Chapter 19 Flashcards
Describe Coronary Artery Disease
when the heart tissue is damaged due to inadequate flow of blood to the heart
When do you show symptoms of coronary artery disease
when 75% of blood flow is blocked
What is Atherosclerosis
a disease of arteries where fatty lesions called plaque build up making the artery walls inelastic and brittle
Plaque can obstruct what
blood flow in the heart, Leading to angina (sever chest pain) or myocardial infarction (heart attack)
What is it called when reduction of bloodflow where hypoxia of cardiac tissue results without killing cardiac muscle cells
Ischemia (can lead to angina pectoris - the pain accompanying myocardial ischemia)
What is myocardial infraction
HEART ATTACK - death of cardiac cells due to lack of oxygen
What causes a heart attack
death of cardiac cells due to lack of oxygen
what is the usual cause of myocardial infraction
thrombus (stationary blood clot) or embolus (blood clot transported to coronary artery)
Define arrhythmia
abnormal heart rhythm
define atrial fibrillation
asynchronous atrial contractions causing them to quiver rather than pump
What is congestive heart failure
when one side of the heart fails (ventricle) is damaged and doesn’t pump efficiently as the other side.
What is peripheral edema
when interstitial fluid builds up (caused my congestive heart failure)
which pump fails during pulmonary edema
the left pump fails fluid builds up in lungs
which pump fails during Peripheral edema
the right pump, noticeable in feet and ankles
Define blood vessels
carry blood in a closed system of vessels, that begin and end at the heart
what are the three main types of blood vessels and where do they carry blood to
1) Arteries: carry blood away from the heart
2) Veins: carry blood towards the heart
3) Capillaries: contract tissue cells and directly serve cellular needs
Define Lumen
central blood containing space surrounded by three tunics
What are the three tunics
arteries and veins are composed of tunics:
1) tunica interna 2) tunica media 3) tunica externa
What are capillaries composed of
endothelium with sparse basal lamina
which tunica layer contains endothelial cells
tunica interna
Describe the tunica media
second tunica layer, has smooth muscle and elastic fibbers, regulated by sympathetic nervous system. Controls vasoconstriction / vasodilation of vessels
describe tunica externa
collagen fivers that protect and reinforce vessels. Larger vessels contain Vasa Vasorum (system of tiny blood vessels that nourish the more external tissues of the blood vessel wall.
briefly describe elastic/conducting arteries
Thick-walled, near the heart, aorta and its major branches; large lumen allow low-reistance conduction of blood, contain elastin in all three tunics, withstand and smooth out large blood pressure fluctuations; allow blood to flow fairly continuously though the body
Briefly describe muscular/distributing arteries
distal to elastic arteries; deliver blood to body organs. Have thick tunica media with more smooth muscle and less elastic tissue. active in vasoconstriction
Arterioles
smallest arteries; lead to capillary beds. control flow into capillary beds via vasodilation and constriction
What are the smallest blood vessels
capillaries, walls consisting of a thin tunica intern one ell thick, allow only a single RBC to pass at a time
What are the three structural types of capillaries
1) continuous 2)fenestrated 3) sinusoids
Describe the anatomy of Continuous capillaries
- abundant in skin and muscles
- endothelial cells = uninterrupted lining
- adjacent cells held together by tight junctions
- intercellular clefts of unjoined membranes allow the passage of fluids
Continuous capillaries of the brain
constitute the blood-brain barrier
Describe Fenestrated Cappillaries
found where active capillary absorption or filtrate formation occurs (e.g.. small intestines, endocrine glands, kidneys)
Which capillary is characterized by an endothelium riddled with pores
Fenestrated capillaries. (greater permeability to elutes and fluids than other capillaries)
Describe Sinusoids structure
-highly modified - leaky - fenestrated capillaries with large lumens
where are sinusoids found
liver, bone marrow, lymphoid tissue, and in some endocrine organs
what function do sinusoids do
allow large molecules (proteins &BC’s) to pass between the blood and surrounding tissues. Blood flows sluggishly allowing for modification in various ways.
Describe true capillaries
10-100 per capillary bed, branch from arterioles and provide exchange between cells and the blood, and metarterioles, which are short vessels that directly connect the arterioles and venules at opposite ends of the bed.
Precapillary sphincter
- cuff of smooth muscle that surrounds each true capillary
- regulates blood flow into the capillary
- blood flow is regulated by vasomotor nerves and local chemical conditions, so it can either bypass or flood the capillary bed
What do venues allow
fluids and WBC’s to pass from the bloodstream to tissues
Describe postcapillary venules
Small vessels through which blood flows after leaving the capillaries and before reaching the veins
-venules do not have vales.
Veins are formed when
formed when venules converge
How many tunics make up a vein
three tunics, with a thunica media and thick tunica externa consisting of collagen fibers and elastic networks
what contains 65% of the blood supply
capacitance vessels (blood reservoirs)
where do veins take blood to
to the heart
do veins have valves
yes
define venous sinuses
specialized, flattened veins with extremely thin walls.
Define anastomoses
merging blood vessels moe common in veins than arteries
Arterial Anastomoses
provide alternate pathways for blood to reach a given body rejion
what are thoroughfare channels examples of
arteriovenous anastomoses
_____ actual volume of blood flowing though a vessel an organ or the entire circulation in a given period
blood flow (ml per min)
_____ fore per unit area extered on the wall of a blood vessel by its contained blood
blood pressure (mmHG)
____ opposite to flow
resistance
what does resistance measure
the amount of friction blood encountered as it passes though vessels (generally encountered in the systemic circulation)
what is resistance referred to as
peripheral resistance
what are the three important sources of resistance
1) blood viscosity 2) total blood vessel length 3) blood vessel diameter
define blood viscosity
thickness of the blood
does resistance increase within longer vessels
the longer the vessel the greater the resistance
Blood vessel diameter
changes in vessel diameter are frequent and significantly alter peripheral resistance.
how are blood flow and blood pressure realted
they are proportional F ∞ ∧P
how are blood flow and resistance related
inversely proportional F ∞ 1/R
what direction to pressure gradients flow from
higher to lower pressure areas
Define systemic pressure
is highest in aorta, declines though out the length of the pathway 0 mmHg in the right atrium
the steepest change in blood pressure occurs_____
in the arterioles
Systemic pressure:
is highest:
is what mmHg in the right atrium:
is highest in the aorta,
is 0 mmHg in the right atrium
declines throughout the length of the pathway
what two factors does aerial BP reflect (i.e. the arteries close to the heart)
1) elasticity (compliance or distensibility)
2) the amount of blood forced into them at any given time
What is systolic pressure
pressure extorted on arterial walls during ventricle contractions
What is diastolic pressure
lowest level of arterial pressure during a ventricular cycle
What is pulse pressure
the difference between systolic pressure and diastolic pressure
what is MAP
mean arterial pressure: pressure that propels the blood to the tissues map= diastolic pressure + 1/3 pulse pressure
why is a low capillary blood pressure desirable
because a high BP would rupture thin walled, fragile capillaries
what range does capillary BP fall into
20-40 mmHg
what is a low capillary BP still capable to do
force filtrate into interstitial space and distribute nutrients, gases, and hormones between blood and tissues.
How does Venous BP change
very little, it is steady and changed little during the cardiac cycle
what is the pressure gradient in venous system
~20mmHg
a cut vein vas a cut artery
vein= even blood flow
artery=spurts in blood flow
** remember this path
Aorta -> Arteries -> Arterioles -> capillaries -> Venules -> Veins -> Venae Cavae
What are the two factors that aid venous return to the heart
1) respiratory “pump”: pressure changes during breathing sucks blood towards the heart by squeezing local veins.
2) muscle “pump”: skeletal muscle contractions “milk” blood toward the heart.
* *valves prevent back flow during venous return
What factors are needed in maintaining BP
1) cooperations of the heart, kidneys, and blood vessels
2) supervision of the brain
What are the three main factors influencing BP
1) Cardiac Output
2) Peripheral resistance
3) Blood volume
P=CO x PR
what has the highest blood volume at rest
systemic veins and venues reservoir = 60%
then systemic arteries and arterioles =15%
pulmonary vessels = 12%
what controls resting heart rate
cardioinhibitory center via the vagus nerves
under stress the cardio __________ centre _______
the cardio accelerator centre increases heart rate and stroke volume
Increased BP stimulates the kidneys to:
stop water, thus reducing BP
Decreased BP stimulates the kidneys to:
increase blood volume and BP
