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Smooth muscle
Contracts in arteries to maintain blood flow and pressure as blood moves further away from the heart.
Tunica intima
Innermost layer in veins and arteries, made up of a single endothelium layer and has elastic fibres in the collagen which can stretch and recoil.
Tunica media
Contains elastic fibres and smooth muscle, and is thicker in arteries than veins, to maintain high blood pressure.
Elastic fibres
Stretch to accomodate for changes in blood flow and pressure caused by the heart pumping too fast or slow. At a certain point they recoil to push blood through the artery.
Tunica externa
Outermost layer of veins and arteries, contains collagen fibres to resist overstreching, which prevents blood cells bursting. Withstands very high pressures.
Open
Type of circulatory system where the blood is not moved around in vessels, but bathes the tissues directly while held in a cavity.
Haemocoel
Cavity where blood is held in open circulatory systems.
Closed
Type of circulatory system where blood is moved in blood vessels. There are two types, single and double.
Single
Type of closed circulation, where blood moves around the heart once in it’s passage of the body.
Dorsal
Top of an animal such as earthworms, for example a type of fin and vessel.
Ventral
Bottom of an animal such as earthworms, for example a type of vessel.
Pseudohearts
Thickened, muscular blood vessels which pump the blood from dorsal to ventral vessels in earthworms.
Double
Type of closed circulation where blood passes through the heart twice in it’s circuit around the body.
Atrium
Part of the heart where blood enters, has less muscle and thinner walls.
Ventricle
Part of the heart where blood leaves, has more muscle and thicker walls.
Left
Side of the heart where oxygenated blood leaves and is pumped around the body, has a thicker and more muscular ventricle.
Right
Side of the heart where deoxyginated blood enters and is pumped towards the lungs.
Pulmonary
Type of circulation that moves from the heart, to the lungs, and back to the heart.
Systematic
Type of circulation that moves from the heart, to the bodily tissues, back to the heart.
Arteries
Carry blood away from the heart, are larger, with less lumen and more tunica externa and media. Vary from 160-120mmHg of blood pressure.
Veins
Carry blood back to the heart, are smaller, with more lumen and less tunice externa and media. Have semi-lunar valves to prevent flow to feet. Around 10mmHg of blood pressure
Capillaries
A vast network which penetrates all tissues and organs of the body, where exchange of materials takes place. From 30mmHg-15mmHg of blood pressure.
Arterioles
Branch off from arteries, and further branch into capillaries. Around 33mmHg of blood pressure.
Venules
Where blood from capillaries collects, takes blood into veins. Around 15mmHg of blood pressure.
Semi-lunar
Valves present in veins, prevent gravity from pushing blood down the body. Also present in the heart, to prevent blood pumped from the ventricle into the pulmonary artery or aorta does not fall back. Open when the heart pumps, and close to stop backflow.
Endothelium
Part of tunica intima in arteries and veins, but alone on capillaries. Lines the vessels, one cell thick. Smooth to prevent friction.
Lumen
Where blood flows, cavity in the vessels.
Tricuspid
A valve on the right side of the heart between the atrium and the ventricle. Closes once pressure in the ventricle is higher than in the atrium.
Bicuspid
A valve on the left side of the heart between the atrium and the ventricle. Closes once pressure in the ventricle is higher than in the atrium.
Myogenic
Type of contraction where contraction and relaxation happen rhythmically and without outside intervention. Used by the human heart.
Atrial systole
Occurs at 0.1 seconds, when atrial walls contract, pushing blood into the ventricles.
Atrial diastole
Occurs at 0.2, once the atrium relaxes, blood begins to enter again via vena cavae and the pulmonary veins.
Ventricular systole
Occurs at 0.2 seconds, when ventricle walls contract and the atrio-ventricular valves close, blood is pushed into the pulmonary artery or aorta and the semi-lunar valves open.
Ventricular diastole
Occurs at 0.4 seconds, when the ventricles relax, semi-lunar valves shut and the atrio-ventricular valves close.
Sinoatrial node
Group of specialised cardiac cells that produce an electrical impulse, located in the wall of the right atrium.
Atrioventricular node
Pases down the SAN impulse to the ventricles, as they are electrically insulated by a thin layer of connective tissue. Allows for a delay between atria and ventricles contracting.
His bundle
Passed the electrical impulse by the AVN, and then pass it down to the left and right bundle branches.
Apex
Part of the heart that recieves the AVN impulse from the left and right His bundle branches and then transports it to the Purkinje fibres.
Purkinje fibres
Inside the ventricle walls, pass the electrical impulse up the ventrical wall muscles to cause the ventricles to contract simultaneously.
Atrio-ventricular valves
Term for the bicuspid and tricuspid valves.
Electrocardiogram
Trace of the voltage changes during a heartbeat, detecting by placing electrodes on the skin.
P wave
Part of electrocardiogram that shows voltage generated by the SAN for atria contraction.
PR interval
Part of a cardiogram that shows the time taken for the voltage from the SAN to reach the AVN.
QRS complex
Part of the electrocardiogram that shows the contraction of the ventricles.
T wave
Part of the electrocardiogram that shows the repolarisation of the ventricle.
Isoelectric line
Line between the T wave and the next P wave of the next heartbeat that shows the baseline of the trace.
Erthrocytes
Word for red blood cells.
Biconcave discs
The shape of red blood cells, allows for a smaller diffusion pathway of oxygen and larger SA.
Haemoglobin
Red pigment in blood that carries oxygen. Takes up around 95% of red blood cell mass. Has two beta chains, and two alpha chains.
Plasma
Pale yellow, the liquid part of blood that is made up of 90% water. It contains amino acids, urea and the red of the blood cells.
Haem
Part of the haemoglobin that contains an iron ion and join to one oxygen molecule. As there are four in haemoglobin, allows it to carry four oxygen molecules.
Oxyhaemoglobin
Complex created when four oxygens bind to haemoglobin.
Cooperative binding
Process in which haemoglobin changes it’s shape to make it easier for oxygen to bond. Happens after the first and second oxygen bond, meaning the fourth requires a large increase in oxygen concentration.
Dissociate
Term for when oxygen unbinds with haemoglobin, happens in respiring tissues.
High affinity
Happens to haemoglobin in lower oxygen conditions - attaches to an increased amount of oxygen but releases a decreased amount. Left shift on a dissociation curve.
Low affinity
Happens to haemoglobin in higher oxygen conditions - attaches to an decreased amount of oxygen but releases a increased amount. Right shift on a dissociation curve.
Myoglobin
In muscles for oxygen storage. Globular tertiary protein with only one haem group.
Dissociation curve
Graph that shows the higher oxygen concentration, the higher concentration of oxygen in haemoglobin. Includes oxygen concentration in exercising tissues, resting tissues and the lung alveoli.
Bohr
Effect that shows that areas of high carbon dioxide concentration oxygen is dissociated easier, for example in the capillaries.
Carbamino-haemoglobin
How 10% of carbon dioxide travels.
5
How much carbon dioxide travels as a solution in the plasma.
HCO3-
How 85% of carbon dioxide travels.
Carbonic anhydrase
Enzyme that catalyses the combination of carbon dioxide and water into carbonic acid.
Carbonic acid (H2CO3)
Created by the combination of carbon dioxide and water in a red blood cell.
Chloride ions (Cl-)
Diffuse into a cell to maintain electrochemical neutrality when HCO3- ions leave.
Chloride shift
The movement of chloride ions into a red blood cells to maintain electrochemical neutrality when HCO3- ions leave.
Haemoglobic acid (HHb)
Caused by the dissociation of oxyhaemoglobin by H+ ions, which then combine with haemoglobin.
Tissue fluid
Plasma without the collodial plasma proteins, carries molecules to allow them to diffuse into the tissues and carries waste products back into the blood.
Collodial plasma proteins
In plasma to reduce solute potential, too large to leave via ultra-filtration.
Ultra-filtration
Procces where substances are pushed out from the blood, such as oxygen, glucose, amino acids, etc, into tissue fluid, allowing cells to absorb them.
Absorption
Process where waste products are diffused into tissue fluid from cells, such as urea and carbon dioxide.
10
Amount of tissue fluid that doesn’t return to the blood and drains into the lymph capillaries.
Venous system
Term for the network of veins around the body.
Thoracic duct
Where the 10% of tissue fluid left behind returns to the venous system, where it then empties into the subclavian vein above the heart.
Hypertension
When blood pressure is too high, causing build up of waste products and carbon dioxide known as oedema.
Hypotension
When blood pressure is too low, causing cells to go without important nutrients and blood volume to increase.
Oedema
Build up of waste materials and carbon dioxide caused by hypertension. Causes swelling in feet.
Sigmoidal
Word for an S shaped curve - such as a dissociation curve. Allows for rapid unloading of oxygen at small oxygen partial pressure changes.
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