Download Ch 38 Digestive and Excretory Systems

Biology
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38–1 Food and Nutrition
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38–1 Food and Nutrition
Food and Energy
Food and Energy
You need to eat food to obtain energy.
The energy in food is measured in Calories
(capital C). One Calorie is equal to 1000 calories.
One calorie is the amount of heat needed to raise
the temperature of one gram of water by one
degree Celsius.
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38–1 Food and Nutrition
Food and Energy
Caloric needs vary for each person.
An average-sized female teenager needs about 2200
Calories a day.
An average-sized male teenager needs about 2800
Calories a day.
If you exercise regularly, your energy needs may be
higher.
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38–1 Food and Nutrition
Nutrients
Nutrients
Nutrients are substances in food that supply the
energy and raw materials your body uses for
growth, repair, and maintenance.
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38–1 Food and Nutrition
Nutrients
The nutrients that the body needs are:
• water
• carbohydrates
• fats
• proteins
• vitamins
• minerals
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38–1 Food and Nutrition
Nutrients
Water
Why is water such an important nutrient?
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38–1 Food and Nutrition
Nutrients
Every cell in the human body needs
water because many of the body's
processes take place in water.
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38–1 Food and Nutrition
Nutrients
Water makes up blood, lymph, and other bodily
fluids.
Water is lost during sweating, when it evaporates to
cool the body.
Water vapor is also lost from the body with every
breath you exhale and in urine.
Humans need to drink at least one liter of water each
day.
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38–1 Food and Nutrition
Nutrients
Carbohydrates
Carbohydrates are the main source of energy for
the body.
There are two types of carbohydrates:
• simple
• complex
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38–1 Food and Nutrition
Nutrients
Simple carbohydrates are found in fruits, honey,
and sugar cane.
Simple carbohydrates do not need to be digested or
broken down.
Complex carbohydrates, or starches, are found in
grains, potatoes, and vegetables.
Complex carbohydrates need to be broken down
before they can be used by the body.
Many foods contain the complex carbohydrate
cellulose, or fiber.
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38–1 Food and Nutrition
Nutrients
Fiber is needed in your diet.
Bulk supplied by fiber helps muscles keep food and
wastes moving through your digestive and excretory
systems.
Whole-grain breads and many fruits and vegetables
have fiber.
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38–1 Food and Nutrition
Nutrients
Fats
Fats, or lipids, are an important part of a healthy
diet.
Fats are formed from fatty acids and glycerol.
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38–1 Food and Nutrition
Nutrients
Fats are needed:
• to produce cell membranes, myelin sheaths
around neurons, and certain hormones.
• to help the body absorb fat-soluble vitamins.
• to protect body organs and insulate the body.
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38–1 Food and Nutrition
Nutrients
Fats are classified as saturated or unsaturated.
When there are only single bonds between carbon
atoms in the fatty acids, the fat is saturated.
Most saturated fats are solids at room temperature—
including butter and other animal fats.
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38–1 Food and Nutrition
Nutrients
Unsaturated fats have at least one double bond in a
fatty acid chain.
Unsaturated fats are usually liquids at room
temperature.
Because many vegetable oils contain more than one
double bond, they are called polyunsaturated.
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38–1 Food and Nutrition
Nutrients
Proteins
Proteins supply raw materials for growth and repair
of structures such as skin and muscle.
They have regulatory and transport functions.
Proteins are polymers of amino acids.
The body can synthesize only 12 of the 20 amino
acids used to make proteins.
The other 8 amino acids are called essential amino
acids; they must come from food.
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38–1 Food and Nutrition
Nutrients
Animal products, including meat, fish, eggs, and milk,
contain all 8 essential amino acids.
Foods derived from plants, such as grains and
beans, do not.
Therefore, people who don’t eat animal products
must eat a combination of plant foods to obtain all of
the essential amino acids.
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38–1 Food and Nutrition
Nutrients
Vitamins
Vitamins are organic molecules that help regulate
body processes, often working with enzymes.
Most vitamins must be obtained from food.
A diet lacking certain vitamins can have serious,
even fatal, consequences.
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38–1 Food and Nutrition
Nutrients
There are two types of vitamins:
• fat-soluble
• water-soluble
The fat-soluble vitamins A, D, E, and K can be stored
in the fatty tissues of the body.
The body can build up stores of these vitamins for
future use.
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38–1 Food and Nutrition
Nutrients
Fat-Soluble Vitamins
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38–1 Food and Nutrition
Nutrients
The water-soluble vitamins dissolve in water and
cannot be stored in the body.
Eating a diet containing a variety of foods will supply
the daily vitamin needs of nearly everyone.
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38–1 Food and Nutrition
Nutrients
Water-Soluble Vitamins
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38–1 Food and Nutrition
Nutrients
Water-Soluble Vitamins
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38–1 Food and Nutrition
Nutrients
Minerals
Inorganic nutrients that the body needs, usually in
small amounts, are called minerals.
By eating a variety of foods, you can meet your
daily requirement of minerals.
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38–1 Food and Nutrition
Nutrients
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38–1 Food and Nutrition
Nutrients
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38–1 Food and Nutrition
Nutrition and a Balanced Diet
Nutrition and a Balanced Diet
The new food pyramid classifies foods into six
categories:
• grains
• vegetables
• fruits
• milk
• meat and beans
• fats, sugars, and salts
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Nutrition and a Balanced Diet
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38–1 Food and Nutrition
Nutrition and a Balanced Diet
The figure climbing up the side of the pyramid
represents exercise.
You should get at least 30 minutes of exercise each
day.
A food label provides information about nutrition.
Daily values are based on a 2000-Calorie diet, and
nutrient needs are affected by age, gender, and
lifestyle.
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Nutrition and a Balanced Diet
When choosing foods, you should compare similar
foods on the basis of their proportion of nutrients to
Calories.
When you choose a food, it should be high in
nutrition and low in Calories.
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38–1
Click to Launch:
Continue to:
- or -
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38–1
Which nutrient is found in fruits, sugars, and
whole-grain breads?
a. protein
b. fat
c. carbohydrates
d. vitamins
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38–1
Organic molecules that help regulate body
processes and often work with enzymes are
a. fats.
b. minerals.
c. vitamins.
d. amino acids.
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38–1
Which two vitamins can be made by the body?
a. vitamins a and B
b. vitamins C and D
c. vitamins A and K
d. vitamins D and K
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38–1
The most important nutrient is
a. fat
b. water
c. vitamins
d. protein.
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38–1
The foods that should make up the largest part
of your diet are
a. fats and sweets.
b. meat, poultry, and fish
c. milk, yogurt, and cheese.
d. breads, cereals, rice, and pasta.
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Biology
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Proce
ss of
Digest
ion
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Digesti
on
What are the organs of the digestive system?
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Digesti
on
The digestive system includes the mouth, pharynx,
esophagus, stomach, small intestine, and large
intestine.
Other structures add secretions to the digestive
system, and aid in digestion. These include the
salivary glands, pancreas, and liver.
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2 The
Proces
s of
Digesti
on
The Digestive
System
Mouth
Pharynx
Salivary
glands
Esophagus
Stomach
Liver
Pancreas
Gallbladder
Large intestine
Small intestine
Rectum
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The
Mouth
What is the function of the digestive system?
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The
Mouth
The function of the digestive system is to help
convert foods into simpler molecules that can be
absorbed and used by the cells of the body.
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The
Mouth
The Mouth
Chewing begins mechanical digestion, which is
the physical breakdown of large pieces of
food into smaller pieces.
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The
Mouth
The teeth cut, tear, and crush food into small
fragments.
As the teeth cut and grind the food, salivary
glands secrete saliva, which moistens food
and makes it easier to chew.
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The
Mouth
Saliva helps ease the passage of food
through the digestive system and also
begins the process of chemical digestion.
Saliva contains amylase, an enzyme that
breaks the chemical bonds in starches and
releases sugars.
Saliva also contains lysozyme, an enzyme
that fights infection.
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The
Esopha
gus
The Esophagus
From the throat, the chewed food passes
through the esophagus, or food tube, into
the stomach.
Food is moved along by contractions of smooth
muscle.
These contractions, known as peristalsis,
squeeze the food through the esophagus
into the stomach.
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The
Esopha
gus
Peristalsis
Esophagus
Bolus
Muscles
contracted
Stomach
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The
Esopha
gus
The cardiac sphincter closes the
esophagus after food has passed into the
stomach.
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The
Stomac
h
The Stomach
Food from the esophagus empties into the
stomach.
The stomach continues mechanical and
chemical digestion.
Alternating contractions of three smooth muscle
layers churn food.
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The
Stomac
h
Chemical Digestion
The stomach lining has millions of gastric
glands that release substances into the
stomach.
Some glands produce mucus, which lubricates and
protects the stomach wall.
Other glands produce hydrochloric acid, which
makes the stomach contents very acidic.
Other glands produce pepsin, an enzyme that
digests protein.
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The
Stomac
h
Pepsin and hydrochloric acid begin
protein digestion.
Pepsin breaks proteins into smaller
polypeptide fragments.
Other enzymes are denatured (broken
down) by stomach acid.
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The
Stomac
h
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The
Stomac
h
Mechanical Digestion
The stomach contracts to churn fluids and food,
gradually producing a mixture known as
chyme.
After 1–2 hours, the pyloric valve between the
stomach and small intestine opens and
chyme flows into the small intestine.
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The
Small
Intestin
e
The Small Intestine
As chyme is pushed through the pyloric valve, it
enters the duodenum.
The duodenum is the first of three parts of the
small intestine, and is where most digestive
enzymes enter the intestine.
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The
Small
Intestin
e
Most chemical digestion and absorption of
food occurs in the small intestine.
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The
Small
Intestin
e
Accessory Structures of Digestion
Liver
Bile duct
Pancreas
Gallbladder
Pancreatic
duct
Duodenu
m
To rest of
small
intestine
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The
Small
Intestin
e
Accessory Structures of Digestion
Just behind the stomach is the pancreas.
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The
Small
Intestin
e
During digestion, the pancreas:
a. produces enzymes that break down
carbohydrates, proteins, lipids, and nucleic
acids.
b. produces sodium bicarbonate, a base that
neutralizes stomach acid so that these
enzymes can be effective.
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The
Small
Intestin
e
Assisting the pancreas is the liver, which
produces bile.
Bile dissolves and disperses droplets of
fat in fatty foods. This enables enzymes to
break down smaller fat molecules.
Bile is stored in the gallbladder.
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Absorption in the Small
Intestine
Absorption in the Small Intestine
The small intestine is adapted for the
absorption of nutrients.
The folded surfaces of the small intestine
are covered with fingerlike projections
called villi.
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Absorption in the Small
Intestine
The Small Intestine
Villus
Small intestine
Circular folds
Epithelial
cells
Villi
Capillaries
Lymph
vessel
Vein
Artery
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Absorption in the Small
Intestine
Cell surfaces of villi have more projections
called microvilli.
These provide an enormous surface area
for the absorption of nutrient molecules.
Slow, wavelike contractions of smooth
muscles move the chyme along this
surface.
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Absorption in the Small
Intestine
Nutrient molecules are absorbed into the
cells lining the small intestine.
Most products of carbohydrate and protein
digestion are absorbed into the capillaries
in the villi.
Molecules of undigested fat are absorbed
by lymph vessels.
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The
Large
Intestin
e
The Large Intestine
When the chyme leaves the small intestine, it
enters the large intestine, or colon.
The large intestine removes water from the
chyme.
Water is absorbed quickly, leaving undigested
materials behind.
Concentrated waste material passes through
the rectum and is eliminated from the body.
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ve
System
Disorde
rs
Digestive System Disorders
Stomach acids sometimes damage the organ’s
own lining, producing a hole in the stomach
wall known as a peptic ulcer. Most peptic
ulcers are caused by the bacterium H. pylori.
Other digestive disorders include diarrhea and
constipation.
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Excret
ory
Syste
m
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the
Excret
ory
Syste
m
Functions
of the Excretory System
a. Every cell produces metabolic wastes.
b. The process by which these wastes are
eliminated is called excretion.
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the
Excret
ory
Syste
m
The
skin excretes excess water and salts
in the form of sweat.
The lungs excrete carbon dioxide.
The kidneys also play a major role in
excretion.
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the
Excret
ory
Syste
m
The
Kidneys
What are the functions of the kidneys?
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the
Excret
ory
Syste
m
The kidneys:
a. remove waste products from the blood.
b. maintain blood pH.
c. regulate the water content of the blood and,
therefore, blood volume.
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The
Kidne
ys
a. The kidneys are located on either side of
the spinal column near the lower back.
b. A tube, called the ureter, leaves each
kidney, carrying urine to the urinary bladder.
c. The urinary bladder is a saclike organ
where urine is stored before being excreted.
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The
Kidne
ys
Structure of the Kidneys
Nephron
Kidney
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The
Kidne
ys
Blood enters the kidney through the renal
artery.
The kidney removes urea, excess water,
and other waste products and passes
them to the ureter.
The clean, filtered blood leaves the kidney
through the renal vein and returns to
circulation.
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The
Kidne
ys
Kidney Structure
a. A kidney has two distinct regions:
The inner part is called the renal medulla.
The outer part is called the renal cortex.
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The
Kidne
ys
Cortex
Renal
artery
Medulla
Renal vein
Ureter
To the bladder
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The
Kidne
ys
The functional units of the kidney are
called nephrons.
Nephrons are located in the renal cortex,
except for their loops of Henle, which
descend into the renal medulla.
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The
Kidne
ys
Bowman’s
capsule
Capillaries
Glomerulus
Collecting
duct
Vein
Artery
To the ureter
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Loop of Henle
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The
Kidne
ys
Capillaries
Each nephron has
its own blood
supply:
a. an arteriole
b. a venule
Collecting
duct
c. a network of
capillaries
connecting them
Vein
Artery
To the ureter
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The
Kidne
ys
Capillaries
Each nephron
releases fluids to a
collecting duct, which
leads to the ureter.
Collecting
duct
Vein
Artery
To the ureter
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The
Kidne
ys
How is blood filtered?
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The
Kidne
ys
As blood enters a nephron through the arteriole,
impurities are filtered out and emptied into the
collecting duct.
The purified blood exits the nephron through the
venule.
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The
Kidne
ys
The mechanism of blood purification
involves two distinct processes: filtration
and reabsorption.
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The
Kidne
ys
Filtration
a. Passing a liquid or gas through a filter to
remove wastes is called filtration.
b. The filtration of blood mainly takes place in
the glomerulus.
c. The glomerulus is a small network of
capillaries encased in the top of the nephron
by a hollow, cup-shaped structure called
Bowman's capsule.
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The
Kidne
ys
Fluid from the blood flows into Bowman’s
capsule.
The materials filtered from the blood
include water, urea, glucose, salts, amino
acids, and some vitamins.
Plasma proteins, cells, and platelets
remain in the blood because they are too
large to pass through the capillary walls.
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The Kidneys
Reabsorption
a. Most of the material removed from the blood
at Bowman's capsule makes its way back
into the blood.
b. The process in which liquid is taken back
into a vessel is called reabsorption.
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The
Kidne
ys
Almost 99% of the water that enters
Bowman’s capsule is reabsorbed into the
blood.
When the filtrate drains in the collecting
ducts, most water and nutrients have been
reabsorbed into the blood.
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The
Kidne
ys
Remaining material, called urine, is
emptied into a collecting duct.
Urine is primarily concentrated in the loop
of Henle.
The loop of Henle is a section of the
nephron tubule in which water is
conserved and the volume of urine
minimized.
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The
Kidne
ys
As the kidney works, purified blood is
returned to circulation while urine is
collected in the urinary bladder.
Urine is stored here until it is released
from the body through a tube called the
urethra.
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Kidne
y
Functi
on
Control of Kidney Function
a. The activity of the kidneys is mostly
controlled by the composition of the blood.
b. In addition, regulatory hormones are
released in response to the composition of
blood.
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Kidne
y
Functi
on
When you drink a liquid, it is absorbed into
the blood through the digestive system.
As a result, the concentration of water in
the blood increases.
As the amount of water in the blood
increases, the rate of water reabsorption in
the kidneys decreases.
Less water is returned to the blood, and
excess water is sent to the urinary bladder
to be excreted as urine.
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Kidne
y
Functi
on
When the kidneys detect an increase in
salt, they respond by returning less salt to
the blood by reabsorption.
The excess salt the kidneys retain is
excreted in urine, thus maintaining the
composition of the blood.
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y
Disord
ers
Kidney Disorders
a. Humans have two kidneys, but can survive
with only one.
b. If both kidneys are damaged by disease or
injury, there are two options:
•
a kidney transplant
•
kidney dialysis
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y
Disord
ers
Kidney dialysis works as follows:
a. Blood is removed by a tube and pumped
through special tubing that acts like
nephrons.
b. Tiny pores in the tubing allow salts and small
molecules to pass through.
c. Wastes diffuse out of the blood into the fluidfilled chamber, allowing purified blood to be
returned to the body.
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y
Disord
ers
Kidney Dialysis
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Shunt
Used dialysis fluid
Air
detector
Dialysis
machine
Fresh
dialysis
fluid
Compressed
air
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END OF SECTION
38–2
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38–2
Food is moved through the esophagus into the
stomach by
a. air pressure.
b. muscle contractions.
c. gravity.
d. swallowing.
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38–2
A gland that has both endocrine and exocrine
functions is the
a. liver.
b. spleen.
c. pancreas.
d. gallbladder.
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38–2
The enzyme in saliva that begins the digestion
of starch is
a. amylase.
b. pepsin.
c. lysozyme.
d. peptidase.
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38–2
Stomach muscles contract to churn and mix
stomach fluids and food, producing a mixture
known as
a. chyme.
b. amylase.
c. bile.
d. acid.
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38–2
Absorption of vitamins, minerals, and digested
food molecules takes place in the
a. stomach.
b. small intestine.
c. large intestine.
d. duodenum.
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Biolog
y
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Excret
ory
Syste
m
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the
Excret
ory
Syste
Functions
m
of the Excretory System
a. Every cell produces metabolic wastes.
b. The process by which these wastes are eliminated is
called excretion
- Skin excretes excess water and salts in the form of sweat.
- Lungs excrete carbon dioxide
- Kidneys also play a major role in excretion.
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the
Excret
ory
The
Syste
m
Kidneys
What are the functions of the kidneys?
a. remove waste products from the blood.
b. maintain blood pH.
c. regulate the water content of blood
- therefore, blood volume
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The
Kidne
ys
The Kidneys
- located on either side of the spinal column
- Ureter carries urine to the urinary bladder
a. - Urinary bladder is where urine is stored
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The
Kidne
ys
Structure of the Kidneys
Nephron
Kidney
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The
Kidne
ys
Kidney Structure
a. A kidney has two distinct regions:
The inner part is called the renal medulla.
The outer part is called the renal cortex.
Blood enters the kidney through the renal artery
The kidney removes urea, excess water, and other waste
products and passes them to the ureter
The clean, filtered blood leaves the kidney through the renal
vein and returns to circulation
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The
Kidne
ys
Cortex
Renal
artery
Medulla
Renal vein
Ureter
To the bladder
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The
Kidne
ys
Nephrons:
- functional units of the kidney
- located in the renal cortex
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The
Kidne
ys
Bowman’s
capsule
Capillaries
Glomerulus
Collecting
duct
Vein
Artery
To the ureter
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Loop of Henle
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The
Kidne
ys
Capillaries
Each nephron has
its own blood
supply:
a. an arteriole
(artery)
Collecting
duct
b. a venule (vein)
c. a network of
capillaries
connecting them
Vein
Artery
To the ureter
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The
Kidne
ys
How is Blood filtered?
As blood enters a nephron, impurities are
filtered out and emptied into the collecting
duct
The purified blood exits the nephron
through the venule (vein)
The mechanism of blood purification
involves two distinct processes: filtration
and reabsorption
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The
Kidne
ys
Filtration
a. - Passing a liquid or gas through a filter to remove
wastes
b. - mainly takes place in the glomerulus
c. The glomerulus is a small network of
capillaries encased in the top of the nephron
by a hollow, cup-shaped structure called
Bowman's capsule.
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The Kidneys
Reabsorption
a. Most of the material removed from the blood
at Bowman's capsule makes its way back
into the blood.
b. The process in which liquid is taken back
into a vessel is called reabsorption
c. Almost 99% of the water that enters
Bowman’s capsule is reabsorbed into the
blood.
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The
Kidne
ys
As the kidney works, purified blood is
returned to circulation while urine is
collected in the urinary bladder.
Urine is stored here until it is released
from the body through a tube called the
urethra.
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Kidne
y
Functi
on
Control of Kidney Function
a. The activity of the kidneys is mostly
controlled by the composition of the blood.
b. In addition, regulatory hormones are
released in response to the composition of
blood.
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Kidne
y
Functi
on
For Example:
When you drink a liquid, it is absorbed into
the blood
- As a result, the concentration of water in the blood
increases
- As the amount of water in the blood increases
the rate of water reabsorption in the kidneys decreases
Therefore:
Less water is returned to the blood, and
excess water is sent to the urinary bladder
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ostasi
s by
Machi
ne
Homeostasis by Machine
a. Humans have two kidneys, but can survive
with only one.
b. If both kidneys are damaged by disease or
injury, there are two options:
•
a kidney transplant
•
kidney dialysis
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ostasi
s by
Machi
ne
Kidney dialysis works as follows:
a. Blood is removed by a tube and pumped
through special tubing that acts like
nephrons
b. Tiny pores in the tubing allow salts and small
molecules to pass through
c. Wastes diffuse out of the blood into the fluidfilled chamber, allowing purified blood to be
returned to the body
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ostasi
s by
Machi
ne
Kidney Dialysis
Blood in tubing flows
through dialysis fluid
Blood pump
Vein
Artery
Shunt
Used dialysis fluid
Air
detector
Dialysis
machine
Fresh
dialysis
fluid
Compressed
air
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38–3
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38–3
A dialysis machine performs the function of
which structure in the excretory system?
a. nephron
b. ureter
c. urethra
d. glomerulus
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38–3
In the human body, the kidneys play an
important role in
a. producing digestive enzymes.
b. circulating the blood.
c. destroying old red blood cells.
d. maintaining homeostasis.
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38–3
In the nephron, most filtration occurs in the
a. renal tubule.
b. capillaries.
c. glomerulus.
d. loop of Henle.
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38–3
Urine leaves the body through the
a. loop of Henle.
b. glomerulus.
c. urethra.
d. bladder.
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38–3
Materials filtered out of the blood include all of
the following EXCEPT:
a. water.
b. urea.
c. amino acids.
d. plasma proteins.
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END OF SECTION