The circulatory system carries blood and dissolved substances to and from different places in the...
-
Upload
pearl-bryan -
Category
Documents
-
view
217 -
download
0
Transcript of The circulatory system carries blood and dissolved substances to and from different places in the...
The circulatory system carries blood and dissolved
substances to and from different places in the body. The Heart has the job of pumping these things around
the body. The Heart pumps blood and substances around
the
body in tubes called blood vessels. The Heart and blood vessels together make up the
Circulatory System.
What is the circulatory system?
Lungs
Body cells
Our circulatory system is a double circulatory system.
This means it has two parts parts.
the right side of
the system
deals with
deoxygenated
blood.
the left side of
the system
deals with
oxygenated
blood.
Two circulatory paths
Pulmonary
Systemic
The double pump
The Heart
These are arteries. They carry blood away from the heart.
This is a vein. It brings blood from the body, except the lungs.
Coronary arteries, the hearts own blood supply
The heart has four chambers
2 atria
2 ventricles
now lets look inside the heart
The Heart
Left Ventricle
Left AtriumRight Atrium
Right Ventricle
valve
Vein from Lungs
Artery to Head and BodyArtery to Lungs
Vein from Head and Body
valve
II.Circulatory System Components
• Heart - divided into four chambers– right atrium, right ventricle, left atrium,
left ventricle
Heart Chambers and Valves
How does the Heart work?
blood from the body
blood from the lungs
The heart beat begins when the
heart muscles relax and blood
flows into the atria.
STEP ONE
The atria then contract and
the valves open to allow
blood
into the ventricles.
How does the Heart work?
STEP TWO
How does the Heart work?
The valves close to stop blood
flowing backwards.
The ventricles contract forcing
the blood to leave the heart.
At the same time, the atria are
relaxing and once again filling with
blood.The cycle then repeats itself.
STEP THREE
Right Heart Chambers: Pulmonary Circuit
• Right Atrium (forms most of posterior of heart)– Receives O2-poor
blood from body via IVC, SVC,
• Right Ventricle– Receives O2-poor
blood from right atrium through tricuspid valve
– Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk
Left Heart Chambers: Systemic Circuit
• Left Atrium– Receives O2-rich blood
from 4 Pulmonary Veins
• Left Ventricle (forms apex of heart)– Receives blood from
Left Atrium via bicuspid valve
– Pumps blood into aorta via Aortic Semilunar Valve to body
Heart Valves: Lub*-Dub**• *Tricuspid Valve: Right AV valve
– 3 Cusps (flaps) made of endocardium and CT
– Flow of blood pushes cusps open– When ventricle in diastole (relaxed),
cusps hang limp in ventricle– Ventricular contraction increases
pressure and forces cusps closed• *Bicuspid (Mitral) Valve: Left AV
valve– 2 cusps anchored in Lft. Ventricle
by chordae tendinae– Functions same as Rt. AV valve
• **Semilunar valves: prevents backflow in large arteries– Pulmonary Semilunar Valve: Rt
Ventricle and Pulmonary Trunk– Aortic Semilunar Valve: Left
Ventricle and Aorta
blood from the heart gets around
the body through blood vessels
There are 3 types of blood vessels
a. ARTERY
b. VEIN
c. CAPILLARY
• Three types of blood vessels – arteries carry blood away
• thicker walls to withstand the pressure of blood being pumped from heart
– veins - toward 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.
The ARTERY
thick muscle and elastic fibres
Arteries carry blood Away from the heart.
the elastic fibres allow the artery to stretch under
pressure
the thick muscle can contract to push the blood
along.
The VEIN
Veins carry blood towards the heart.
thin muscle and elastic fibres
veins have valves which act to stop the blood from going in the wrong direction.
body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.
The CAPILLARY
Capillaries link Arteries with Veins
the wall of a capillaryis only one cell thick
they exchange materials between the blood and other body cells.
The exchange of materials between the blood and the body can only occur through capillaries.
• 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 aortacompleting circulatory loop
L. LUNGR. LUNG
HEART
AORTIC ARCH
SUP. VENA CAVA
INF. VENA CAVA AORTA
PUL. ARTERY
PUL. VEINS
Artery/Vein differencesArteries (aa.) Veins (vv.)
Direction of flow
Blood Away from Heart
Blood to Heart
Pressure Higher Lower
Walls THICKER: Tunica media thicker than tunica externa
THINNER: Tunica externa thicker than tunica media
Lumen Smaller Larger
Valves No valves Valves (see next)
what’s in
red blood cells
white blood cells
platelets
plasma
carbon dioxide
digested food
waste (urea)
hormones
oxygen
The Blood
plasma
red blood cell
white blood cell
platelets
Red Blood Cells
contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it.
can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.
a biconcave disc that is round and flat without a nucleus
White Blood Cells
there are many different types and all contain a big nucleus.
the two main ones are the lymphocytes and the macrophages.
some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
macrophages ‘eat’ and digest micro-organisms .
`
PlateletsPlatelets are bits of cell broken off larger cells.
Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.
Plasma
A straw-coloured liquid that carries the cells and the platelets which help blood clot.
• carbon dioxide
• glucose
• amino acids
• proteins
• minerals
• vitamins
• hormones
• waste materials like urea.
It also contains useful things like;
Heart Chambers and Valves