3.2 - B - Transport In Animals Flashcards
Define transport
The movement of substances such as oxygen, nutrients, hormones, waste and heat around the body
What is the difference between a double circulatory system and a single circulatory system?
Double - blood has to flow through the heart twice for each circuit of the body
Single - blood flows through the heart once for each circuit of the body
What are the 3 main factors that influence the need for a transport system?
Size
SA:V
Level of metabolic activity
What are the differences in circulatory system between fish and mammals?
Fish have a single circulatory system
Mammals have a double circulatory system
What will an effective transport system (3) and an efficient transport system (2) include?
Effective - A fluid/medium to carry nutrients, oxygen and waste around the body (blood)
Pump to create pressure that will push the fluid around the body (heart)
Exchange surface that enable substances to enter and exit blood (capillaries)
Efficient - Tubes or vessels to carry the blood by mass flow
2 circuits, one to pick up oxygen the other to deliver it
Explain what an open circulatory system consists of
A heart that pumps blood through short vessels into a large body cavity. The blood bathes the cells and tissues where substances are exchanged with the cells. The blood then returns to the heart through pores called ostla.
Most suitable for smaller organisms (eg. insects)
Explain what a closed circulatory system consists of
From the heart, blood is pumped through a series of progressively smaller vessels. Capillaries are where exchange happens. Blood is then returned to the heart through a series of progressively larger vessels. More suitable for larger animals (mammals fish).
The tissue fluid bathes the cells instead
What is the pulmonary circuit?
Part of the double circulatory system - carries blood to and from the lungs and heart to become oxygenised
What is the systemic circuit?
Part of the double circulatory system - carries blood containing oxygen and nutrients to the body’s cells and removes waste (carbon dioxide)
What are the advantages of a double circulatory system?
Blood can be maintained at a higher pressure in the systematic circuit so it is delivered quicker.
Slightly lower pressure can be maintained in the pulmonary circuit to prevent damage to capillaries of the lungs.
Define artery
Vessels that carry blood away from the heart
Define arteriole
Small blood vessels that distribute blood from an artery to the capillaries
Define capillary
Very small vessels with very thin walls
Define closed circulatory system
One in which the blood is held in vessels
Define open circulatory system
One in which the blood is not held in vessels
Define vein
Vessels that carry blood back to the heart
Define venule
Small blood vessels that collect blood from capillaries and lead into the veins
Define endothelium
A tissues that lines the inside of a structure
What do arteries have more of than veins?
Smooth muscle
What is considered the main feature (and difference from arteries) of veins and what is its purpose?
Valves to stop them moving backwards due to low pressure in them
Give 4 reasons why closed circulatory systems are better than open ones
Higher pressure, so blood can flow quicker
More rapid delivery of oxygen and nutrients
More rapid removal of carbon dioxide and other wastes
Transport is independent of body movement
What are the 3 layers of an artery wall? Explain their purposes
Inner layer - a thin layer of elastic tissue which allows the wall to stretch and recoil
Middle layer - a thick layer of smooth muscle
Outer layer - a relatively thick layer of collagen and elastic tissue. It provides strength to withstand the high pressure, and recoil to maintain the pressure
What is collagen and what does it do?
The most abundant protein in the human body. A long, fibrous structural protein that supports tissues and gives structure to individual cells.
Define blood
The fluid used to transport materials around the body
Define hydrostatic pressure
The pressure that a fluid exerts when pushing against the sides of a vessel or container
Define lymph
The fluid held in the lymphatic system, which is a system of tubes that returns excess tissue fluid to the blood system
Define oncotic pressure
The pressure created by the osmotic effects of the solutes
Define plasma
The fluid portion of the blood
Define tissue fluid
The fluid surrounding the cells and tissues
What are 3 types of fluid?
Blood
Tissue fluid
Lymph
List the 9 components that are found in blood
Erythrocytes, Neutrophils, Platelets, Large proteins, Glucose, Amino acids, Oxygen
(Some) fats
(Little) carbon dioxide
List the 7 components found in tissue fluid
Neutrophils (Some) large proteins (Some, if any) fats (Less - respired) glucose (Less - cells use) amino acids (Less - respired) oxygen (More - released) carbon dioxide
List the 8 components found in lymph
Neutrophils, Lymphocytes, Fats, Carbon dioxide (Some) large proteins (Little) glucose (Few) amino acids (Little) oxygen
List and define the 2 types of valves found in the heart
Atrio-ventricular valves - valves between the atria and ventricles, which ensure that blood flows in the correct direction
Semilunar valves - valves that prevent blood re-entering the heart from the arteries
Define cardiac muscle
Specialised muscle found in the walls of the heart chambers
What are the 2 types of atrio-ventricular valve, how many flaps are there and where are they found?
LA to LV - 2 flaps of tissue - Bicuspid valve
RA to RC - 3 flaps of tissue -Tricuspid valve
Explain the route of blood around the heart, starting with the vena cava
From vena cava (inferior and superior) into right atrium then right ventricle, up the pulmonary artery to the lungs, back via pulmonary vein, left atrium then left ventricle, out of aorta to body
What do coronary arteries do?
Supply blood to the heart muscle
What is the name of the wall that separates the 2 sides of heart?
Septum
Which ventricle has the bigger muscle and why?
Left ventricle, blood needs to be pumped the whole way round the body instead of just to the lungs
What part of the heart has the thinnest walls and why?
Atria - low pressure and doesn’t need to pumped anywhere
What is the cardiac cycle?
The sequence of events in one full beat of the heart
What are the 3 parts of the cardiac cycle?
Diastole
Atrial systole
Ventricular systole
Explain what happens in diastole
Atria and ventricles relax and recoil
Blood flows from veins into atria, meaning pressure in the ventricles is lower than in atria.
Blood flows through open A‐V valves into ventricles.
The volume in the atria and ventricles increase and therefore the pressure in atria and ventricles slowly increases aswell
Explain what happens in atrial systole
Both atria contract, this causes further increase in pressure in the atria.
Increase in pressure causes blood to be pumped through the open A‐V valves into the ventricles (causing the volume in the ventricles to increase)
Explain what happens in ventricular systole
When the ventricles are full, they begin to contract (from the apex
upwards)
The pressure in the ventricles increases above the pressure in the atria.
The A‐V valves snap shut which stops blood returning to atria.
At this point the semilunar valves are also shut as the pressure in the
major arteries is higher than in the ventricles.
The pressure in the ventricles increases quickly as the blood can’t escape. When the pressure in the ventricles exceeds the pressure in the major arteries, the semilunar valves open and the blood is pumped out of the heart due to this pressure.
The volume in the ventricles then drops quickly. This causes pressure to drop in the ventricles, below the pressure of the major arteries which causes semilunar valves to be pushed closed by blood in the arteries and
stop it flowing back into ventricles.
When are the atrioventricular valves closed?
When the pressure is higher in the ventricles than the atria
When are the semilunar valves closed?
When the pressure is higher in the major arteries is greater than the pressure in the ventricles
What is the purpose of the tendious cords?
They stop the valves inverting
Explain the “lub-dub” motion
The first, louder “lub” is the A-V valves slapping shut
The second, quieter “dub” is the semilunar valves closing
Out of the 3 stages of the cardiac cycle, when is the ventricular pressure highest?
Ventricular systole
Define bradycardia
A slow heart rhythm
What is an ectopic heartbeat?
An extra beat or an early beat of the ventricles
What is an electrocardiogram?
A trade that records the electrical activity of the heart
Define fibrillation
An uncoordinated contraction of the atria and ventricles
What is a myogenic muscle?
Muscle that can initiate its own contractions
Define purkyne tissue
It consists of specially adapted muscle fibres that conduct the wave of excitation from the AVN down the septum to the ventricles
What is the bundle of His?
It transmits impulses from the atrioventricular node, located at the inferior end of the interatrial septum, to the ventricles of the heart. These fibers distribute the impulse to the ventricular muscle.
What is the sino-atrial node?
The SAN - The heart’s pacemaker. It is a small patch of tissue that sends out waves of electrical excitation at regular intervals in order to initiate contractions
Define tachycardia
A fast/rapid heart rhythm
What does the SAN do and where is it found?
Creates a wave of excitation (electrical energy)
The top of the right atrium
What does the atrio-ventricular node do and where is it found?
The AVN delays the wave of excitation
Describe the journey of a wave of excitation
SAN across atria to AVN - contract
Pause, down purkuyne tissue to inter-ventricular septum
Moves back up from base (apex) as ventricle contract from the bottom
Define sinus rhythm
Normal rhythm
Define atrial fibrillation
Atria besting more frequently than ventricles - no clear P waves
What piece of equipment allows us to monitor electrical activity of the heart?
An electrocardiogram (ECG)
What does the the P wave show?
The excitation of the atria
What does the QRS complex show?
The excitation of the ventricles (ventricular stimulation)
What does the T wave show?
Diastole
Define affinity
A strong attraction
Define dissociation
The breakdown of a molecule into 2 molecules
oxyhaemoglobin into oxygen and haemoglobin
Define fetal haemoglobin
The type of haemoglobin usually found only in the fetus
What is haemoglobin?
The red pigment used to transport oxygen in the blood
Where is haemoglobin found?
Erythrocytes (red blood cells)
Explain the structure of haemoglobin
A complex protein with 4 subunits (2 alpha minus, 2 beta minus)
Each subunit consists of a polypeptide chain and a haem (non-protein)
The haem groups contain 1 Fe 2+ each which has an affinity for oxygen
Each one can attract and holds 1 oxygen molecule
Define partial pressure
The amount of pressure exerted by a gas relative to the total pressure exerted by all the gases in the mixture
Define oxygen tension
Equivalent to the concentration of oxygen in an area e.g. tissues. It
is the proportion of the total pressure exerted by a mixture of gases produced by oxygen
What is partial pressure measured in?
Kilopascals (kPa)
What is the graph regarding haemoglobin called?
The oxygen dissociation curve
How is fetal haemoglobin different from adult haemoglobin and how does this affect the association graph?
Fetal haemoglobin has a higher affinity for a oxygen
Moves to the left
Define carbonic anhydrase
The enzyme that catalyses the combination of carbon dioxide and water
What is a chloride shift?
The movement of chloride ions into the erythrocytes to balance the charge as hydrogen-carbonate ions leave the cell
What is the Bohr effect?
The effect that extra carbon dioxide has on the haemoglobin, explaining the release of more oxygen
Define haemoglobonic acid
The compound formed by the buffering action of haemoglobin as it combines with excess hydrogen ions
Explain the use/association of carbon dioxide in the body
5% dissolves in plasma
10% combines with haemoglobin to form carbaminohaemoglobin
85% in the form of hydrogencarbonate ions (HCO^3-) in the plasma
Explain how carbonic acid is formed (part 1)
The carbon dioxide in the blood plasma fuses into the erythrocytes and combines with the water.
The reaction is catalysed by the carbonic anhydrase enzyme
Explain the process of haemoglobonic acid being formed (part 2)
The carbonic acid dissociates to release hydrogen ions and hydrogencarbonate ions.
The hydrogencarbonate ions diffuse out of the red blood cell. This is
controlled by the chloride shift.
Meanwhile, the oxyhemoglobin dissociates due to low partial pressure. The oxygen is released into the blood plasma and the haemoglobin reacts with the hydrogen to form haemoglobonic acid
How do hydrogen ions impact conditions in red blood cells and what prevents this effect?
It makes it acidic
The chloride shift
What is a conformational change?
A slight change in the shape of the haemoglobin molecule, caused by an oxygen molecule entering the haemoglobin molecule associating with one of the haem groups
What does a greater partial pressure and a lower partial pressure of carbon dioxide have on an oxygen dissociation curve?
Higher - shallower line
Lower - steeper line
Define myoglobin
Used as an oxygen reserve. Releases last of the oxygen if in a suffocation scenario in order to give the body a few more seconds
