Chapter 30: The Respiratory System Flashcards
LO: List four things necessary for gas exchange to occur in multicellular animals and explain why each is required (Lab Guide, Minicourse 2, p. 2).
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Aerobic respiration
Consumes oxygen gas and generates carbon dioxide gas as a waste product.
Respiratory system
Organ system that does the breathing, works with the circulatory system to deliver oxygen gas (O2) to cells and to eliminate carbon dioxide (CO2) to cells.
Respiration
Means:
- Breathing: the physical movement of air into and out of the body
- The act of exchanging gas
External respiration: gas exchange between an animal’s body and its environment
Internal: gas exchange between tissue cells and bloodstream
Respiratory surface
Area of animal’s body where external expiration occurs.
Humans: lungs
Shares three characteristics:
- Surface area must be large
- Must come into contact with either air or water. Air has a higher concentration of O2 and is lighter so less energy is required to move air across a respiration surface.
- Consist of moist membranes across which O2 and CO2 diffuse.
Where does gas exchange occur in very small or flat animals?
Gas exchange occurs across the moist body wall, as gases simply diffuse into and out of each cell.
Tracheae
Internal, air-filled tubes that connect to the atmosphere though openings, called spiracles, along each side of the abdomen. It branches into tiny tubules that extend around individual cells.
What animals have a tracheae?
Insects and many arthropoda.
Gills
Highly folded structures containing blood vessels that exchange gases with water across a thin layer of epithelium. Mollusks, fishes and amphibians.
Countercurrent exchange
Two adjacent currents flow in opposite directions and exchange materials with each other.
How bony fish’s gills work
LO: describe how the respiratory surfaces of unicellular organisms, insects, fish and animals (30.1 and figure 30.2) maintain an adequate surface area to volume ratio for gas exchange.
See respiratory surface.
Capillaries
The tiniest of blood vessels. Each filament includes platelike lamellae that house a dense network of capillaries.
The direction of water flow across lamellae opposes that of blood flow in the capillaries. The concurrent relationship maximizes gas exchange between water and blood.
Lungs
Saclike organs that exchange gases. Homologous to the gas bladders of bony fish.
Nose
Forms the external entrance to the nasal cavity, functions in breathing, immunity, and the sense of smell.
Epithelial tissue secretes a sticky mucus.
Nasal cavity adjusts temperature and humidity of incoming hair. Back of nose leads to the pharynx
Upper respiratory tract
Nose, pharynx, and larynx
Lined with epithelium that secretes mucus. Inhaled particles are swept away by waving cilia.
Pharynx
Throat. Inhaled air and swallowed food pass through here.
Larynx
A boxlike structure that produces the voice.
Located below and in front of the pharynx. Adam’s apple.
Direct ingested food and drink away from the respiratory system.
Vocal cords
Stretched over the larynx. Two elastic bands of tissue that vibrate as air from the lungs passes through the glottis.
Glottis
Slit like opening. Vibrations of the vocal cords produce the sound of speech.
Epiglottis
Cartilage flap that covers the glottis so that food enters the digestive tract instead of the lungs.
Lower respiratory tract
Trachea and lungs
Trachea
Windpipe. Tube just below the larynx.
C-shaped rings of cartilage hold the trachea open and accommodate the expansion of the esophagus.
Branch into two bronchi
Bronchi
Branched from the trachea. Each bronchi leads to each lung.
Bronchioles
Finest branches of bronchi. Contain no cartilage, but their walls contain smooth muscle. The automatic nervous system controls contraction of these muscles.
Narrows into several alveolar ducts, and each duct opens into a grape like cluster of alveoli, where gas exchange occurs.
Alveolus
Tiny sac with a wall of epithelial tissue is one cell layer thick. Gas exchange occurs here. Branched from bronchioles.
Respiratory cycle
Consists of one inhalation and one exhalation.
Inhale
Air moves into the lungs
Skeletal muscles of the rib cage and diaphragm contract,,
Exhale
Air flows out of the lungs
Does not require ATP
What drives the back and forth motion of breathing?
Air flows from areas of high concentration to low. Air enters the body when the pressure inside the lungs is lower than the pressure outside the body.
Hiccup
Diaphragm contracts unexpectedly, causing a sharp intake of air. The hic sounds occur when the epiglottis closes.
Tidal volume
Amount of air inhaled or exhaled during a quiet breath taken at rest.
Vital capacity
Total amount of air that a person can exhale after taking the deepest possible breath.
Functions of the human respiratory system: a summary
- Gas exchange: lungs exchange oxygen and carbon dioxide with blood.
- Olfaction (sense of smell): breathing moves air across the nose’s olfactory epithelium, which detects odors.
- Production of sounds, including speech: movement of air across the vocal cords in the larynx produces sounds.
- Maintaing blood pH homeostasis: breathing more slowly or rapidly adjusts the concentration of CO2 in blood, which affects blood pH.
Why do we exhale a different gas composition than inhaled air?
O2 from the atmosphere enters the capillaries surrounding the alveoli; CO moves in the opposite direction from the capillaries to the alveioli.
Blood
Connective tissue consisting of cells and platelets suspended in plasma.
Plasma
Liquid component of blood. Only 1% of O2 in blood is dissolved in plasma. Red blood cells transport the rest.
Red blood cells
Transports the rest of the O2 not dissolved by plasma. Contains hemoglobin.
Hemoglobin
Iron-rich pigment protein that binds with O2. Can carry up to 4 O2 molecules.
Blood carries CO2 absorbed at tissue cells in three ways
- About 5% to 10% is dissolved in plasma
- Hemoglobin transports 23%
- Most CO2 (75%) is transported by as bicarbonate ions.
What are the important parts that contribute to blood’s ability to buffer pH changes and maintain homeostasis?
Carbonic acid and bicarbonate
External respiration and gas exchange
Occurs in the lungs. O2 diffuses from the alveoli into the bloodstream where the concentration of O2 is lower.
Internal respiration and gas exchange
O2 diffuses from the bloodstream to the tissue fluid and then into the body’s respiring cells which have the lowest O2 concentration. CO2 diffuses in the opposite direction.
Brain’s breathing controls
Pons and the medulla. Chemoreceptors in the medulla and in the body’s largest arteries monitor blood CO2 levels.
