Transcript Unit 10 The Human Body - Jamestown School District

Unit 10 The Human Body
Ch. 38 Digestive & Excretory
Systems
Food & Energy

The energy available in food can be
measured by burning the food
 When food is burned, the energy content of
the food is converted to heat, which is
measured in calories
Food & Energy

The average energy needed for a teenager is
2200 Calories per day
Nutrients

The nutrients that the body needs are water,
carbohydrates, fats, proteins, vitamins, &
minerals
 Every cell in the body needs
water because many body
processes, including chemical
reactions, take place in water
Nutrients

Carbohydrates – main source of energy for
the body
– Sugars & starches are main source of carbs
– Starches are broken down by digestive system
into simple sugars &
carried to cells
through blood
Nutrients
– Sugars not immediately used for energy are
converted into complex carbs & stored in the
liver & in skeletal muscles
Nutrients

Fats – lipids – important to the body to
produce cell membranes, myelin sheaths, &
certain hormones
Nutrients

Proteins – supply raw materials for growth
& repair of structures like skin & muscle
– Also have regulatory & transport functions
Nutrients

Vitamins – organic molecules that help
regulate body processes, often working with
enzymes
Vitamins
Nutrients

Minerals – inorganic nutrients the body
needs
– Includes: calcium, iron, & magnesium
Important Minerals
Nutrition & a Balanced Diet

The Food Guide Pyramid classifies foods
into 6 groups & indicates how many
servings from
each group
should be eaten
every day
The Process of Digestion

The digestive system includes: the mouth,
pharynx, esophagus, stomach, small
intestine, & large intestine
 Several major accessory structures,
including the salivary glands, the pancreas,
& the liver, add secretions to the digestive
system
The Digestive System
The Mouth

The function of the digestive system is to
help convert foods into simpler molecules
that can be absorbed & used by the cells of
the body
 Teeth cut & grind the food, while the
salivary glands secrete saliva, which helps
to moisten the food & make it easier to
chew
The Mouth

Amylase – enzyme found in saliva, that
breaks the chemical bonds in starches &
releases sugars
The Esophagus
Esophagus – food tube, connects to the
stomach
 Food travels through esophagus by process
of peristalsis – contractions of the smooth
muscle tissue in the esophagus

The Stomach

Stomach – large muscular sac, continues the
mechanical & chemical digestion of food
The Small Intestine

Small intestine – where almost all of the
digestive enzymes enter the intestine
– Most chemical digestion & absorption of food
occurs in the small intestine
Accessory Structures of
Digestion

Pancreas – gland that serves 3 important
functions:
– 1. Produce hormones that regulate blood sugar
levels
– 2. Produces enzymes that break down carbs,
proteins, lipids, & nucleic acids
– 3. Produces sodium bicarbonate, a base that
neutralizes stomach acid so enzymes can be
effective
Accessory Structures of
Digestion

Liver – large organ just above & to the right
of the stomach
– Produce bile, a fluid loaded with lipids & salts
– It acts like detergent, dissolving & dispersing
the droplets of fat found in fatty foods
– Bile is stored in the gallbladder
Accessory Structures
The Large Intestine

Large intestine – primary function is to
remove water from undigested material that
is left
Digestive System Disorders
Peptic ulcer – when powerful acids released
into the stomach damage the organ’s own
lining, producing a hole in the wall
 Diarrhea occurs when not enough water is
absorbed
 Constipation occurs when too much water is
absorbed

The Excretory System

The kidneys play an important role in
maintaining homeostasis
 They remove waste products from the
blood; maintain blood pH; &
regulate the water content of
the blood &, therefore, blood
volume
The Kidneys
Kidneys – located on either side of the
spinal column near the lower back
 Ureter – tube that leaves each kidney,
carrying urine to the urinary bladder
 Urinary bladder – saclike organ where urine
is stored before being excreted

Kidney Structure
Nephron – the functional units of the kidney
 As blood enters a nephron through the
arteriole, impurities are filtered out &
emptied into the collecting duct
 The purified blood exits the nephron
through the venule

Filtration
Filtration – passing a liquid or gas through a
filter
 Glomerulus – where the filtration of blood
takes place

Reabsorption
Reabsorption – process where liquid is
taken back into a vessel
 Material that remains, called urine, is
emptied into a collecting duct
 Urine contains urea, excess salts, & water
 Urine is stored in the urinary bladder until
released from the body through the urethra

Structure Of The Kidneys
Kidney Stones

Sometimes, calcium, magnesium, or uric
acid salts in the urine, crystallize & form
kidney stones