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exchange surfaces must be _____ for gas exchange.
wet
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_____________ --->better diffusion
more surface area
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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
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what are 3 transport systems used by complex animals to minimize diffusion distance?
- gastrovascular cavity
- open circulatory systems
- closed circulatory systems
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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
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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
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describe close circulatory systems. what are some organisms with open circulatory systems.
- blood confined to vessels
- annelids, cephalopods, vertebrates
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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)
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where does blood go after entering the atria?
--> ventricles --> arteries--> arterioles-->capillaries-->venules--> veins--> atria
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describe the circulatory system of fish. (2)
- single circulation
- heart has 1 atrium, 1 ventricle
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describe the circulatory system of amphibians. (3)
- double circulation
- 2 atria, 1 ventricle
- oxygenated and deoxygenated blood mix in ventricle
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describe the circulatory system of reptiles.
3 chambers but have partial septum (less mixing of oxygenated and deoxygenated blood)
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describe the circulatory system of mammals or birds. (2)
- 2 atria; 2 ventricles
- separate pulmonary and systemic circulations
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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
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how do the heart chambers in the heart contract?
both atria contract at once, then both ventricles
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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
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define the cardiac cycle.
sequence of events around one heart beat
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in humans, what is the average beats/min at rest?
65-75
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in smaller animals, the heart rate is ______.
faster
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compare systole and diastole.
- systole: ventricular contraction
- diastole: ventricular relaxation
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what is the pacemaker of the heart and where is it located?
- sinoatrial (SA) node
- in wall of right atrium
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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
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heart rate and stroke volume regulated by what 2 systems?
nervous system and endocrine system
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what are the 3 layers in artery and vein walls?
- endothelium
- smooth muscle
- connective tissue
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between artery and vein, which is thicker and why?
artery walls thicker due to more smooth muscle
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what layers do capillaries have and why?
capillaries have only endothelium because minimizes diffusion distance
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blood moves mostly due to what?
pressure created by heart
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pressure decreases to ______ in veins.
zero
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what are 2 ways that blood pressure is adjusted?
changing vessels diameters and blood volumes
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why does blood pressure decrease farther from the heart?
blood pressure slows down because total diameter of all the vessels increases
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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
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what is the function of the capillaries?
exchange of fluids, gases, nutrients and wastes between blood and interstitial fluid (and then body cells)
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local control of blood flow to capillaries is via __________________.
sphincters around arterioles
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exchange at capillaries is due to what 3 things?
- diffusion
- active transport
- bulk flow
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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
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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
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what is leftover interstitial fluid called?
lymph
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where do viruses and bacteria attack?
lymph nodes
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what is the pH of blood?
7.4
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describe the components of blood.
- made of connective tissue
- cells (dead and living) =formed elements, in a liquid matrix= plasma
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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
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what are electrolytes?
dissolved inorganic ions
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what are plasma proteins?
buffers, clotting factors, lipid-transporters
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what do electrolytes, plasma proteins, gases, nutrients, wastes, hormones help with?
help maintain osmotic balance with interstitial fluid
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what are the 2 components of formed elements in blood?
- erythrocytes: red blood cells
- leukocytes: white blood cells
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what is the function of erythrocytes and how is this process done?
- transport some oxygen and some carbon dioxide
- oxygen binds to hemoglobin
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where are erythrocytes produced and what makes them "dead" cells?
- produced in red bone marrow
- lose nucleus and last only 3-4 months
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what is a characteristic about leukocyte and where is it produced?
- when functional, their true living cells
- produced in bone marrow
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what is the function of leukocytes?
immune and defensive functions
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what happens to leukocytes during infections?
leukocytes number increases
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what are the 4 specific types of functions for leukocytes?
antibodies, histamine, phagocytosis, cell killers
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what are platelets and what are its functions?
- cell "pieces" (not alive)
- involved in clotting
- forms a mesh that traps formed elements
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What are the 3 steps in clotting?
- cascade of reactions
- fibrinogen (water soluble)
- fibrin (insoluble)
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what are some characteristics for a great respiratory surface for gas exchange? (4)
- moist
- thin
- large surface area
- rich blood supply
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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
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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
- insects
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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
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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
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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)
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where is oxygen found in the blood?
99% attached to heme of hemoglobin, 1% dissolved in plasma
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what are 2 characteristics of oxygen in blood?
- not very soluble in water
- most bound to respiratory pigments
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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)
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arthropods and molluscs use _____________ to transport gases in blood.
hemocyanin (dissolved in the plasma)
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Vertebrates use _______________ to transport gases in blood.
hemoglobin
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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
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___________ stores oxygen in muscle cells.
myoglobin
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