Download Chapter 18: Digestive and Excretory System

Chapter 18: Digestive and
Excretory System
Essential Question: How is our food
broken down so our cells can use it?
I. Digestive system
A. Digestion: process of breaking down food
into molecules the body can use
B. Gastrointestinal tract: location where
digestion occurs
Section 38-2
The Digestive System
Mouth
Pharynx
Salivary glands
Esophagus
Liver
Gallbladder
(behind liver)
Stomach
Pancreas (behind
stomach)
Large intestine
Small intestine
Rectum
Interactive slide
1. Mouth: teeth tear and chew food into small
particles
a) Mechanical digestion: chewing Digestion
b) Chemical digestion: involves a change in the
chemical nature of the nutrients Chemical
c) Salivary glands produce saliva: mixture of
water, mucus, and amylase (enzyme)
d) Saliva softens and lubricates food and breaks
down some starch
2. Esophagus: muscular tube that connects pharynx
with the stomach
a) Bolus: chewed up food that is swallowed into the
pharynx and then into the esophagus
b) Epiglottis closes over the trachea
c) Peristalsis: series of rhythmic
muscular contractions that move
bolus through the esophagus
3. Stomach: sac like organ involved in mechanical and
chemical digestion
a) Three layers of smooth muscles turn and twist the
stomach to help churn the contents of the stomach
(mechanical digestion)
b) Inner lining of the stomach
is a thick, wrinkled mucus
membrane
c) Gastric pits: small openings in lining that release
secretions into the stomach
d) Acidic digestive fluid: mucus, enzymes, and
hydrochloric acid Stomach
C. Chemical Digestion
1. Gastric fluid: carries out chemical digestion in
the stomach
a) Pepsin: enzyme that breaks down proteins
b) Hydrochloric acid: lowers the pH for pepsin
to work and kills bacteria and dissolves minerals
c) Mucus: forms protective coating for the
stomach against the hydrochloric acid
d) Ulcer: sore in stomach because mucus lining
breaks down, caused by a bacteria
2. Formation of chyme: food and gastric fluid mixture
a) Cardiac sphincter: circular muscle between
esophagus and stomach
b) Pyloric sphincter: circular muscle between
the stomach and small intestine that regulates the
flow of chyme
3. Liver: large organ located to the right of stomach
a) Many different functions
b) Secretes bile
c) Bile: breaks down fat into smaller pieces
d) Gallbladder: stores bile and releases it into the
small intestine
4. Pancreas: organ that lies behind the stomach
a) Secretes digestive enzymes into the small
intestines
b) Contains sodium bicarbonate that changes the
acidic chyme into a base so enzymes can work
The Liver and the Pancreas
Section 38-2
Liver
Bile duct
Gallbladder
Pancreas
Pancreatic duct
Duodenum
To small intestine
5. Small intestine: coiled tube 21 feet long that
finishes digestion and absorbs nutrients into the
blood
a) Duodenum: first section that finishes chemical
digestion of chyme
b) Jejunum: middle section
c) Ileum: last section
Section 38-2
The Small Intestine
Villus
Small Intestine
Circular folds
Epithelial cells
Villi
Capillaries
Lacteal
Vein
Artery
6. Absorption: end products ( amino acids,
monosaccharides, glycerol, and fatty acids) of
digestion are transferred into blood and lymph
a) Villi: fingerlike projections on the folded lining
of the small intestine
b) Villi produce a large surface, where nutrients are
absorbed by diffusion and active transport into the
blood and lymph
Absorption
D. Large intestine or colon
1. Minerals, vitamins, and water are absorbed from
the undigested material
2. Four parts: ascending, transverse, descending,
and sigmoid
3. Reflex contractions move the remaining material
out of the body through the anus
Digestive System Chart Prezi
(Interactive slide)
II. Urinary System
A. Excretion: process of removing metabolic wastes
and helps to maintain homeostasis by regulating the
content of water and other substances in the blood
B. Kidneys
1. Remove nitrogen wastes made by the breakdown
of proteins
2. Two bean-shaped organs located in the back
behind the stomach and liver
3. Structure
a) Cortex: outermost portion
b) Medulla: inner portion
c) Renal pelvis: funnel-shaped structure in the
center
d) Renal artery: transports nutrients and wastes
into the kidneys
e) Renal vein: carries blood out of kidneys
Section 38-3
The Urinary System
Vein
Kidney (Cross Section)
Kidney
Cortex
Medulla
Ureter
Urinary bladder
Urethra
Artery
f) Urea: metabolic waste that is made in the liver
from ammonia and enters bloodstream to the
kidneys
4. Nephrons: functional units of kidneys that remove
wastes
Structure of the Kidneys
Section 38-3
Kidney
Nephron
Bowman’s
capsule
Cortex
Capillaries
Glomerulus
Medulla
Renal
artery
Renal vein
Ureter
Collecting
duct
Vein
To the bladder
Artery
Loop of Henle
To the ureter
a) Urine: produced in nephrons and contains
toxins, urea, water, and salts
b) Each kidney has over a million nephrons
c) Bowman’s capsule: cup-shaped structure
that holds glomerulus
d) Glomerulus: group of capillaries that receives blood
from renal artery
e) High pressure forces fluids from the blood through
the capillary walls and into Bowman’s capsule
f) Renal tubule: long tube that collects fluids filtered
from the blood
g) Three parts of the tubule: proximal convoluted
tubule, loop of Henle, and distal convoluted tubule
h) Materials are exchanged between tubule and blood
by three major processes
Section 38-3
The Nephron
Reabsorption
Filtration
Most filtration occurs in the
glomerulus. Blood pressure forces
water, salt, glucose, amino acids,
and urea into Bowman’s capsule.
Proteins and blood cells are too
large to cross the membrane; they
remain in the blood. The fluid that
enters the renal tubules is called
the filtrate.
As the filtrate flows through the
renal tubule, most of the water
and nutrients are reabsorbed into
the blood. The concentrated fluid
that remains is called urine.
Secretion
Substances such as hydrogen
ions are transferred from the
blood to the filtrate.
5. Filtration: materials from blood are forced out into
Bowman’s capsule
a) Forces filtrate out of blood (water, urea, glucose,
vitamins and salts)
b) Large molecules like proteins and blood cells
remain in the blood
6. Reabsorption: many of the needed substance are
transported across the walls of the tubule back to
the blood
a) Occurs in proximal convoluted tubule
b) Water moves by osmosis
c) Glucose and minerals are moved back by active
transport
7. Secretion: substances pass from blood into filtrate in the distal
convoluted tubule
a) Wastes and toxic materials
b) Hydrogen ions to adjust pH of blood
8. Formation of urine: remaining fluid and wastes in the distal
convoluted tubule form urine
a) Flows into a collecting duct where more water moves out
b) 99% of water is returned to the blood by the end of the
process
Process
9. Loop of Henle: helps the collecting duct return water
to blood by osmosis
a) High concentration of sodium chloride is created
by the loop of Henle so water will move out of
collecting duct
Nephrons
Kidney
Structure of the Kidneys
Section 38-3
Kidney
Nephron
Bowman’s
capsule
Cortex
Capillaries
Glomerulus
Medulla
Renal
artery
Renal vein
Ureter
Collecting
duct
Vein
To the bladder
Artery
Loop of Henle
To the ureter
C. Elimination of urine
1. Urine from collecting ducts enters the renal
pelvis
2. Ureter: narrow tube that leads from each kidney
to bladder
3. Urinary bladder: muscular sac that stores urine
4. Urethra: tube from bladder that leads out of the
body
Section 38-3
The Urinary System
Vein
Kidney (Cross Section)
Kidney
Cortex
Medulla
Ureter
Urinary bladder
Urethra
Artery
5. Body must remove 500 ml of urine each day to
remove toxic materials from body
6. Adult removes 1.5 L to 2.3 L a day
III. Excretory system
A. Kidneys are the primary organs of the excretory
system
1. Life –threatening situation if kidneys fail
2. Can survive using one kidney
Kidney Dialysis
Section 38-3
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Used dialysis fluid
Shunt
Air detector
Dialysis
machine
Fresh
dialysis
fluid
Compressed
air
• Dialysis
B. Lungs
1. Eliminate carbon dioxide
2. Carry out detoxification: altering harmful
substances so that they are not poisonous
C. Skin: secretes sweat to remove excess water and salt
1. Person working in extreme heat can excrete 1L
of water per hour by sweating
2. 10-30 g of salt per day
Types of excretion
Calculation
How much blood does the glomerulus (kidneys)
filter per day?
125 mL of blood is filtered per min
Answer
125 ml/min x 60 min x 24 hr = 180,000 mL /day
1 hr
1 day
180,000 mL x 1 L
= 180 L / day
1000 mL
180L is 47.5 gallons