Chapter 21 - The Cardiovascular System: Blood Vessels Flashcards
This is all the events associated with one heartbeat
Cardiac cycle
The cardiac cycle consists of what?
Systole & diastole of the atria and systole & diastole of the ventricles
When the heart rate is 75 beats per minutes how long does the cardiac cycle last?
.8 seconds
This is the volume of blood ejected per beat from each ventricle.
Stroke volume
What is normal stroke volume?
70mL (a little more than 2 oz)
This is the volume of blood ejected from the left ventricle into the aorta each minute (or from the right ventricle into the pulmonary trunk each minute)
Cardiac output
This Is the number of heartbeats per minute.
Heart rate
What is the normal heart rate?
75 beats per minute.
What is the formula for cardiac output?
Stroke volume X heart rate = cardiac output
Any condition that effects heart rate can also effect?
Cardiac output
List some examples of things that effect heart rate.
Age, gender, physical fitness, body temperature, and hormones
This is an abnormally rapid resting heart rate (over 100 beats/minute)
Tachycardia
This is a a slow resting heart rate (under 50 beats/minute)
Bradycardia
What are the 5 main types of blood vessels?
Arteries, arterioles, capillaries, venues, veins
These blood vessels carry blood away from the heart to other organs.
Arteries
These blood vessels are small arteries that deliver blood to capillaries
Arterioles
These blood vessels are microscopic blood vessels located between arterioles and venules
Capillaries
These are small veins that collect blood from capillaries
Venules
These carry blood from organs back to the heart
Veins
Arteries carry blood away from the heart through?
The hollow lumen
What are the 3 wall layers that make up arteries?
Tunica interna, tunica media, tunica externa
This is the innermost coat of an artery. It contains a lining of endothelium, a basement membrane, and an internal elastic layer
Tunica interna
This is the middle coat and thickest layer of the artery wall. I consists of elastic fibers and circular smooth muscle fibers
Tunica media
This is the outer layer of the artery wall. It is composed of elastic and collagen fibers
Tunica externa
Increased sympathetic stimulation from the ANS causes this as smooth muscle in the tunica media contractions. This decreases the diameter of the lumen of an artery.
Vasoconstriction
Decreases sympathetic stimulation causes this as the smooth muscle relaxes. This increases the diameter of the lumen.
Vasodilation
Blood flows from arterioles to venules through?
Capillaries
The capillaries are found near?
Almost every cell in the body
These are involved the exchange of nutrients and oxygen with wastes and CO2 between the blood and tissue cells through interstitial fluid
Capillaries
The walls of the capillaries are composed of? They have no?
Only a layer of endothelium an a basement membrane / tunica media or tunica externa
Capillaries form?
Extensive branching networks
Veins have the same three layers in their walls as? These layers are?
Arteries / tunic interna, tunica media, tunica externa
Why are the walls of veins thinner than that of arteries?
The walls have less muscle and fewer elastic fibers.
The lumens in veins are what sized compared to arteries?
Larger
Veins appear how in relation to arteries?
Seem what flattened
Veins have valves that do what?
Prevent the backward flow of blood.
What percentage of an individual’s blood volume is in veins and venules while at rest? These vessels are called?
64% / blood reservoirs
The volume of blood that flows back to the heart (into the right atrium) through systemic veins is called?
Venous return
Name 3 factors that affect venous return
The pumping action of the heart, milking by the alternating contraction and relaxation of skeletal muscles in the legs, respiratory pumping caused by movement of the diaphragm during breathing.
The pressure exerted by blood on the walls of a vessel is called?
Blood pressure
Where is blood pressure the highest? It gradually decreases as?
Aorta / as it flows into arterioles, capillaries, venules and veins,
Whereis the velocity of blood the greatest? It slows as?
Large diameter arteries / slows as the blood moves into smaller diameter vessels (arterioles and capillaries)
Where is blood flow the slowest? Why is it slow here?
Capillaries / it allows time for exchange of materials between the blood and body cells
As blood travels back to the heart, what happens to the speed of blood flow?
It flows faster as it moves into vessels with larger lumen diameters
While an individual is at rest, how long does it take a drop of blood to travel through the body?
1 minute
What are two things that adjust blood pressure as needed?
Cardiovascular center & hormones
This is in the medulla oblongata and helps regulate heart rate, stroke volume, force of contraction of the heart, and blood vessel diameter (vasoconstriction and vasodilation). This region of the brain receives input from higher brain regions and from sensory receptors.
Cardiovascular center
These also help regulate blood pressure in various way (ex: epinephrine and norepinephrine are releases by the adrenal glands in response to sympathetic stimulation).
Hormones
What are the 3 main types of sensory receptors that provide input for the cardiovascular center are?
Proprioceptors, baroreceptors, chemoreceptors
Proprioceptors provide information to the cardiovascular center about?
Monitor body movements and position
These sensory receptors for the cardiovascular center monitor changes in pressure and stretch in the walls of blood vessels. Located primarily in the aorta (ascending and arch portions) and the internal carotid arteries.
Baroreceptors
These sensory receptors for the cardiovascular center monitor the concentration of various chemicals in the blood; located near the baroreceptors in the aorta and internal carotid arteries they detect changes in levels of O2, CO2, and hydrogen ions (H+)
Chemoreceptors
Output from the cardiovascular center travels along where?
both sympathetic and parasympathetic neurons of the autonomic nervous system
An increase in sympathetic stimulation results in?
an increase in heart rate and contractility
A decrease in sympathetic stimulation results in?
a decrease in heart rate and contractility
parasympathetic stimulation by way of cranial nerve X (vagus nerve) does what to the heart rate?
decreases it
The cardiovascular center also sends impulses to smooth muscle in blood vessel walls by way of these nerves which cause vasoconstriction or vasodilation
vasomotor nerves
Where is blood pressure usually measured? What device is used to measure blood pressure?
in the brachial artery in the left arm / sphygmanometer
What is normal blood pressure?
less than 120mm Hg / 80mm Hg
What does the top number in a blood pressure reading represent?
systolic pressure (the force of blood against the walls of the artery just after contraction of the left ventricle).
What does the bottom number in a blood pressure reading represent?
the diastolic pressure (the force of blood against the walls of the artery as the left ventricle relaxes)
This carries blood from one capillary network (in the GI organs and spleen) to another (in the liver).
hepatic portal vein
After an individual eats, what does the hepatic portal vein do?
carries blood that is full of nutrients absorbed from the GI tract to the liver before the nutrients pass into general circulation
What can happen to harmful substances such as alcohol when the hepatic portal vein sends it to the liver?
it can be detoxified
Besies the hepatic portal vein, what else does the liver receive blood from?
the hepatic artery
The hepatic artery branches from?
celiac trunk artery
Blood leaves the liver through? These drain into?
hepatic veins / inferior vena cava
The circulatory system of a fetus contains special features that allow it to?
exchange materials with its mother
Because the lungs (and kidneys and GI organs) do not begin to function until birth, how does the fetus receive 02 and nutrients and disposes of CO2 and wastes?
from maternal blood
The exchange of materials between fetal and maternal circulations occurs through?
the placenta
The placenta forms in the mother’s uterus and attaches to the fetus by?
the umbillical cord
How are the substances exchanged between the mother and the fetus?
The capillaries from the umbilical cord and from the uterus come in very close contact with one another so the exchange of sunbstance occurs between the vessels
Is there a mixing of maternal and fetal blood?
no
What carries deoxygenated blood from the fetus to the placenta?
two umbilical arteries
The umbilical arteries are branches of?
the internal iliac arteries of the fetus
What do the umbilical arteries pick up and dispose of?
pick up O2 and nutrients and give up CO2 and wastes
oxygenated blood returns from the placenta by way of a single?
umbilical vein
The umbilical vein carries blood toward?
the liver of the fetus where it divides into two branches
After the umbilical vein divides into two branches, where does some of the blood flow? Most of the blood flows into the other branch called?
through the branch that joins the hepatic portal vein and enters the liver / ductus venosus
The ductus venosus drains into?
the inferior vena cava
In the inferior vena cava, oxygenated blood from the ductus venosus mixes with?
deocygenated blood
Along with this, the mixed blood in the inferior vena cava enters?
deoxygenated blood from the superior vena cava / the right atrium
Most of the fetal blood does not pass from? It does pass through?
the right ventricle to the lungs (as it does after birth) / foramen ovale
This is an opening in the interatrial spetum in a fetus
foramen ovale
The foramen ovale carries?
blood from the right atrium to the left atrium
Some fetal blood does pass into the right ventricle and from there it moves into?
the pulmonary trunk
From the pulmonary trunk the blood of a fetus travels through?
the ductus arteriosus
This is a vessel in a fetus that connects the pulmonary trunk with the aorta
ductus arteriosus
Does fetal blood ever enter reach the nonfunctioning lungs
little
In a fetus, the blood in the aorta is carried to?
all fetal tissues through systemic circulation
The blood in a fetus that reaches the internal iliac arteries travel into? Then onto?
umbilical arteries and onto the placenta
Shortly after birth, the foramen ovale closes to become?
the fossa ovalis
This is a depression in the interatrial septum after the foramen ovale closes.
fossa ovalis
Complete closure of the foramen ovale happens how long after birth?
1 yr
The ductus arteriosus closes and becomes this how long after birth
ligamentum arteriosum / several months
