Download Circulatory

Circulatory System
Circulatory System Intro
The Circulatory or cardiovascular system
consists of:
• The Heart
• The Blood
• Blood Vessels
Together with the lymphatic system, the
circulatory system:
• Delivers oxygen and nutrients to cells
• Removes waste from cells
• Maintains the balance of water in the body
Animation of the Heart
Blood
• A Specialised type of connective tissue
• It is a thick liquid with a metallic taste
• Blood accounts for about 8% of our
total body weight
• Blood volume in a healthy adult:
Male = 5-6L
Female = 4-5L
Functions of Blood
Blood performs a number of specialised
functions:
• Transports nutrients, oxygen, carbon dioxide,
waste products and hormones to cells and
organs around the body.
• Protects us from bleeding to death, via
clotting, and from disease, by destroying
invasive microorganisms and toxic
substances.
• Acts as a regulator of temperature (vessels
constrict to conserve or dilate to release heat
to the surface for cooling), the water content
in cells and body pH.
Composition of Blood
1. Solid component (Blood Cells)
• 45% of total blood volume.
• Red blood cells (erythrocytes), white blood
cells (leukocytes), or platelets
(thrombocytes).
2. Liquid component (Blood Plasma)
• 55% of total blood volume.
• Composed of 91.5% water and 8.5% of
nutrients, waste products, proteins,
enzymes and hormones.
• Straw coloured or yellowy solution.
• Nutrients from the small intestine is
absorbed into the plasma and transported
around the body.
Red Blood Cells
Bi-concave discs
Contains an oxygen-carrying pigment
called Haemoglobin (Hb). This gives
blood its red colour.
Oxygen (O2) is carried by Hb and
transported from the lungs to all cells.
This reaction forms oxyhaemoglobin
(aided by iron molecules).
Carbon Dioxide(CO2) is also transported
this way. Formation is called
carbaminohaemoglobin.
Red Blood Cells
Red Blood Cell shape
Red Blood Cell cut in half
Red Blood Cells as they
appear in a blood clot
Red Blood Cells
Life Cycle is approximately 120 days
and they are replaced at the rate of 2
million per second. They are destroyed
in the spleen.
They are reproduced in red bone
marrow from stem cells.
Red Blood Cells function is to transport
O2 and CO2 around the body.
Platelets
Small colour-less bodies that usually
appear as irregular spindles or discs
that are much smaller than RBC & WBC.
Produced in red
bone marrow.
Life cycle is approximately 5 to 9 days.
Platelets are involved in the process of
clotting and they help to repair slightly
damaged blood vessels.
White Blood Cells
Slightly larger than red blood cells.
Classified according to the presence of
absence of granules in their cytoplasm.
Life cycle is from a few hours to a few
days.
Produced in bone marrow and lymph
tissue.
They move to areas of infection or
disease to engulf invading bodies (puss
is the accumulation of WBC).
White Blood Cells
See overhead or handout for
diagram
Phagocytosis
See overhead or handout for
diagram
Blood Vessels
Heart > Arteries > Arterioles > Capillaries >
Venules > Veins > Heart
Arteries
• Carry blood away from the heart to
tissues
• Thick elastic walls as blood is pumped
through them at high pressure in surges.
Arteries
• Three layers – endothelium lining
- involuntary muscle
- tough fibrous tissue
• Surges are called heartbeats
• Pressure decreases as distance from
the heart increases. Blood passes
through small vessels called
arterioles.
Veins
Carry blood from tissues
to the heart
Thinner walls and less
elastic as pressures
decreases the blood gets
closer to the heart.
The contraction and relaxation of the
muscles assists the blood to stream back
steadily to the heart.
Gravity affects blood flow – blood above
the heart flows easily.
Veins
Valves prevent the blood from
flowing back the wrong way against
the force of gravity. After standing
for a long time, legs can feel heavy
and swollen. Blood pools in the lower
legs because of gravity and lack of
movement. Once moving, the
mucsles squeeze the blood up
through the veins towards the heart.
Capillaries
A very small network
of vessels.
One cell wide
Lie between arterioles and venules,
connecting both systems
Capillaries
Arterioles branch off
arteries and venules
branch off veins. They
meet in the middle to form
capillaries.
Semipermeable membrane where O2, CO2
and nutrients are exchanged between the
blood and cells of the body.
Feeds muscles, joints, tissues and organs
in clusters.
Blood Vessels
Circulatory System
See overhead or handout for
diagram of vital blood vessels of the
body.
Heart
Involuntary muscle.
Pericardium is a triple layered bag
that surrounds, anchors and protects
the heart.
Four hollow chambers
- 2 Atria
- 2 Ventricles
Atria act as receiving chambers for
blood returning to the heart. Small
and thin as they only pump next
door.
Heart
Ventricles are large as they propel the
from the heart into circulation around
the body.
Dense connective tissue called valves,
prevent the back flow of blood into the
chambers by opening and shutting
when the heart contracts and relaxes.
Tricuspid and Bicuspid valves.
Heart contracts and squeezes blood into
arteries – systole.
Heart
Heart relaxes and fills with blood –
diastole.
Pulmonary artery has deoxygenated
blood travelling in it. Other arteries
have oxygenated blood. Being an
artery it still travels away from the
heart.
Pulmonary vein has oxygenated blood.
Other veins have deoxygenated blood.
Heart
Heart
See overhead for a greater zoom into
the heart
Anatomy of the Heart
Atrium:
Ventricle:
Septum:
Vena Cava:
Pulmonary Artery:
Pulmonary Vein:
Anatomy of the Heart
Atrioventricular Valves:
Semilunar Valves:
Sinuatrial Valves:
Papillary Valves:
Myocardium Walls:
Aorta: