84 terms

IGCSE Topic 26: The circulatory system and the heart

The structure and function of blood vessels and the heart.
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Absorption
Process that takes useful products of digestion from the gut into blood or lymphatic system
Accelerator nerve
Involved in the control of heart rate. Runs from the brain to the heart.
Adrenaline
A hormone involved in the fight or flight response. Raises heart and breathing rates and shuts down blood supply to non-vital organs
Aerobic respiration
Process by which substrates are oxidised to carbon dioxide and water in order to release energy for cells.
Anaerobic respiration
Process by which substrates are oxidised to release some energy for cells in the absence of oxygen.
Anoxic
Without oxygen.
Aorta
The major artery that carries blood from the heart to the rest of the body.
Arterial blood
Blood found in an artery - usually high pressure and well-oxygenated.
Arteriole
Small branches of main arteries.
Artery
A major blood vessel carrying blood, usually oxygenated, under pressure from the heart.
Atrio-ventricular node
The secondary pacemaker controlling the heart beat.
Bicuspid (mitral) valve
The valve between the left atrium and left ventricle that prevents blood flowing back into the atrium when the ventricle contracts.
Blood
Liquid tissue that is the main transport medium in animals.
Blood serum
The liquid portion of the blood left after it has clotted
Bypass
Surgery where a blood vessel from one part of the body is used to allow blood to flow round a blockage in a vessel supplying the heart muscle
Carbon dioxide
Gas produced by respiration that is essential for photosynthesis
Cardiac
Relating to the heart.
Cardiac centre
Region of the medulla that regulates heart rate via the accelerator and decelerator nerves.
Cardiac cycle
The sequence of muscle contractions and relaxation that pumps the blood
Cardiac muscle
Specialised type of muscle that is found only in the heart.
Carotid artery
Artery that carries blood to neck and head.
Cholesterol
A type of fat that can collect in the arteries and cause heart disease if eaten in excess over a long period of time.
Circulatory system
Organ system involved in transport of materials around the body. Includes heart and blood vessels.
Clot
Mass of blood and fibres that forms at the site of a wound preventing loss of blood and entry of microorganisms.
Coronary artery
Branch of aorta that carries blood to the muscle of the heart.
Decelerator nerve
Involved in the control of heart rate. Runs from the brain to the heart.
Deoxygenated
Blood that is low in oxygen and high in carbon dioxide.
Diastole
Term used to describe the point in the cardiac cycle when the heart is relaxing and filling with blood.
Diastolic pressure
The lowest number in a BP reading measures this.
Double circulatory system
Characteristic of warm-blooded animals, where blood passes through the heart twice for every complete circuit of the body
ECG
Abbreviation for electrocardiograph
Echocardiogram
A non-invasive way of imaging the heart using sound waves
Electrocardiograph
A measure of the electrical activity of the heart sensed using electrodes on the chest
Gas exchange surface
Specialised tissue that is adapted for exchange of gases. Examples include the alveoli in the lungs of animals and the spongy mesophyll in the leaves of plants.
Haemoglobin
The iron-containing protein in red blood cells that carries oxygen.
Heart
Pump responsible for circulation of the blood in animals.
Heart and lung machine
Device that can take over gas exchange and blood circulation for a short period during a major heart or heart and lung operation
Heart assist device
A mechanical device that can temporarily take over the function of the heart while a patient waits for a donor heart to become available
Heart transplant
Complete replacement of a diseased heart with a healthy one obtained from a donor who has died of other causes
Hepatic portal vein
Vein that takes blood from the digestive system to the liver.
Hole in the heart
A birth defect reducing the efficiency of the heart that can be treated by surgery
Hypothalamus
Region of the brain above pituitary gland. Senses changes to the internal environment of the body. Controls body functions and homeostasis e.g. thermoregulation.
Inferior (lower) vena cava
Branch of the vana cava returning deoxygenated blood from the lower half of the body to the heart.
Left atrioventricular or bicuspid valve
Valve preventing backflow of blood into left atrium when the ventricles contract
Left atrium
Upper chamber of the heart that fills with blood returning from the lungs via the pulmonary vein.
Left ventricle
Lower chamber of the heart that pumps high pressure blood into the systemic circulation via the aorta.
Lymphatic system
System of vessels that collect excess tissue fluid and drain it back into the blood. Plays an important role in collecting the products of fat digestion from the gut, and in defence against infection.
Nutrients
Food molecules.
Organ
Group of tissues with a comon function
Organ system
Group of organs with a common function
Oxygen
Gas required by most living things. Allows energy to be released from food molecules by the process of aerobic respiration.
Oxygen debt
Respiration in the absence of sufficient oxygen leads to a build up of lactic acid that has to be cleared when sufficient oxygen is available.
Oxygenated
Blood that is high in oxygen and low in carbon dioxide.
Oxyhaemoglobin
The form in which oxygen is carried in red blood cells; bound to haemoglobin.
Pacemaker
Region of the heart that controls the heart beat.
Pacemaker
An artificial portable device for supplying the heart with the electrical impulses it needs to maintain regular contractions
Physiological
Relating to the internal chemistry or metabolism of an organism.
Pulmonary
Relating to the lungs.
Pulmonary artery
The major blood vessel that carries deoxygenated blood from the heart to the lungs.
Pulmonary circulation
Blood circulation into and out of the lungs via the right side of the heart.
Pulmonary vein
The major blood vessel that carries oxygenated blood from the lungs back to the heart.
Renal artery
Carries unfiltered blood to the kidney from the aorta.
Renal vein
Carries filtered blood from the kidney to the vena cava.
Respiratory system
Organ system concerned with breathing and gas exchange. Includes lungs.
Right atrioventricular (tricuspid) valve
Valve preventing backflow of blood into right atrium when the ventricles contract
Right atrium
Upper chamber of the heart that fills with blood returning from the body via the vena cava.
Right ventricle
Lower chamber of the heart that pumps high pressure blood into the pulmonary circulation via the pulmonary artery.
Semi-lunar valves
The name of the non-return valves in the aorta and pulmonary artery.
Single circulatory system
A more primitive system where blood only passes through the heart once for each circuit of the body
Sino-atrial node
The main biological pacemaker for the heart that starts the heart beat by sending an electrical impulse through the atria
Superior (higher) vena cava
Branch of the vena cava bringing blood to the heart from the upper pat of the body and the head.
Surface area to volume ratio
Key ratio in biology that is influenced by the size and shape of an organism. Determines the need for specialised transport systems and the rate of heat loss and water loss.
Systemic circulation
Circulation to the rest of the body from the left side of the heart via aorta.
Systole
Term used to describe the point in the cardiac cycle when the heart is contracting and actively pumping blood.
Systolic pressure
The highest number in a BP reading measures this.
Tendinous cords or tendons
Structures that hold the atrioventricular valves in place, stopping them from turning inside out when the ventricles contract.
Thorax
The chest.
Tissue
Groups of the same type of cell with the same function
Valve
Flap in a blood vessel that prevents back-flow of blood.
Vasoconstriction
Closing down the small arteries supplying the capillary beds in the skin to reduce blood flow and therefore heat loss.
Vasodilation
Opening up the small arteries supplying the capillary beds in the skin to reduce blood flow and therefore heat loss.
Vein
A large, thin-walled vessel that allows deoxygenated blood to drain back to the heart.
Vena cava
The major vessel carrying deoxygenated blood back to the heart from the rest of the body.
Venous blood
Blood found in a vein - low pressure and usually poorly oxygenated.