Circulatory Sys Flashcards
Forms the inner lining of a blood vessel
Tunica interna
innermost thin layer of flattened
cells
Endothelium
Facilitates efficient blood flow
Endothelium
Influences contraction of vessels over smooth
muscles
Endothelium
Influences contraction of vessels over smooth
muscles
Endothelium
Assists with capillary permeability
Endothelium
anchors endothelium to
underlying connective tissue
Basement membrane
Guides cell movement during repair of blood
vessels
Basement membrane
outermost thin sheet of
elastic fibers with windowlike openings
Internal elastic lamina
Facilitate diffusion
Internal elastic lamina
Thick, muscular and connective tissue layer
comprising mainly smooth muscle cells and amounts
of elastic fibers
Tunica media
occurs due to decrease in
sympathetic stimulation, presence of chemicals
(e.g. nitric oxide, hydrogen, lactic acid), or in
response to a need for oxygen or nutrients
Vasodilation
network of elastic fibers
separating the tunica media from the tunica externa
External elastic lamina
Outermost covering of a blood vessel consisting of
elastic and collagen fibers
Tunica externa
TUNICA EXTERNA
Contains numerous nerves and tiny blood vessels
called
Vasa vasorum
Supplies the vessel wall with nerves and self-vessels
Tunica externa
Anchors the vessels to the surrounding tissues
Tunica externa
Transports blood under high
pressure to tissues
Have strong vascular walls
Away from heart
Arteries
Last small branches of the arterial
system
Arterioles
Act as control conduits
Have strong muscular walls that can
close or dilate the vessel
Arterioles
Site of exchange for various
substances
Capillaries
Have thin walls and numerous
minute capillary pores
Capillaries
Collect blood from capillaries and
gradually coalesce into
progressively larger veins
Venules
Conduit for transport of blood from
venules back to the heart
Veins
Serve as a major reservoir of extra
blood
Veins
Have thin walls due to low pressure
Veins
IS CONTROLLED
ACCORDING TO THE
TISSUE NEEDS
Blood flow
IS
THE SUM OF ALL THE
LOCAL TISSUE
FLOWS
Cardiac output
IS GENERALLY
INDEPENDENT OF EITHER
LOCAL BLOOD FLOW
CONTROL OR CARDIAC
OUTPUT CONTROL
Arterial pressure regulation
quantity of blood that passes a
point in circulation in a period of time
Bloodflow rate
Expressed in milliliters per minute or liters per
minute
Bloodflow
Overall blood flow in the total circulation of an
adult at rest is at
5000 ml/min
AKA Cardiac Output
Blood flow
when blood flows at a steady rate
and when the blood stays in the center of the
vessel
Laminar flow
AKA Streamline flow
Laminar flow
when blood flows crosswise in the
vessel and along the vessel, forming whorls in the
blood called eddy currents
Turbulent flow
The force exerted by the blood against any unit area of the vessel
wall
Blood pressure
highest pressure attained in arteries during
systole or ventricular contraction
Systolic BP
lowest pressure attained in the arteries during
diastole or ventricular relaxation
Diastolic BP
Ability of the vessel to dilate and
decrease resistance under increased
pressure
Vascular distensibility
Results in a smoother and greater
amount of blood flow
Vascular distensibility
Allows accommodation of pulsatile
output of the heart and to average
out the pressure pulsations
Vascular distensibility
Veins are 8x more distensible
than _____
Arteries
Pulmonary arteries are 6x more
distensible than ______
Systemic arteries
waves of
pressure that travel through the
blood
Pressure pulsations
pressure at
the top of each pulse
Systolic pressure
pressure at
the lowest point of each pulse
Diastolic pressure
difference
between the systolic and
diastolic pressures
Pulse pressure
Stiffening of arteries due to
plaque causing ↓ compliance
and distensibility
High blood pressure
Arteriosclerosis
Flow of blood from aorta to pulmonary
artery causing ↓ diastolic pressure and
↑ systolic pressure
= ↑ pulse pressure
Patent ductus arteriosus
Reduced diameter of aortic valve
causing ↓ stroke volume
= ↓ blood pressure
Aortic valve stenosis
Aortic valve is unable to close therefore
backflow of blood occurs and aortic
pressure falls to 0
= ↑ systolic blood pressure & ↓
diastolic blood pressure
Aortic regurgitation
pressure in the
right atrium
Central venous pressure
Ability of heart to pump blood out of right
atrium and ventricle into the lungs
Venous pressure
Character of blood flow from peripheral
veins
Venous pressure
↑ right atrial pressure or valve incompetence
backing up of blood in
the veins causing ↑ peripheral venous pressure
↑ Intra-abdominal pressure
↑ peripheral venous pressure in the legs
Achieved by rapid changes in local vasodilation or vasoconstriction of blood vessels to provide
maintenance of appropriate local tissue blood flow
Acute control
Increase in tissue metabolism
↑ blood flow
Decrease in oxygen availability
↑ blood flow
the greater the rate of metabolism or the less the availability of O2, the
greater the rate of formation of vasodilator substances
Vasodilator theory
decreased O2 results to less contraction of blood vessels =
relaxation or dilation of blood vessels
Oxygen demand theory
Slow, controlled changes in flow over a period of days, weeks, or months
Long term
Provides control via (1) direct nerve
stimulation and (2) indirect effects of
the hormone in the circulating blood
Norepinephrine and epinephrine
Powerful vasoconstrictor that can
increase arterial pressure by 50 mmHg
or more with one millionth of a gram
Angiotensin II
Constricts small arterioles
Contributes to total peripheral
resistance
Angiotensin II
Increases water reabsorption from the
renal tubules into the blood
Vasopressin
Causes intense arteriolar dilation
and increased capillary porosity
Bradykinin
Causes intense arteriolar dilation
and increased capillary porosity
Histamine
Allows leakage of fluid and plasma
protein into the tissues
Histamine
increase resistance to blood flow,
heart rate, and contractility
Sympathetic nervous system
decrease heart rate and
contractility
Parasympathetic nervous system
transmits parasympathetic impulses through
the vagus nerves to the heart and sympathetic impulses through the
spinal cord and peripheral sympathetic nerves to all blood vessels
Vasomotor center
located bilaterally in the anterolateral portions
of the upper medulla
Vasoconstrictor
located bilaterally in the anterolateral portions of
the lower medulla
Vasodilator
located bilaterally in the nucleus tractus solitarius
Sensory area
pressure-sensitive sensory receptors located in
the aortic arch, internal carotid arteries, and other large arteries
in the thoracic and neck regions
AKA pressoreceptors
Baroreceptors
helps regulate blood pressure in the brain;
initiated by baroreceptors in the carotid sinus
Carotid sinus reflex
regulates systemic blood pressure; initiated by
baroreceptors in the wall of ascending aorta
Aortic reflex
are sensitive to low oxygen or
elevated carbon dioxide and hydrogen ion levels
Chemoreceptor cells
Becomes important at lower pressures (below 80 mmHg)
and prevent further decreases in arterial pressure
Chemoreceptor reflex
Located in chemoreceptor organs about 2 mm in size
Chemoreceptors reflex
found in the atria and
pulmonary arteries
Low-pressure reflex
Minimize arterial pressure changes in
response to changes in blood volume
Low pressure reflex
The degree of sympathetic vasoconstriction caused by____________ is often so great that some of the peripheral vessels become totally or almost occluded
intense cerebral ischemia
Can elevate arterial pressure dramatically to as high as ____mmHg for as long
as __ mins
250, 10
