Chapter 42: Circulation and Gases Flashcards
Respiratory System
how ventilation and diffusion at the respiratory surface are accomplished
Collection of cells tissues and organs responsible for gas exchange
Skin in some animals, in most species located in specialized organ like lungs, gills, or tracheae
Circulatory System
responsible for moving O2, CO2, and other materials around the body
Many cases, involved muscular heart rate propels special liquid transport tissue through the body
Lungs of Snails and spiders
simple lungs, air movement takes places via diffusion only
Vertebrate Lungs
actively ventilate lungs by pumping air via muscular contractions
Two mechanisms of lung structure
positive pressure ventilation, used by frogs
Two mechanisms of lung structure
positive pressure ventilation, used by frogs
negative pressure ventilation, used by humans and other mammals
Boyle’s Law
volume goes down, pressure goes up (vice versa)
Two steps involved: inhalation and exhalation
Inhalation
Diaphragm moves down, pressure in chest cavity is lowered
This causes the lungs to expand and air to move in
Exhalation
Diaphragm relaxes, chest cavity decreases and air is exhaled
Passive process! Driven by elastic recoil of lungs and chest walls, diaphragm and rib muscles relax
**energy demanding/active during exercise
How do vertebrate lungs work?
Air enters body through the mouth and nose
Trachea carries inhaled air to narrow tubes called bronchi
Bronchi: they branch off into even narrower tubes called bronchioles
Lung: organ of ventilation
Examples: animals, such as fished, amphibians, reptiles, birds and mammals
Lungs can vary in structure! BUT they all have these structures in general
Frog and Amphibian Lungs
lung is simple sac lined with blood vessels
Mammalian lungs
divided into tiny sacs called alveoli
Alveoli
greatly increase the surface area for gas exchange; provide an interface between air and blood (0.2 micrometers) that consists of:
* Thin aqueous film
* Layer of epithelial cells
* ECM: extracellular matrix material
* Wall of a capillary
Humans have approx. 150 million alveoli
Oxygen process in red blood cells
Red blood cells use hemoglobin to carry Oxygen: Oxygen loads onto hemoglobin; Hemoglobin carries up to 4 oxygen molecules
Up to 1 billion oxygen molecules;250 million or so hemoglobin molecules per RBC
Oxygen unloads once the RBCs get to capillaries in systemic tissues
Dalton’s Law of partial pressures
gases are transported and unload on tissues; Oxygen unloads into tissues because oxygen is consumed there
CO2 generated in tissues and loads into blood
each gas has its own partial pressure (fraction of total pressure)
Partial pressure of oxygen (PO2 – fraction of oxygen in the gas) is lower in the tissues than in the lungs
Flow from high to low, (A PRESSURE GRADIENT)
o Moves from high PO2 to low PO2
o Moves from low PCO2 to high PCO2
Functions of Circulatory system
Transport:
O2 and nutrients to tissues (in arterial blood) CO2 and wastes away from tissues for elimination
Regulation
o Hormone transport
o Temperature regulation: Radiate heat to the environment to cool off, storing it to keep warm
Protection
o Blood clotting: Seals up gas in circulatory system
o Immune defense
materials in blood
plasma, RBCs, WBCs, platelets, blood vessels
Plasma
liquid portion -> 55%
o Contains ions, electrolytes, various nutrients, various wastes, various hormones, various proteins, etc.
