Transcript The Circulatory System

The
Circulatory
System
Functions of the Circulatory
system
1.
2.
3.
4.
Transportation of water, Oxygen, CO2
Distribution of nutrients
Maintenance of body temp
Circulation of hormones
BLOOD
Average amount of blood in a human body (70kg)
=5L
Constituents of blood
1.
2.
3.
4.
Plasma
Erythrocytes (red blood cells)
Leucocytes (white blood cells)
Platelets
PLASMA
• Pale yellow liquid component of the blood
• Contains
- dissolved gases
- nutrients
- wastes
- hormones (factor 8 for blood clotting)
- RBC
- WBC
- Platelets
Red Blood cells (Erythrocytes)
• No Nucleus!
• Responsible for transporting O2 and CO2
• Contains haemoglobin molecules that
allow the bonding of oxygen to the cells to
occur
(with haemoglobin, blood can carry enough O2 to support
life for around 5 mins, without Haemoglobin the blood
could support around 5 seconds of life)
White Blood cells (Leucocytes)
• Protect the body against disease
• Much fewer in numbers than RBC
• Several Types (all contain nucleus)
-Some engulf foreign particles,
-Some produce anti bodies and form the
basis of the immune system.
Platelets
Small fragments of
bone marrow
Primary function is to
assist in the clotting of
blood
Chemical Composition of blood
(per 1L)
Blood in centrifuge
TASK
BLOOD CONSTITUENTS
• Read pages 121 – 124 of Nelson Biology 1 & 2
• Summary of red blood cells, white blood cells, plasma and platelets
• Review Questions 1 – 18
THE CIRCULATORY SYSTEM
• Read pages 124 – 128
• Summary of subheadings in text book
• Draw Diagram of the heart labelling all chambers, valves, arteries and
veins
• Review Questions 19 – 27
COMPLETE CHAPTER 5 GLOSSARY!
THE CARDIO
VASCULAR SYSTEM
TYPES OF CIRCULATION
OPEN vs CLOSED
OPEN: e.g. Fish, insects, arachnids
• Some animals do not have specialised fluid such as blood for transport, rather they use
the fluid in between cells called Interstitial fluid
•This is known as an Open circulatory system
•There is still the presence of a heart in organisms with an open circulatory system
•This fluid is used to carry everything from CO2, O2 – carbohydrates and Hormones
CLOSED: e.g. Mammals, Marsupials, etc (see next slides)
Chambers of the heart
THE HEART AND THE FLOW OF BLOOD
FOUR CHAMBERS: 2 atrium (top), 2 ventricles (bottom)
FUNCTION:
The heart pushes blood around the body by its chambers contracting and forcing blood into the
next chamber
The blood needs to be pumped between the lungs and the cells of the body to carry O2 to the
cells, and CO2 back to the lungs
Backflow of blood is stopped by the valves
THREE MAJOR VALVES
Tricuspid valve between R ventricle and R atrium
Mitral valve between the L Atrium and L Ventricle
Pulmonary valve between rest of the body and the L Ventricle
Blood flow through the heart
OXYGENATED BLOOD
Flow of blood:
(From the body) Anterior Vena cava / Pulmonary vein, Right Atrium, Right Ventricle, Pulmonary Artery,
Gives CO2 to lungs
LUNGS
Collects O2
from lungs
Left Atrium, Left Ventricle, Aorta / Pulmonary Artery (To the body)
THE BLOOD VESSELS
Arteries: Carry blood away from the heart (oxygenated)
Arterioles: Small arteries
Capillaries: small veins, extend circulatory network right in between cells
Veins: Carry blood to the heart (de-oxygenated)
Capillaries
Arterioles
Arteries
Heart
cell
Veins
STRUCTURE OF ARTERIES
Arteries are more muscular and thicker than veins, this is because they
swell as each wave of blood is ejected from the heart. They then recoil to
propel elastically to push blood further on
STRUCTURE OF VEINS
The Lumen of a vein is much larger than that of an artery. (over 60% of
blood is distributed in the veins as a reservoir, should extra volume be
required (exercise)
Veins have valves to help prevent backflow
Veins rely on the contraction of skeletal muscles to help propel blood back
to the heart against gravity (draw diagram)
LUNG STRUCTURE
The lungs are basically a
series of air sacs that fill with
air due to the pressure
difference inside the lungs
and outside the body
The air travels through a
series of passages
Trachea
Bronchus
Bronchioles
Alveoli (point of diffusion)
GAS EXCHANGE IN MAMMALS
•One of the main functions of the blood is to carry O2 to the cells and CO2 back to
the lungs to be expelled
•This is achieved via diffusion occurring in the Alveoli in the lungs (see below)
•Blood pathways carry blood past the alveoli were there is a very thin membranous
surface where the CO2 can diffuse out of the RBC and into the alveoli sacs, and O2
Diffuses from the alveoli sacs into the RBC
CONDITIONS REQUIRED FOR DIFFUSION
•Surface must be moist (gases dissolve in an
out by dissolving into water)
•Must be a thin permeable membrane
•Must have a concentration gradient allowing
passive diffusion
CELL PERFORMANCE
To function the cells require O2 for respiration
The more O2 cells get, the harder they can work (e.g. high
intensity exercise)
Very fit athletes can posses several factors that increase
the levels of respiration they can undertake
1. Large lungs to take in large amounts of CO2
2. High diffusion efficiency between the lungs and blood
3. High O2 carrying capacity in the blood (high RBC +
hemoglobin count)