-
blood volume of open system
20-40%
-
-
hemocoel
lies between the ectoderm and endoderm
-
hemolymph
fluid contained within the hemocoel
-
pressures in open circulatory systems are low, arterial pressures seldom exceed
0.6-1.3 kilopascals
-
insects have an open circulation, but they do not depend on it for oxygen transport, instead they have evolved __
tracheal system
-
peripheral circulation consist of
arterial system, capillaries, and venous system
-
lymphatic system
in vertebrates has evolved to recover fluid lost to tissues from the blood in this manner
-
ultrafiltration
separation of an ultrafiltrate(fluid devoid of ccolloidal protein particles) from blood plasma
-
circulatory system is divided into
systemic circuit and respiratory or pulmonary circuit
-
right side of the heart pumps blood through the
pulmonary circuit
-
left side pumps blood through the
systemic circuit
-
veins are
low-pressure flexible structures
-
venous system contains most of the
blood acts as a reservoir
-
mammalian heart has __ chambers
4. 2 atria and 2 ventricles
-
cardiac muscle fibers distinguishing features
presence of gap junction
-
myocardium (heart muscle) consist of __ types of fibers
3
-
myocardial cells in the sinus node and atrioventricular are
auto rhythmic , weakly contractile, and exhibit very slow electrical conduction
-
the largest myocardial cells
found in inner surface of the ventricular wall weakly contractile but are specialized for fast electrical conduction and constitute the system for spreading excitation over the heart
-
intermediate-sized myocardial cell
strongly contractile and constitute the bulk of the heart
-
-
-
in fish the pacemaker is situated in the
sinus venosus
-
sinoatrial node
where most pacemakers are located
-
pacemaker consists of
group of small, weakly contractile, specialized muscle cells that are capable of spontaneous activity
-
hearts are categorized by type of pacemaker
neurogenic or myogenic
-
ectopic pacemaker
able to have irregular beats
-
pacemaker potential
brings the membrane to the threshold potential in less than a second. giving rise to another all-or-none cardiac action potential
-
a faster pacemaker depolarization brings the membrane to firing level sooner thus
increases the freq of firing and faster heart rate vice versa
-
how does acetylcholine affect heartbeat
slows it by increasing the K+ conductance and reducing the Ca2+ conductance of pacemaker cells
-
Adenosine
also slows down the heart by modifying K+ conductance
-
norepinephrine
accelerates the pacemaker potential increasing heart rate
-
catecholamines
bind to beta-adrenergic receptors on the cell surface, activating adenylate cyclase and increasing cAMP
-
cardiac fibers ap begin with
rapid depolarization that results from a large and rapid increase in Na + conductance
-
PAcemaker potentials begin with
slow depolarization which depends on a stable Na+ conductance and decreasing K+ conductance
-
depolarization of the plasma membrane is delayed
hundreds of milliseconds during the plateau phase
-
long duration of the cardiac AP produces a prolonged contraction
so entire heart chamber can fully contract before any portion begins to relax
-
prolonged plateau of cardiac AP results from
maintenance of a high Ca2+ conductance and delay in subsequent increase in K+ conductance
-
initial P-wave is associated with depolarization
of the atrium
-
QRS is associated with
depolarization of the ventricle
-
T-wave is associated with
repolarization of the ventricle
-
desmosomes
anchoring structure that help with adhesion of cells at intercalated disks
-
wave of excitation begins in the sinoatrial node and spreads over both atria at a velocity of
0.8 ms^-1
-
the atria are connected electrically to the ventricles only though the
atrioventricular
-
excitation through small junctional fibers velocity is slowed to about
0.05 ms^-1
-
junctional fibers are connected to nodal fibers which are connected via
bundle of his
-
purkinje fiber
extend into the myocardium of the two ventricles
-
endocardium
internal lining of the heart wall
-
epicardium
external covering of the heart wall
-
negative chronotropic effect
decrease in heart rate due to ACh
-
atrioventricular block
high levels of ACh allowing ectopic pacemaker to take over
-
catecholamines epinephrine and norepinepherine have three distinct positive effects on heart function:
- -increase the rate of myocardial contractions (positive chronotropic effect)
- -increase the force of myocardial contractions (positive inotropic effect)
- -increase the speed of conduction of the wave of excitation over the heart (positive dromotropic effect)
-
cardiac output
the volume of blood pumped per unit time from a ventricle
-
stroke volume
volume of blood ejected form a ventricle by each beat of the heart
-
end diastolic volume is determined by four parameters:
- -venous filling pressure
- -pressures generated during atrial contraction
- -distensibility of the ventricular wall
- -time available for filling the ventricle
-
end systolic volume is determined by these two parameters:
- -pressures generated during ventricular contraction
- -pressures in the outflow channels from the heart
-
many hearts have grooves and ridges within the chambers and vessels these:
allow contraction to facilitate blood movements in other chambers, create complex patterns that direct and maintain momentum reducing energy
-
cardiac muscles behave similarly to skeletal muscle in that:
stretch of the relaxed muscle in a certain range results in the development of increased tension during contraction.
-
contraction of cardiac muscle can be divided into two phases:
isometric contraction and isotonic
-
isometric contraction
tension in the muscle and pressure in the ventricle increase rapidly
-
isotonic contraction
tension doesnt change
-
cardiac muscles have a much higher capillary density and
more mitochondria, also high myoglobin
-
heart primary relies on __ to generate energy
aerobic pathways
-
adenosine
cause dilation of coronary vessels, also reduces heart rate and energy expenditure
-
pericardium
connective tissue membrane surrounds the heart
-
bradycardia
slowing of the hear
-
crocodilian reptiles have a heart with
completely divided ventricle
-
the __ side pumps blood to the lungs; the __ side pumps blood around the body
right, left
-
blood returning from the lungs enter the __ passes into the __, and is ejected into the
left atrium,left ventricle, systemic circulation
-
blood from the body collects in the __ passes into the __ and is pumped to the __
right atrium, right ventricle, lungs
-
valves prevent
back flow of blood from the aorta to the ventricle, the atrium , and the veins
-
atrioventricular valves
bicuspid and tricuspid
-
ductus arteriosus
joins the pulmonary artery to the systemic arch, short large-diameter blood vessel
-
heart functions of mammalian fetus features:
- -blood flows from pulmonary to the systemic circuit
- -most of the blood ejected by R ventricle is returned to the systemic circuit through ductus arteriosus
- -blood flow through pulmonary circuit is greatly reduced
-
in mammalian fetus
lungs are collapsed
-
at birth
lungs are inflated, blood now passes into the pulmonary arteries,increasing venous return to the left side of the heart, placental circulation disappears, and resistance to flow increases markedly in the systemic circuit
-
vena cava
vein that empties into the right atrium
-
foramen ovale
opening in the interatrial septum
-
bird embryo (egg)
network of blood vessels called the chorioallantois
-
arteries have the __ cross sectional area whereas capillaries have the __
smallest, largest
-
the slow of blood in the capillaries has functional significance because
time-consuming exchange of substances between blood and tissues take place
-
laminar flow
smaller vessels streamlined blood flow, parabolic velocity profile. silent
-
viscosity is a measure of
resistance to sliding between adjacent layers of fluid
-
__have elastic walls
vessel
-
turbulent flow
fluid moves in directions not aligned with he axis of flow, thus increasing the energy needed to move. noisy
-
reynolds number
indicates whether flow will be laminar or turbulent. flow will be turbulent if Re is greater than 1000
-
hematocrit
volume of red blood cells per unit volume of blood
-
compliance
ratio of change in volume to change in pressure
-
poiseuille's law
- flow of fluid through pipes
-
the __ are very compliant
venous system
-
blood pumped from the __ carries oxygenated blood via the __system to capillary beds in tissues
left ventricle,arterial
-
___ system returns the deoxygenated blood to the __
systemic venous,right atrium
-
endothelium
lines the lumen of all blood vessels
-
walls of larger blood vessel comprise of three layers:
tunica adventitia, tunica media, tunica intima
-
tunica adventitia
limiting fibrous outer coat
-
tunica media
middle layer, consists of circular and longitudinal smooth muscle
-
tunica intima
inner layer , closest to lumen, composed of endothelial cells and elastic fibers
-
vasa vasorum
thick walls of large blood vessels that require own capillary circulation
-
arteries serve 4 main functions
- 1. act as a conduit for blood between the heart and capillaries
- 2.act as a pressure reservoir for forcing blood into the small-diameter arterioles
- 3. damp the oscillations in pressure and flow generated by the heartbeat and produce a more even flow of blood into the capillaries
- 4.control the distribution of blood to different capillary networks via selective constriction of the terminal branches of the arterial tree
-
countercurrent exchanges
in many animals arteries and veins run next to each other with their blood flows moving in opposite directions. this causes exchange of heat
-
rete mirabile
countercurrent arrangement of small arterioles and venules
-
capillaries size
1mm long and 3-10 um. large enough for red blood cells but white blood cells may be trapped
-
arterioles are surrounded by
smooth muscle
-
capillary walls are completely devoid of
connective tissue and smooth muscle, consist of a single later of endothelial cells surrounded by a basement of membrane of collagen and muscopolysaccharide
-
pericyte cells
elongated cells able to contract wrap around capillaries
-
capillaries are classified into 3 types:
continuous capillaries, fenestrated capillaries,sinusoidal capillaries
-
continuous capillaries
least permeable located in muscle, neuronal tissue, the lungs connective tissues and exocrine glands
-
fenestrated capillaries
exhibit intermediate permeability, found in renal glomerulus, and endocrine glands
-
sinusoidal capillaries
most permeable, present in liver, bone marrow, spleen, lymph nodes, and adrenal cortex
-
arterioles
tiny branch of an artery. nearest a capillary
-
venules
small vessel that connects a capillary bed
-
edema
net filtration of fluid across capillary walls result in increase tissue volume
-
lymph
transparent milky fluid. collected from interstitial fluid in all of the body and returned to blood via lymphatic system.
-
thoracic duct
lymph vessels drain via,into low pressure region usually close to the heart
-
filarisasis
disease invades lymphatic system causing blockage, edema result elephantiasis
-
lymph hearts
reptiles and amphibians have them
-
lymphocytes
type of leukocyte ability to recognize foreign substances
-
lymphocytes 3 ways respond
- 1. b cells develop into plasma cells,which secrete antibodies that bind and mark pathogens
- 2.Tc cells recognizes tumors, this stimulates Tc to mature into active cytotoxic T lymphocytes
- 3. recognition of antigen by Th cells stimulate and secrete cytokines, promote growth of B, Tc Cells ,and macrophages increasing strength of immune
-
extravastation
leukocytes leaving lymphatic and circulatory systems
-
excluding aortic and pulmonary semilunar valves, arteries
dont have valves to prevent back flow
-
vasoconstriction and vasodilation can be induced by
chemicals as well as by autonomic nervous system activity
-
the normal relative blood viscosity is approx
4x water
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