The Circulatory

System

Functions of the Circulatory system

1. Transportation of water, Oxygen, CO2

2. Distribution of nutrients

3. Maintenance of body temp

4. Circulation of hormones

BLOODAverage amount of blood in a human body (70kg)

= 5 L (8% of body weight)

Constituents of blood1. Plasma

2. Erythrocytes (red blood cells)

3. Leucocytes (white blood cells)

4. 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

TASKBLOOD CONSTITUENTS• Summary of red blood cells, white blood cells, plasma and platelets

THE CIRCULATORY SYSTEM• Draw Diagram of the heart labelling all chambers, valves, arteries and

veins

Questions from ‘Nature of Biology’ Chapter 6

1-5, 8,9,10

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

FOUR MAJOR VALVES

Tricuspid valve between R ventricle and R atrium

Mitral valve between the L Atrium and L Ventricle

Pulmonary valve between R Ventricle and the Pulmonary artery

Aortic Valve between the L ventricle and the Aorta

Blood flow through the heart

OXYGENATED BLOOD

Flow of blood: (From the body) Superior / Inferior Vena cava , Right Atrium, Right Ventricle, Pulmonary Artery,

LUNGS

Pulmonary Vein, Left Atrium, Left Ventricle, Aorta (To the body)

Gives CO2 to lungs

Collects O2 from lungs

Cardiovascular system

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)

Arteries Arterioles

Capillaries

Veins

cellHeart

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

TracheaBronchusBronchiolesAlveoli (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)

TASK

The Respiratory System

Questions from ‘Nature of Biology’ Chapter 6

11-14, 16

Chapter 6 Review Questions – P171

1, 3,5,6,7,14