chapter 6 barriers of the body interfaces with the outside
Post on 20-Dec-2015
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TRANSCRIPT
Chapter 6
Barriers of the Body
Interfaces with the outside
Barriers of the Body
• Skin, Lungs, and Digestive System
• The controlled exchange of molecules and heat
• Warm blooded animals are very expensive
• Rapidly turning over cells
• Damage repair
The Skin
• The surface barrier of the Body– Skin cells– Replacement skin cells– A few hairs– Sweat glands– Nerves (information: touch, temperature,
and pain)
Heat, what is it?
Heat Capacity
Heat Transfer
Control of Body Temperature
Information in to the brain
>Surface sensors: “I feel hot or cold”
>Temperature of blood circulating to the brain
Why is Heat Important?
• 106° F: Fried Brains
• 86 ° F: Dysfunctional Brain unable to warm its self
• Rate of reactions is a function of temperature
• Reactions are energy transfer among molecules
• To much heat destroys large molecules
Heat Exchange• Three Processes
– Radiation
– Conduction
– Evaporation
Radiation
Put something in between and it is blocked
Conduction
• Moves heat around the body and to the surface of the body
• Molecules of water bumping into each other
• Sweat is water containing heat that can be “thrown away”
Evaporation and Convection
Colder, DRY Air
Warmer, Moist Air
Evaporation
Warmer, Moist Air
Evaporation
Colder, DRY Air
Temperature Regulation
Drunk
Lungs
• Gas exchange
• Composition of Air– 78% Nitrogen (N2)
– 21% Oxygen (O2)
– .04% Carbon Dioxide (CO2)
– Traces of other gasses
Breathing
Bronchial Tree
Hemoglobin
>Binds O2
>The concentration of O2 controls the ability of Hb to bind O2
Only free O2 plays in the concentration game
Only free CO2 plays in the concentration game
Molecules flow from a high concentration to a low concentration
SinksA sink is a way to remove O2 and CO2 from the concentration game
Oxygen sink
2O2 + Hb HbO4
Carbon Dioxide Sink
CO2 + H2O H2CO3 H+ + HCO3-
Lungs: Gas exchange
Blood
Tissues: Gas exchangeWater around cells Blood in capillary
Control of Respiration
Other Factors
• Stress: Open airways, increase depth of breathing, increase blood flow
• pH: drug or condition that changes blood H+ concentration
• Drugs: Any drug that depresses brain function
Digestion
Digestive System
>What we put inProtein, fat, carbohydrate,
vitamins, minerals, water
>Three processesMovement
Breaking up big molecules
Absorption into blood
Mouth
Why your mother told you not to talk and eat at the same time
Stomach• More water plus H+ Cl-
• Digestive enzymes that are “ turned on” by H+
• H+ destabilizes bonds
in protein between amino acids
Small Intestine
• Put in OH- to neutralize H+
• H+ + OH- H2O
• “Turns off” protein digestive enzymes
• Fat digestion: bile salts make oil and water mix
• Absorption into blood
Absorption
Sifting the stream for molecules and other nutrients
Nutrient filled blood goes to the liver (Hepatic Portal Vein)
Large Intestine
• Additional digestine by bacteria
• Water recovery
Control of Digestive System
• If you eat and when you eat
• What you eat
• Movement
• Release of secretions
• Distribution of Blood
Problems with Digestion
• Excessive stomach acid– Mild: heartburn – Severe: ulcers
Drugs
Antacids: H+ + OH- H2O , disturbs blood pH, acid rebound
Tagamet, Pepcid etc: Antihistamine that blocks production of HCl
Other Problems with Digestion
• Malabsorption (small intestine) eg celiacs disease an autoimmune disease
• People do not spend enough time on digestion and absorption
• Many drugs cause acid production: coffee, tea, coke, alcohol, heart medicine
• Antibiotics can kill the “good” bacteria in the large intestine