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Exercise Physiology > CH. 6 & 7 - Cardiovascular System and Respiration > Flashcards

CH. 6 & 7 - Cardiovascular System and Respiration Flashcards

1
Q

cardiovascular system function

A
  • > delivers nutrients and O2
  • > removes CO2 waste
  • > transports hormones
  • > immune function
  • > acid-base balance
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2
Q

3 major circulatory elements

A
  1. Heart
    - > generates pressure to drive blood through vessels
  2. Channels (Blood vessels)
  3. Fluid
    - > BF must meet metabolic demands
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3
Q

anatomy of the hear

A

4 chambers

  • > R/L atrium (receiving)
  • > R/L ventricles (pumping)

all of which covered in thick sac called pericardium and pericardial fluid (fills the thin cavity between the heart and pericardium)

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4
Q

explain blood flow through R and L heart

A

R heart (pulmonary circulation)

  • > pumps deox blood from body to lungs via…

sup vena cava - > R atrium - > tricuspid valve - > R ventricle - > pulmonary valve - > pul arteries - > lung

L heart (systemic circulation)

  • > pumps oxy blood from lungs to body

lungs - > pulmonary veins - > L atrium - > mitral valve - > LV - > aortic valve - > aorta

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5
Q

mycardium

A

aka cardiac or myocardial muscle

  • > myocardial thickness varies according to the amount of stress regularly placed on the myocardium
  • > LV has the most myocardial/thickest walls (hypertrophy)
  • > only has 1 fibre type (similar to type 1; high mitochondria, striated)
  • > connected by intercalated discs

*desmosomes hold cells together and gap junctions rapidly conduct AP

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6
Q

myocardial vs skeletal muscle cells

A

Myocardial cell

  • > continuous, involuntary rhythmic contractions, short, branched and one nucleus

Skeletal

  • > large, long, multi-nucleated, intermittent, voluntary contraction, Ca released from SR
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7
Q

myocardial blood supply and their branches

A

R Coronary Artery

  • > supplied R side of heart
  • > divided into marginal, post interventricular arteries

L coronary artery (main)

  • > supplies L side of heart
  • > divides into circumflex and ant descending arteries
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8
Q

artherosclerosis

A

coronary heart disease

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9
Q

4 main components of the cardiac conduction system

A

Sinoatrial (SA) node

  • > Atrioventricular (AV) node
  • > AV bundle
  • > Purkinje fibres
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10
Q

arterial and venous O2 content

A

Arterial

20mL O2/ 100ml blood

Venous

At rest

  • > 15-16mL O2/ 100mL blood

Heavy exercise

  • > 4-6 mL O2/100mL blood
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11
Q

intrinsic controls of heart activity

A

cardiac muscle has the ability to generate its own electrical signal, this is called spontaneous rhythmicity

  • > electrical signals spread via gap junctions
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12
Q

SA node

A

initiates contraction signal

  • > pacemaker cells in upper post RA wall
  • > signal spreads from SA node via RA/LA to AV node
  • > stimulates RA, LA contraction
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13
Q

AV Node

A

delays and relays signals to ventricles

  • > in RA wall near centre of heart
  • > delay allows for RA,LA to contract before RV and LV (Fill)
  • > relays signal to AV bundle after delay
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14
Q

AV bundle

A

relays signal to RV and LV

  • > travels along interventricular septum
  • > divides into R and L bundle branches
  • > sends signal to apex of hear
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15
Q

purkinje fibres

A

send signal into RV and LV

  • > terminal branches of R and L bundle branches
  • > spread throughout ventricle wall; stimulates RV and LV contraction
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16
Q

extrinsic control of heart activity

A

parasympathetic and sympathetic nervous control

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17
Q

parasympathetic nervous system control over the heart

A

reaches heart vis vagus nerve (cranial nerve nerve X 10)

  • > carries impulse to SA and AV nodes
  • > signals the release of Ach

*dec. HR and force of contraction

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18
Q

sympathetic nervous control over the heart

A
  • > opposite effect of Para NS
  • > carries impulse to SA and AV nodes
  • > releases norepinephrine

*inc HR and force of contraction

  • > endocrine system has similar effect
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19
Q

cardiac arrythmias

A
  • > bradycardia (RHR lower than 60bpm) and tachycardia (RHR higher than 100bpm)
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20
Q

cardiac cycle

A

all mechanical and electrical events that happen during 1 heart beat

  • > diastole (fill) is twice as long as systole (pump)
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21
Q

stroke volume (SV)

A

volume of blood pumped in one heart beat

  • > during systole; most (not all) blood ejected

SV = End diastolic volume (EDV) - End systolic volume (ESV)

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22
Q

ejection fraction (ef)

A

% of EDV pumped out

SD/EDV = EF

  • > clinical index of heart contractile function
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23
Q

Cardiac output (Q)

A

total volume of blood pumped per minute

Q = HR x SV (L/min)

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24
Q

resting Q

A

around 4.2 - 5.6 L/min

(avg total blood volume is around 5L)

  • > total BV circulates once every minute
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25
Q

what is required by all tissues

A

blood flow

26
Q

what is pressure; relate it to blood flow

A

a force that drives flow

  • > provided by heart contraction
  • > bloods flows from regions of high pressure (LV arteries) to regions of low pressure (veins and RA)
27
Q

resistance

A

force that opposes flow

  • > provided by physical properties of a vessel
  • > radius (r) is the most importnant factor
28
Q

blood flow formula

A

p/R

  • > pressure/radius
  • > easiest way to change BF is to change the radius of the vessel (vasoconstriction/dilation
29
Q

characteristics of arterioles

A
  • > controls systemic R
  • > site of most potent VC and VD
  • > responsible for 70-80% of pressure from LV to RA
30
Q

characteristics of the distribution of blood

A

it goes to where its needed the most

  • > often regions of increased metabolism = increase BF
  • > blood flow changes after eating and in heat
31
Q

describe blood distribution at rest and during heavy exercise

A

At rest (Q=5L/min)

  • > liver and kidneys receive 50% of Q
  • > skeletal muscles receive 20ish%

Heavy exercise (Q=25L/min)

  • > exercising muscles receive 80% of Q via VD
  • > flow to liver, kidneys decrease via VC
32
Q

intrinsic control of blood flow

A

Metabolic mechanisms (VD)

  • > buildup of local metabolic by-products
  • > decrease availability O2, increase CO2, K, H, lactate

Endothelial mechanisms (mostly VD)

  • > substances secreted by vascular endothelium
  • > Nitric oxide (NO), prostaglandins, EDHF

Myogenic mechanisms (VC,VD)

  • > local pressure changes can cause VC and VD
  • > increase pressure = increase VC; decrease pressure = increase VD
33
Q

extrinsic (neural) controls of blood flow

A

the redistribution of flow at organ system level is controlled by neural mechanisms

  • > sympathetic NS innervates smooth muscle in arteries and arterioles
  • > it extrinsic because the control comes from outside the specific area
34
Q

what are the effects of baseline, increased and decreased sympathetic activity

A

baseline activity

  • > vasomotor tone; a constant, moderately contracted state to maintain adequate BP

Increased activity

  • > causes increased VC

Decreased activity

  • > causes decreased levels of VC (passive VD)
35
Q

what is the purpose of the respiratory system; what carries out this process

A

to carry O2 and remove CO2 from all body tissues

carried out by 4 processes…

  • > pulmonary ventilation (external resp.)
  • > pulmonary diffusion (external resp.)
  • > transportation of gases via blood
  • > capillary diffusion (internal respiration)
36
Q

pulmonary ventilation

A

process of moving air into an out of the lungs

  • > transport and exchange zone
  • nose, mouth, nasal conchae to pharynx to larynx to trachea to bronchial tree to alveoli*
37
Q

explain the process of inspiration

A
  • > its an active process that involves the flattening of the diaphragm and the elevation of the ribcage and sternum by the external intercostals
  • > this expands thoracic cavity, volume inside thoracic cavity and lungs
  • > as lung vol increases intrapulmonary pressure decreases
  • > air passively rushes in due to pressure difference
38
Q

forced vs normal inspiration

A

forced breathing uses additional muscles

  • > scalenes
  • > sternocleidomastoid
  • > pectorals
  • raise ribs even further*
39
Q

Boyle’s Gas Law

A

states that pressure and volume are inversely correlated

  • > If volume increases, then pressure decreases and vice versa, when the temperature is held constant.
40
Q

explain the process of expiration

A

usually a passive process

  • > inspiration muscles relax and lung volume decreases, intrapulmonary pressure increases

if it is active (forced breathing)

  • > internal intercostal muscles pull ribs down, abdominal muscles force diaphragm back up
41
Q

types of pulmonary volumes

A

measure using a technique called spirometry

Tidal Volume

  • > amount of air entering and leaving the lungs with each breath

Vital Capacity (VC)

  • > the greatest amount of air that can be expired after maximal inspiration

Residual Volume (RV)

  • > the amount of air remaining in the lungs after maximal expiration, cannot be measured with spirometry

Total lung capacity (TLC)

  • > sum of VC and RV
42
Q

respiratory membrane

A

where gas exchange between the air in the alveoli and the blood in the pulmonary capillaries occurs

comprised of…

  • > the alveolar wall
  • > the capillary wall
  • > their respective basement membrane
43
Q

main 2 functions of pulmonary diffusion

A

replenish blood O2 supply and remove CO2 from the blood

44
Q

explain the process of pulmonary diffusion

A

it’s gas exchange between alveoli and capillaries

  • > inspired air path: bronchial tree then goes to alveoli
  • > blood path: ventricles - > pulmonary trunk - > pulmonary arteries - > pulmonary capillaries (capillaries surround alveoli)
45
Q

composition of air

A
  1. 04% nitrogen
  2. 93% O2
  3. 03% CO2
46
Q

total air pressure (atmospheric pressure)

A

760mmHg

total air P = PNitrogen + POxygen + PCO2

P = 600.7 + 159.1 + 0.2mmHg

47
Q

henry’s law

A

gases dissolve in liquids in proportion to partial pressure

partial pressure: the individual pressures from each gas in a mixture

48
Q

why are partial pressure gradients important in determining gas exchange

A

par. press is the most important factor for determining gas exchange as pp gradients drive gas diffusion
- > without gradient, gases are in equilibrium and there is no diffusion

49
Q

explain the change of oxygens partial pressure as it goes through the body

A

outside the body (atmospheric P)

  • > 159mmHg

when air is inhaled and enters the alveoli

  • > 105mmHg

enters the pulmonary capillary with a PO2

  • > 40mmHg

PO2 across respiratory membrane

  • > 65mmHg
50
Q

ficks law

A

rate of diffusion is proportional to the surface area and partial pressure gas gradient

51
Q

oxygen diffusion capacity

A

the rate at which oxygen diffuses from alveoli into the blood

52
Q

lung O2 diffusion capacity at rest vs during exercise

A

At rest

  • > diffusion capacity is limited to to incomplete lung perfusion
  • > only bottom ⅓ of lung is perfused with blood
  • > top ⅔ have poor gas exchange due to due to less blood due to gravity and weak contractions

During Exercise

  • > O2 diffusion capacity increases due to more even lung diffusion throughout the lung
  • > systemic BP increases and opens top ⅔ of lung for perfusion; gas exchange over full lung area
53
Q

explain the change in PCO2 in the lung

A

PCO2 in pulmonary artery = 46mmHg

PCO2 in alveoli is 40mmHg

  • > although this pressure gradient is small (6mmHg) the gradient still permits for diffusion
  • > diffusion is allowed despite the low gradient due to CO2 diffusion constant being 20x greater than O2
54
Q

oxygen transport capacity of blood

A

can carry around 3ml of O2/1L of plasma

  • > 98% is bound to hemoglobin (Hb) in RBC
  • > >2% is dissolved in plasma
55
Q

Hb +/- O2

A

Hb + O2 = oxyhemoglobin

Hb alone = deoxyhemoglobin

56
Q

Hb saturation

A
  • > depends on PO2 and affinity between hemoglobin and O2

High PO2 (in lungs)

  • > loading portion of O2-Hb dissociation curve
  • > small change in Hb saturation per mmHg change in PCO2

Low PO2 (in body tissues)

  • > unloading portion of O2-Hb dissociation curve
  • > large change in Hb saturation per mmHg change in PO2
57
Q

factors that affect Hb saturation

A

blood pH

  • > more O2 unloaded at acidic exercising muscles

blood temp

  • > warmer blood promotes tissue O2 unloading during exercise

inc pH and decreased temp will increase O2-Hb saturation; hot and basic will decrease saturation

58
Q

CO2 transport

A

CO2 is released as waste from cells

Carried in the blood in 3 ways…

  • > as bicarbonate ions (60-70% of CO2 in blood to lungs)
  • > dissolved in plasma (7-10)
  • > bound to Hb (carbaminohemoglobin; 20-33%)
59
Q

oxygen transport in muscle

A

O2 transported in muscle by myoglobin

  • > similar structure as Hb but has a higher affinity to O2
60
Q

arterial-venous oxygen difference

*(a-v) O2 difference

A

the difference between arterial and venous O2 levels

  • > reflects tissue O2 extraction; as extraction inc, venous O2 decreases, (a-v) O2 difference increases

Exercise Physiology (19 decks)

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