Shared Flashcard Set

Details

Chapter 14 The Cardiovascular System
Test 3
49
Physiology
Undergraduate 2
03/29/2010

Additional Physiology Flashcards

 


 

Cards

Term
Equation for flow rate
Definition
o Flow=pressure gradient/resistance
 ΔP/R
Term
What is the flow of a fluid governed by?
Definition
pressure gradient
Term
What generates pressure difference in the flow equation?
Definition
heart
Term
What has higher pressure? arteries or veins?
Definition
arteries
Term
What are the pressure gradients across the systemic and pulmonary circuits? 
Definition

o   Aortic mean arterial pressure = 90 mm Hg

o   Central venous pressure in large returning veins = 2-8 mm Hg

o   Pulmonary artery pressure = 15 mm Hg

o   Pulmonary venous pressure = 0

Term
 Why are the pressure gradients so different in pulmonary and systemic circuits?
Definition

o  ΔP of pulmonary circuits is much lower than systemic circuit

o   Flow in both circuits is same ~ 5 L/min

o   How? Resistance has to be higher or lower to = 5

Term

    How is the flow rate equal in both the pulmonary and systemic circuits?

Definition

 Resistance has to be higher or lower to = 5

Term

Where is pressure drop the greatest as blood travels through the various types of vessels in the systemic and pulmonary circuits?

Definition

 Pressure drops as blood travels through circuits – 14.3

                               i.   Systemic circuit – starts at 90, ends at 0

                              ii.   Pulmonary circuit – starts at 30, ends at 0

                             iii.   Greatest pressure drop at arterioles

Term
What is resistance? 
Definition

 Resistance impedes blood flow

Term
How does resistance change based on the properties of the vessel or blood itself?
Definition

                               i.   Increased radius, decreased resistance

                              ii.   Increased length, increased resistance

                             iii.   Blood viscosity – increased concentration of cells/proteins, increased resistance

Term

What is total peripheral resistance?

Definition

  Total peripheral resistance (TPR)

                               i.   Combined resistance of all vessels in the systemic network

                              ii.   Vasoconstriction – increased TPR

                             iii.   Vasodilation – decreased TPR

Term

relationship between cardiac output, mean arterial pressure and total peripheral resistance.

Definition

a.   Pressure gradients and resistance

                               i.   Fact: flow = ΔP/R

                              ii.   Flow is cardiac output (CO)

                             iii.   ΔP=MAP

                             iv.   Resistance = TPR

                              v.   Therefore, CO=MAP/TPR

Term

 What are common characteristics of all blood vessels?  How does lumen size and thickness of smooth muscle vary between the different types of vessels?  What is the order of vessels through which blood moves to and from the heart?

Definition

1.  Lumen-hollow interior

2.  Endothelium-lining, release and respond to chemical messengers

3.  Smooth muscle-regulate vessel diameter

4.  CT-vessel strength and elasticity

Term
What does blood pressure detect?
Definition
aortic pressure
Term
Where do you detect BP?
Definition

                                 Brachial artery, close to and same height as heart

Term
What exactly are systolic and diastolic blood pressures?
Definition

                               i.   Systolic-highest pressure, ventricular contraction

                              ii.   Diastolic-minimum pressure, ventricular relaxation

Term
What is laminar and turbulent flow?
Definition

                               i.   Laminar flow-free flow of blood through an artery

                              ii.   Turbulent flow – blood cells hit side of wall, but can slowly flow through artery

Term
How do you calculate pulse pressure?
Definition

                                 Pulse pressure, PP=SP-DP

Term
What does an elevated pulse pressure indicate?
Definition
hardening arteries
Term
What is mean arterial pressure and how is it weighted?
Definition

                               Mean arterial pressure (MAP) is weighted mean, average pressure in arteries during one cardiac cycle: 

MAP=[SP+(2 x DP)]/3

Term
What is the major function of arterioles?
Definition

a.   Arterioles-major regulators of BP and direct blood flow

                               i.   60% of TPR attributable to arterioles

                              ii.   Largest pressure drop

                             iii.   Little elastic material, lots of SM

Term
What properties do arterioles have that helps them perform their major function?
Definition
microcirculation
Term
What is arteriole diameter regulated by?
Definition
SM
Term
Vessel smooth muscle is regulated by what intrinsic mechanisms?
Definition

                               i.   Intrinsic mechanisms-local metabolites that regulated blood flow to match local needs

a.   Intrinsic control

                               i.   Blood flow between different organs and blood flow in regions of same organ

                              ii.   Vasodilation-drop in 02, nutrients, rise in CO2, wastes

                             iii.   vasodilation IRT increased metabolic activity

 

 

Term
Vessel smooth muscle is regulated by what extrinsic mechanisms?
Definition

                               i.   Extrinsic-autonomic nervous system and hormones regulate MAP

a.   extrinsic control by sympathetic innervations

                               i.   NE-binfing to alpha1, receptors cause vasoconstriction

                              ii.   Alpha1 receptors predominate in gut

                             iii.   No parasympathetic innervations of most arteriolarism

 

 

Term
How do hormones affect smooth muscle?
Definition

                               i.   Epinephrine-binding to B2 receptors à vasodilation…………………binding to alpha1 receptors àvasoconstriction

                              ii.   Arteriolar SM of skeletal and cardiac has lots of B2

                             iii.   Arteriolar SM of most other tissues (especially guts) has mostly alpha1

Term
How does ADH regulate blood pressure?
Definition

It acts on the kidneys

                               i.   Antidiuretic hormone (ADH) – posterior pituitary limits urine output, increases blood volume

1.  AKA vasopressinàvasoconstriction in most tissues (at very high doses)

 

Term
How does angiotensin II regulate blood pressure by acting on the kidneys?
Definition

                               i.   Other plasma precursors converted to angiotensin II which promotes vasoconstriction Ang I à Ang II à increased BP

1.  Increased ACE ang converting enzyme

2.  ACE inhibitors-lower BP

Term
How does exchange occur at capillary beds?
Definition

                               i.   Walls are one cell thick

                              ii.   O2, CO2, monosaccharides, amino acids, H20, need to cross only a short distance

                             iii.   Body capillary surface area >600m2

                             iv.   Easy access for all cells

                              v.   Exists in networks (beds)

Term
What are two types of capillaries?
Definition

a.   Most capillaries are continuous

                               i.   14.17

                              ii.   Continuous- relatively tight, proteins cannot leave lumen

                             iii.   Fenestrated- porous, proteins and large species can leave lumen (kidneys and intestines)

Term
Describe the pressure gradient that exists between capillary and surrounding tissue.
Definition

                               i.   ΔP causes flow

                              ii.   ΔP varies along length of capillary

                             iii.   Fluid exchange between capillary and surrounding tissue

Term
What are the 2 types of pressure that occur in capillaries?
Definition

                               i.   Hydrostatic pressure (P)-fluid pressure

                              ii.   Oncotic pressure (π) – osmotic pressure exerted by non-permeable proteins

Term
What are the 4 types of pressures or "starling forces"?
Definition

                               i.   Capillary hydrostatic pressure PCAP

                              ii.   Capillary oncotic pressure πCAP

                             iii.   Interstitual hydrostatic PIF

                             iv.   Interstitual oncotic πIF

Term
How do you calculate net filtration pressure?
Definition

                                Wet filtration pressure (NFP)=(PCAP+ πCAP)

Term
What is the difference between filtration and absorption pressures?
Definition

                               i.   Hydrostatic pressure is only thing that changes significance!

                              ii.   Filtration occurs at arteriolar end, absorption at venule (14.20)

Term

Why is all filtered fluid not absorbed?  Where does the remainder go to?  What happens if the fluid is not returned back to the cardiovascular system?

Definition

a.   Loss of fluid from CAP into IF is retrieved by lymphatic system

                               i.   3 L/day enters lymphatics, eventually returns to blood

                              ii.   Lymph is clear with yellow tinge

                             iii.   Failure of lymph-net accumulation of IF

Term
What is the main function of veins?
Definition

a.   Large veins are large diameter, thin walled

                               i.   Highly compliant volume reservoir

Term
What are the 2 types of veins and what is an important difference between them?
Definition

                               i.   Central veins-in thoracic cavity

                              ii.   Peripheral veins-outside thoracic cavity-equipped with one-way valves

Term
In which vessels are majority of blood found at rest?  During exercise?
Definition

                                  Veins contain highest proportion of blood volume at rest

Term
What are 4 ways to influence venous pressure and return?
Definition
  1. Skeletal muscle pump
  2. respiratory pump
  3. blood volume
  4. venomotor tone
Term
Skeletal muscle pump
Definition
Venous return is aided by skeletal muscle pump.
Term
Respiratory pump
Definition

a.   . Venous return is aided by respiratory pump

                               i.   Inhalation expands rib cage, pulls diaphragm down

                              ii.   Increases abdominal pressure, decreases thoracic pressure

                             iii.   ΔP favors venous return

                             iv.   Exhalation reverses ΔP, but valves in abdominal veins prevent backflow

Term
Blood volume and venous return
Definition

a.   Blood volume influences venous return

                               i.   Increased blood volume=increased venous pressure and increased venous return

                              ii.   Bleeding or dehydration=decreased venous return

                             iii.   Failure to excrete H2O and salts leads to fluid accumulation, hypertension (high MAP)

Term
venomotor tone
Definition

                               i.   Alpha receptors in SM of veins

                              ii.   Contract in response to increased sympathetic output

                             iii.   Increased venous pressure, increased venous return to heart

Term

1.     How do baroreceptors regulate pressure via negative feedback mechanisms?

Definition

a.   Baroreceptors are pressure sensors

                               i.   Relay to control center in brainstem

                              ii.   Increase stretch of vessel causes increased parasympathetic output to SA node, decreased sympathetic

                             iii.   Decreased HR & SV àdecreased MAP

                             iv.   Orthostatic hypotension

Term

What different dysfunctions lead to heart failure?

Definition

a.   Heart failure is inability to maintain adequate CO

                               i.   Weak myocardium (ie myocardial infarction)

                              ii.   Reduced HR through conduction block

                             iii.   Valve obstruction

                             iv.   May affect 1 or both sides

Term
What causes congestive heart failure? 
Definition

a.   Inadequate left ventricle activity leads to congestive heart failure

                               i.   Failure to contract increases left atrial pressure

                              ii.   Decrease in venous return from pulmonary circuit

Pulmonary congestion and edema- shortness of breath, fatigue, death

Term
How is congestive heart failure treated?
Definition

a.   Congestive heart failure treated with digitalis

                               i.   Digitalis inhibits Na+/K+ ATPase

                              ii.   Leads to accumulation of intracellular [Na+]i

                             iii.   Increased [Na+]i leads to increased [Ca2+]i

                             iv.   Increased [Ca2+]i gives stronger myocardium contraction

Supporting users have an ad free experience!