Chapter 42 Flashcards
Ventilation
air or water moves through specialized
gas-exchange organ (lungs or gills, etc
Gas exchange
CO2 & O2 diffuse between air or water
& blood at respiratory surface
circulation
dissolved O2 & CO2 are transported
throughout body
Where gas exchange (diffusion) between blood and cells occur
Tissues where cell respiration occurs
How does gas exchange occur between environment and cells
Diffusion since
Oxygen is high in environment; low in tissues
Carbon dioxide is high in tissues; low in environment
Gills
outgrowths of body surface in aquatic animals
Have extremely large surface area for gasses to diffuse across extremely thin epithelium
Invertebrate gills
diverse; can be external or internal
Bony fish gills
Have internal gills on both sides of head
Water must be driven over them
How do fish ventilate gills
by opening & closing their
mouth & operculum (stiff flap over gills)
Ram ventilation
Process where fast swimmers force water through gills by swimming with
mouths open
Countercurrent
exchange system
Flow of blood
through capillaries is
in opposite direction
to flow of water over
gill surface; sets up
What does Countercurrent exchange system create
large pressure differences of oxygen & carbon dioxide in water vs blood
result is efficient exchange of gases over gills!
Insect tracheal system
Contains tracheae-series of tubes extending throughout body; connects to exterior through openings (spiracles)
Trachae allow gas exchange to take
place directly across cells’
plasma membranes; circulatory
system NOT involved
Vertebrate lung process
- Air enters through lungs
- Trachea carries inhaled air to tubes called bronchi; bronchi branch into even narrower tubes (bronchioles)
Bronchi lung structure
Mammal lungs divided into tiny sacs called alveoli that greatly increase surface area for gas
Negative pressure ventilation
Occurs in only mammals
Pumping action achieved by muscle - diaphragm
Inhalation: Diaphragm contracts, ribcage expands as rib muscles contract
Exhalation: Diaphragm relaxes (moves up) as rib muscles relax
Functions of blood
-Transport oxygen & carbon dioxide
– Transport nutrients to cells from digestive system
– Convey hormones to target tissues & organs
– Deliver cells of immune system
– Distribute heat
Structure of blood
- Platelets- cell fragments that minimize blood loss
– White blood cells (WBCs)- part of immune system
– Red blood cells (RBCs) transport oxygen from lungs to body tissues; participate in transporting carbon dioxide from tissues to lungs
Hemoglobin
Oxygen carrying molecule in red blood cells
Consists of four polypeptide chains, each has iron (Fe2+) containing group (heme)
Each hemoglobin can bind up to four O2 molecules
Carbonic anhydrase
Catalyzes the formation bicarbonate ions & hydrogen ions from Co2
Important because it maintains a strong partial pressure gradient favoring the entry of more CO2 into the red blood cells
How is CO2 transportaed in the plasma
It is transported in form of bicarbonate ion, HCO3−
What do protons produced by carbonic anhydrase do?
Induce Bohr shift, or acidity makes hemoglobin more likely to release oxygen
How does Pco2 in blood drop?
when CO2 converted to bicarbonate, maintaining strong partial pressure gradient favoring entry of Co2 into RBCs
How tiny and large animals maximize diffusion
- Tiny animals have small enough volume that diffusion over body surface is adequate to keep them alive
– Larger animals require a circulatory system in order to achieve a large ratio of surface area to volume
What are walls of arteries or areries made of
Smooth muscle tissue since it allows for elasticity of vessels
Aorta
Largest artery; receives blood directly from heart
What do the sphincters?
Muscles in arterioles that allow diameter of vessel to be regulated
Where are capillaries located
in circulatory system where materials
are exchanged between blood & other tissues
Structure of veins
thinner walls & larger interior diameters than
arteries because blood is under relatively low pressure when it leaves the body tissues
What helps the return of blood in veins
Compressing of skeletal muscle in extremities and valves - thin flaps of tissue that
prevent backflow of blood
Open system
fluid pumped by heart(s) throughout body
in open vessels, hemolymph comes in direct contact with body tissues (most invertebrates)
Closed system
fluid (blood) flows in continuous circuit
of closed vessels via pumping action of heart (vertebrates)
2 chambers of heart
- Atrium receives blood returning
from circulation - Ventricle generates force to
propel blood through system
What heart structure does fish contain
2-chambered heart with a single circulatory circuit
Double circulatory system
Land vertebrates have this
Contains
- Pulmonary circulation:
to & from lungs - Systemic circulation: higher-pressure circuit
to & from rest of body
How are pulmonary circulation and systemic circulation separated
4 chambered hearts in birds and mammal
Partially separated into 3 chambered hearts in amphibians
Pulmonary and Systemic circulation process
Flow of blood
- Body to right atrium via superior vena cava
- Right atrium to right ventricle via right AV vale
- Right ventricle to lungs via pulmonary valve and pulmonary artery
Systemic circulation
4. Oxygenated blood from lungs to left atrium via pulmonary veins
5. Left atrium to left ventricular via left AV valve
6. Left ventricle to body via aorta and aortic valve
Diastole
relaxation, or filling, phase
Systole
contraction, or pumping phase
What might be the function of the muscle contraction in the walls of veins?
Muscle contraction reduces the volume of veins, increasing blood pressure and, thereby, increasing the velocity of blood flow.
Where is the velocity of blood flow the slowest in your body?
The very high total cross-sectional area of capillaries means that blood flow there is very slow, providing opportunity for diffusion into and out of the blood.
Disadvantage of breathing air
Can dehydrate animal tissues exposed to air at the respiratory surfaces.
What promotes oxygen release from hemoglobin
An increase in carbonic anhydrase activity
A decrease in pH
Oxygen-rich tissues
Bohr effect
hemoglobin’s lower affinity for oxygen secondary to increases in the partial pressure of carbon dioxide and/or decreased blood pH.
Disadvantages of open circulatory system
- Because the pressure is lower in an open circulatory system, there is a slower flow of hemolymph.
- An open circulatory system cannot direct the hemolymph toward specific organs.
Partial pressure of oxygen or PO2 meaning
Measurement of oxygen pressure in arterial blood
Indicates how well oxygen is able to move from the lungs to the blood
What is the main factor for controlling ventilation rate in mammals
Change in partial pressure of Co2 in blood
Partial pressure of Co2 can increase while exercising, thus increasing ventilation rate
In insects, what is the adaptive significance of spiracles?
They close off tracheae to minimize water loss.
Primary function of nasal cavity
Warm, filter, humidify air
What happens if hydrogen ions are not carried by hemoglobin
The hydrogen ions could reduce the ph or increase the acidity of the blood
Which barrier(s) must O2
and CO2 cross to pass between air and blood inside lungs?
capillary wall
epithelial cells
extracellular fluid
What is the driving force for the diffusion of oxygen into tissues?
Difference in PO2 levels between the blood (100 mm Hg when oxygenated) and body tissues (40 mm Hg at rest).
What is cooperative binding
When the binding of one oxygen molecule to hemoglobin stimulates the binding of other oxygen molecules.
What happens during inhalation
- The diaphragm and rib muscles contract, increasing the volume of the lungs.
- Air enters the nose or mouth and flows down the trachea, bronchi, and bronchioles, and into the alveoli.
What happens during exhalation
The diaphragm and rib muscles relax, decreasing the volume of the lungs.
Air leaves the alveoli and flows up the bronchioles, bronchi, and trachea, and exits through the nose or mouth.
Why is cooperative binding of oxygen to hemoglobin an important adaptation for gas exchange
allows hemoglobin to release much more oxygen to an animal’s body tissues.
What happens as blood flows through the lungs
There is a decrease in blood pressure
Why do vertebrates have separate circuits to lungs and rest of body
The changes in blood pressure as blood moves through the lungs of land-dwelling vertebrates make it necessary to have
separate circuits to the lungs and the rest of the body.
What structure prevents backflow of blood into atria
Valves
What happens in the diastole phase of heart
Relaxation phase of heart where chambers of the heart are relaxed and blood can enter them passively.
Which event of the cardiac cycle occurs when systolic blood pressure is measured
The ventricles contract, carrying blood into the aorta, and blood flows into the relaxed atria since systolic blood pressure is peak blood pressure, resulting from contraction of the ventricles
What is hemoglobin most likely to bind too
Most likely to bind to oxygen where the partial pressure is high like in the lungs, and is more likely to release oxygen when it the pO2 is lower
What is the cause of enlarged hearts in people with cardiovascular disease
In people with cardiovascular disease, the heart muscle often enlarges as it works harder to pump blood through hardened arteries.
