Transcript The Digestive and Excretory Systems

The Digestive and
Excretory Systems
Chapter 32
32.1 Nutrients and Homeostasis
 Until the 1740s, British sailors on long
voyages were crippled by scurvy, an illness
that produced weakness, bruising, bleeding
gums, and painful joints.
 All the British had to do was take a note
from the Dutch and Add ORANGES that are
high in VITAMIN C and they had NO MORE
SCURVY!
 Your body is AMAZING but it has 6 very
different types of needs that you are
responsible to know about.
6 types of Nutrients
 1. WATER- your body is made up of 55-60% H2O and is
a natural solvent used by nearly EVERY cell in your
body.
 It also helps maintain your body temp, keep sin
moist, and maintain blood volume.
 2. Carbohydrates – a main source of energy
 simple carbs are made of sugars
 complex carbs are starches found in veggies, grains,
and potatoes.
 Carbs are broken down into simple sugars, any extra
are converted to glycogen and are stored in the LIVER
and MUSSLE tissue for the future.
6 types of Nutrients Continued
 3. Proteins – the raw materials used for growth and repair
of the body’s cells and tissues, also make up ALL enzymes
and many hormones used in the body.
 Your body can only MAKE 12 of the 20 needed amino
acids so you MUST get them through your diet.
 These essential A.A. are found in meat, cheese, and eggs
 (Most plants lack at least one of these A.A. so vegans
MUST eat a varied diet.)
 4. Fats – provide energy and key components in cell
membranes, myelin sheaths for neurons, and certain
hormones.
 Consist of long chains of fatty acids hooked to glycerol
molecules. Your body can only make a few fatty acids, but
most MUST be obtained through your diet.
nutrients cont.
 4. Fats – provide energy and key components in cell
membranes, myelin sheaths for neurons, and certain
hormones.
 Consist of long chains of fatty acids hooked to glycerol
molecules. Your body can only make a few fatty acids, but
most MUST be obtained through your diet.
 Saturated fats are solid at room temp, from animal products
 unsaturated fats are liquid at room temp, from plant oils or
some fish
 Unsaturated fats are usually considered better for a person’s
health
nutrients cont.
 5. Minerals- are inorganic materials the body uses to
carry out processes in cells and to build or repair
tissues. (page973)
Nutrients cont
 6. Vitamins- are inorganic molecules that work with
enzymes to regulate cell functions, growth, and
development. p 974
– vitamins are fat-soluble and water-soluble
– regulate cell functions, growth, development
– replenished by eating variety of foods
Meeting nutritional needs
supports good health
 During development (birth to
early twenties) you need extra
nutrients to be healthy.
– One Calorie equals one
kilocalorie, or 1000
calories.
– 1g of protein or
carbohydrate equals 4
Calories.
– 1g of fat equals 9
Calories.
Growth and energy Needs
p 975
MALES
FEMALES
Nutrition Labels
Chapter 32 section 2
The
Digestive
System
The digestive system
 The digestive system breaks
down food into energy
cells can use.
 After digestion is complete,
nutrients are absorbed and
transported to all cells.
 Undigested materials are
eliminated as liquid and
solid wastes.
mouth
esophagus
liver
gallbladder
large
intestine
small intestine
rectum/anus
Where digestion begins
 Digestion of carbohydrates begins in
the mouth.
• Digestion of proteins occurs in the
stomach.
• Digestion of fats and sugars occur in
the
small intestine.
Mechanical vs. Chemical
Body part
Mechanical fxn
Chemical fxn
Mouth
Chewing shreds and
grinds food into smaller
particles.
Salivary AMYLASE
breaks down
starches into simple
sugars.
Stomach
Smooth muscle
contractions churn food
to break it down and mix
it with digestive juices.
HCL and PEPSIN
break down
proteins.
Small
intestine
Muscular contractions
break down and mix food
with digestive enzymes,
bile, and hormones.
Enzymes, bile, and
hormones finish
digestion of
proteins, sugars,
and fats.
• Most digestion
takes place in
the duodenum.
• The pancreas,
liver, and
gallbladder aid
in digestion.
– pancreas helps digest fat and protein
– bile from the liver/gallbladder helps
digest fats (p 980)
Chapter 32.3
Absorption
of Nutrients
Most absorption occurs in the
sm.Intestine p 982
 Three structures in the small intestine help absorb
nutrients.
 folded lining: adds surface area, slows food
 villi: absorb nutrients
 microvilli: cover villi, absorb nutrients.
absorption cont.
 Duodenum, jejunum, and ileum absorb different
nutrients.
• Nutrients enter the circulatory or lymphatic systems.
• Liver stores excess glucose for future use.
Water is absorbed and solids are eliminated.
• The colon helps to maintain the body’s fluid
balance.
• Undigested material forms the solid feces.
– stored in rectum
– eliminated through anus
The LIVER and absorption
 Nutrient-rich blood leaves the sm.intestine and
enters the liver.
 Enzymes in the liver use some of the nutrients to
build more complex molecules, or stores others in
the liver tissue
 When large amounts of energy are needed,
glycogen in the liver can be converted back into
glucose to keep glucose levels in your blood
relatively stable.
 Pre-meal about 83 mg/dL
 two hours after meal under 120 mg/dL
The large intestine.
 Absorbs about 1 liter of water per day with salts
to help maintain fluid balance.
 Solid left over mass is called feces.
 Bile pigments from the liver give it its brown color.
 Contains many bacteria
– some synthesize important vitamins
– Some, like E. coli, can cause severe diarrhea if an
overabundance occurs.
chapter 32.4
The
Excretory
System
The excretory system eliminates
nonsolid wastes from the body.
 Nonsolid wastes are eliminated
through lungs, skin, and
kidneys.
skin
lungs
 Lungs exhale carbon dioxide
and water vapor.
 Sweat glands in skin release
kidneys
excess water and salts.
ureters
 Kidneys filter and clean the
blood to produce urine.
urethra
urinary bladder
The kidneys help to maintain
homeostasis by filtering the blood.
• Kidneys are a pair of
bean-shaped organs.
– two layers: medulla
and cortex
– filtering units called
nephrons
– renal artery and
renal vein
cortex
medulla
renal
artery
renal vein
ureter
(to
bladder)
Kidneys have three basic functions
in maintaining homeostasis.
– remove waste from blood
– help to maintain electrolyte, pH,
and fluid balances
– release key hormones
Nephrons
 Nephrons clean the blood in a three step process.
1. Filtration: water, electrolytes, amino acids, glucose,
urea, and other small molecules diffuse out of the
blood, creating the filtrate.
2. Reabsorption: As the filtrate enters the rest of the
tubule, most of the materials are reabsorbed into
the blood. Materials not reabsorbed make up the
urine, which flows into the loop of Henle.
3. Excretion: In the loop of Henle, water can be
reabsorbed one final time to reduce the volume of
urine. the remaining urine flows into a collecting
duct that leads to the ureter.
Kidney damage
 May occur from injury or disease like diabetes or high
blood pressure
 by two much glucose in the blood or the elevated pressure
 you can live comfortably with only one healthy kidney,
but you have to have at least one.
 patients who need kidney transplants can usually receive
one from a relative like a sibling , parent, or child as long
as the blood matches.
 Someone with one kidney must avoid heavy contact
sports or activities to prevent injury to their lone kidney.
Kidney Dialysis
 Dialysis is a treatment in which a patient’s blood is cleaned
and chemically balanced through a mechanical process
outside the body.
 the process takes between 3 and 5 hours, depending on
the patient’s size and is done 3 times a week .