Lesson 3- circulatory system Flashcards
definition of diffusion?
net movement of molecules moving from a region of high concentration to a region of low concentration
where does the movement of molecules in diffusion come from?
achieved by the random collision of molecules up against each other. Rate at which they collide with each other depends on the temperature of the fluid. higher temp = better diffusion
what is bulk flow?
The movement of a fluid from a region of high pressure to a region of flow pressure
in bulk flow, the pressure gradient is established by what?
an external motive force (the muscular heart)
does blood flow bidirectionally or unidirectionally down a network of interconnected blood vessels?
unidirectionally
what escapes when blood courses through blood capillaries?
plasma carrying dissolved nutrients and other molecules
which phyla have open circulatory systems?
arthropods and most mollusks
what fluid circulates through open circulatory systems?
hemolymph, moving by the heart’s pressure gradient
what happens when the heart relaxes in an open circulatory system?
the pressure in the vessels drops and the hemolymph is pulled back through pores equipped with one-way valves.
the contracting heart…?
keeps fluid in motion, constantly washing over internal organs.
what is the fluid that circulates through closed circulatory systems?
blood confined within vessels
which phyla have closed circulatory systems?
cephalopods within the mollusk phylum
-annelids
-all vertebrates within the chordate phylum
list the vessels in order from the heart. (7)
- Aorta
- arteries
- arterioles
4.capillaries
5.venules - veins
- vena cava (returns blood back to the heart)
what is systolic pressure?
the spike in blood pressure caused by the powerful contractions of the ventricles stretch in the arteries
for healthy adults, what is a healthy amount of systolic pressure?
120 mmHg
when the heart is relaxed, pressure within the arteries drops to…?
80 mmHg
what is diastolic pressure?
a drop in pressure caused by the elastic recoiling of the arteries
what is reduced as the blood flows through narrower tubes?
maximum flow is greatly reduced
what controls blood flow to capillary beds?
- precapillary sphincters, when they constrict, blood flows directly to the venule.
- smooth muscle around the arteriole constricts blood flow
on average, what is the blood pressure on the walls of blood capillaries?
20 mmHg
where does blood pressure push out fluid in the capillaries?
towards the arteriole end of the capillary
how do our capillaries prevent from releasing all of the blood within them despite their thin membrane?
osmotic pressure drives it back along the venous end of the capillary.
what is responsible for creating the osmotic drive of water back into blood capillaries?
a protein called albumin that is suspended in blood plasma
what is edema?
a condition characterized by an excessive accumulation of fluid in the interstitial space. (AKA not getting enough protein/ amino acid)
what is responsible fo recapturing interstitial fluid? (2)
- Osmotic pressure
- the lymphatic system
what are lymphatic vessels?
blunt-ended tubes intimately associated with blood capillaries.
unlike arteries, veins are separated into segments by… that prevent backflow and ensure a unidirectional path toward the heart
one-way valves
what are the motive forces for driving blood back to the heart?
-smooth muscle (contract, forcing blood towards the next section of the conduits)
- skeletal tissue (contractions apply pressure to returm blood back to the heart )
how many chambers does the mammalian heart have?
4
how many atria does the mammalian heart have?
2
how many ventricles does the mammalian heart have?
2, lying below the 2 atria
do the aorta and arteries carry blood towards or away from the heart?
away
which cells composed the mammalian heart?
cardiocytes
what are 25% of the single nucleus of the cardiocytes of the heart filled with
large mitochondria
what is the specialized junction joining two cardiocytes called?
intercalated discs
what are the 2 specialized clusters of cardiocyte cells that reside in the right atrium called? and what are their functions?
- the sinoatrial node (initiates impulse that causes both atria to contract in unison)
- atrial ventricular node (signal is transmitted down the Purkinje fibers allowing the ventricles to contract in unison)
function = generating and transmitting the electrical impulses that cause the atria and ventricles to contract
what are the 3 stages of the cardiac cycle?
how long does each last?
- the atrial and ventricular diastole (0.4sec)
- the atrial systole and ventricular diastole (0.1 sec)
- the ventricular systole and atrial diastole (0.3 sec)
what happens during atrial and ventricular diastole?
the heart is completely at rest while the atria fill with blood from veins returning blood to the heart. As the atria fill, some of this blood pools into the ventricles below from the pull of gravity
what happens during atrial systole and ventricular diastole?
atria contract in unison forcing whatever blood remained within the atria into the ventricles below
what happens during the ventricular systole and atrial diastole stage?
completes the cardiac cycle. the ventricles contract in unison while the atria are at rest and partially filling with blood. As the ventricular contract, the atrioventricular valves are shut preventing blood from entering the atria and the semi-lunar valves open to direct blood into the pulmonary and systemic circuits
what does the cardiac output (CO) measure?
the volume of blood pumped/minute by each ventricle.
beats/minute x stroke volume
stroke volume= blood pumped out by each ventricle during ventricular systole
what type of tissue is blood?
connective tissue
what is the function of blood?
transport of substances in defence of other tissues and fluid balance
what is blood composed of?
- extracellular matrix called plasma (55%) = carries dissolved substances.
-water, ions, plasma proteins, nutrients, waste products, respiratory gases, and hormones - cellular elements (45%).
-leukocytes, platelets, and erythrocytes (red blood cells)
what is the cell type of blood cells? and their function?
leukocytes (white blood cells)
function = defence and immunity
