Ch 4. Vasculature Flashcards
Define Vasculature
All of the blood vessels in the body
What are the several types of blood vessels?
ARTERIES, ARTERIOLES, CAPILLARIES
VENULES, VEINS
What do Arteries/Veins do?
Arteries: Carry blood AWAY from the heart
Veins: Carry blood TO the heart
What are the smallest blood vessels in the body?
Capillaries! Its walls only consist of Endothelium and a Basement Membrane.
Fun fact: They are also more capillaries in the body than any other blood vessel and their walls are porous! About 10 billion of them exist in the body.
How many miles does blood travel throughout the body?
Altogether, blood travels through about 60,000 miles of blood vessels!
What do all blood vessels have?
What do all blood vessels have except for capillaries?
- At least an inner layer of Endothelium surrounded by a basement membrane
- Layers of Connective Tissue and Smooth Muscle that surround the basement membrane
Endothelium
Endothelium: A layer of epithelial cells that is closest to the lumen (or interior space) in a blood vessel
Because of its location, the endothelium is in direct contact with the blood that passes through the blood vessel!
The Endothelium of a typical capillary contains 2 types of pores:
- Intercellular Clefts: located between the endothelial cells of a capillary
- Fenestrations: run through individual endothelial cells of a capillary
Basement Membrane
Basement Membrane: A thin layer of extracellular material that surrounds and provides support to the endothelium and has pores
Smooth Muscle
Smooth Muscle: May be present toward the middle of the blood vessel wall.
The Smooth Muscle can contract or relax, thereby altering the diameter of the blood vessel.
Connective Tissue
(2 types of connective tissues may be present in the wall of a blood vessel
The 2 types of Connective Tissue that can be found:
- Elastic Connective Tissue
- Fibrous connective tissue.
Elastic: contains elastic fibers that allow the blood vessel to stretch and is typically found deeper within the wall of a blood vessel
Fibrous: contains collagen fibers that resist stretch, which prevents the blood vessel from over-stretching. This tissue usually forms the outer layer of a blood vessel.
How do blood vessels vary?
- They vary with the respect to the amount of Elastic and Fibrous connective tissues that they contain
What allows CAPILLARIES to serve as THE blood vessels that undergo gas, nutrient, and waste exchange with cells in the surrounding tissues?
FUNCTIONS OF BLOOD VESSELS ARE BELOW
It’s thin wall and pores.
Arteries, arterioles, venules, and veins are too thick AND lack pores so the gases, nutrients, and waste can’t move across the walls of these blood vessels.
Arteries
Arteries carry blood away from the heart, to arterioles
Arterioles
Arterioles deliver blood, to capillaries
Capillaries
Capillaries function as the “exchange vessels”.
They permit the exchange of gases, nutrients, and wastes between blood and the cells of the body. Transforming oxygenated blood into deoxygenated blood.
Fun fact: They are also more capillaries in the body than any other blood vessel and their walls are porous! About 10 billion of them exist in the body.
Venules
Venules drain capillary blood, and then deliver the blood to veins
Veins
Veins carry blood back to the heart
CAPILLARY EXCHANGE
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What can pass through a capillary’s walls?
Only relatively small molecules such as:
- Gases, Water, Ions, Glucose, Amino acids, & Hormones
Which substances typically diffuses across capillary walls directly through the LIPID BILAYER of endothelial cell plasma membranes?
Lipid-soluble substances (aka hydrophobic substances)
- Oxygen, Carbon Dioxide, and Steroid hormones
Which substances typically diffuses across capillary walls directly through the PORES?
Most small water-soluble (aka hydrophilic substances) -Ions, and Polar Molecules such as Glucose and Amino Acids
(in other words, the intercellular clefts and fenestrations of the capillary endothelium and pores of the basement membrane).
Fun fact
Recall that although water is a hydrophilic molecule, it is small and has NO charge.
What can move across the capillary wall via
transcytosis?
(which refers to endocytosis followed by exocytosis)
PROTEINS.
Fun Fact Notes from Prof
Any water that diffuses out of the blood goes into the interstitium
What is Lymph?
Extracellular fluid that is located within a lymphatic vessel
VENOUS VALVES, SKELETAL MUSCLE PUMP, AND VENOUS RETURN
.
What’s venous return?
Venous return refers to the process by which veins return blood back to the heart.
How are veins able to return blood back to the heart despite having to go against gravity and lower blood pressure?
Venous Valves & the Skeletal Muscle Pump
Venous valves: consists of folds of the endothelium of the vein that function to prevent back-flow of blood.
The Skeletal Muscle Pump: refers to contractions of skeletal muscles surrounding veins that help push blood up the veins.
Fun Fact: If you stand for a long period of time, you should periodically contract the muscles in your legs, in order to make sure that blood goes back to the heart.
OTHERWISE, blood can pool in the veins & you might pass out since the heart isn’t pumping enough blood to the brain.
ALTERATION OF BLOOD VESSEL DIAMETER
.
Which blood vessels can change their diameters (Vasoconstrict or Vasodilate) by contracting or relaxing the smooth muscle in their walls?
Arteries, Arterioles, Venules, and Veins
note capillaries do NOT constrict or dilate because they do NOT have smooth muscle!
Vasoconstriction DETAILS
The Smooth Muscle within its wall CONTRACTS.
- Consequently, the blood vessel lumen becomes SMALLER which causes a decrease in blood flow and an increase in blood pressure.
NOTE: blood pressure is pressure that occurs when blood interacts with the wall of a blood vessel. So, if there is more interaction between blood and the blood vessel wall, blood pressure increases.
Vasodilation DETAILS
The Smooth Muscle within its walls RELAXES.
- Consequently, the blood vessel lumen becomes WIDER and larger. Vasodilation causes an increase in blood flow and a decrease in blood pressure (because there’s more room between the blood and blood wall)
BLOOD DISTRIBUTION
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What is the average blood volume when the body is normally hydrated?
About 5 liters
Blood Distribution (blood volume) DETAILS
Heart: 7% Systemic Arteries and Arterioles: 13% Systemic Capillaries: 7% Systemic Veins and Venules: 64% Pulmonary Blood Vessels: 9%
What is deemed the “Blood Reservoirs” of the body?
Systemic Veins and Venules
Note:
You would think that most of the blood volume would be found in capillaries, since there are so many capillaries in the body.
However, blood is only found in capillaries when the organ that contains these capillaries is active. If that organ is not active, then blood bypasses the capillaries in that organ.
VASCULAR COMPLIANCE
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Define compliance
The ability of an object to stretch
- Veins have a HIGH compliance because they have thin walls that are easily stretched. Consequently, veins are called the capacitance elements and contain the majority of blood volume in the body
- Arteries have a LOW compliance compared to veins because arteries contain thick walls that are not as easy to stretch
Is venous pressure low or high?
LOW. It’s low because even higher blood volume simply stretches the walls of veins, it doesn’t make the blood pressure go up.
- 5 to 10 mmHg in small veins and about 0 mmHg in the vena cavae as they empty in the right atrium
Is arterial pressure low or high?
aka: Does an increase in blood volume of the arteries cause an increase or decrease in Arterial Pressure?
HIGH/INCREASES. Blood pressure in arteries increases because they have low compliance and aren’t able to stretch and adjust like veins do, causing more interaction between the blood and the blood wall.
- 110 mmHg and 70 mmHg.
BLOOD PRESSURE
.
Define Blood Pressure
The pressure that blood exerts on the wall of a blood vessel. The more interaction between blood and the blood vessel wall, the higher the blood pressure.
All blood vessels have blood pressure… DETAILS
Arterial pressure: BP that occurs in the aorta and other arteries
Arteriolar pressure: BP that occurs in the arterioles.
Capillary pressure: BP that occurs in the capillaries.
Venular Pressure: BP that occurs in the venules.
Venous pressure: BP that occurs in veins, including the venae cavae
Put the blood vessels in ORDER from Highest to Lowest blood pressure:
arterial pressure is most important
Arteries (aorta, arteries, arterioles) Capillaries Venules Veins Vena Cavae
Fun Fact: the term blood pressure usually refers to the arterial pressure
What does blood pressure usually depend on?
Because arteries are so close to the heart, BP depends on whether the ventricles are in systole or diastole. aka Systolic pressure and the diastolic pressure
- Systole aka contracting: ventricles eject blood into arteries, causing the arterial pressure to increase
- Diastole aka relaxing: ventricles are no longer ejecting blood into arteries, which means that arterial pressure is lower
Systolic pressure
The maximum pressure exerted by blood on arterial walls during ventricular systole
- It normally equals about 110 mmHg
Diastolic pressure
The minimum pressure exerted by blood on arterial walls during ventricular diastole
- It normally equals about 70 mmHg.
Blood pressure cuff DETAILS
BP is generally written as: systolic pressure over the diastolic pressure.
In other words, a normal blood pressure is 110 over 70. Blood pressure is usually measured in the brachial artery using a device called a sphygmomanometer, which is also known as a blood pressure cuff.
- The cuff is inflated to about 160 to 180 mmHg.
- The first sound that you hear corresponds to the systolic pressure. They last sound that you hear corresponds to the diastolic pressure.
FUN FACT: The sounds are called Korotkoff sounds.
FACTORS THAT AFFECT BLOOD PRESSURE
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What factors affect BP?
- blood vessel diameter.
- cardiac output. (which is determined by stroke volume and heart rate so that affects BP by altering cardiac output)
***So the ANSWER is 4 major factors:
Stroke volume. Heart rate.
Cardiac output. Blood vessel diameter!!!
How to INCREASE blood pressure in case of a hemorrhage or something?
- Vasoconstrict blood vessels
- Increase cardiac output
So, in case you hemorrhage:
- Sympathetic nerves that innervate the heart will cause an increase in stroke volume and an increase in heart rate. Increasing these parameters increases cardiac output.
- At the same time this is happening, vasomotor nerves that supply blood vessels other than capillaries cause vasoconstriction. The increase in cardiac output and the vasoconstriction both increase blood pressure back to normal.
How to DECREASE blood pressure in case of over-hydraton?
- Vasodilate blood vessels
- Decrease cardiac input
Parasympathetic nerves via the vagus nerves that decrease heart rate and, therefore, decrease cardiac output.
Parasympathetic Nerves do not alter stroke volume. This means that there is NO way to decrease the stroke volume.
STEPS to Decrease:
- Parasympathetic nerves that innervate the heart will cause a DECREASE in heart rate.
- The decrease in heart rate will cause a decrease in cardiac output. At the same time that this is happening, the lack of sympathetic stimulation to blood vessels via the vasomotor nerves causes blood vessels to automatically vasodilate.
- The decrease in cardiac output and the vasodilation both decrease blood pressure back to normal.
NEURAL REGULATION OF BLOOD PRESSURE
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What controls blood pressure
Cardiovascular Center
- aka cluster of neurons located in the medulla oblongata of the brain stem
What are the outputs to the cardiovascular center that help regulate BP?
- Parasympathetic nerves (vagus)
- Sympathetic nerves (cardiac accelerator nerves)
- Vasomotor Nerves (sympathetic): stimulation causes vasoconstriction
What are the input connections to the cardiovascular center that help regulate BP?
- Baroreceptors: sensory receptors that respond to BP changes
The 2 types:
Aortic Arch Baroreceptors & Carotid Sinus Baroreceptors
What is the process called in which the cardiovascular center uses input and output connections to maintain a normal BP?
The Baroreceptor Reflex
The 2 Versions are:
- The reflux that responds to an increase in BP
- The reflux that responds to a decrease in BP
Baroreceptor Reflex response to a DECREASE in BP STEPS/DETAILS
- A stimulus (ex. a hemorrhage) causes decrease in bp
- Causing baroreceptors to stretch less than normal
- Causes baroreceptors to send less action potentials to the cardiovascular center
- The cardiovascular center responds by activating the cardiac accelerator nerves that supply the heart
- Causes increase in stroke volume & heart rate
- Cardiovascular center activates the vasomotor nerves that supply most blood vessels in the body resulting in vasoconstriction
- The increase in HR & stroke volume lead to an increase in cardiac output and therefore, an increase in BP
- The increase in BP gets rid of the decrease that happened, which means it goes back to normal
Baroreceptor Reflex response to a INCREASE in BP STEPS/DETAILS
- A stimulus (ex. over-hydration) causes increase in bp
- Causing baroreceptors to stretch more than normal
- Causes baroreceptors to send larger amount of action potentials to the cardiovascular center
- The cardiovascular center responds by activating the parasympathetic nerves that supply the heart
- Heart rate decreases, which decreases cardiac output
- Lack of sympathetic stimulation of blood vessels result in vasodilation
- Decrease in cardiac output and vasodilation both decrease blood pressure
- The decrease in BP gets rid of the increase in BP, which means it goes back to normal
Blood Pressure is dependent on what?
cardiac output, systemic vascular resistance, and blood volume
What are the primary factors that influence circulation?
Mean Arterial BP (MABP)
Cardiac Output (CO) = ————————————-
Systemic Vascular Resistance(SVR)
Note
Right Atrial Pressure is so low that it’s discounted, and directly proportional to MABP
Note
note: Right Atrial Pressure is so low that it’s discounted, and directly proportional to MABP
note: Viscosity and blood vessel length also affect SVR, but because these factors do not change quickly, they do not play a role in rapid changes in SVR.
Define Blood Pressure + DETAILS
The driving force that causes blood to flow through arteries into capillaries, then veins and back to the heart
- Highest during ventricular systole (systolic blood pressure)
- Lowest during ventricular diastole (diastolic pressure)
Measuring BR SV and HR tools:
Sphygmomanometer (blood pressure cuff):
- measures Systolic and Diastolic blood pressures
Magnetic Resonance Imaging (MRI):
- measures stroke volume
Electrocardiography (ECG):
- measure heart rate
QUESTIONS: POWERPHYS PRELAB
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When systemic vascular resistance (SVR) decreases, blood pressure…..
DECREASES.
Vasoconstriction (increasing SVR) causes blood pressure to……
INCREASE.
Average blood pressure in arteries over the course of the cardiac cycle is…..
MEAN ARTERIAL BLOOD PRESSURE.
Increasing blood pressure causes blood flow to…..
INCREASE.
Korotkoff sounds can be heard when the cuff pressure…..
IS BETWEEN SYSTOLIC AND DIASTOLIC BP.
During exercise…
BLOOD VESSELS TO SKELETAL MUSCLES DILATE.
Vasodilation causes systemic vascular resistance to…..
DECREASE.
The arterial blood pressure measured during ventricular contraction is….
SYSTOLIC BLOOD PRESSURE.
As cardiac output (CO) increases, blood pressure…..
INCREASES.
The arterial blood pressure measured during ventricular relaxation is…..
DIASTOLIC BLOOD PRESSURE.
POWERPHYS ACTIVITY LAB EXPERIMENT
.
Dependent Variable
The measurement of HR, SV, and BP
Independent Variable
The level of activity (because this will cause an effect on the dependent variable)
Controlled Variables
Age & Gender (because these were the same through out all persons - all male - all 25)
EQUATIONS & HOW TO CALCULATE
Mean Arterial Pressure (MAP):
MAP=DBP + [(SBP-DBP)/3]
Cardiac Output:
CO = HR × SV
Systemic Vascular Resistance:
SVR = MAP/CO
QUESTIONS: QUESTION SET 5
.
1) DP + 1/3 (SP – DP) is the formula for…
MEAN ARTERIAL PRESSURE (MAP)
2) MAP/CO is the formula used to calculate…
SYSTEMIC VASCULAR RESISTANCE (SVR)
3) In this experiment, exercise caused systolic blood
pressure to
Increase by 20%
4) In this experiment, exercise caused diastolic blood
pressure to
Not change significantly
5) In this experiment, exercise caused MAP to
Increase slightly
6) In this experiment, exercise caused CO to
Increase by 180%
7) In this experiment, exercise caused SVR to
Decrease by 200%
MATH NOTES SORRY LOL
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