Physiology 3120 Lecture Notes - Lecture 30: Pulmonary Vein, Pulmonary Artery, Pulmonary Circulation
2 May 2018
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Human Physiology Lecture 30
The Cardiovascular System
November 24 2017
Functions of the CV System – role as a transport system
- Homeostasis!! – maintenance of the internal environment
o Transports oxygen and nutrients to the various tissues of the body .
▪ Tissue needs oxygen to make ATP
o Transports carbon dioxide and waste products from the tissues to the external
environment.
o Regulates body temperature (by transporting excess heat out of the body or conserving
heat)
▪ Too hot – blood vessel divert blood toward skin, away from core
▪ Too cold – blood vessel divert blood toward core to maintain body temperature
o Transports and distributes hormones and other substances within the body
▪ E.g. clotting factors, antibodies
- The components of the transport system include:
o 1. Central pump – the heart
o 2. A closed system of blood vessels
▪ 2 circulatory systems separated by the heart
o 3. The fluid medium, blood, through which various substances are transported
General Organization
- Two circulatory systems
o 1. Pulmonary Circulation
▪ Blood TO the lung to pick up oxygen,
drop off some carbon dioxide and
bring blood back to heart
▪ Blood vessels that carry blood to
and from the lungs
o 2. Systematic Circulation
▪ Send blood out to the rest of the
body
▪ All the vessels that carry blood to
and from the rest of the body
- Note: the heart is excluded from both circulatory
systems b/c circulatory refers to blood vessels
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find more resources at oneclass.com
Pulmonary circulation;
- Right atrium right ventricle pulmonary artery pulmonary capillaries
o Picked up O2 as it passes through the lungs and drops off some CO2
- Pulmonary circulation + lungs provide for exchange of gases b/w atmosphere and blood
- Contraction or right ventricle ejects venous blood into the pulmonary artery
o This blood is LOW in oxygen, HIGH in carbon dioxide
- Pulmonary artery branches into smaller vessels until they become pulmonary capillaries, where
blood picks up oxygen from air and removes SOME carbon dioxide from the blood
- Capillaries drain into the venules, then into the pulmonary vein that carries oxygenated blood back to
the left atrium of the heart
o When the atria contract, the blood is pumped into the left ventricle
- Note: when the heart contracts, both atria contract at the same time AND both ventricles contract at
the same time
- Artery= take blood AWAY from heart
o Not all arteries have high oxygen, low carbon dioxide because pulmonary artery contains
blood low in oxygen and high in carbon dioxide
- Vein = return blood back TO the heart
- Capillaries = exchange vessels
o Designed for gas exchanged
o In lungs, pick up oxygen and drop off carbon dioxide
- Gas exchange in lungs is VERY efficient – blood that leaves the lungs is almost 95% saturated with
oxygen
Systematic circulation;
- Pulmonary vein left atrium left ventricle aortaarteriesarterioles capillaries
- Capillaries reunite back into venules, then pulmonary vein
- Aorta is the beginning of the systemic circulation
- Gas exchange: occurs in tissues
o Drop off oxygen, pick up carbon dioxide and waste products
- Systemic circulation starts when left ventricle contracts and ejects the blood into the aorta
o Aorta splits into smaller arteries for distribution of the blood into the tissues
- Arteries branch to form smaller arterioles that continue to branch into smaller capillaries
- Capillaries are exchange vessels where O2 and nutrients diffuse into the tissues and CO2 and waste
products are picked up
- Capillaries reunite to form the venules and veins, which return the venous blood to the right atrium
o From the right atrium blood flows into the right ventricle, cycle repeats
Pulmonary circulation;
- Capillaries venules veins right atrium
NOTE: regardless of oxygenation, blood is ALWAYS red
- Oxygenated is just darker red
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find more resources at oneclass.com
Series and parallel circuits
- Vascular (capillary) beds are arranged in parallel and/or in series
o Parallel: arranged side by side
▪ Ex. capillary bed in the arm and capillary bed in the brain
▪ PARALLEL = SYSTEMIC CIRCULATION
o Series: one right after the other
▪ Ex. capillary beds in the kidney – glomerular and peritubular capillaries
▪ SERIES = PULMONARY CIRCULATION
- NOTE: most capillary beds are in parallel, not series
- GC – glomerular cap
- PTC – peritubular cap
Advantages of capillaries in parallel:
1. The amount of blood flow to individual vascular beds can be controlled separately by dilating or
constricting the artery supplying a vascular bed
o Important b/c it enables shifting of blood flow in accordance with physiological demand
o Ex. go for run, want to divert blood to legs – increase blood flow to legs, but decrease blood
flow to digestive tract
o To deliver more O2 and nutrients to exercising muscles, the blood to muscles can be
increased by temporarily decreasing blood flow to other organs such as kidney, liver and the
gastrointestinal tract.
o If they were in series, you would not be able to do that. You shut down one, all of the
capillaries in series will be shut down
2. There is relatively low resistance to blood flow;
o Lowers the pressure requirement for blood to flow
▪ Need pressure (high to low) for blood to move through the circulatory system
▪ Therefore, need less pressure gradient
o Decreases the work load on the heart T
▪ The heart is generating the pressure gradient to push the blood through the rest of
the circulatory system. With less pressure requirement, it decreases the world load
on the heart
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Functions of the cv system role as a transport system. A closed system of blood vessels: e. g. clotting factors, antibodies. The components of the transport system include: 1. The fluid medium, (cid:498)blood(cid:499), through which various substances are transported: 2 circulatory systems separated by the heart. Pulmonary circulation: blood to the lung to pick up oxygen, drop off some carbon dioxide and bring blood back to heart, blood vessels that carry blood to and from the lungs, 2. Send blood out to the rest of the body: all the vessels that carry blood to and from the rest of the body. Note: the heart is excluded from both circulatory systems b/c circulatory refers to blood vessels. Right atrium right ventricle pulmonary artery pulmonary capillaries: picked up o2 as it passes through the lungs and drops off some co2. Pulmonary circulation + lungs provide for exchange of gases b/w atmosphere and blood.
