The Respiratory System Flashcards
Cellular Respiration
Glucose + Oxygen - Carbon Dioxide + Water
Requirements for Gas Exchange
•diffusion of gases works best across a moist membrane
•the more surface area, the more gas exchange
•delicate membranes must be protected
•need a constant flow of O2 across the exchange membranes
•need a way to transport gases to all cells in the organism
Microorganisms
•very small (most uni-cellular)
•constant contact with their external environment
•gas exchange occurs by diffusion across their membranes
Diffusion
the movement of molecules from a high concentration to a low concentration. It occurs passively - no energy required - so if there was more oxygen in one area (high concentration), the oxygen molecules would automatically move to an area with less oxygen (low concentration)
Large Aquatic Organisms (not a big idea)
•moist membrane is no problem
•transport is by a circulatory system
•surface area is increased by gills
•gills are very delicate so must be protected by gill cover
•they need a fresh supply of oxygenated water so the organism either keeps moving or has moving parts
Terrestrial Organisms
•secrete own moisture across the exchange membranes
•can be highly folded to increase surface area
•membranes are inside the body for protection
•highly vascularized: lots of blood flow near the membranes to exchange and transport gases
•require a mean of oxygenated air across the lung membranes: breathing
Breathing
•the mechanism is based on a pressure system
•when a container increases in volume, it creates a partial vacuum so air is drawn in and when it decreases in volume, air is pushed
•external intercostals pull rib cage out when contracted, internal intercostals pull rib cage in when contracted
Diaphragm
•lines the bottom of the lungs and the rib cage, lowers when contracted
•the outer surface of the lungs is connected to the inside of the chest cavity by pleural membranes when the chest cavity increases or decreases they pull these elastic membranes and the lung tissue almond with them
Inhaling
•diaphragm and external intercostal muscles contract
•lungs are pulled out and down
•air pressure is reduced in the lungs
•air is drawn in
Exhaling
•external intercostals and diaphragm relax
•internal intercostals contract
•lungs (due to there elasticity) regain their normal size
•air pressure is increased
•air is pushed out
Nostrils and Nasal Cavity (1a)
•functions: warming, moistening, and filter air, sense of smell
•lined with mucus and cilia to trap dust particles
Components of the Gas Exchange System
Nostril and Nasal Cavity and Mouth, Trachea, Bronchi and Bronchioles, and Aveoli
Mouth (1b)
•greater volume of air can enter and exit, however, it is not warmed or filtered as much
Trachea (2)
•the glottis is the opening between the pharynx and the upper end of the trachea
•the glottis is protected by the epiglottis during swallowing, the larynx (voice box) sit just below the glottis: inhaled air passes around it, exhaled air can pass around it or through it
Structure of the Trachea
•series of C-shaped cartilage rings are imbedded in the walls (prevents collapse)
•lined with cilia and mucus: these trap and sweep out dust particles
Bronchi and Bronchioles (3)
•the trachea branches into the bronchi (one to each lung)
•these branch into several bronchioles
•there structures are similar to that is the trachea (although the smallest bronchioles have no cartilage)
Alveoli (4)
•each terminal bronchioles ends in a cluster of avellane sacs
•the walls of the aveoli are only one cell thick, surrounded by a dense bed of blood
•the infoldings of the aveoli provide a large surface area
•this is the site of gas exchange
Oxygen Transport
•O2 dissolves poorly in water, and blood is mostly water (1.5% dissolves)
•instead (98.5%) it is carried by binding to hemoglobin molecules in red blood cells (RBC)
•hemoglobin (Hb) is a protein consisting of 4 polypeptide chains and 4 iron atoms
•about 280 million Hb molecules per RBC
Carbon Dioxide Transport
•20-30% of CO2 is carried to the lungs by Hb
•5-10% dissolves in plasma (this makes blood slightly acidic)
•60-70% is transported as bicarbonate ions after CO2 reacts with water in RBC to form carbonic acid, which then dissolves
•therefore, as we exhale and release CO2 our blood becomes more basic
Gas Exchange (Carbon Dioxide)
•as blood containing CO2 flows to the cooler temperature of the lungs, the CO2 diffuses out of the blood and into the aveoli
•this frees up Hb and it can now pick up oxygen gas
Gas Exchange (Oxygen)
•at cooler temperatures and neutral pH, O2 binds strongly to Hb
• these conditions exist in the lungs, so O2 readily diffuses from alveoli to capillaries and into red blood cells
•at warmer temperatures and acidic pH, O2 does not bind as strongly to Hb, so it is released
•these conditions exist in body tissue, so O2 leaves blood and diffuses into surrounding cells
Oxygen Use
•cells use absorbed O2 to help produce energy during cellular respiration, therefore, your level of activity determines how much O2 you use
•blood pressure is measured in millimeter of mercury (mmHg)
VO2
•the rate at which oxygen is used by the body (units = mL of O2/kg of body mass/minute
VO2max
•a persons maximum VO2
•can be used as a measure of respiratory health and/or fitness