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GCSE OCR BIOLOGYTHE CHALLENGES OF SIZE IN ANIMALS Complete Revision Summary

The CHALLENGES OF SIZE IN ANIMALS 

CIRCULATORY SYSTEM

The system that provides the bosy with oxygen, nutrient, hormones and all the essential things required by the body to survive. It also eliminate the waste products.

PUMPING ORGAN

• It the heart that pumps the transporting medium all around the body.
• HEART

TRANSPXTING MEDIUM

• It is the blood which contains all the dissolved substances and oxygen required by the body.
• BLOOD

VESSELS

• They carries the blood from one part to another.
• ARTERIES
• VEINS
• CAPILLARIES

BLOOD

BLOOD PLASMA

• It is the liquid component of the blood.
• It makes 55% of the blood.

It is composed of:-

• Glucose
• Amino Acids
• Hormones
• Waste Products like Urea
• Carbon Dioxide

BLOOD CELLS

RED BLOOD CELLS

• It transport oxygen all around the body. It is a specialised cells
• Biconcave disc
• Increases the surface area for oxygen transport
• No nucleus
• To provide more room for oxygen contains haemoglobin
• Binds with oxygen to carry it around the body

WHITE BLOOD CELLS

• They are soldiers of the cells
• The protect the body from infections
• They are made up of lymphocytes which produce antibodies.
• They also have phagocytes which engulfs the pathogen

PLATELETS

• They are involved in blood clotting
• They have fibrin proteins which forms the mesh around the blood

The CHALLENGES OF SIZE IN ANIMAL

GCSE OCR BIOLOGY THE CHALLENGES OF SIZE IN ANIMALS Complete Revision Summary

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NEED FOR CIRCULATORY SYSTEM

LOW SURFACE AREA TO VOLUME RATIO

• Multicellular organisms due to their bigger size have very low surface area to volume ratio.
• As a result, diffusion alone is not effective to meet the demands of the cell so it requires a circulatory system.

METABOLICALLY ACTIVE

• The multicellular organisms are metabolically active. So they need constant supply of oxygen and food and constant removal of waste products.

MULTICELLULAR

• Being multicellular many cells are deep and the diffusion distance is larger.
• So they need a circulatory system that transport substance deep inside the cells.

DOUBLE CIRCULATON

• In One complete cycle the blood is pumped into the heart twice.
• It involves two circulation: Pulmonary: Circulation between Lungs and Heart
• Systemic Circulation: Circulation between heart and the body
• Double circulation makes the circulation more efficient by preventing the mixing of oxygenated blood and helps to alter the pressure from the different chambers of the heart

Heart        

• Heart is the pumping organ
• Working all day and night
• It has four chambers
• Atrium are at the top and Ventricles are at the bottom.
• Ventricles have thicker wall than the atrium.
• Left Ventricle have the thickest wall amongst all other chamber

BLOOD VESSELS

CORONORY HEART DISEASES

• Coronory Artery that supplies the blood to the arteries become narrow.
• The fatty materials like cholesterol gets deposited and narrow the artery.
• The narrowed artery reduced the blood flow to the heart.
• The blood flow to the heart is reduced.
• The heart do not get enough oxygen.
• This causes heart pain, chest pain and heart attack.

Treatment of Coronory Heart Disease.

• A Stent is placed with the baloon in the blocked artery.
• The blocked artery is opened by inflating the baloon.
• The metal mesh stent keep the stent in place.
• This resumes the blood flow.
• People can also be given statin which lowers the blood cholesterol and prevent the deposition of the cholestrol.
• The blood flow to the narrow artery is byepassed to the graft taken from another part of the body

PROBLEMS TO THE HEART

LEAKY VALVES

• Due to increases pressure of blood flow the valves start to leak.

VALVE REPLACEMENT

• The valves made up of metal or polymers or the biological valves from animals can be used to replace the faulty valve

IRREGULAR HEART BEAT

• The natural pacemaker which are the group of cells at the top of the right atrium that regulates the heart beat do not function properly.

ARTIFICIAL PACEMAKER

• Electrical devices called the artificial pacemaker takes over the function of natural pacemaker.

HEART FAILURE

• When the heart do function properly

HEART TRANSPLANT OR ARTIFICIAL HEART

• Artificial heart or heart transplant from the donor.

HUMAN GAS EXCHANGE SYSTEM

MECHANISM OF BREATHING

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GAS EXCHANGE

ALVEOLI

GREATER SURFACE AREA

SHORTER DIFFUSION DISTANCE

STEEP CONCENTRATION GRADIENT

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