Unit 1.L1-Overview of the Circulatory Systems & Hemodynamics Flashcards
What is the leading cause of death in the United States?
Cardiovascular Disease (CVD)
What incidences rise steeply after the age 65?
Heart disease and stroke
Heart disease and stroke acccount for more than 40% of deaths among age ____ to _____.
65 to 74
Heart disease and stroke acccount for more than 60% of deaths among age ____ and _____.
85 and above
What cardiovascular disease has the highest percentage of deaths?
Coronary Heart Disease
What is another name for the Circulatory system?
Cardiovascular system
What are the 3 major parts of the Cardiovascular sytem?
- Heart: a centralized pump
- Blood vessels: distribute blood through the body
- Blood: transportation of different substances
How is the heart seprated?
2 loops, both begin and end at the heart
List the 2 circuits of the heart
- (Shorter) Pulmonary Circuit
- (Longer) Systemic Circuit
Describe the Pulmonary Circuit
- Shorter circuit
- Exchanges blood btw the heart and lungs for oxygenation
Describe the Systemic Circuit
- Longer circuit
- Distributes blood throughout all other systems and tissues of the body
- Lungs not included
What are the main functions (3) of the circulatory system?
- Transport essential substances to the tissue (O2, electrolytes, nutrients, hormones, etc)
- Remove metabolic waste products (CO2, urea, lactate, heat,etc)
- Homeostasis (temperature regulation, fluid maintance, meeting metabolic demands during different physiological states)
How many gallons of blood does the heart pump every day
1,800 gallons
How much gallons does the heart pump in an average lifetime (75 years)?
approx. 50 million gallons
If streched end-to-end how long are the arteries, veins and other vessels of the circulatory system?
60,000 miles
How many chambers does the have & name them?
- 4 chambers
1. Right Atrium
2. Right Ventricle
3. Left Atrium
4. Left Ventricle
What does the right atrium consist of?
- Superior Vena Cava
- Inferior Vena Cava
What collects blood from the upper body?
Superior Vena Cava (SVC)
What collects blood from our lower body?
Inferior Vena Cava (IVC)
What does the right ventricle consists of?
- Tricupsid valve
- Pulmonary valve
Explain the blood flow of the heart
Deoxy blood from SVC, IVC and coronary sinus enters the RA–>then enters the RV through the tricupsid valve–>Deoxy blood in RV goes to pulmonary artery through the pulmonary valve–>(Blood goes to the lungs)–>Oxy blood enters LA through the pulmonary vein—> LA to LV through mitral valve–> LV to aorta through aortic valve
Define Cardiac Cycle
The cardiac cycle is the performance of the human heart from the beginning of one heartbeat to the beginning of the next. It consists of 2 phases
What are the 2 phases of the cardiac cycle
- Phase 1: Systole
- Phase 2: Diastole
Define Systole
Occurs when the heart contracts to pump blood out
Define Diastole
Occurs when the heart releases after contractions and is filled with returning blood
List the steps of the Cardiac cycle
- Venous return to the right atrium (Systemic circuit)
- Venous flow arrives in the right ventricle (Diastole)
- Venous blood is sent in the lung via the pulmonary artery (Pulmonary circuit)
- Affter oxygenation in the lung the blood (red blood) returns to the left atrium
- Red blood arrives in left ventricle
- Red blood is sent in the arteries to the tissues
List the vessel type and their relative size (diameter)
- Aorta:25 mm
- Large Arteries:1.0-4.0 mm
- Small Arteries: 0.2-1.0 mm
- Arterioles: 0.01-0.20 mm
- Capillaries: 0.006-0.010 mm
- Venules: 0.01-0.20 mm
- Veins: 0.2-5.50 mm
- Vena Cava: 35 mm
Which vessels have the function of distribution?
- Aorta: Pulse dampening and distribution
- Large Arteries: Distribution of arterial blood
- Small Arteries: Distribution and resistance
Which vessels have the function of resistance?
- Small Arteries: Distribution and resistance
- Arterioles: Resistance (pressure + flow regulation)
Which vessels have the function of exchange?
- Capillaries: Exchange
- Venules: Exchange, collection, and capacitance
Which vessels have the function of capacitance?
- Veins: Capacitance function (blood flow)
- Vena cava: collection of venous blood
What tissues make up the vessels walls?
- Endothelium
- Elastic tissue
- Smooth muscle
- Fibrous tissue
Which vessel types have endothelium?
- Aorta
- Artery
- Vein
- Vena cava
- Arteriole
- Capillary
- Venule
Which vessel types have elastic tissue?
Important for regulation
- Aorta
- Artery
- Vein
- Vena cava
- Arteriole
Which vessel types have smooth muscle?
Important for regulation
- Aorta
- Artery
- Vein
- Vena cava
- Arteriole
Which vessel types have fibrous tissue?
- Aorta
- Artery
- Vein
- Vena cava
- Arteriole
- Venule
How much of our body is blood?
8%
How much of the blood composition is plasma?
55%
What is contained in plasma?
Proteins, water and other solutes (ions, nutrients, waste products, gases & regulatory substances)
What are the proteins in the plasma?
- Albumins (57%)-maintain hydrostatic pressure
- Globuluns (38%)-immune system
- Fibrinogen (4%)- blood coagulation
- Prothrombin (1%)
How much of the blood composition is Formed Elements?
45%
What is contained in the formed elements of the blood?
Erythrocytes (RBC)
How much of the blood compositon is the Buffy coat?
1-2%
What is contained in the buffy coat of the blood?
Contains platelets and leukocytes
Explain the blood functions in the respiratory system?
- Transport O2 from lungs to tissues
- Transport CO2 from tissues to lungs
Explain the blood functions in nutrition of the body?
Transport “food” from gut to tissue (cells)
Explain the blood functions in the excretory system?
Transport waste from tissue to kidney and skin (urea, uric acid, water)
Explain the blood functions in the regulatory system?
- Water content of tissues
- Water exchange through vessel walls to tissue
Explain the blood functions in body temperature (protective)?
Antibodies, antitoxins, white blood cells (WBC)
Explain the blood functions of acid-base balance in the body
pH 7.35-7.45, NaHCO3/H2CO3
What is another blood function in the body?
Coagulation
What is the normal hematocrit percentage of the blood?
Hematocrit: Red blood cells
- Males: 37-47% hematocrit
- Females: 42-52% hematocrit
What occurs to the hematocrit levels in a patient w/ anemia?
Depressed hematocrit %
What occurs to the hematocrit levels in a patient w/ polycythemia?
Elevated hematocrit %
What percentage of our blood is in the systemic circulation?
82%
What part of the heart is the pump and what % of blood is present?
Left Ventricle-4%
What part of the heart is the distributing system and what % of blood is present?
Arteries-16%
What part of the heart does exchange occur and what % of blood is present?
Capilliaries-4%
What part of the heart is the collecting system and what % of blood is present?
- Veins-64%
- Right heart-4%
What percentage of our blood is in the pulmonary circulation?
8%
When role does the veins play in the systemic circulation?
Blood reserve
What is the blood reserve?
- The area that allows control of blood volume and makes up for the fact capillaries are not always open.
- Veins
What is blood pressure?
Pressure of circulating blood against the walls of the blood vessels
Explain systolic pressure
the highest measured blood pressure
Explain diastolic pressure
the lowest measured blood pressure
Explain mean pressure
Mid-point pressure, is consistant b/n aorta and large arteries, drops @ the small artery to arterioles
Explain pulse pressure
Difference btw systolic and diastolic pressure
What blood vessel has the largest pressure drop?
Arterioles
Mean BP falls succesively from______ to _____
Aorta to vena cava
What is the Volume Flow of blood
- Volume Flow (Q): flow volume (displacement of blood) per unit time (cm3 or ml/sec)
- Equation: Q=∆Q/∆t
What is Flow Velocity of the blood?
- Flow Velocity (V) : linear flow distance per unit time (cm/sec)
- V=∆d/∆t
What is the interrelationships of volume (V), volume flow (Q), and Cross-sectional area (A)
- Equation : V=Q/A
- Q (volume flow) is constant throughout the circuit
- V (volume) is inversely proportional to A (cross-sectional area)
Explain the linear velocity (V) throughout the blood vessel types
- V is high at the aorta + arteries
- V is low at the arterioles, capillaries+ venules
- V increases again at the veins + vena cava
Explain the cross-sectional area (A) through the blood vessel types
- A is low at the aorta + arteries
- A is high at the arterioles, capillaries (the highest) + venules
- A is low again at the veins + vena cava
Explain blood pressure through the blood vessel types
- BP is high @ aorta + arteries
- BP drops @ the arterioles, capillaries + venules+ veins + vena cava
What is the equation for Poiseuille’s Law?
Q=laminar flow (e.g. cardiac output)
Pi=inflow pressure (e.g. arterial pressure)
Po=outflow pressure (e.g. venous pressure)
r=tube radius
L=tube length
η=fluid viscosity
What is the equation for the blood pressure, blood flow and resistance relationship
Q=∆P/R
What is resistance determined by? and what is the equation?
- Tube radius, length and Fluid viscosity
- Equation: R≅ηL/r^4
What is the effect of tube length on resistance?
Resistance varies positively with tube length
Why is tube length not a significant factor in controlling vascular resistance?
Blood vessel length remais relatively constant
Why is resistance important?
Regulates blood flow and blood pressure
What is the effect of change in tube radius on resistance?
- Small decrease in tube radius produces large change in the resistance of flow
- Resistance of a tube varies inversely as the 4th power of the radius
What is the main determinant of resistance (R)?
Tube radius
How is blood flow controlled primarly?
By regulating vessel radius
What vessels are the main area for regulating your blood flow and blood pressure?
Arterioles
Biggest drop in BP
What is the equation for resistance in series-coupled circuits?
- Rtotal=R1+R2+R3….
What happens to pressure along a series-coupled circuit?
- Pressure drops progressively
- Pressure downstream is lower than pressure upstream
What happens to upstream and downstream pressure and flow when a given area of vasculature contracted?
- Upstream pressure: increased; flow: increasesd
- Downstream pressure: decreased; flow: decreased
What is the equation for resistance in parallel-coupled circuits
1/Rtotal= 1/R1+1/R2+1/R3…
What are two important principles regarding the parallel arrangement of blood vessels?
- The Rtotal of a network of parallel vessels is less than the resistance of the vessel having the lowest resistance. Therefore, a parallel arrangement of vessels greatly reduces resistance to blood flow
- When there are many paraller vessels, changing the resistance of a small number of these vessels will have a relatively small effect on Rtotal for the segment
What does the large number of parallel-coupled circuits (e.g. capillaries) mean for the resistance?
The smaller the total resistance
Define Rheology
a science dealing w/ the deformation and flow of matter
Define laminar flow
- Linear
- Smooth parabolic profile of velocity
- Energy efficient
- Quiet
Define Turbulent flow
- Irregular, turbulent flow
- More energy required
- Harmful to the vessel wall
- Generate sound
What are the rheological properties of blood?
Non-homogenous, non-newtonian fluid b/c the different componets w/ different viscosities
Define blood viscosity
How thick each property present in blood is and how it effects resistance
Changes in blood viscosity are depended on?
- Tubing dimesions
- The hematocrit
Hematocrit-proportion of blood that consists of RBC
What is the equation to the determine the effects of viscosity on blood flow?
Q~1/η
Blood viscosity is not constant
True or False: Blood viscosity is not constant throughout the circulatory system
True
What is the relationship b/n flow and viscosity
Flow varies inversely with fluid viscosity
What occurs in small vessels due to blood viscosity (η)?
- Blood viscosity (η) decreases, thereby decreasing the resistance of blood flow
- Decrease tube diameter=decrease viscosity= decrease resistance= increase blow flow
What is the blood viscosity levels in big vessels vs. small vessels?
- Big vessels: High viscosity
- Small vessels: Low viscosity
What occurs d/t viscosity at the arterioles and capillaries?
- Arterioles: Can control resistance @ viscosity level
- Capillaries: reduction in viscosity decreases resistance and increase flow
Which vessel types is the hematocrit concentration high and low?
High in larger vessels, Low in smaller vessels
Which vessel types is the hematocrit concentration high and low?
High in larger vessels, Low in smaller vessels
What do red blood cells do in small vessels?
Accumulate in the center of small vessels and flow at a faster rate
Note: velocity vectors in cross-section of laminar flow
What do RBC do in small vessels?
Accumulate in the center of small vessels and flow at a faster rate
Note: velocity vectors in cross-section of laminar flow
What is the fluid near the capillary wall?
Plasma (slow velocity)
What occurs when hematocrit is decreased?
Blood can flow faster + in the center of the vessel
What is shear?
- Shear occurs when adjacent layers of blood travel at different velocities
- Highest @ the blood vessel wall
What is the physiological significance (viscosity, resistance) of a low hematocrit ratio?
- Lower hematocrit ratio, lower the viscosity, lower resistance to flow
- B/c of this blood can be pumped at a much reduced pressure, leading to lower blood flow to benefit efficient nutrient delivery + removal of waste, and no requirement for a strong vessel wall
- The load on the heart is significantly reduced
All of the following are functions of the circulatory system except:
A.Remove lactate and urea
B.Transport oxygen to the lungs from the peripheral tissues
C. Regulate temperature
D. Transport hormones
b. Transport oxygen to the lungs from the peripheral tissues
Arterioles have all of the following functions except:
a.Regulate blood flow
b. Maintain a reservoir of blood
c. Site of largest blood pressure drop
d.Changes in viscosity to affect resistance
b. Maintain a reservoir of blood
Which of the following correctly describes a vessel whose function is capacitance?
a. Diameter of 0.01mm
b. Large amounts of elastic tissue and smooth muscle cells
c. Small amounts of elastic tissue and moderate amounts of smooth muscle cells
d. Single layer of endothelial cells
c. Small amounts of elastic tissue and moderate amounts of smooth muscle cells
Which of the following is true regarding capillaries?
a. Maintains a high blood pressure and low resistance to increase blood flow
b. Has the highest resistance and slow blood flow to increase time for gas and nutrient exchange
c. Maintains a low blood pressure and increased viscosity to increase time for gas and nutrient exchange
d. Has an increased cross-sectional area and reduced resistance to decrease the overall drop in blood pressure
d. Has an increased cross-sectional area and reduced resistance to decrease the overall drop in blood pressure
All of the following are true regarding resistance except:
a. Resistance is inversely proportional to blood flow
b. Resistance causes an increased drop in pressure along a series-coupled circuit
c. Resistance is directly proportional to blood vessel diameter
d. A small change in blood vessel diameter causes a large increase in resistance
c. Resistance is directly proportional to blood vessel diameter