Exam 2: Circulation and Gas Exchange Flashcards
What is the most important purpose of circulation?
Movement of gases
How is oxygen solubility affected in water?
Decreased significantly
How does oxygen move?
High partial pressure to low (high conc. to low)
How does temperature affect O2 solubility in water?
Solubility of O2 decrease with temperature in water
How does water affect oxygen diffusion?
Oxygen can only diffuse distances of 1 mm in water due to decreased solubility
How is the low diffusion capability of O2 accommodated by bodies?
Move oxygen using convection
What powers movement of oxygen from the atmosphere to the mitochondrion?
A cascade of oxygen partial pressure that decreases from atmosphere to mitochondrion
What are invaginated breathing structures?
breathing structures inside the body
What is a con of invaginated breathing structures?
requires active ventilation to bring gas inside
What are envaginated breathing structures?
breathing structures inside the body
What is a benefit of evaginated breathing structures?
energy is not required to bring gas to respiration structures
What is a con of evaginated breathing structures?
Breathing structures aren’t protected
What is a pro of invaginated breathing structures?
breathing structures are protected
What are RAM ventilators?
Fish that breath by moving in a way that forces water over their gills
What causes tidal gas exchange to occur?
The partial pressure of blood leaving lungs in lower than air in the lungs
What is tidal gas exchange?
Air enters and exits through the same tube
Why is tidal exchange successful despite mixing high and low O2 air?
Because air is practically infinitely available in the atmosphere so partial pressure of O2 in blood in always lower
How does countercurrent exchange gas exchange work?
Partial pressure of blood leaving the gills is higher than the water leaving the gills which maintains a gradient
Which form of gas exchange is most efficient?
Countercurrent exchange
Why do fish need countercurrent gas exchange?
Because O2 availability in water is really low
How does salinity affect solubility of O2?
O2 solubility decreases as salinity increases
How does crosscurrent gas exchange occur?
Vessels run perpendicular to the flow of oxygenated fluid and have slight mixing that causes decrease in partial pressure of oxygen in blood going down the fluid flow; However oxygen concentration in the fluid also decrease
What organisms employ crosscurrent gas exchange?
Birds
Is tidal exchange or cross current exchange more efficient and why?
cross current because mixing of oxygen partial pressures is minimized
Why do birds employ crosscurrent gas exchange?
Flight has very high energy requirements and it is best to use aerobic respiration
What is the pulmonary circuit?
circulatory circuit that carries deoxygenated blood from the heart to the body
What is the systemic circuit?
circulatory circuit that carries oxygenated blood from the heart to the body
What is systole?
contraction of the myocardium
What is diastole?
relaxation of myocardium
What are the steps of four chambered heart contraction
Atria and ventricles are diastole -> atria systole pushes blood into ventricles -> ventricle systole pushes blood out of heart and atria diastole brings blood back in -> ventricle diastole
What is cardiac output measured by?
The volume of blood leaving the heart per minute
What is stroke volume?
The volume of blood pump per beat
What controls stroke volume?
Strength/size of cardiac muscle
What controls the heart beat of neurogenic hearts?
The nervous system
How do system do neurogenic hearts employ to function?
Central pattern generators
What controls the heart beat of myogenic hearts?
Muscle cells that generate pacemaker potentials
What kind of polarization generates pacemaker potentials? Why?
Hyperpolarization because the hyperpolarization threshold slows the generation of the potential; creates delay between each contraction
Does blood leave for lungs using the left or right ventricle?
right
Does blood leave for the body using the left or right ventricle?
right
How are four chambered hearts unique from other hearts?
The two sides of the heart do not mix
Where does systemic circulation actually occur?
Capillary beds
What is the structure and function of arteries?
Lined with smooth muscle, they carry fast moving blood out of the heart
What is the structure and function of veins?
Not as robust as arteries, carry blood back to the heart with the help of some muscle
What are two forms of control of blood distribution?
Precapillary sphincters and arteriovenous anastomoses
What are precapillary sphincters?
Muscle that pinch off blood flow to capillaries
What is the purpose of arteriovenous anastomoses?
They are vessels that bypass capillary beds
What is ultrafiltration?
Transfer of fluid to tissues from capillaries increases solute concentration in blood vessels
How does osmotic pressure change from the arterial to venous end of the circulatory system?
Highest at the arterial end and lowest and the venous end
What is the Starling-Landing hypothesis?
Loss of osmotic pressure in the circulatory system due to fluid filtration
How does body size affect cardiac output?
Smaller animals have higher cardiac outputs due to high heartrates, despite having a lower stroke volume
What function of blood distribution is unique to three chambered hearts?
Selective distribution; controls where blood flows in the body
What organisms have three chambered hearts?
amphibians and reptiles
How is an amphibian heart structured?
2 atria and 1 ventricle with a ridge in the center to prevent blood mixing
How are reptile hearts structured?
Have 2 atria and 2 ventricles; ventricles are loosely connected
How does blood flow through amphibian hearts?
blood comes from lungs into one atria, body into another atria, and both exit from one ventricle, then go to lungs and body
How does blood flow through reptile hearts?
Similar to four chambered with blood mixing
How is a crocodilian heart structured?
Four chambered heart with two aortas and two ventricles
What is the foramen of panizza?
Connects crocodilian ventricles
What does the foramen of panizza do?
Opens under pressure, when a crocodile is diving, and diverts blood flow away from the lungs
What is the structure of a fish heart?
two chambers
What is a con of having a two chambered heart?
oxygen inputted by the gils is used by the body before it returns to the heart
Why is a lack of oxygen supply to heart tissue not an issue for fish?
Because they have ectotherms and thus low oxygen requirements
How do fish conduct gas exchange besides using gills?
Specialized gas exchange organs
What is ventilation-perfusion matching?
When fish change blood flow to certain areas based on oxygen concentration in water
What kind of hearts do arthropods have?
multiple tubular hearts
What kind of circulation do arthropods exhibit?
open circulation
What is hemolymph?
arthropod circulatory fluid
What is the function of hemolymph?
to cycle hormones and nutrients NOT oxygen
How do arthropods get access to oxygen?
Pores called trachea bring oxygen into the body then into tracheoles embedded in tissues
