Blood Flow And Control Of Blood Pressure

Question 1

What is the meaning of two pumps and one? And what provides the initial pressure to push blood through the vessels?

Answer 1

Blood flows through systemic and pulmonary circuits and the heart provides the initial pressure to push the blood through the vessels

Question 2

What is pressure reservoir and how does it help maintain blood pressure?

Answer 2

Arteries elastic and muscular help maintain blood pressure and pressure reservoir

Question 3

What are arterials surrounded by and how do they contribute to blood flow

Answer 3

Arterials are surrounded by vascular smooth muscle that are able to partially constrict/daily to vary blood flow (variable resistance: size, length,) 

Question 4

Meta-arterials and anastomoses

Answer 4

• Meta-arterials are bypass of vessels through capillary beds that can be constricted or dilated by precapillary sphincters that can cause an increase or decrease in capillary circulation.
• anastomosis are the shunt vessels that allow blood to bypass around the capillary beds (arterials to veins)

Question 5

Capillaries

Answer 5

Are only one Cell thick endothelium only and are the site of tissue gas exchange

Question 6

Venules

Answer 6

Venules are similar to capillaries at distal end of capillary beds but get larger and can start to have a smooth muscle around them. 

Question 7

Veins

Answer 7

Are larger, more superficial and compliant then arteries may have valves and contain the largest volume of blood 60% of blood reservoir 

Question 8

How does blood pressure initiate

Answer 8

Through ventricular contraction which is periodic

Question 9

How is blood pressure achieved by a pump that is essentially repeatedly turning off and on

Answer 9

Elastic recoil of arteries and peripheral resistance of arterioles

Question 10

Kinetic energy created during Ventricular systole

Answer 10

Is one of the two ways blood pressure is maintained. Kinetic energy a.k.a. elastic recoil is transferred to the expanding walls of the aorta and stored as potential energy then released as kinetic energy again as the artery walls return to an unexpanded state (they recoil) ballooning effect allows for continuous blood flow through rest of vessels.
* also responsible for your pulse

Question 11

Peripheral resistance in maintaining blood pressure

Answer 11

Peripheral resistance is one of two ways to maintain blood pressure. through contraction of vascular smooth muscles around the outside of the arterials.
* smooth muscles exist in a tonic state partially contracted that allows for both dilation and constriction for varying metabolic needs

Question 12

How is blood pressure typically measured and what does it take into account ?

Answer 12

Blood pressure is typically measured through mean arterial pressure MAP
which takes into account the pressure difference between
(ventricular systole - diastole = pulse pressure ) 
MAP= diastolic pressure + (1/3 pulse pressure)

*whiteboard/ YouTube **

Question 13

Why is mean arterial pressure only 1/3 of pulse pressure?

Answer 13

Because diastole lasts about twice as long as systole 

Question 14

What are the four laws that dictate blood flow

Answer 14

Pressure, resistance, volume, flow

Question 15

Define pressure gradient

Answer 15

There must be a difference in pressure for fluids to flow from areas of high pressure to low pressure (pressure)

Question 16

How is pressure usually measured

Answer 16

Millimeters of mercury (mm Hg) or torr (1torr=1mmHg)

Question 17

Define hydrostatic pressure

Answer 17

Fluid in a closed container exerts pressure on the walls of the container.
(Resistance)
* fluid will flow from high pressure to low pressure least path of resistance

[ flow is directly proportional to differences in pressure. P1-P2 = pressure gradient ] no difference = no flow

Question 18

What does flow of blood depend on

Answer 18

The difference in pressures, this allows flow to happen under the driving pressure of a pump example the heart or passively through vasodilation

Question 19

How does mean systemic pressure and mean arterial pressure compare when they move further away from the heart

Answer 19

They are directly proportional going from high pressure in the aorta and lower pressure as it moves away from the heart

Question 20

Where is systolic and diastolic pressure measured

Answer 20

In the arteries and arterioles

Question 21

Flow is inversely proportional to

Answer 21

Resistance (R), meaning that it opposes flow
Flow is directly proportional to 1/R
[^flow=decrease in resistance/ Decrease flow=^ in resistance]

Question 22

Three things that are responsible for creating resistance of flow

Answer 22

1. Radius (r)
2. Length (L)
3. Viscosity (n)

Question 23

Poiseuilles law

Answer 23

Measuring the amount of resistance taking in consideration radius, length, and viscosity

R=8 L n / 🥧 r4
(8and 🥧 are constants so we can drop and simplify)
R= L n/r4

Question 24

Looking at each variable of (R) individually

Length

Answer 24

^ length = ^ resistance :
Imagine trying to drink soda through short straw compared to a long straw, the short one is much easier. In the body the length of the blood vessel is relatively constant so this variable has a little effect on blood flow

Question 25

Looking at each variable of (R) individually | Viscosity

Answer 25

^n=^R: Keep the straws length constant and imagine drinking water compared to thick milkshake, the less viscous the water the much easier it is to drink. Bloods viscosity is determined by the ratio of red blood cells to plasma which is fairly constant

Question 26

Looking at each variable of (R) individually | Radius

Answer 26

^r = less R Now imagine drinking a milkshake with the same length of straw with a larger radius. It’s much easier as the radius increases. *This is the factor that will largely determined resistance and blood flow because our bodies can and do bury the radius of blood vessels through there’s a dilation and construction. *Very small changes in radius have a large effect on flow

Question 27

Flow: change pressure/resistance

Answer 27

Bloodflow can change by altering the pressure differences and or resistance mostly through vessel radius 

Question 28

Velocity of flow

Answer 28

(v measured in cm/min ) Speed of flow Depends on the amount/volume of blood being moved (flow rate Q measured in L/min) And the cross-sectional area of the tube it’s flowing through (A) Mathematically: v=Q/A 

Question 29

Velocity of flow | Vasodilation and vasoconstriction

Answer 29

* Vasoconstriction: less flow rate (Q) / ^velocity (v) | * vasodilation: ^ flow rate (Q) / low velocity

Question 30

Why in the capillaries must blood flow rate be slow

Answer 30

Needs a higher cross-sectional area for gas exchange to happen this is accomplished by increasing the number of capillaries (One aorta but a lot of capillaries therefore increasing cross-sectional area) 

Question 31

Mean arterial pressure is primarily determined by

Answer 31

Cardiac output and peripheral resistance If either heart rate or stroke volume increases then cardiac output and mean arterial pressure also increase

Question 32

How can you maintain a relatively constant blood pressure MAP

Answer 32

By adjusting cardiac output or peripheral resistance

Question 33

What are factors that affect MAP

Answer 33

Cardiac output( HR & SV [ preload {EDV & venous rerun } contractility {ca2+} Afterload ) Peripheral resistance: vasoconstriction vasodilation which are altered by ANS symp ans parasymp chemicals (ACh and Epi)

Question 34

Peripheral resistance is regulated through

Answer 34

Variable Resistance of arterioles that account for 60% of peripheral resistance. Control is through local and systemic mechanisms Local control , sympathetic reflex, hormones Vasoconstriction vasodilation

Question 35

Peripheral resistance local control

Answer 35

Intended to quickly match metabolic needs of the tissues, regulation of blood flow. local control can have a stronger overriding effect to remote ones. Includes: myogenic auto regulation and paracrine signals

Question 36

Myogenic auto regulation of local Peripheral resistance control

Answer 36

Vascular smooth muscle around arterioles have the ability to regulate its own state of contraction. Increased blood pressure makes the arterials constrict (opposite if regular) 

Question 37

Paracrine signals of local Peripheral resistance control

Answer 37

Include gases CO2, O2, NO Active hyperemia: (from activity) as aerobic metabolism increases, O2 levels decrease while CO2 increase which dilates arteries increasing blood flow Reactive hyperemia: increased concentration of NO, and CO2 and other paracrine molecules immediately trigger significant vasodilation and restore tissue blood flow the radius of the arterial gradually return to normal(an increase in tissue blood flow following a period of low perfusion due to occlusion is known as reactive hyperemia)

Question 38

Sympathetic reflexes in peripheral resistance regulation through systemic mechanisms

Answer 38

Act to maintain mean arterial pressure and redistribute blood to various tissues across the body for a homeostatic needs example thermal regulation

Question 39

Example of a sympathetic reflex works

Answer 39

SNS signals maintain vascular muscle tone around most systemic arterioles (but not all) which allows room for both vasoconstriction and vasodilation.

Question 40

Sympathetic reflexes during SNS activation (systemic control) Epi and NE

Answer 40

Fight or flight response Epi and NE : (NE higher affinity) binds to alpha receptors adrenergic ( most systemic arterioles) causing vasoconstriction Epi binds to beta 2 receptors adrenergic ( vascular smooth muscle of heart, liver, skeletal muscle arterioles ) causing vasodilation [beta 1 receptor on Autorythmic cells NE] * there is no SNS innovation to these receptors, it’s solely due to epi-release

Question 41

Hormones on Peripheral and Resistance (systemic)

Answer 41

Hormones have varying affects some simultaneously acting on other homeostatic mechanisms to maintain MAP. Ex: atrial natriuretic hormone (ANP) and angiotensin ii I have both an effect on vasodilation/vasoconstriction, but also regulate excretion of ions and water by kidneys 

Question 42

What are two other factors that are important for maintaining blood pressure besides elastic recoil and peripheral resistance

Answer 42

Distribution of blood in the systemic circuit and blood volume

Question 43

Distribution of blood in the systemic circuit

Answer 43

Recall that most blood about 60% is in the veins as a blood reservoir. If blood pressure suddenly drops the sympathetic nervous system can constrict the veins (venoconstriction) and push the blood into circulation. Therefore ^venous return=^ SV

Question 44

Blood volume maintaining blood pressure (BV)

Answer 44

The circulatory system as a close circuit any addition or removal of blood will increase or decrease blood pressure. - Increase in blood volume can occur through ingestion of food or liquids. The kidneys can control this to some extent urination ( slow response mechanism ) - decrease in blood volume can happen through blood loss or dehydration. The kidneys can slow fluid loss but not very effectively. Cardiovascular responses can help to some extent by increase heart rate and/or stroke volume, vasoconstriction (a fast response)

Question 45

Nutrient demands of oxygen and glucose

Answer 45

Varies from different organs and tissues with metabolic needs and is distributed accordingly through mechanisms we talked about. Total blood flow always equals cardiac output about 5 L per minute and vessels are arranged in a parallel circuit which means arterioles receive blood at the same time from the aorta

Question 46

Total blood flow redistribution can happen through (mechanistic)

Answer 46

Meta-arterioles, increasing/decreasing arterial resistance, and modulation by ANS/hormonal input. Example: at rest most blood flows to liver, kidneys and skeletal muscle about 20% of cardiac output each. When active blood flows to skeletal muscle increases four times to 85% of cardiac output

Question 47

How much of cardiac output flows to the lungs same as Q of pulmonary vessels

Answer 47

5liters per minute

Question 48

What are the two exceptions to the distribution of blood flow (have little neural input on control)

Answer 48

* Cerebral blood flow: remains nearly consistent, just about any cessation of oxygen or glucose supply to the brain will cause unconsciousness and or bring damage * coronary blood flow: follows its metabolic demands more strictly the neural input and has additional local controls to maintain flow (myocardium uses 75% of o2 compared to 25% and other tissues)

Question 49

What controls Organ perfusion through homeostasis a blood pressure

Answer 49

Micro control mechanisms are mainly controlled in the medulla oblongata with input from other parts of the brain what is referred to as a Cardiovascular and Control Center CVCC

Question 50

How does the CVCC monitor MAP?

Answer 50

Through barrow receptors in the carotid artery (monitor BP going to the brain) and aorta (monitoring BP going to the rest of the body) constantly telling the brain the MAP is which is constantly and almost instantaneously making adjustments to all the micro controls HR, SV, PR ETC through baroreceptor reflex

Question 51

If Vessel A constricts it will cause an overall increase in Mean arterial pressure as peripheral resistance increases an adjustmen must be made to bring down mean arterial pressure

Answer 51

- Barrow receptors detect the increase in Mean arterial pressure and a signal is sent to the medulla oblongata (efferent signals are sent to the heart): - decrease in sympathetic input, increase in parasympathetic input> decrease in norepinephrine, increase in ACh release > decrease stimulation of alpha, beta1, beta2 adrenergic receptors by norepinephrine, increase stimulation of cholinergic muscarinic receptors by ACh> decrease in HR and force of contraction (decrease in CO > increase vasodilation > decrease MAP)

Question 52

Three types of capillaries

Answer 52

1. Continuous capillaries: make up most found in the body have a little space between endothelial cells allows passage of gases and ions between or through them paracellular, intercellular, or transcytosis** via vessels. 2. Fenestrated capillaries: have larger pores between endothelial cells that allow higher volumes of fluids between the plasma and interstitial fluid located in the kidneys and small intestines 3. Sinusoids have large gaps between cells up to five times larger than capillaries an incomplete basal lamina that allows passage of blood cells and plasma proteins. Found in bone marrow liver and spleen

Question 53

What determines the density of capillaries

Answer 53

Density of capillary depends on typical metabolic requirements of the tissue think Forman function. More metabolic needs more blood means more capillaries 

Question 54

Hydrostatic pressure

Answer 54

Pressure and Blood pushing from inside vesicles (Ph)

Question 55

Osmotic pressure

Answer 55

‘Pull’ on fluids based on solute concentration

Question 56

Colloid osmotic pressure

Answer 56

Type of osmotic pressure a.k.a. Oncotic pressure. Pulls on fluid by dissolve plasma proteins mainly albumin‘s (🥧)

Question 57

Bulk flow

Answer 57

Mass movement of fluid due to hydrostatic and osmotic pressure gradients

Question 58

Absorption

Answer 58

Bulk flow of fluid into capillaries from interstitial fluid

Question 59

Filtration

Answer 59

Bulk flow of fluid out of capillaries into interstitial fluid

Question 60

Recall that flow depends on a change in pressure, so pressure differences along the length of capillaries either

Answer 60

Deliver fluids (filter) or pick up (absorb) fluids, *positive change in pressure equals filtration and negative change and pressure equals absorption

Question 61

Hydrostatic pressure (Ph) decreases as

Answer 61

As blood moves from one end of the capillary beds to the other end

Question 62

colloid osmotic pressure 🥧

Answer 62

does not change, plasma proteins normally stay in the plasma and are not found in interstitial fluid (or have a negligible effect)

Question 63

Blood coming into capillary beds (arterial end)

Answer 63

Ph=32mmhg; 🥧=-25mmhg; Pressure change = +7 mmhg (same as net filtration occurs at the arterial end)

Question 64

Blood leaving the capillary beds (Venous end)

Answer 64

Ph= 15mmhg;🥧=-25mmhg; Pressure change =-10mmhg (Same as net absorption occurs at venous end)

Question 65

Somewhere along the middle of capillary beds

Answer 65

Ph=🥧; pressure change = 0 (same as no net flow)

Question 66

What happens to blood pressure if Colloid osmotic pressure decreases

Answer 66

(Higher net filtration) Overall there is a net bulk flow of about 3 L of fluid leaving the blood and going to tissues. What happens to all that fluid? Luckily the lymphatic capillaries are there to absorb it as lymph and return it back to the general blood circulation! Otherwise tissue swell up causing edema

Question 67

Cardiovascular diseases

Answer 67

The umbrella term describing problems of the heart and blood vessels. They are the number one cause of deaths worldwide. Myocardial infarction are 85%

Question 68

Vessel Diseases include

Answer 68

Peripheral arterial disease, deep vein thrombosis, pulmonary embolism‘s etc.

Question 69

Heart diseases include

Answer 69

Coronary heart disease (myocardial infarction #1) CHD or a coronary artery disease CAD arrhythmia, heart valve disorders, heart failure. *one exacerbates another eg: peripheral arterial disease > increase risk of CHD , stroke, pulmonary embolism

Question 70

Risk factors uncontrollable and controllable for heart disease

Answer 70

Uncontrollable genetics age and sex | Controllable diet activity weight smoking alcohol diabetes stress hypertension

Question 71

Main causes of heart disease

Answer 71

Atherosclerosis hardening of the arteries, plaque builds up in coronary vessels that includes blood and oxygen supply to the heart. 6.7% of people 20+ years of age have coronary heart disease, 20% of deaths are people 65 years

Question 72

Atherosclerosis is an inflammatory disease tied to the ratio of cholesterol CHL to Lipo proteins therefore my complex that makes CHL more soluble in plasma

Answer 72

HDL - C good cholesterol, LDL - C bad cholesterol. It’s the ratio of each other hi LDL can lead to atherosclerosis

Question 73

Formation of atherosclerosis 3 steps

Answer 73

1. Fatty streak formation: 2. Stable fibrous plaque formation 3. Vulnerable plaque formation

Question 74

Hypertension categories/types

Answer 74

1. Essential hypertension: or primary idiopathic 90% no identical cause other than hereditary but also associated with factors such as obesity salt and alcohol intake 2. Secondary hypertension: has pathological causes such as endocrine and renal diseases

Question 75

Hypertension is linked to

Answer 75

Blood vessel damage atherosclerosis, myocardial infarction, stroke, aneurysm, hydroxy of cardiac tissue due to an increase afterload leading to pulmonary Adema and congestive heart failure, renal failure, blindness, metabolic diseases such as diabetes and dementia

Question 76

Treatments for hypertension

Answer 76

Aside from changing lifestyle habits include •calcium channel blocker‘s that decrease heart contraction force, and increase vasodilation. •Diuretics that decrease blood volume, •beta blockers that decrease the beta one receptor catecholamines stimulation, •ace inhibitors that decrease angiotension a vasoconstrictor