External respiration - exchange of O 2 & CO 2 between respiratory surfaces & the blood [breathing]. Internal respiration - exchange of O 2 & CO 2 between the blood & cells.
Cellular respiration - process by which cells use O 2 to produce ATP .
Gas Exchange in Animals Describe the 4 functional processes involved in most animal respiration. Compare to gas exchange in plants.
Types of Respiratory Surfaces All respiratory surfaces MUST be: large enough to meet metabolic needs of organism Aquatic organisms - H 2 O contains only 1/30 of the O 2 present in air.
Terrestrial organisms - must prevent desiccation of respiratory surface.
Respiratory Organs Respiratory adaptations, as it relates to lifestyle.
simplest gas exchange mechanism adapted to moist environment
may be associated with circulatory system
2. Tracheae - highly branched system of internal tubules. adapted to terrestrial environment NOT associated with a circulatory system
Large, active arthropods use abdominal & flight muscles to ventilate tubules.
Tracheal System in Insects Each cell has a nearly direct means of gas exchange via the tracheal system (2-4 spiracles on the thorax, 6-8 on abdomen). (May serve as storage reserve)
3. Gills - featherlike extensions of the body surface. adapted to aquatic environment may be external or internal
amphibian larvae; some adult salamanders
Diversity in gills Describe the dual function of gills in bivalves and polychaetes. p. 983
Two of these animals utilize structures for body movement in gas exchange as well. Describe.
protects gills & pumps water over their surfaces
water flow is countercurrent to blood flow
Countercurrent Mechanism for Gas Exchange Draw a similar picture showing blood flow and water flow in the same direction. How would oxygen diffusion change? Nearly 80% of the O 2 is removed from the water as it passes over the gills. Is this more or less efficient than gas exchange at the lungs? Why ? p. 984
Ventilation in Birds p. 987
4. Lungs - paired internal sacs lined with moist epithelium. adapted to terrestrial environment
interact with circulatory system
Human Respiration Involves the process of cellular respiration and gas exchange. a) cellular respiration : glucose + O2 H2O + CO2 + 36 ATP’s
exchange of gases between the internal and external environment with the use of lungs.
Blood Transports Gases Between Lungs and Tissues
(I) Human Respiratory System Works closely with circulatory system, exchanging gases between air and blood: Takes up oxygen from air and supplies it to blood (for cellular respiration). Removal and disposal of carbon dioxide from blood (waste product from cellular respiration).
Regulates blood oxygen and carbon dioxide levels.
1 - nasal cavity 2 - pharynx (throat) 3 - (blue) alveoli or air sacs 4 - (yellow) bronchioles 5 - (pink) lung 6 - (red) diaphragm 7 - nostril 8 - (orange) larynx or voice box 9 - (green) trachea 10 - (light green) bronchus
Lined with a ciliated mucus membrane .
nasal cavity pharynx larynx What prevents food from entering larynx? epiglottis What causes deepening of male voice during puberty ? testosterone
contains vocal cords; conducts air
It “covers” the trachea when swallowing food.
Trachea Kept open by rings of cartilage Lined with a ciliated mucus membrane.
One cigarette paralyzes the cilia for 20 minutes .
Bronchi Trachea divides into two major divisions known as bronchi. The bronchi contain cartilage rings as well.
The bronchi subdivide many times forming smaller tubules known as bronchioles .
Tiny bronchioles subdivide and terminate (end) with structures known as alveoli.
Alveoli Are thin, moist and surrounded by capillaries Are the functional units for gas exchange between the lung and the blood Alveoli increase surface area for gas exchange
O2 diffuses into the blood from the alveoli and CO2 and water diffuse out of the blood and into the alveoli
Structure of Lung Alveoli
Path of air flow in external respiration:
Occurs in response to pressure differences between lungs & atmosphere. Inhalation (active process) diaphragm & external intercostal muscles contract thoracic cavity volume & air pressure External intercostal muscles
air pulled inward; lungs expand
Exhalation (passive process) diaphragm & external intercostal (rib) muscles relax ; lungs recoil thoracic cavity volume & air pressure Forced exhalation is active - caused by contraction of internal intercostal muscles & abdominal muscles.
air pushed outward; lungs deflate
Human Breathing: Inhalation and Exhalation
Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles). rhythmicity center
Breathing is regulated by the rhythmicity center in
The most important factor affecting the rhythmicity center is CO 2 in arterial CO 2 causes in acidity (below 7.4) of cerebrospinal fluid (CSF). in CSF acidity is detected by pH sensors in medulla.
medulla rate & depth of breathing.
Human Breathing is Automatically Controlled
(III.) Gas Exchange Transports oxygen (binds in the alveoli to form oxyhemoglobin . Transport carbon dioxide carried in the plasma forms bicarbonate ions. As carbon dioxide is picked up from tissues it is converted into carbonic acid: CO 2 + H 2 O <-----> H 2 CO 3 <----> H + + HCO 3 - Carbon Carbonic acid Carbonate ion
Hemoglobin picks up most H + ions, so they don’t acidify the blood.
Hemoglobin Loading and Unloading of Oxygen
IV. Diseases of the Respiratory System
Respiratory rate: 10 to 14 inhalations/minute. In one day, an average human: Most of us breathe in air that is heavily contaminated with solid particles, ozone, sulfur oxide, carbon monoxide, nitrogen oxides, and many other damaging chemicals.
Breathing contaminated air can cause a number of diseases including asthma, bronchitis, emphysema, and lung cancer.
Cigarette smoke is one of the worse air pollutants. Over 1 million people start smoking every year. Kills about 350,000 people every year in U.S. Contains 4000 different chemicals. Each cigarette smoked subtracts about 5 minutes from life expectancy. Cigarette smoke paralyzes cilia in airways, preventing them from removing debris and from protecting delicate alveoli. Frequent coughing is the only way airways can clean themselves.
Cigarette smoke also causes fetal damage, which can result in miscarriage, premature birth, low birth weight, and poor development.
Inflammation of the membrane of the bronchial tubes.
An allergic response characterized by constriction of the bronchial tubes.
Emphysema Disease in which the walls of the alveoli breakdown, decreasing surface area for gas exchange.
Characterized by shortness of breath, difficulty in breathing, and decreased lung capacity.
The alveoli become filled with fluid, preventing gas exchange between the alveoli and the capillaries .
Cancerous growth that invades and destroys lung tissue. Very high fatality rate. Symptoms include bloody sputum, persistent cough, difficulty breathing, chest pain, and repeated attacks of bronchitis or pneumonia.
Causes: Smoking (50% of all cases) and pollution (radon, asbestos). Smokers are 10 times more likely to develop lung cancer than nonsmokers.