The Respiratory System

Why Do We Need Oxygen? Respiration a series of chemical reactions to release energy when breaking down compounds Aerobic Respiration use of oxygen to break down compounds C6H12O6 + 6O2  6CO2 + 6H2O + Energy Anaerobic Respiration not using oxygen to break down chemicals C6H12O6 C2H5OH + 2CO2 +Energy (alcohol) C6H12O6 2C3H6O3 + Energy (lactic acid)

Why Do We Need Oxygen? What do we do that requires energy? Muscle contraction Digestion Cell division Absorbing nutrition ENZYMES!! Homeostasis healthy point for a living organism What is the energy unit of a cell? ATP Where is ATP made? Mitochondria

Gas Exchange in the Lungs Lungs organ where gas exchange occurs Air moves through nose/mouth then… 1) Larynx “voice box”; muscles in throat that produce sounds 2) Trachea “windpipe”; tube connecting throat to lungs Protected by C-shaped cartilage 3) Bronchi split in of trachea into left and right lung 4) Bronchioles smaller division of bronchi through out lungs 5) Alveoli “air sacs”; where gas exchanges happens with blood

Separating Food and Air Food has to pass by the trachea (entrance to the lungs) so a small cartilage cover (epiglottis) blocks the opening Eating too fast can send food “Down the Wrong Pipe”

The Chest Lungs organ for breathing Ribs and Sternum protect lungs and heart Intercostal muscles muscle the fill space between ribs Pleural membranes wet soft area to prevent the lungs from rubbing against the ribs Diaphragm muscle across bottom of ribs that controls breathing Contracts to expand chest and allow lungs to fill with air

Breathing Lungs cannot be controlled! Only muscles! Inspiration Breathing In Intercostal muscles and diaphragm contract Chest volume increases, so pressure on lungs decreases Lungs expand, air is sucked in to fill space Boyles’ Law if the volume goes up, the pressure goes down (inversely proportional)

Breathing (Part 2) Expiration Breathing Out Keep it Clean! Internal intercostal muscles contract while outer intercostal muscles and diaphragm relax Chest decreases in volume, so pressure on lungs increases Lungs shrink so air is forced out Keep it Clean! Cilia move a stream of mucus through the throat and nose Mucus catches bacteria and dust Enter digestion system when you swallow

What is Air? 21% 0.04% 78% < 1%; varies 78% 4% 16% Saturated What is the composition of the air you breath in? Oxygen? CO2 ? Nitrogen? Water Vapor? What is the composition of the air you breath out? CO2 ? Water vapor? 21% 0.04% 78% < 1%; varies 78% 4% 16% Saturated

Gas Exchange 16% O2 exhaled comes from: Need of oxygen in body Dead air space; air that never makes it to alveoli How do O2 and CO2 enter and leave the blood? Diffusion What factors limit diffusion rate? Concentration Gradients Surface Area Distance Material

In The Alveolus 0.04% 21% 4% 16% Concentration gradients: Surface Area O2 21% vs. 16% CO2 0.04% vs. 4% Surface Area Small, numerous alveoli make lots of membrane space Distance Walls of alveoli and capillaries are only 1 cell thick Material Watery surface is easier for gasses to dissolve into alveoli 0.04% 21% 4% 16%

Respiratory Rate Relaxed 12-16 breaths /min Exercise increases dramatically; varies with person Muscles need more O2 and make more CO2 Breath faster and deeper Relaxed 0.5 L / breath Exercise 4.5L/ breath Vital Capacity max of 5 L After exercise, O2 is still too low and CO2 is still too high, so heart rate and breath rate stay high till normal

Controlling Respiratory Rate Which causes you to breath faster during exercise; Low O2 or High CO2? High CO2 What will raised CO2 do to your blood? Lower the pH; make is acidic Brain scans blood, if pH is too low, send signals to breath faster What is your brain trying to maintain? Homeostasis!

Fermentation In the absence of oxygen，cells can still produce ATP through fermentation (anaerobic respiration) There are two major types of fermentation: Alcoholic fermentation Lactic Acid fermentation

Alcohol Fermentation C6H12O6 C2H5OH + 2CO2 +Energy Used by man to make various products: CO2 released causes bread and cakes to expand Ethanol used to make beer and wine

Lactic Acid Fermentation C6H12O6 2C3H6O3 + Energy Helps energy supply during hard exercise Lactic acid can not be broken down in the muscles cells; must be sent to the liver Oxygen debt O2 needed to removed lactic acid before homeostasis is reached Lactic acid builds up too fast and changes the pH of muscle cells Change in pH slows performance and weakens the muscle cells; sore

Oxygen is Key P 235