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exchange surfaces must be _____ for gas exchange.
_____________ --->better diffusion
more surface area
how do small animals and complex animals exchange gas?
- small animals: body surface for gas exchange
- complex animals: need a transport system to minimize diffusion distance
what are 3 transport systems used by complex animals to minimize diffusion distance?
- gastrovascular cavity
- open circulatory systems
- closed circulatory systems
how does the gastrovascular cavity minimize diffusion distance for complex animals? (2)
- exposes more cells to the "outside"
- may be multi-branched
- allows for more surface area= better diffusion
briefly describe the open circulatory system. Give an example of some organisms.
- hemolymph (instead of blood) leaves vessel and enters open areas called sinusesarthropods and most molluscs
describe close circulatory systems. what are some organisms with open circulatory systems.
- blood confined to vessels
- annelids, cephalopods, vertebrates
what are the 2 chambers in the heart called and what are their functions?
- 1,2 atria (receive blood)
- 1,2 ventricles (pumps the blood to lungs and rest of body)
where does blood go after entering the atria?
--> ventricles --> arteries--> arterioles-->capillaries-->venules--> veins--> atria
describe the circulatory system of fish. (2)
- single circulation
- heart has 1 atrium, 1 ventricle
describe the circulatory system of amphibians. (3)
- double circulation
- 2 atria, 1 ventricle
- oxygenated and deoxygenated blood mix in ventricle
describe the circulatory system of reptiles.
3 chambers but have partial septum (less mixing of oxygenated and deoxygenated blood)
describe the circulatory system of mammals or birds. (2)
- 2 atria; 2 ventricles
- separate pulmonary and systemic circulations
what are the walls of the heart made of and how are the cells connected?
- walls mostly of cardiac muscle
- cells connected by gap junctions into 2 networks; atrial and ventricular
how do the heart chambers in the heart contract?
both atria contract at once, then both ventricles
what are the 2 types of valves in the heart and what are their functions?
- 2 atrioventricular valves prevent backflow into atria
- 2 semilunar valves prevent backflow into ventricles
define the cardiac cycle.
sequence of events around one heart beat
in humans, what is the average beats/min at rest?
in smaller animals, the heart rate is ______.
compare systole and diastole.
- systole: ventricular contraction
- diastole: ventricular relaxation
what is the pacemaker of the heart and where is it located?
- sinoatrial (SA) node
- in wall of right atrium
describe the routes of the electrical signals of the heart and how the heart contracts.
- contraction begins at SA node
- wave of contraction spreads through atria
- blood pumped to ventricles
- excitation reaches atrioventricular (AV node)
- travels to heart apex along branch bundles
- spreads upwards through the ventricles along purkinje fibers
- ventricular contraction pushes blood up towards lungs and aorta
heart rate and stroke volume regulated by what 2 systems?
nervous system and endocrine system
what are the 3 layers in artery and vein walls?
- smooth muscle
- connective tissue
between artery and vein, which is thicker and why?
artery walls thicker due to more smooth muscle
what layers do capillaries have and why?
capillaries have only endothelium because minimizes diffusion distance
blood moves mostly due to what?
pressure created by heart
pressure decreases to ______ in veins.
what are 2 ways that blood pressure is adjusted?
changing vessels diameters and blood volumes
why does blood pressure decrease farther from the heart?
blood pressure slows down because total diameter of all the vessels increases
If venous pressure is zero, why does the blood return to the heart? (3)
- valves ensure one way flow
- veins squeezed by skeletal muscles
- pressure changes in the thorax during breathing
what is the function of the capillaries?
exchange of fluids, gases, nutrients and wastes between blood and interstitial fluid (and then body cells)
local control of blood flow to capillaries is via __________________.
sphincters around arterioles
exchange at capillaries is due to what 3 things?
- active transport
- bulk flow
define bulk flow.
- at upstream end, fluid pushed out of capillaries by blood pressure (big solutes stay in vessels)
- at downstream end, most fluid returns due to osmotic pressure
what is the function of lymphatic system, where is lymph returned?
- lymphatic system collects "leftover" interstitial fluid
- lymph returned to venous blood flow near collar bones
what is leftover interstitial fluid called?
where do viruses and bacteria attack?
what is the pH of blood?
describe the components of blood.
- made of connective tissue
- cells (dead and living) =formed elements, in a liquid matrix= plasma
what is plasma mostly made of and what are its components?
- 90% water + electrolytes=dissolved inorganic ions
- +plasma proteins= buffers, clotting factors, lipid-transporters
- +gases, nutrients, wastes, hormones
what are electrolytes?
dissolved inorganic ions
what are plasma proteins?
buffers, clotting factors, lipid-transporters
what do electrolytes, plasma proteins, gases, nutrients, wastes, hormones help with?
help maintain osmotic balance with interstitial fluid
what are the 2 components of formed elements in blood?
- erythrocytes: red blood cells
- leukocytes: white blood cells
what is the function of erythrocytes and how is this process done?
- transport some oxygen and some carbon dioxide
- oxygen binds to hemoglobin
where are erythrocytes produced and what makes them "dead" cells?
- produced in red bone marrow
- lose nucleus and last only 3-4 months
what is a characteristic about leukocyte and where is it produced?
- when functional, their true living cells
- produced in bone marrow
what is the function of leukocytes?
immune and defensive functions
what happens to leukocytes during infections?
leukocytes number increases
what are the 4 specific types of functions for leukocytes?
antibodies, histamine, phagocytosis, cell killers
what are platelets and what are its functions?
- cell "pieces" (not alive)
- involved in clotting
- forms a mesh that traps formed elements
What are the 3 steps in clotting?
- cascade of reactions
- fibrinogen (water soluble)
- fibrin (insoluble)
what are some characteristics for a great respiratory surface for gas exchange? (4)
- large surface area
- rich blood supply
what are the 3 structure for gas exchange?
define gills. (2) which way does they blood flow in gills?
- gills= outward extensions of body surface for gas exchange
- often sheltered,may be ventilated (for water to pass though)
- blood flows counter-current to the water
what is a trachea? (2) which organisms use this for gas exchange?
- air tubes leading inwards from surface holes (spiracles)
- tubes come into contact with almost all cells
what is a lung and what is its function?
- vascularized invaginations of body surfaces
- circulatory system transports gases between the lungs and the body's cells
In the mammalian respiratory system, how is are freshened and how is it controlled?
- air freshened by ventilation
- controlled by nervous system by monitoring pH
Describe the respiratory system of a bird. where does gas exchange take place?
- one way air flow through lungs; via bellow-like air sacs
- gas exchange at parabronchi (not alveoli)
where is oxygen found in the blood?
99% attached to heme of hemoglobin, 1% dissolved in plasma
what are 2 characteristics of oxygen in blood?
- not very soluble in water
- most bound to respiratory pigments
what are 3 characteristics about carbon dioxide?
- 7% dissolved directly in plasma
- 23% bound to globin of hemoglobin
- 70% in the form of dissolved bicarbonate ions (HCO3)
arthropods and molluscs use _____________ to transport gases in blood.
hemocyanin (dissolved in the plasma)
Vertebrates use _______________ to transport gases in blood.
what are the 4 adaptations diving mammals have for gas exchange?
- greater blood volume (more hemoglobin)
- large spleen (stores erythrocytes)
- high myoglobin levels
- diving reflex: shunts blood to vital organs
___________ stores oxygen in muscle cells.