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Your TA reminding youβ¦
β’ 2nd Quiz (1%)β’ Opens: Dec 2nd @ 4pmβ’ Closes: Dec 4th @ 4pm
β’ 2nd Midterm (15%)β’ When: Dec 19th @ 9am-10amβ’ Room Assignments:
β’ ABBA-GANE: Alumni Hall 15β’ GHAB-POSA: Alumni Hall 201β’ PRIM-WOOD: Alumni Hall Stageβ’ WU-ZIA: Somerville House 2316
β’ 2nd Midterm review sessionβ’ When: Monday Dec 16th from 6-8pm β’ Where: Auditorium B University Hospital, 3rd floor
Today
β’ Group work activity
β’ Learning Catalytics Question
β’ Almost finish cardiovascular anatomy
Heart Rate (HR)
β’ Average: 70 bpm
β’ Lower HR = βhealthierβ (i.e. athletes: 45 bpm)
β’ Max HR = 220 β age
β’ Controlled by autonomic nervous systemβ’ PS-NS: decreases HR
β’ S-NS: increases HR
Stroke Volume = EDV -ESV
β’ End-Diastolic Volume (EDV): volume of blood in ventricles at end of ventricular diastole (just before they contract; end of Phase 1)
β’ End-Systolic Volume (ESV): volume of blood in ventricles at end of ventricular systole (just after contraction; end of Phase 3)
β’ Stroke volume = EDV βESV
= 160 ml β90 ml
= 70 ml
β’ Altering either EDV or ESV will change stroke volume
Cardiac output can be determined by which of the following formulas?
A. HR β SV
B. HR divided by SV
C. HR + SV
D. HR x SV
Cardiac output can be determined by which of the following formulas?
A. HR β SV
B. HR divided by SV
C. HR + SV
D. HR x SV
Cardiac Output (CO)β’ Volume of blood pumped by each ventricle per minute
β’ CO = Heart Rate x Stroke Volumeβ’ Heart Rate = Beats per minuteβ’ Stroke Volume = Amount of blood pumped by each ventricle per beat
β’ At rest:β’ CO = 5 L/minβ’ HR = 70 beat/min β’ SV = 70-80 mL/beat β’ CO = (70 beat/min)(0.07 L/beat) = 4.9 L/min
β’ During exercise:β’ CO can increase to 20-40 L/min β’ How? By changing HR and/or SV!
Which of the following is INCORRECT regarding diastole (filling of the heart)?
a. Atrioventricular valves are open.
b. Semilunar valves are closed.
c. Blood is flowing from the atria into the ventricles.
d. Pressure in the ventricles is greater than in the atria.
Which of the following is INCORRECT regarding diastole (filling of the heart)?
a. Atrioventricular valves are open.
b. Semilunar valves are closed.
c. Blood is flowing from the atria into the ventricles.
d. Pressure in the ventricles is greater than in the atria.
Overall Control of SV by ANS
β’ Stroke volume is amount of blood pumped by each ventricle per beat
β’ Two factors that affect stroke volume:β’ ANSβ’ Preload (End diastolic volume)
β’ PS-NS decreases SVβ’ Ca2+ flow into cardiac cellsβ’ force of contraction
β’ S-NS increases SVβ’ Ca2+ flow into cardiac cellsβ’ force of contraction
Stroke Volume
β’ During exercise, the S-NS is activated:β’ Heart contracts more forcefully and ejects
more blood
β’ Thus, ESV decreases
β’ Meanwhile, the heart is filling with more bloodβ’ Thus, EDV increases
Stroke Volume and Preload
β’ Preload: The βloadβ on the cardiac muscle before contraction
β’ This βloadβ comes from the blood in the ventricles that stretches the ventricular muscleβ’ Thus, higher EDV = greater preload
PNS Effect on HR
β’ PNS innervates SA and AV nodes through vagus nerveβ’ PNS releases Ach, which binds to
receptors on cells of SA and AV nodes
β’ K+ permeability (i.e. more exits cell) and Ca2+ permeability (i.e. less enters cell)
β’ Net effect: β’ K+ = HYPERPOLARIZATIONβ’ Ca2+ = Decreases slope of pacemaker
potential
SNS Effect on HRβ’ SNS innervates SA, AV nodes and
ventricular musclesβ’ SNS releases NE, which binds to
receptors on cells of nodes and muscle
β’ Na+ and Ca2+ permeability (i.e. more enters cell)
β’ Net effect: DEPOLARIZATION and increased slope of pacemaker potential
Which graph represents sympathetic influence on heart rate (in both cases the
light grey line is under resting conditions)?
Which graph represents sympathetic influence on heart rate (in both cases the
light grey line is under resting conditions)?
Summary of ANS Control of Heart Rate
PSNSβ’ Acetylcholine released onto these areas
β’ Increase K+, decrease Ca2+ permeabilitiesβ’ Decreases slope of pacemaker potential
SNSβ’ Release norepinephrine onto these areas (indirect:
epinephrine)β’ Increases heart rate and force of contraction
β’ Increase Na and Ca permeabilityβ’ Increase slope of pacemaker potential
Frank-Starling Law
An increase in EDV = An increase in preload
Increases the stretch of myocardial cells
Increases the force of contraction of these cells when the heart contracts
Increases the amount of blood ejected
Increases Stroke Volume (Increases Cardiac Output)
β’ Frank-Starling Law states that βan increase in EDV will increase stroke volumeβ
Frank-Starling Law and Venous Return
β’ How to increase EDV? Increase venous return to the heart!
β’ During dynamic exercise:
1. Muscle Pump: Contracted skeletal muscle around veins pushes blood to heart
2. Respiratory Pump: Changes in pressure during breathing pushes blood towards the heart
3. S-NS: Constriction of veins squeezes blood to heart
The aortic semilunar valve prevents blood from returning to the _____.
A. left ventricle
B. Aorta
C. Right ventricle
D. Left atrium
The aortic semilunar valve prevents blood from returning to the _____.
A. left ventricle
B. Aorta
C. Right ventricle
D. Left atrium
Blood Vessels
β’ Structural properties of vessels are what contribute to the blood pressure characteristics seen in circulation
Relationship Between Pressure, Flow and Resistance (Page 232)
πΉπππππππππ =π³ πΌ
ππ
πΉπππππππππ =π
ππ
π©ππππ ππππ =π·πβπ·π
π
ππ
= π·π β π·π β ππ
L = length of vesselπ = viscosity of the fluidr = radius of the vessel
A small change in radius will have a LARGE effect on blood flow
Just know this part of the equation
Relationship Between Pressure, Flow and Resistance
π©ππππ ππππ = π·π β π·π β ππ
π©ππππ ππππ = π β π β ππ
π©ππππ ππππ = π L/min
π©ππππ ππππ = π·π β π·π β ππ
π©ππππ ππππ = ππ β π β π. ππ
π©ππππ ππππ = π. π L/min
A small change in radius will have a LARGE effect on blood flow
Defining termsβ’ Blood velocity (cm/sec): speed at which
blood is moving through particular blood vesselβ’ Fluid flows faster through a narrow tube
than a larger tube
β’ As cross sectional area increases mean velocity decreases
β’ Blood flow (L/min): volume of blood moving through set of vessels.
Overall blood flow does not changeβ’ Blood velocity can change but total blood flow needs to
remain constantβ’ If you have 5L of blood you canβt add or subtractβ¦ unless you have a wound
Arteries and Veinsβ’ Contain three layers:β’ Outer Layer β Tunica externa
βͺ Fibrous connective tissue
β’ Middle Layer β Tunica mediaβͺ Smooth muscle and elastic tissue
β’ Inner Layer β Tunica internaβͺ Endothelial cells
β’ Veins contain valves
β’ Capillaries have single layer of endothelial cells
Aorta and Large ArteriesBlood Characteristics Structure Purpose
Aorta/Large Arteries
- High blood pressure- 80-120 mmHg- High blood velocity
- Large diameter- Elastic tissue- Thin wallsβͺ Easily distendedβͺ Low resistance to blood flowβͺ Small drop in blood pressure
- βShock absorbersβ- Distribute the blood
CapillariesBlood Characteristics Structure Purpose
Capillaries
- Low blood pressure- Small drop in blood
pressure- Very low blood velocity (1-
2 cm/sec)
- One endothelial cell thick- Large cross sectional area- Very large surface areaβͺ Diffusion of gas, nutrients and
waste
- Exchange vessels
VeinsBlood Characteristics Structure Purpose
Veins
- Low blood pressure- Low to medium blood
velocity (5-10 cm/sec)
- Very thin walls with large diameter
- Contain valves- Some elastic tissue- Smoth of smooth muscle
innervated by ANSβͺ Vasoconstriction/dilation
- Capacitance vessels: 70% of TBV
Starling Forcesβ’ Two hydrostatic pressuresβ’ Capillary hydrostatic pressure
β’ Interstitial fluid hydrostatic pressure
β’ Two osmotic pressuresβ’ Plasma osmotic pressure
β’ Interstitial osmotic pressure
Exchange In Capillariesβ’ Diffusion
β’ Down concentration gradients
β’ Oxygen, CO2, O2, lipid soluble substances
β’ Filtration and reabsorption (Starling forces)β’ Filtration: movement of fluid out of capillary
β’ Reabsorption: movement of fluid back into capillary
Capillary Hydrostatic Pressure (Pc)β’ Pressure exerted by fluid in the capillary
β’ Pressure drives fluid OUT of capillary and is generated by ventricular systole (Filtration)
25 mmHg10 mmHg
Interstitial Fluid Hydrostatic Pressure (PIF)β’ Pressure exerted by fluid in the interstitial space between
cells in the tissue
β’ Movement depends on pressure in the tissueβ’ Can be negative β Filtration into tissue
β’ Can be positive β Reabsorption into capillary
Subcutaneous tissues: -6mmHgInterstitial fluid: +6mmHg
Interstitial Osmotic Pressure (π IF)β’ Pressure caused by osmosis due to few proteins in interstitial
fluid (5mmHg)
β’ Pressure drives fluid OUT of capillary and into tissue (Filtration)
Plasma Osmotic Pressure (π P)β’ Pressure caused by osmosis due to proteins in plasma
(28mmHg)
β’ Pressure drives fluid INTO capillary (Reabsorption)
Balance of Starling Forcesβ’ Starling-Landis equation used to calculate net
fluid movement (NFM) across capillary bedππΉπ = πΎπ ππ β ππΌπΉ β ππ β ππΌπΉ
β’ πΎπ is filtration coefficient, which represents permeability of capillary (assume 1)ππΉπ = 1 25 β (β6) β 28 β (+5)ππΉπ = +8πππ»π
β’ If positive filtration OUT of capillary, if negative reabsorption INTO capillary
PC = 10, PIF = 1, ΟIF = 5, ΟC = 28
β’ππΉπ = πΎπ ππ β ππΌπΉ β ππ β ππΌπΉβ’ππΉπ = 1 10 β (1) β 28 β 5
β’ππΉπ = 1 9 β 23
β’ππΉπ = β14
β’ Thus, reabsorption into plasma from interstitial fluid