Chapter 15. Cardiovascular system cont.. Flashcards
What is Cardiac Output, how do you calculate it and what is a normal volume? What is heart rate and what is the normal amount of beats per minute? What is stroke voulme and what is a normal volume?
- Cardiac output:
a. is the volume of blood pumped each minute by either the left or right ventricle.
b. HR(beats/min) x SV(ml/beat) = CO(ml/min)
c. the average CO for a male would be 5.6 and a female 4.9 ml/minute - Heart rate:
a. is the number of times the heart contracts per minute
b. average HR is 60-100bpm - Stroke volume:
a. blood pumped by ventricle per contraction
b. average SV is 65 - 70ml/beat
What percentage of the bodys blood supply do skeletal muscles receive at rest? What percentage of the blood supply do skeletal muscles receive during exercise? What happens to CO during increassed heart rate?
- At rest skeletal muscles receives %20 of the blood supply.
- Skeletal muscles receive about %80-85 of the blood supply
- CO increases 5times due to increased heart rate
Why do the right and left sides of the heart function as independent pumps? How is blood flow maintained in the via systemic arteries? How do systemic veins serve as a reservoir?
- Each side of the heart acts independently so that the left side may receive oxygenated blood to pump it through the body where oxygen is exhcanged and lost and carried to the right side to pump it to the lungs for more oxygen.
- Systemic arteries are elastic as serve as a pressure reservoir which helps maintain blood flow during ventricular relaxation.
- Systemic veins serve as volume reservoir with their capacity to expand.
How do arterioles maintain variable resistance? Where does gas exchange betweeen blood and cells take place?
- Arterioles have adjustable screws that alter their diameter
- gas exchange between blood and cells takes place only in the capillaries.
How does the cardiovascular system pathway work when viewed as a sinlge closed loop?
The lungs send oxygenated blood through the pulmonary veins into the left atrium throught the mitral valve. Once the oxygen rich blood passes through the mitral valve into the left ventricle, it is pumped out through the aortic valve through the aorta. Systemic artieries help tranpsort the blood and uses its elasticity to force blood throughout the body until it braches down to the arterioles. As the arterioles have variable resistance, it reduces pressure to transition the blood through the capilaries.
After the exhcange, blood traveles through the venules to the systemic veins. From here it travels to the venae cavae then right atrium. Blood travels through the tricuspid valve into the right ventricle where it is forced through the pulmonary valve. Blood then traveles through the plumonary artery to the lungs.
What are the 5 blood vessels? Detail the thickness, diameter, endothelium, elastic tissue, smoooth muscle and fibrous tissue of each.
Recall that structure determines function
Why are arteries close to the heart elastic? How are the arteris distal to the heart different? What role do arterioles play?
- The elastic arteries near the heart stretch as blood is being pumped and recoil when ventricles relax.
- The muscular arteries distal from the heart have more smooth muscle and smaller lumen
- Arterioles help regulate **blood flow and Blood pressure. **
What size are the capillaries? What occurs in the capillaries? How is blood flow regulated in capillaries?
- Capillaries are 7-10micrometers in diameter making them the smallest blood vessels.
- Gases and nutrients are exchanged between blood and tissue.
- Blood flow regulated by vasoconstriction or dilation of arterioles and precapillary spchinters
- If precapillary sphincters constrict, blood flow bypasses capillaries and flow through metarterioles.
What are the three types of capillaries? What are their characteristics and where are they found?
- Continuous, fenestrated, dsicontinuous sinusoids
- a. Continuous: cells are close together. Found in most cells in body, muscles, adipose, and CNS
b. Fenestrated: have small pores. Found in kidneys, intestines, and endocirne glands
c. Discontinuous sinusoids: have large gaps between cells. Found in bone marrow, liver, and spleen.
How are veins different from arteries? What is another characteristic of veins? What is the pressure of blood in the veins?
- Veins: greater capacity to hold blood, thinner walls with less smooth and elastic tissue, and larger lumen.
- Veins collapse when empty and expand easily
- Veins have a relatively low pressure at about 10mm Hg
Where does depolarization of the heart occur? What part of the brain regulates the Heart rate? What two systems increase or decrease heart rate?
- The spontaneous depolarization of the heart occurs at the SA node when Na+ channels open allowing more Na+ to enter
- Heart rate is regulated by the cardiac center of the medulla oblongata
- a.Sympathetic increaases HR by keeping Na+ channels open with norepinephrine and adrenal epinephrine
b. Parasympathetic decreases HR by opening K+ channels with acetylcholine
What three variables regulate stroke volume? What effect does each have?
- a. The end diastolic volume (EDV): which is the volume of blood in the ventricles at the end of diastole
b. Increased EDV also increases stroke volume - a. Contractility: which is the strenght of ventricular contraction
b. strenght of Contractility increases stroke volume - a. total peripheral resistance: which is the frictional resistance in the arteries
b. inversely related to stroke volume
What increases Contractility of the heart and why?
- The increased amount of EDV stretches the myocardium which then increases contraction strength or contractility.
- The sympatheitc chemicals norephineprhine and adrenal epinephrine increases contractility by increasing opening time of calcium channels which leads to more forceful contraction
What increases EDV? What factors are involved in contributing to the amount of blood in the pathway to EDV?
- An increase in the amount of blood that returns(venous return) increase EDV
- a. skeletal muslces pumps: squeeze blood upward
b. Venous valves: ensure one directional flow of blood
c. Breathing: presure differences in thoracic vs abdominal cavities
d. Pressure is higher in venules and lower in veins closer to the heart
e. Increase in blood volume.
What is the tissue/capillary fluid exchange?
Predicts movement of fluid OUT at the arteriole end of capillaries and IN at the venule end.
How is water distributed throughout the body?
- 2/3 of our body water is found in the cells
- the remaining 1/3 is found in extracellular fluid
a. 80% is found in the interstitial fluid and the remaining 20% is found in the blood plasma
What is edema and what are the causes?
- Edema is the excess accumulation of interstitiial fluid
- Possible causes are:
a. high arterial blood poressure
b. decreassed plasma protein concentration, typically due to starvation
c. obstruction of lymphatic drainage
What problems can rise due to protein plasma deficiency?
Usually caused by starvation and can lead to:
a. edema
b. Kwashiorker: muscle tissue canabalizes and wastes away. Low protein also leads to low blood osmolarity and thus fluid buildup in tissues
What are the* two physical laws** *that regulate blood flow?
- Blood flows from a region of higher pressure to a region of lower pressure
- the rate of blood flow is proportional to the differences in pressure
What are the factors that influence Blood pressure? How?
- Blood volume: dtermined by fluid intake and fluid loss. Fluid loss may be done passively or regulated by kindeys
- Efficiency of the heart pumping: determined by the heart rate and stroke volume
- Resisteance of the system to blood flow: determined by diameter of arteries
- Relative distribution of blood between arteries and venous blood vessels: determined by diamter of veins
What does blood pressure measure? What is it measured in? What is the process of measuring blood pressure?
- Blood pressure meassures the pressure exerted by blood on the walls of blood vessels
- measured in mmHG
- A sphygomanometer is used to measure BP by:
a. BP cuff produces turbulant blood flow in brachial artery of arm that can be heard with a sthethoscope, also called the sounds of Kortkoff
b. cuff is then inflated beyond systolic BP to close the artery where pressure is then released. The first sound heard is called the systole
c. the last sound heard is the diastole which is when the pressre of the cuff reaches the diastolic pressure
What are the normal and abnormal ranges for BP?
- Normal: 120/80mmHg
- High blood pressure: 140/90mmHg
- Low BP: 90/60mmHg
How does blood pressure respond to high blood volume in negative feedback?
High blood volume leads to high blood presssure which triggers either:
a. a fast response: compensation by cardiovascular system to either vasodilation or decreased cardiac output.
b. slow response: compensation by the kidneys to excrete fluid in urine to decrease blood volume
both lower blood pressure to normal
What senses changes in Blood pressure? What effect does high BP have?
- Baroreceptors in the aortic arch and carotid sinuses sense change in B
- Increased BP stretches these receptors and increases AP to control centers in the medulla
a. in the medulla the vasomotor center controls vasodilation and constriction
b. cardiac center contrs the HR
