = Tiny finger-like projections filled
with capillaries and lymph vessels for
absorption
Capillaries absorb carbohydrates and protein
Lymph vessels absorb fats and fatty acids
Chyme leaving small intestine is mostly
nutrient-free!
Pancreas
Pancreas = Gland in the body
Releases pancreatic amylase (enzyme that
breaks down starch/carbohydrates), trypsin
(enzyme that breaks down protein), and lipase
(enzyme that breaks down fat)
Liver and Gallbladder
Liver = Organ that produces bile (lipids & salts)
Gallbladder = Sac that stores bile and releases it
into small intestine when needed
BILE breaks down globs of FAT
Gallstones
Form if there is too much cholesterol, bilirubin,
or not enough bile salts, not emptying properly
Can cause pain; blockage
Appendix
Passing from small intestine to large intestine,
food passes by the appendix
Humans do not use appendix (if food enters it
becomes inflamed)
Some animals digest cellulose in appendix
Large Intestine
Chyme from small intestine
Made up of mostly water, cellulose, other
indigestible substances
Shorter than small intestine, larger diameter
Function of large intestine = Remove WATER
and undigested material
Bacterial population ~ produces Vitamin K
Elimination
At the end of the digestive system, feces
(concentrated waste material after water and
nutrients have been removed) exits the body
through the anus
Digestive System Overview
Excretory System
MAJOR STRUCTURES:
Kidneys
Urinary bladder
Urethra
FUNCTION: Elimination of wastes; regulate pH
and volume of blood
EXCRETION ~ Maintaining homeostasis
Excretion maintains homeostasis
Excretion = Elimination of wastes generated by
cellular metabolism
VIDEO (Crash Course Biology):
https://goo.gl/FBMyp0
How the body performs EXCRETION
SKIN ~ Sweat releases extra water, salt, and tiny
bit of urea
LUNGS ~ Eliminates carbon dioxide during
exhalation
LIVER ~ Converts nitrogen wastes into urea
(nitrogen is generated during breakdown of
proteins)
KIDNEYS ~ Filter blood to remove excess water,
urea, and metabolic wastes
KIDNEY Excretion
KIDNEYS ‘clean’ the blood
Filter out impurities
Collect waste products
Return purified blood to circulatory system
Occurs in nephrons
TWO PARTS: Filtration and reabsorption
Nephrons
Each kidney contains millions of nephrons
Nephrons are the primary site of kidney
function
RENAL artery and RENAL vein connect kidneys
to circulatory system
Structure and Function of Kidneys
Structure and Function of Kidneys
Filtration
When liquid or gas is passed through a filter to
remove wastes, the process is called filtration
Where is blood filtered in the kidneys?
At each end of the kidney are structures called
the Bowman’s capsule
Filtration
Bowman’s capsule contains glomerulus
(network of capillaries)
Blood diffuses into Bowman’s capsule where it
is filtered
Filtration
Filtrate = materials filtered (removed) from
blood
Blood filtrate contains: water, urea, glucose,
salts, amino acids, excess vitamins (NO proteins
or blood cells!)
Reabsorption
WOW! ~ 180 LITERS of filtrate pass through the
kidneys every day
NOT all filtrate is excreted—just the EXCESS!
MAINTAINS HOMEOSTASIS
Reabsorption is how water and dissolved
materials RETURN to the blood
99% of water in Bowman’s capsule is reabsobed
Loop of Henle conserves water
2 liters
Loop of Henle ~ part of nephron
Where does the EXCESS filtrate go?
EXCESS filtrates are removed from the body in urine
Urine is the liquid waste product of the kidneys
Urine is transported to the urinary bladder through the
ureters
Urine is stored in bladder until it is released through
the urethra
Urine Pathway
Diagrams for Excretory System
VIDEO: Digestive & Excretory Systems
LINK to video: https://goo.gl/ivdI7x