Pulmonary and Peripheral Systems

The hearts supply to itself is part of the

systemic circulation

Deoxygenated (O2-poor) blood return enters ______________with small amount from coronary sinus

RA via SVC and IVC

In pulmonary circulation where does blood go from RA?

to RV via TV

From the right ventricle where does blood go?

Pulmonary trunk via pulmonary valve

Pulmonary trunk to L and R pulmonary arteries, to smaller pulmonary arterioles, and finally to capillaries where

gas exchange (discharging CO2 and picking up O2).

In the lungs, gas exchange happens in the

alveoli

Pressure in capillary bed in pulmonary circulation

the artery behaves like a vein because they have a thinner wall and less smooth muscle

Main function of pulmonary circulation is

• Gas exchange

• Filtering blood: remove micro emboli

• Metabolic regulation of hormones

• Endothelium keeps homeostasis

Inflammation/infection damages this endothelium results in

extravasation of proteins, cells, and fluid

Pulmonary Circulation and Lymphatic System

• keep alveolar membrane dry and helps drain pleural fluid

• With venous drainage, it helps create negative pleural pressure (-4 to -7 mmHg) helping alveoli to tether to visceral pleura, avoiding collapse

Bronchial vasculature (blood supply for the lungs) is part of ________ circulation.

systemic

Bronchial vasculature supplies blood to the

tracheobronchial tree and terminal bronchioles

What are the two pathways for the bronchial veins?

1. Deep bronchial veins 

2. Superficial veins

Deep bronchial

veins partially drain into pulmonary venous system then to LA (~0.5% total return).

Superficial bronchial

veins drain into azygos veins on the right, and hemiazygos vein on the left, part of systemic venous system.

ABG is 

Arterial Blood Gas

Normal pH for blood is

7.35 - 7.45

Alkalosis

• too much bicarbonate in the blood

• a condition in which the body fluids have excess base

• pH 7.45 or higher

Acidosis

• caused by an overproduction of acid that builds up in the blood, an excessive loss of bicarbonate from the blood, or by a buildup of carbon dioxide in the blood that results from poor lung function or depressed breathing

• pH 7.35 or lower

What HC03?

bicarbonate

What is bicarbonate and why is it important?

Bicarbonate is also known as HCO3. It's a byproduct of your body's metabolism. Your blood brings bicarbonate to your lungs, and then it is exhaled as carbon dioxide. Your kidneys also help regulate bicarbonate. Bicarbonate is excreted and reabsorbed by your kidneys.

Hydration and Dehydration process

Cells release CO2, brought to lungs by blood as Bicarb (HC03) and again exhaled as CO2.

Describe the buffering system of the blood. 

Buffering system in the blood keeps the balance between Carbonic acid (H2CO3), and Bicarbonate (HCO3-) so the body maintains homeostasis.

Pulmonary Vascular Resistance (PVR)

• Resistance against blood flow from 4 pulmonary veins to the LA

• Low pressure. It is 1/10 of the systemic vascular resistance (SVR)

PVR Formula is

PVR = (Mean PAP - LAP / CO) x 80

Normal measurement for PVR is 

Normal is .25-1.6mmHg.min/L

Pulmonary resistance (and blood flow distribution) is highest in

the capillaries unlike systemic circulation

Normal artery pressure (PAP) is

25/10 mean is 15mmHg.

PVR is influenced by

• Pulmonary intravascular pressure

• Lung volumes

• Gravity (highest in PVR zone 1 from higher alveolar pressure)

• Alveolar hypoxia

• Smooth muscle tonicity, less smooth muscle

Pulmonary vascular pressure (CO=Cardiac output)

When CO increases, PVR decreases, increasing flow to alveoli, facilitating gas exchange such as in exercise. This happens by capillary distention and recruitment.

Alveolar hypoxia

(sensed by chemoreceptors) induces vasoconstriction, shunting blood to better areas

Smooth Muscle Tonicity; lower vascular tone, less smooth msucle

Increasing PVR: serotonin, epi, norepi, thromboxane A. Pulmonary. Endothelial cells cause vasodilation by producing nitric oxide (NO).

Why is nitric oxide important?

Allows for vasodilation 

Gas Exchange

• Gases can dissolve and diffuse between the lungs and the circulatory system. Oxygen diffuses into red blood cells. Co2 diffuses into alveolus. This is why we breath.

• Pick up oxygen and discharge C02.

Additional Controls: Baroreceptors

Stretch-sensitive baroreceptors are present throughout the vasculature playing a role in BP regulation

Low pressure baroreceptors

cardiopulmonary baroreceptors

Sympathetic stimulation via ____ _____ increases vascular resistance.

Alpha receptors

Parasympathetic _______ ______ vasorelaxation of pulmonary arteries

cholinergic-mediated

Parasympathetic ______ arteries

relaxes, dilates

Hormones involved in pulmonary circulation control

thyroid, serotonin, estrogen, progesterone 

Peripheral circulation

Blood vessels provide channels of delivering O2 and nutrients to body tissues

Elastic vessels

large artery, especially aorta, low resistance

Resistance in vessels 

• Resistance (< 1mm, small arteries and arterioles) ~90% of SVR.

• Normal SVR = 700-1500 dynes/sec/cm- 5

• SVR = (MAP – RA or CVP/CO) x 80

Major resistance vessels in systemic circulation is

arterioles

Capacitance

large veins that can store and mobilize large amounts and regulate venous return

Vessels can 

shunt or clamp down and send blood back to vital organs

Local arteriole is modulated by

ANS (primarily sympathetic) and cause blood vessel constriction and in the heart vasodilation

ANS predominates in ____

skin, splanchnic, and resting skeletal muscles

Increased O2 consumption and release of CO2 results in ________, increased blood flow.

vasodilatation

Vasconstriction

decreases vessel diameter, increasing resistance

Vasodilation

increases vessel diameter – reducing resistance

Microcirculation

Arterioles + Capillaries+ Venules

How does sympathetic nervous system affect systemic blood vessels?

• In blood vessels, sympathetic activation constricts arteries and arterioles (resistance vessels), which increases vascular resistance and decreases distal blood flow.