Hemodynamics

Question 1

Factors that affect distribution of CO (x4)

Answer 1

Heart rate

Stroke volume

Pressure difference (high P –> low P)

Resistance to BF (opposition)

Question 2

Water and BP

Answer 2

Water retention increases BP (hydrostatic pressure)

Question 3

What generates most of BP?

Answer 3

Ventricular contraction

Drives blood through the system during contraction AND relaxation

Question 4

Pressure: aorta –> capillaries

Answer 4

Pressure is high at aorta, steadily drops as it gets to the capillaries

Question 5

Cross sectional area & velocity

Answer 5

Vary inversely with each other

At capillaries (smallest), velocity is slowest (helps with diffusion exchange)

Question 6

What is systolic pressure?

Answer 6

Highest pressure in the arteries (occurs during ventricular systole)

Question 7

What is diastolic pressure?

Answer 7

Lowest pressure (occurs during ventricular diastole)

Question 8

Blood pressure cuff: how does it work?

Answer 8

Inflates to compress brachial a.

Deflates –> blood spurts (Korotkoff sound)

First sound = systolic pressure (force of BP on arterial wall right after ventricular contraction)

Last sound heard = diastolic pressure (ventricular relaxation)

Question 9

Pulse pressure

Answer 9

Difference between systolic and diastolic pressures

Question 10

Mean arterial blood pressure

Answer 10

Average blood pressure during the entire cardiac cycle

Mean ABP = HR x SV x TPR

Question 11

Where are pulse points found?

Answer 11

Where arteries are at the surface of the body & can be pressed against a bony structure

Question 12

Factors affecting BP (x3)

Answer 12

Cardiac output (HR, SV)

Blood volume (blood loss, H2O)

Peripheral vascular resistance

Question 13

BP formula

Answer 13

Pressure = flow x resistance

Question 14

What is vascular resistance?

Answer 14

Friction between blood and vessel walls

Question 15

What affects vascular resistance? (x3)

Answer 15

Vessel radius: larger the lumen = lower resistance

Blood viscosity: ratio of RBCs to plasma, dehydration = more viscosity and depletion of RBCs = less viscosity

Vessel length: larger the vessel = greater the resistance

Question 16

How do arterioles control BP?

Answer 16

By changing diameter

Question 17

NO and BP

Answer 17

NO causes vasodilation of BVs –> decreased BP

Question 18

Ways to regulate BP (x2)

Answer 18

Neural regulation (short term): baroreceptors + chemoreceptors

Hormonal regulation

Question 19

Types of hormonal regulation (BP)

Answer 19

Short term: epinephrine & norepinephrine

Long term: RAA, ADH, ANP

Question 20

How do baroreceptors work?

Answer 20

Detect changes in stretch

Aortic reflex: receptors in asc. aorta & aortic arch send signals through CN 10 –> medulla oblongata

Carotid sinus reflex: receptors in the internal carotid arteries send signals through CN 9 –> medulla oblongata

Question 21

How do chemoreceptors work?

Answer 21

Located close to baroreceptors

Detect changes in blood levels in O2, CO2 and H2O

In response to low O2, low pH or high CO2 –> increased sympathetic stimulation (vasoconstriction and increased BP)

Chemoreceptors send signals to the MO and respiratory center to adjust rate of breathing

Question 22

Epinephrine, norepinephrine & BP

Answer 22

Short term

Increased sympathetic stimulation causes the adrenal glands to release these catecholamines

Increases HR and force of contraction

Vasoconstriction of skin + abdominal organs

Vasodilation of cardiac muscle (increases BF)

Question 23

RAA system and BP

Answer 23

Long term

Angiotensin II vasoconstricts arterioles

Aldosterone increases water reabsorption –> increased blood volume

Question 24

ADH and BP

Answer 24

Long term

Released from post. pituitary in response to dehydration/decreased blood volume

Increases renal water absorption and increased systemic vasoconstriction –> increases BP

Question 25

ANP and BP

Answer 25

Long term

Released from right atrium to due increased stretch

Increases renal loss of salt and water and systemic vasodilation –> decreased BP

Question 26

Heart failure and BP

Answer 26

Prolonged increase of pressure on BV walls can damage vessel walls –> scars, tears + plaque buildup

Causes vessels to narrow + stiffen –> increased vascular resistance (higher BP)

Increased BP = increased afterload

Overtime, heart has to work harder

Question 27

Right sided HF

Answer 27

More blood remains in RV

Backup of blood in venous circulation

Fluid buildup in legs (peripheral edema)

Question 28

Left sided edema

Answer 28

Backup of blood in the lungs –> pulmonary edema

Leads to suffocation and lack of O2 to tissues