OCR As Level Biology - Module 3.2
Single Circulatory System
Blood only passes through the heart one for each complete circuit of the body
Double
... [Show More] Circulatory System
Blood passes through the heart twice for each complete circuit of the body
Systemic System
Loop in circulatory system that sends blood to the rest of the body
Pulmonary System
Loop in circulatory system that sends blood to the lungs
Closed Circulatory System
Blood enclosed inside the blood vessels
Heart
Pumps blood into arteries
Veins
Take blood back to the heart
Open Circulatory System
Blood isn't enclosed in blood vessels all the time instead flows freely through the body cavity
Arterioles
Smaller versions of arteries that control amount of blood flowing to tissues
Venules
Join together to form veins
Pulmonary Arteries/Veins
Carry the opposite type of blood that normal arteries/veins
Tissue Fluid
Fluid that surrounds cells in tissues, made from substances that leave the blood plasma such as water, oxygen and nutrients
Oncotic Pressure
Pressure generated by plasma proteins present in the capillaries which lower the water potential
Red Blood Cells
Found in the blood but not in the tissue fluid and lymph as they're too big to get through capillary walls
White Blood Cells
Found in the blood and some tissue fluid. but not lymph and only found in the tissue fluid when there is an infection
Platelets
Found in blood only and in tissue fluid if the capillaries are damaged
Proteins
Found in the blood, some tissue fluid and only antibodies in the lymph as most plasma proteins are too big to get through capillary walls
Water
Found in blood, tissue fluid and lymph
Right Side of the Heart
Pumps deoxygenated blood to the lungs
Left Side of the Heart
Pumps oxygenated blood to the rest of the body
Atrioventricular Valves
Link the atria to the ventricles
Semi-Lunar Valves
Link the ventricles to the pulmonary artery and the aorta
Higher Pressure Behind a Valve
Valve forced open
Higher Pressure in front of the Valve
Valve forced shut
Lub Sound
Atrioventricular valves closing
Dub Sound
Semi-Lunar valves closing
Myogenic
Heart can contract and relax without receiving signals from nerves, pattern of contractions controls the regular heartbeat
P - Wave
Caused by contraction of the atria
QRS Complex
Caused by contraction of the ventricles
T - Wave
Due to relaxation of the ventricles
Bradycardia
Heartbeat too slow - below 60 beats per minute at rest
Ectopic Heartbeat
Extra heartbeat, caused by earlier contraction of the atria or ventricles
Fibrillation
Really irregular heartbeat
Haemoglobin
A large protein with a quaternary structure that contains iron and has a high affinity for oxygen
Oxygen Dissociation Curve
Shows how saturated the haemoglobin is with oxygen at any given partial pressure
Elastic Fibres
Composed of Elastin, can stretch and recoil, provide flexibility
Smooth Muscle
Contracts/ relaxes changing the size of the lumen
Collagen
Provides structural support to maintain the shape and volume of the vessel
Arteries
Carry blood away from the heart to the tissues of the body, contain elastic fibres, smooth muscle and collagen
Vasodilation
Smooth muscle in the wall of an arteriole relaxes so blood flows into the capillary bed
Capillaries
Microscopic blood vessels that links the arteriole with the venues
Inferior Vena Cava
Carries deoxygenated blood from the lower parts of the body
Superior Vena Cava
Carries deoxygenated blood from the head and upper body
Blood
Consists of a yellow liquid called plasma that carries a wide variety of other components including dissolved glucose and amino acids, hormones and large plasma proteins
Hydrostatic Pressure
As blood flows through the arterioles into the capillaries, under pressure from the surge of blood that occurs every time the heart contracts
Arteriole End of the Capillary
Hydrostatic pressure that forces fluid out of the capillaries is relatively high, higher than the oncotic pressure attracting water by osmosis, so fluid squeezes out of the capillaries
As Blood moves towards the Venous System
Balance of forces changes, the hydrostatic pressure falls as fluid has moved out and the pulse is completely lost, oncotic pressure is stronger than hydrostatic pressure so water moved back into the capillary by osmosis
Lymph
Liquid that leaves the blood vessels that drains into lymph capillaries and is composed of plasma and tissue fluid but less oxygen
Erythrocytes
Red blood cells with a biconcave shape and contains haemoglobin
Oxyhaemoglobin
Formed when oxygen binds loosely to the haemoglobin
High Partial Pressure of Oxygen in the Lungs
Haemoglobin in the red blood cells is rapidly loaded with oxygen
Bohr Effect
As the partial pressure of carbon dioxide rises at higher partial pressure of oxygen, haemoglobin gives up oxygen more easily
Fetal Haemoglobin
Has a higher affinity for oxygen than adult haemoglobin at each point along the dissociation curve so it removes oxygen from the maternal blood as they move past each other
Carbonic Acid
Formed when carbon dioxide reacts slowly with water, then dissociates to form hydrogen ions and hydrogen carbonate ions
Chloride Shift
When hydrogen carbonate ions move out of the erythrocytes into the plasma, negatively charged chloride ions move into the erythrocytes, which maintains the electrical balance of the cells
Coronary Arteries
Supply the cardiac muscle with the oxygenated blood it need to keep contracting and relaxing
Septum
Inner dividing wall of the heart which prevents the mixing of deoxygenated and oxygenated blood
Diastole
Heart relaxes, atria and ventricles fill with blood, volume and pressure of the blood in the heart build as the heart fills, but the pressure in the arteries is at a minimum
Systole
Atria and ventricles contract, pressure inside the heart increases dramatically, and blood is forced out of the right side of the heart to the lungs and from the left side to the main body circulation, the volume and pressure of the blood in the heart are low and blood pressure in the arteries is at a maximum
Aortic pressure rises when...
Ventricles contract as blood is forced into the aorta
Atrial pressure is lowest when...
Left atrioventricular valve closes and its walls relax, atria fills with blood, increasing pressure until atrioventricular opens and some blood moves into the ventricle
Ventricular pressure is highest when...
The ventricles fill with blood as the atria contract, left atrioventricular valves close and pressure rises as ventricles contract, blood is forced into the aorta, pressure falls as ventricles empty and relax
Ventricular volume rises when...
Atria contract and the ventricles fill with blood
Wave of electrical excitation begins in the...
Pacemaker called the Sino-Atrial Node (SAN), causes atria to contract, initiating the heartbeat
Electrical activity from the SAN is picked up by the...
Atrio-Ventricular Node (AVN)
Bundle of His
Conducting tissue made up of fibres which penetrate through the septum between the ventricles
Echocardiogram
Recording of the electrical activity of the heart
Oxyhaemoglobin
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