Transcript circulatory system

SBI 3U
CIRCULATORY
SYSTEM

Circulatory System



heart, blood, and blood vessels
transport oxygen and nutrients
to organs and tissues
throughout the body
carry away waste products
I. Functions

Increases blood flow



conveys disease-fighting elements of
immune system to regions under
attack


meet increased energy demands during
exercise
regulates body temperature
white blood cells and antibodies
sends clotting cells and proteins to
the affected site

stop bleeding and promote healing
II.Circulatory System Components

Heart - divided into four chambers

right atrium, right ventricle, left atrium,
left ventricle

Chamber walls composed of
myocardium

contracts continuously and
rhythmically to pump blood.
Pumping
action of the heart -two
stages for each heart beat
Diastole-when
Systole-when
the heart is at rest
the heart contracts to
pump deoxygenated blood toward
the lungs and oxygenated blood to
the body.


During each heartbeat,
typically about 60 to 90 ml
(about 2 to 3 oz) of blood are
pumped out of the heart.
If the heart stops pumping,
death usually occurs within
four to five minutes.

Three types of blood cells



oxygen-bearing red blood cells
disease-fighting white blood cells
blood-clotting platelets, all of which
are carried through blood vessels in
plasma

plasma is yellowish, consists of water, salts,
proteins, vitamins, minerals, hormones,
dissolved gases, and fats.

Three types of blood vessels

arteries carry blood away


veins - toward heart



thicker walls to withstand the pressure of blood
being pumped from heart
lower pressure
one-way valves to prevent blood from flowing
backwards away from heart
capillaries


tiny links b/w arteries and veins where oxygen
and nutrients diffuse to body tissues
smallest of blood vessels, are only visible by
microscope ten capillaries lying side by side are
barely as thick as a human hair.

Inner layer of blood vessels


lined with endothelial cells - create
a smooth passage for blood transit
surrounded by connective tissue
and smooth muscle for:
Expansion - during exercise to meet demand
for blood and to cool body
 Contraction - after injury to reduce bleeding
and/or conserve body heat


If all the arteries, veins, and
capillaries in the human body
were placed end to end, the
total length would equal more
than 100,000 km (more than
60,000 mi)—they could stretch
around the earth nearly two
and a half times.

Arteries, veins, and capillaries - divided
into two systems:

Systemic - carries oxygenated blood from
heart to all tissues in body except lungs
and returns deoxygenated blood carrying
waste products, such as carbon dioxide,
back to heart.
oxygen-rich blood ejected under high pressure out of
heart's main pumping chamber (L. ventricle) through
largest artery (aorta)
 smaller arteries branch off from aorta to various parts
of the body
 smaller arteries in turn branch out into even smaller
arteries (arterioles)
 arterioles become progressively smaller eventually
forming capillaries - blood pressure is greatly reduced


interstitial fluid fills the gaps between the cells of
tissues or organs



dissolved oxygen and nutrients then enter the cells
from interstitial fluid by diffusion
carbon dioxide and other wastes leave the cell via
interstitial fluid, cross capillary walls, and enter
blood.
after delivering oxygen to tissues and absorbing
wastes, deoxygenated blood in capillaries then
starts the return trip to heart
capillaries merge to form tiny veins, called
venules
 venules join together to form progressively
larger veins
 veins converge into two large veins:




inferior vena cava-brings blood from the lower half of
body
superior vena cava-brings blood from upper half
Both join at the right atrium of heart
FYI

Varicose Veins
 pressure is dissipated in arterioles and
capillaries
 blood in veins flows back to heart at very low
pressure, often running uphill when a person is
standing
 Flow against gravity allowed by one-way valves
 several centimeters apart in veins
 Veins with defective valves (allow the blood to
flow backward) become enlarged or dilated to
form varicose veins
Varicose
veins

Pulmonary Circulation







deoxygenated blood returning from organs and
tissues travel from R. atrium to R. ventricle.
pushed through pulmonary artery to lung
pulmonary artery divides forming pulmonary
capillary region
microscopic vessels pass adjacent to alveoli (air
sacs) - gases are exchanged across thin membrane
oxygen crosses membrane into blood while carbon
dioxide leaves blood through same membrane
newly oxygenated blood then flows into pulmonary
veins and is collected by L. atrium of the heart
(collecting pool for L.ventricle)
contraction of L. ventricle sends blood into aorta
completing circulatory loop
SUP. VENA CAVA
AORTIC ARCH
L. LUNG
PUL. ARTERY
R. LUNG
HEART
INF. VENA CAVA
PUL. VEINS
AORTA
On
average, a single
blood cell takes roughly
30 seconds to complete a
full circuit through both
the pulmonary and
systemic circulation.
III. Additional Functions
& Features

Transports nutrients and removes
toxins

Absorbed through intestine wall via network of
capillaries and veins that drain the intestine hepatic portal circulation (HPC)

HPC – carries nutrients/toxins to the liver for further
metabolic processing.
 Liver stores sugars, fats, and vitamins & releases
to the blood as needed
 Liver also cleans blood by removing waste product
and toxins. After hepatic portal blood has crossed
the liver cells veins converge to form the large
hepatic vein that joins the vena cava near the
right atrium.

Body Temperature
Regulation


exercise = muscles
generate heat
blood supplying muscles
with oxygen and
nutrients absorbs much
heat and carries to other
parts of body


If body gets too warm,
vessels near skin enlarge
= disperse excess heat
outward through skin
If cold, blood vessels
constrict to retain heat.

Hormone Transportation

Endocrine system = collection of hormoneproducing glands

Regulates rate of metabolism, growth, sexual
development, and other functions.
chemical messengers (hormones) released
directly into bloodstream
 transported to specific organs and tissues


WBC & Antibody Transport and
Clotting
WBC and antibodies circulate in blood
 transported to infection sites
 coagulation system - composed of



Platelets and clotting factors circulate in blood
Damaged blood vessels are repaired by forming
clots

Supporting Organs

Brain/nervous system



Bone Marrow


Site of new blood cell manufacture
Spleen



monitor blood circulation
send signals to heart or blood vessels to maintain
constant blood pressure.
Old blood cells are broken down
valuable constituents, such as iron, are recycled
Kidneys




metabolic waste products removed from blood
also screens for excess salt
maintains blood pressure
balance of minerals and fluids