Lymphatics, Pulmonary Circulation/Mechanics/Ventilation, Neural Regulation of Respiration, Exercise Implications

Lymphatic system primary functions, go!

Overflow mechanism (starling), removal of excess proteins, immune response

Lymphatic pathway!

Lymphatic capillaries → vessels → nodes → ducts → venous system → heart

Lower body + L side upper drain into what?

R side upper drain into what?

• Thoracic duct → L IJ and L subclavian veins

• Right lymphatic duct → R IJ and R subclavian veins

Lymph nodes are the - of the system, contain - and -

organs, lymphocytes and macrophages

What are the two primary factors that impact lymph flow?

Interstitial fluid pressure, lymphatic vessel pumping (one-way)

How does exercise change lymph flow?

It increases lymph flow

• Increased hydrostatic capillary pressure, protein return to vasculature, MAP, etc

What are the characteristic of pulmonary and bronchial circulation?

Pulmonary is low-pressure and high-flow, bronchial is high-pressure and low-flow

Pulmonary circulation serves as -

Pulmonary blood flow must = - -

Reservoir

Cardiac output

What is this hydrostatic pressure gradient in the lungs?

• What are the zones and when are they active?

• How would gas exchange change with exercise?

Base is 8 mmHg greater than heart, Apex is 15 mmHg less than

• Zone 1 is no blood flow, Zone 2 (mid lung) is intermittent (systole), Zone 3 is continuous blood flow

• Occurs more in zone 3 (expansion) with increased intensity

What is hypoxic pulmonary vasoconstriction?

When O2 concentration in an alveoli decreases, vasoconstriction occurs to redirect the blood to more oxygen-rich alveoli

Lungs accommodate for increased blood flow during exercise in what ways?

Pulmonary capillary recruitment and distension, increased pulmonary arterial pressure

Increased CO during exercise does not affect - -, despite decreased - to do so

Gas exchange, time (0.8 → 0.3 seconds)

Pulmonary capillary forces have a higher - - - than peripheral ones, still rely on - to prevent - -

Net filtration pressure (1 instead of 0.3), lymphatics to prevent edema (pulmonary)

Respiration requires movement of what two structures in what ways?

Diaphragm: flattens during inhalation

Ribs: upper move like pump handle, lower like bucket handle

Normal quiet breathing phases/needs?

Inspiration: Diaphragm contracts

Expiration: Passive

Heavy or forced breathing phases/needs?

Inspiration: Accessory muscles used (external intercostals)

Expiration: Accessory muscles used (rectus abdominus)

What does surfactant (type II alveolar epithelial cells create it) do for the lungs?

Reduces alveolar surface tension, makes inflation of lungs easier

In order to keep lungs inflated, you want the - - to be more negative than - -

Intrapleural pressure, Barometric pressure

What does transpulmonary pressure calculate and what does it tell us?

It tells us what direction the lungs are going (expansion/recoil)

• it is Palv-Ppl

• if transpulmonary pressure is zero, we have pneumothorax (collapse)

What is…

• Tidal volume

• Inspiratory reserve volume

• Expiratory reserve volume

• Residual volume

• TV is normal amount you breathe in

• IRV is max breath in

• ERV is max breath out

• RV is amount left in lungs after max breath out

How would you calculate…

• Vital capacity

• Functional residual capacity

• Inspiratory capacity

• Total lung capacity

• VC= IRV+TV+ERV

• FRC= ERV + RV

• IC= IRV + TV

• TLC= VC + RV

Lung disorders are either - or -

Obstructive: Lack of air expulsion out of lungs due to blockage/airway resistance

or

Restrictive: Lack of expansion to get air into lungs

FEV vs FVC and what the ratio means at 1 second?

FEV: amt of air expelled at different time intervals

FVC: amt of air expelled after max inhale

• FEV1/FVC should be greater than or equal to 0.8 (lower number indicates obstruction

What is alveolar ventilation rate (VE)?

Rate at which new air reach gas exchange areas (TV*RR= 6L/min)

What is dead space?

Volume of air inhaled that does not participate in gas exchange, anatomical + alveolar = physiologic DS

Bronchodilation is caused by - stimulation of bronchial tree at - receptors

Bronchoconstriction is caused by - stimulation of lung parenchyma at - receptors

Sympathetic, B2 (epi, nor)

Parasympathetic, Muscarinic (Ach)

Describe partial pressure changes for O2 and CO2 through circulation (including pulmonary capillaries)

OXYGEN

PC: 40→104 mmHg (arterial to venous ends)

Systemic: 95 → 40 mmHg (95 due to pulmonary shunted blood

CO2

PC: 45 → 40

S: 40 → 45

During exercise, - - increases but - - stays the same

• How??

Cardiac output, O2 saturation

• Capillary distension and recruitment

What is oxygen saturation?

% of hemoglobin bound to oxygen

How is tissue PO2 determined?

Balance between rate of use by tissues and rate of delivery to the tissues (blood flow)

What is ventilation perfusion matching? what is normal?

Airflow ratio to blood flow (VA:Q), normal is 1

Where is the respiratory center?

• What are the groups?

Located in medulla and pons

• Dorsal for inspiratory rhythm (in NTS), Ventral for heavy expiration

What is the pneumotaxic center?

Switches off inspiratory ramp (limits filling time)

What is the goal of respiration?

Maintain/regulate proper levels of O2, CO2, H+

What does the chemosensitive area primarily respond to?

Changes in CO2, H+ (increases RR in response)

How can kidneys help with blood acidity?

Release bicarbonate

Peripheral chemoreceptors in - -, detect much faster than -

Carotid bodies, central

Ventilation is primarily driven by what in healthy vs hypoxemia conditions?

CO2 and H+ in healthy, O2 in hypox

How do people at high altitudes respond?

Hyperventilation, Erythropoiesis

What is central command?

Parallel activation of muscles (motor) and respiration (ANS)

Describe the mechano/metabo interaction with ventilation during exercise!

Group III afferents (mech) and IV (met) sent to dorsal horn, Dorsal group in NTS raises ventilation

What is the hering breuer inflation reflex?

Protective reflex to inhibit respiration slightly when lungs too stretched

Primary fuel source is -.

• What are the three responses?

Oxygen (ATP)

• Increased oxygen consumption (ventilation), increased cardiac output, changes in blood flow (BP increases)

What is VO2 max and what is Fick’s equation?

VO2 max is the maximum rate of oxygen consumption achievable during exercise

• VO2= HR * SV * (A-V O2 difference)

With acute exercise, what goes up in CO formula?

All elements (HR, SV, CO)

• SV plateaus early, HR goes up linearly

What changes with sympathetic for…

• Coronary arteries

• Vessels in general

• Near muscle (functional sympatholysis)

• Pulmonary capillaries with low O2 (Pulmonary Hypoxic Vasoconstriction)

• Vasodilate

• Vasoconstrict

• Vasodilate

• Vasoconstrict to redirect

What is pulse pressure? What does it mean to be less or greater than 30-40?

PP= SBP-DBP, wider for increased SV/TPR and narrower for reduced cardiac output

What are some vasodilators?

Adenosine, potassium, lactic acid, CO2, nitric oxide (shear stress)

What does A-V O2 difference looking out?

Amount of oxygen extracted from the blood

Total blood flow -, plasma -, hematocrit -

up, down, up

HR increases - bpm per MET

Systolic - per, diastolic - per MET

ECG and SPO2 should be - throughout

10

10, 0 (or decrease)

Normal

Post-exercise:

HR should go down by approximately - bpm

BP should be normal after - minutes

12

6

What are the chronic changes with exercise?

• HR

• SV

• CO

• A-V O2 difference

• VO2 max

• Decreases

• Increases

• Increases during max workloads

• Increases

• Increases (mainly due to CO)

Chronically.. what happens with capillaries, arteries, blood volume?

More # of capillaries, increased capillary density, local arterial expansion, increased blood volume

Resting BP should - with chronic exercise

Decrease

What BP would rule out exercise testing?

Greater than 180/105

x protocol for clinical populations, y protocol for athletes

Bruce, Balke

What are some warning signs for exercise intolerance?

Lack/excessive HR changes, resting tachycardia, excessive dyspnea, fatigue

What is a primary brain area to remember for central command?

Periventricular nucleus of the hypothalamus

Baroreflex is set to a new - - during exercise

Operating point

Baroreflex checks changes in - - to manage - -, cardiopulmonary reflex checks senses - - to manage - -

arterial stretch (BP), venous filling (blood volume)

Group III/IV → _ (_) → Sympathetic stim (-) → Local BV near muscle → - -

Brain (ergoreflex), (NE), functional sympatholysis

What do patients with CHF demonstrate?

High sympathetic activity, depressed parasympathetic modulation, attenuated baroreflex, exaggerated pressor reflex, massive bodily vasoconstriction and reduced local vasodilation