Exam 3: Chapter 25: Circulation Flashcards
blood supplies what to muscles?
oxygen
muscle is dependent on what for activity
ATP supply
during activity, muscles depend on what for their supply of ATP
oxygen
Blood pressure is important for production of
urine
Thermoregulation or vascular heat exchangers are important for
warm or cool weather
Circulation within the body moves…
blood, O2, CO2, nutrients, organic waster, hormones, immune system products, and heat
What is muscle tissue of the heart made of?
cardiac tissue known as myocardium
What are the 2 parts of the left side of the human heart?
a weakly muscular atrium and a strongly muscled ventricle
oxygenated blood is received from the _____ and sent to the _______.
received from the lungs and then sent to the body
Blood arrives to the left atrium via the _______.
pulmonary veins
Blood leaves the left ventricle via the ______.
systemic aorta
Blood returns to the heart via the ________.
venae cavae
where does blood enter the heart?
right atrium
Role of the right side of the heart:
pump deoxygenated blood to the lungs
After leaving the right ventricle, blood enters the ______.
pulmonary trunk, then to the pulmonary arteries and the lungs
During the beating of the heart there is contraction a (_______) and a relaxation (________).
systole; diastole
isometric contraction
the volume of blood in the ventricle is constant
When pressure of blood in the heart is high enough:
the aortic valve opens, and the blood is pushed from the ventricle
After blood enters the aorta, ventricular pressure drops and….
you have isovolumetric relaxation; next you have ventricular filling
What is the hearts most important feature?
cardiac output; the volume of blood it pumps per unit time; output of the left ventricle
cardiac output
HR x stroke volume
circulation must deliver…
oxygen to the myocardium
The ventricular myocardium is second only to the brain in its’ need for
aerobic catabolism and O2 demand
The heart muscle gets blood and O2 from
the coronary arteries
Blood goes to the ______ in the heart muscles and then enters the ________.
capillaries; coronary viens
Blockage of the coronary artery can cause a:
heart attack; O2 can’t get to the heart muscle, so the muscle quickly breaks down
The electrical impulses for heart contraction may originate in….
muscle cells or neurons
Depolarization of the muscle cell membranes causes
the contraction
myogenic vs. neurogenic
myogenic: electrical impulse to contract is in the muscle cells
neurogenic: impulse comes from nerve cells
vertebrate have what types of hearts
myogenic hearts
Muscle cells are electrically coupled by
gap junctions; occurs at intercalated discs
The pacemaker in mammals
sinoatrial node (SA), located above the right atrium
SA cells are specialized:
have a high frequency of depolarization, first cells to depolarize
Conduction:
the process whereby depolarization spreads through heart muscle cells
Conducting system pathway:
atrioventricular node (A-V node), A-V bundle, bundle branches, Purkinje cell fibers
a heart produces an electrical signature:
the electrocardiogram
voltage differences of the heart are recorded by
EKGs
P wave of EKG
made by heart muscle depolarization of the 2 atria (atrial contraction)
The QRS
comes from the depolarization of the 2 ventricles (ventricular contraction)
T wave
repolarization of the ventricles
Heart action is modulated by:
hormonal, nervous, and intrinsic controls
with fear our heart races, and these hormones are produces
epinephrine and norepinephrine; produced by the adrenal medullary glands
Connects from heart to CNS
some are sympathetic (excitatory) and parasympathetic (inhibitory) parts of the autonomic nervous system
with exercise, ________ stimulation is greater
sympathetic
intrinsic controls are things like:
the stretching of the heart muscle during contraction; increases force and allows the heart to match in input with the output
Frank-Starling mechanism:
present in vertebrates; allows the cardiac output to be synchronized with the venous return, arterial blood supply and humoral length, without depending upon external regulation to make alteration
perfusion in the vascular system:
the forced flow of blood through the blood vessels
Blood pressure:
the force moving the blood; measure in mm of mercury (mmHg)
The greatest pressure during cardiac contraction:
the systolic pressure
The lowest pressure:
the diastolic pressure during relaxation
In resting young adults the systolic to diastolic pressure is:
120/75
hydrostatic pressure:
present in vessels, increases with height; pressure in the leg arteries is greatest, much lower in the head and neck
Factors that go into affecting blood flow; make up total fluid energy of the blood
potential energy of the beating heart, kinetic energy of the blood in motion, and potential energy of the blood as a result of the earth’s gravity
Blood always moves from ___ to _____ total fluid energy
high to low
The rate of blood flow depends on:
differences in blood pressure and on vascular resistance
What regulates the rate of blood flow?
when muscles of the walls of a blood vessel changes the radius of the vessel by contracting or relaxing
blood flow rate
∆P/R, where ∆P is the entry and exit BP and R is vascular resistance
resistance relationship to vessel radius
resistance is inversely proportional to the vessel radius
The dissipation of energy:
pressure and flow turn to heat during circulation of the blood
laminar flow
the fluid in the center moves without resistance, whereas the fluid at the walls doesn’t move at all
slipperiness
the viscosity of the fluid, contributes to flow
high viscosity means:
greater friction, loss of kinetic energy, and heat production
pressure is converted to
heat
a drop in blood pressure from one point to another is a measure of
the energy cost of blood flow
in arterioles and capillaries, BP:
drops a lot with blood flow
Energy cost change in arterioles and capillaries
greater
circulation has the lungs in series with
the systemic tissues; O2 delivery can be maximized to the systemic tissues
mammals have a ______ circulatory system
closed
each part of the systemic vascular system has distinctive
anatomical and functional features
all vessels have a layer of _______ on the inside
vascular endothelium
vascular endothelium may secrete:
nitric oxide or prostacyclin into the blood, or secrete hormones, degrade hormones, or have an immune role
nitric oxide or prostacyclin functions
affect contraction and relaxation of smooth muscle and also may play a role in clotting
thick walls of arteries function to:
handle high blood pressures and stretch
Artery walls are thick with:
lots of smooth muscle and connective tissue
Elasticity of arteries allows for
BP to be more stable
arterioles and capillaries wall size
thinner; deal with lesser BP
microcirculatory beds consist of 3 types of vessels:
arterioles, capillaries, and venules
arterioles
smaller versions of arteries; have smooth muscle and connective tissue but are not as thick
the smooth muscle in arterioles has a role in:
the vasomotor regulation of where blood is sent; vasoconstriction and dilation apply here
arteriolar muscles are regulated by:
the sympathetic part of the autonomic nervous system
circulation hormones and chemicals like NO (a vasodilator) are generated from the:
vascular endothelium
precapillary sphincters
have a role in blood flow
change of blood flow to skeletal muscle during exercise:
can increase by a factor of ten or more
vasodilation and constriction allow for what time of blood flow regulation
sensitive temporal and spatial regulation
capillaries:
once cell layer thick, just vascular endothelium, walls are fenestrated (have openings); aquaporins are present
capillaries are the main location for:
the exchange of O2 and water, as well as other substances from the blood to the cells
capillary density
important with high levels in skeletal muscle, brain, and heart muscle
angiogenesis of capillaries
making new capillaries and is regulated by activators and inhibitors like paracrine chemicals
venules carry
deoxygenated blood
veins have
low BP and thin walls
passive one-way valves help with
blood flow
skeletal muscle contractions
help move blood
veins are elastic:
can expand to hold blood
mammals and birds have what type of circuit
high-pressure systemic circuit
greater blood flow is needed for
increased demands of O2 transport
BP and rate of flow decreases in the
arterioles and capillaries
a closed circulatory system is:
energetically expansive
blood plasma osmotic pressure
greater osmotic pressure than extracellular liquid; water tends to move into the blood from the extracellular tissues
blood plasma proteins
a lot don’t cross membranes, makes plasma richer than liquid in tissues
hydrostatic pressure of the blood
greater than tissues liquid; efflux occurs in the capillaries
excess fluid goes to the
lymphatic system
as blood enters the venules; pressure
decreases
pulmonary system differences
low pressure system to keep the lungs “dry”; shorter, has less resistance, and is a low-pressure system
if water left the blood i the lungs, it would result in
pulmonary edema
during exercise, blood flow is increased by:
orchestrated changes in cardiac output and vascular resistance
rate of O2 delivery =
cardiac output x (arterial O2 concentration - venous O2 concentration)
during exercise in humans, venous blood is more _______ than at rest
more deoxygenated
trained althetes changes
cardiac output is 6-7x resting, and resistance is reduced during exercise; BP is prevented from being too high
what helps reduced resistance
vasodilation; more muscle capillaries are open and carrying blood
endurance training increases capillaries where?
muscles
How much cardiac output do human skeletal muscles recieve?
20% of cardiac output at rest and 80% with hard whole-body exercise; blood flow to internal organs is reduced by vasoconstriction
smaller animals heart rate
higher to keep up with their demand for O2
Giraffes BP
higher BP of 220 mmHg to get blood to their brains with a 1.6m neck
vascular countercurrent exchangers
blood flowing from the body core to the periphery (like the legs & feet) carries heat that can be readily lost through the skin; example is to keep the testis cool in males
