Common Requirements of living things - ANIMALS – Chapter 5 Pt B

The Circulatory System an Internal Transport System

• Distributes :– nutrients, – gases – wastes– hormones

• Blood is :– vital in defence, immunity, – blood clotting and – transfer heat around the body of mammals

and birds.

Open Circulatory System• No specialised transporting fluid.• Instead interstitial fluid is moves freely around the body before eventually

returning to the heart.• Very low blood pressure and long circuit times.

Closed circulatory systems• Blood is enclosed in a system of vessels

connected to a muscular heart. Which pumps the blood around the body.

• Blood is returned very rapidly to the heart and there is a higher blood pressure.

• Blood is also separated from the interstitial fluid vessel walls allowing the blood to be used for transport and defence.

• Small molecules like nutrients, gases, water and waste are freely exchanged by diffusion across capillaries.

• Because larger molecules(blood proteins) can’t diffuse out of the blood, this exerts osmotic effect drawing water back into the blood.

Closed Circulatory System

Closed System 2 Chambered Heart

Closed System 3 Chambered Heart

Closed System 4 Chambered Heart

Mammalian Transport Systems

• There are 2 transport systems in mammals:– The blood circulatory system- majority of the

animal’s transport needs.

– The lymphatic drainage system-open system that maintains osmotic and fluid balance in tissues and in immune defence.

Internal transport systems

Features of effective transport systems• Large surface area for exchange both with the

environment and internally.• A reliable and responsive way of moving

fluid(blood) around the body.• A fluid that can carry the maximum amount of

material.• A way to regulate transport according to the

needs of the body.

The human circulatory system– A fluid material in which substances are transported; blood– A system of blood vessels or spaces throughout the body in which

fluid moves– A pump such as the heart that pushes through the blood vessels and

spaces.THE CARDIOVASCULAR SYSTEM = heart and blood vessels

Blood

Red blood cells• Biconcave • Very flexible• No nucleus • Packed with haemoglobin• Main function is transporting gases

• Oxygenated blood• Deoxygenated Blood

White blood cells

• Larger than red blood cells• About 1WBC to every 700 RBC• Several types but all involved in

defence.– Phagocytes: remove debris and

fight infection– Lymphocytes: produce

antibodies.

Platelets• Fragments of cells, important in

preventing blood loss and promoting blood clotting.

Arteries and Veins• Arteries carry blood away from the heart.• Veins carry blood towards the heart.• Arteries and veins have the same number of walls but arteries

have more muscular walls and veins more elastic walls.

Arteries• Conduct blood away from the

heart.• Because of their thicker walls they

can withstand greater pressure.• Arteries flow into arterioles that

then flow into capillaries. • Blood pressure decreases as blood

flows further along.

• Conduct blood towards the heart.

• Pressure in veins is much lower than in arteries.

• Blood moves along due muscles compressing the veins.

• Veins have lots of one way valves, that push the blood towards the heart.

• In the legs the blood has to be returned against gravitational pressure.

• The negative pressure in the lungs assists in drawing the blood up from the legs.

Veins

Blood Movement in the Veins

Capillaries• Tiny, many branched blood

capillaries provide a vast surface for exchanging blood.

• Most cells are no more than 1mm from the nearest capillary.

• Same diameter as a red blood cell, so they fit in one by one.

• When the wall of a red blood cell presses on the capillary wall there is an exchange of oxygen and carbon dioxide.

• blood vessels

Mammalian HeartFour chambers:The Atria (singular: atrium):

– Two top chambers, thinner walls.

The Ventricles:– Two bottom chambers, thicker

walls.

One way valves ensure blood flows in one direction.

The heart is very coordinated first the atria contract forcing the blood into the ventricles then the ventricles contract.

Blood Circulation2 Circulatory pathways-– Pulmonary:To and from

the lungs. – Systemic :To and from

the rest of the body.

The heartVeins and arteriesPulmonary vesselsSystemic vesselsCapillariesBlood

Blood flow animation

Circulatory animations various

Blood Flow in heart

Pulmonary and System Circulation

Blood pressure

• Caused by the contraction of the ventricles.

• The right ventricle is much thinner than the left so the pressure caused by the left ventricle is greater than the right.

• In the arteries blood pressure changes with every heart beat, this is the pulse you hear on your wrist.

• The higher systolic pressure occurs when the ventricles contract.

• The lower diastolic pressure occurs when the ventricles relax.

BLOOD PRESSURE• Blood pressure is described by these two limits. • Normally this is 120/80mmHg, so that is the systolic pressure/diastolic

pressure.

Right Atria receives

deoxygenated blood from body

Right Ventricle pumps

deoxygenated blood to lungs

Left Atria receives oxygenated blood

from lungs

Left Ventricle pumps out aorta

to the body

Vena cavae Aorta

Cardiac Surgury You Tube