Living things process energy
Where does that energy come from?
Animals need Food
Food provides nutrients:
Lipids
Carbohydrates
Proteins
Minerals
Vitamins
Water
Food energy
Calories
1 calorie = 1 g H2O raised 1oC
Kilocalories
Primarily procured from lipids and carbohydrates
Lipids
Essential for life
Phospholipids = cell membranes
Cholesterol = cell membranes, hormones, bile
Triglycerides = energy
Excellent energy storage
3600 Calories/lb of fat
Insulation
Carbohydrates
Quick energy source
Storage:
Sugar
Starch
Cellulose
Glycogen
Proteins
Comprised of amino acids
Required to build new proteins in body
Humans can synthesize
11 amino acids
Other 9 are “essential”
Provided by meat or
some plants
Minerals
Elements required by body
Variable functions- see table 34-2
Tissue formation
pH balance
Cellular communication
Vitamins
Organic compounds required for cell function
Growth, development, enzyme function
Water soluble
C, B complex
Fat soluble
A, D, E, K
Summary in table 34-3
Water
You are 2/3 water!
Component of bodily fluids
Thermoregulation
Eliminate waste in urine
2500 mL (10 cups) daily
A Balanced Diet
Includes ALL nutrients
In the proper proportions
Digestion breaks down food
Ingestion
Mechanical breakdown
Chemical breakdown
Absorption
Elimination
Simple Digestive Systems
Sponges rely on individual cells for
digestion
Intracellular digestion
Gastovascular cavities are simple
digestive sacs
Extracellular digestion
Single opening- incomplete
digestive system
Complete digestive
systems are more efficient
A tubular digestive tract for orderly food processing
Can be specialized
Teeth vary according to diet
Ruminant chambered stomach digests plant cellulose
Longer intestines can more efficiently process plant material
Human Digestion
Omnivores need to digest a range of foods
Digestion begins in the
mouth
Mechanical breakdown by
teeth
Chemical breakdown by
saliva
Amylase enzyme begins
starch breakdown & kills
bacteria
Food enters the pharynx
The tongue pushes food back into the pharynx
The epiglottis prevents food from entering the trachea
The esophagus carries
food to the stomach
Peristalsis- muscular contractions- forces food
through tube
The stomach continues
digestion
Muscular sac
Can expand
Controlled by:
Lower esophageal
sphincter
prevents backward
movement of food and acids
Pyloric sphincter
regulates passage of food to
small intestine
The stomach continues
digestion
Stores food for gradual release to small intestine
Mechanical digestion
Muscular churning
Chemical digestion
Pepsin- protein digesting enzyme
Hydrochloric acid lowers pH to activate pepsin
Mucus- lines stomach for protection
Stomach problems
Heartburn/Acid reflux
stomach acid enters the esophagus
Stomach ulcers
weakened mucus layer allows stomach acid to
eat away at the stomach itself
Majority of digestion is in
the small intestine
Chyme – digested food and gastric secretions – leave
stomach
Small intestine continues
chemical digestion
Bile helps break down fats
Produced by liver
Stored by gallbladder
Released to SI by bile duct
Bile salts isolate fat
particles and make them
accessible to lipases
The Pancreas also helps
Insulin & glucagon regulate blood sugar
Pancreatic juice
Bicarbonate buffer
neutralizes chyme
Enzymes digest carbs,
lipids, proteins
Intestinal cells line the
small intestine
Specialized enzymes on external membranes complete
process
Nutrient absorption
Small intestine is ~10 feet long
Villi and microvilli increase surface area
Chyme sloshes back and forth across intestinal walls
Nutrient absorption
Each villus contains blood capillaries
Carries away most absorbed nutrients
And lymph capillaries
Carries away absorbed glycerol and fatty acids
The large intestine absorbs
water
Digestive leftovers enter the colon
Intestinal bacteria digest remnants and produce vitamins
Vitamins and water are absorbed
Remaining semisolid feces are stored in rectum
Defecation is controlled by sphincters
Control of digestive system
Under nervous and hormonal control
Food stimuli triggers production of secretions
Food moves through system by stimulating nervous
reflexes
Hormonal regulation
Gastrin
Stimulates acid secretion in response to proteins &
amino acids
Secretin & Cholecystokinin
Stimulate release of digestive fluids into small intestine
Gastric inhibitory peptide
Stimulates insulin release in response to fatty acids &
sugars
External Control of
Digestion
Appetite suppressants
Fat digestion blockers
Surgical options
Diet & Exercise
Living things maintain homeostasis
What does this have to do with homeostasis?
The Urinary System
Helps maintain body’s chemical composition
through water balance- osmolarity
The amount of dissolved substances
Excretion
Elimination of waste or excess substances
Basics of excretion
Filtration of blood and body fluids
Reabsorption of nutrients
Excretion of excess water, nutrients & wastes
The simplest excretory systems
Protonephridia
Direct contact with blood or
interstitial fluid
Current draws water and
wastes out excretory pore
The simplest excretory systems
Malpighian tubules
Open into hemocoel
Remove waste and salt through
active transport; water through
osmosis
The simplest excretory systems
Nephridia
Collect waste from body fluids
Association with capillaries
allows reabsorption
Remaining waste exits
nephridiopore
Vertebrate Urinary System
Blood filtered by kidneys
Variable depending on environment
Nitrogenous Wastes
Result from protein digestion
Toxic ammonia excreted by fish
Terrestrial vertebrates convert ammonia to urea
in the liver and filter it into urine in the kidneys
To reduce water loss, reptiles excrete uric acid
Urinary Basics
Renal artery carries wastes
to the kidneys
Renal vein carries filtered
blood away
Urine leaves kidneys through
ureters
Bladder stores urine
Urine exits through urethra
Gotta pee? Here’s why
Sphincters control the release of urine
Stretch receptors signal contractions
Internal sphincter opens, external sphincter
under voluntary control by brain
Urinary disasters
When to go: The strange
death of Tycho Brahe
When NOT to go: The dreaded candiru
Urine formation
Occurs in the renal cortex
Dense array of nephrons
well-supplied with blood
Urine formation
The nephrons are the filters
Glomerulus- network of
capillaries
Bowman’s capsule- surrounds
glomerulus
Collecting duct- carries fluid
from nephrons
Filtration
Materials filtered from glomerulus into Bowman’s capsule
Reabsorption
Water and nutrients return to blood at proximal (near) tubule
Secretion
Additional wastes actively secreted from distal (far) tubule
into blood
The Loop of Henle
Between proximal and distal
tubules
Builds concentration gradient
by transporting salt to
surrounding fluid
Allows urine to become more
concentrated through osmosis
of water out of nephron
Concentration
Additional water loss at collecting duct
Homeostasis and the kidney
Water concentration
Reabsorption of water
prevents excessive loss
Controlled by antidiuretic
hormone (ADH)
Hangover and your kidneys
Alcohol interferes with ADH
Production of dilute urine – dehydration
Headache
Fatigue
Nausea
Homeostasis and the kidney
Blood pressure and oxygen levels
Release of proteins and hormones
Homeostasis and the kidney
Dissolved substances
Monitors and regulates blood composition
Adjusting secretion & reabsorption rates
Filters some toxins
Kidneys adapt to different
environments
Fish are in close contact with their environment
Kidneys adapt to different
environments
Water conservation enabled by Loops of Henle
Longer loops = higher concentration gradient = more
water conservation