Flashcards in Transport In Animals Deck (118):
What will an effective transport system include?
Fluid/medium to carry nutrients, oxygen and waste around the body (blood)
Pump create pressure that will push fluid around body (heart)
Exchange surfaces that enable substances to enter blood and leave it again where they are needed these are capillaries
Tubes/vessels to carry blood by mass flow
Two circuits one to pick up oxygen and another to deliver oxygen to the tissues
Single and double circularity system?
Blood flows through heart once for each circuit of body
Heart-> gills-> body-> heart
Blood flows through heart twice for each for each circuit of body
Heart -> body-> heart-> lungs-> heart
Disadvantages of single circulatory system in fish
Blood pressure drops as blood passes through tiny capillaries if gills
Blood has low pressure as flows towards body won't flow quickly
Rate of oxygen and nutrients delivered to respiring tissues and carbon dioxide and urea are removed is limited
Disadvantage of double circularity of mammals
Blood pressure must not be too high in pulmonary circulation otherwise may damage delicate capillaries in lungs
Heart can increase pressure of blood after passed through lungs so blood is under higher pressure as flows to body and flows more quickly
Systemic circulation can carry blood at higher pressure than pulmonary circulation
Open and closed circulatory system
Open- one in which the blood is not held in vessels
Closed- one in which the blood is held in vessels
Disadvantages of open circularity systems
Blood pressure is low and blood flow is slow
Circulation of blood may be affected by body movements or lack of body movements
Advantages of closed circularity system?
High pressure so blood flows quicker
More rapid delivery of oxygen and nutrients
More rapid removal of carbon dioxide and other wastes
Transport is independent of body movements
Types of blood vessels
Carry blood from heart
Thick and muscular elastic walls to stretch and recoil as heart beats helps maintain high pressure
Inner endothelium folded allowing artery to expand helps maintain high pressure
Artery carry oxygenated blood except pulmonary artery
What is the need for transport system affected by?
Surface area to volume ratio
Level of metabolic activity
Artery branches into Arterioles
Much smaller than arteries
Have layer of smooth tissue less elastic tissue
Smooth muscle allows them to expand/contract controlling amount of blood following to tissues
Smallest blood vessels
Substances like glucose and oxygen exchanged between cells and capillaries
Adapted for efficient diffusion
Walls one cell thick
Capillaries walls properties are
Single layer of flattened endothelial cells, reduces diffusion distance for materials being exchanged
Leaky allow blood plasma and dissolved substances to leave blood
Very thin walls contain muscle cells
Join together to form veins
Take blood back to heart under low pressure
Very little elastic/ muscle tissue
Contain valves stop blood flowing backwards
Blood flowed through vein helped by contractions of body lurked surrounding them
Carry deoxygenated blood except pulmonary veins carry oxygenated blood to heart from lungs
What is blood plasma?
Fluid that our blood is held in
What does the plasma contain?
Oxygen, carbon dioxide, minerals, glucose, amino acids, hormones and plasma proteins
Cells include erythrocytes and leucocytes and platelets
What are erythrocytes and leucocytes
Erythrocytes are red blood cells
Leucocytes are white blood cells
Features of tissue fluid
Doesn't contain most of cells found in blood or plasma proteins
Formed by plasma leaking from capillaries
Surrounded by cells in tissue and supplies them with oxygen and nutrients they require
Blood plasma leaks from capillaries carries all dissolved substances into tissue fluid
Movement called mass flow
Waste products from cell metabolism carried back into capillary as some of tissue fluid returns to capillary
Making of tissue fluid first two steps
When artery reaches tissue branches off into smaller Arterioles and then into capillaries leading to Venules to carry blood back to veins, blood flowing into organ/ tissue is contained in capillaries
At end of arterial end of capillary blood at relatively high hydrostatic pressure which pushes blood fluid out of capillaries through capillary wall, fluid can leave through tiny gaps in capillary wall
Making tissue fluid last two steps
Fluid leaves blood consists of plasma with dissolved nutrients and oxygen all red blood cells, platelets, plasma proteins and most white blood cells remain in blood as too large to be pushed out of gaps of capillary wall
Tissue fluid surrounds body cells so exchange by diffusion, facilitated diffusion and active uptake. Oxygen and nutrients enter cells carbon dioxide and other wastes leave cells
Pressure that fluid exerts when pushing against sides of a vessel or container
How does some of the tissue fluid return to capillary
Blood pressure at venous end of capillary is much lower
What else happens to tissue fluid after leaving blood?
Some is directed into lymph system or lymphatic system
Drains excess fluid of tissues and returns to blood systems in subclavian in chest
Lymph in lymphatic system composed of similar composition to tissue fluid but contains more lymphocytes as produced by lymph nodes
Where are lymph nodes found?
Swellings found at intervals along lymphatic system have important part to play in immune response
Fluid held in lymphatic system
What is the lymphatic system?
A system of tubes that return excess fluid to blood system
What is oncotic pressure?
Pressure created by osmotic effects of solutes
What is the hydrostatic pressure if blood plasma, tissue fluid and lymph?
Blood plasma- high
Tissue fluid- low
What is the oncotic pressure of blood plasma, tissue fluid and lymph?
Blood plasma- more negative
Tissue fluid- less negative
Lymph- less negative
Cells found in blood plasma, tissue fluid and lymph?
Blood plasma- red blood cells- neutrophils, lymphocytes
Tissue fluid- some neutrophils especially in infected areas
Proteins in blood plasma, tissue fluid and lymph?
Blood plasma- plasma proteins
Tissue fluid and lymph- few proteins
Fats blood plasma, tissue fluid and lymph?
Blood plasma- transported in lipoproteins
Tissue fluid- few fats
Lymph- more fats, especially near digestive system
Influences on movement of fluid
Tissue fluid has own hydrostatic pressures
Oncotic pressure of solutes
Hydrostatic pressure of blood
What does each influcence do?
Hydrostatic pressure of blood tends to push fluid out into tissues
Hydrostatic pressure of tissue fluid tends to push fluid tends to push fluid into capillaries
Oncotic pressure of blood tends to pull water back into blood
Oncotic pressure of tissue fluid pulls water into tissue fluid
What is the muscle called and like in texture?
Firm dark red
Chambers of the heart
Right atrium Left atrium
Right ventricle Left ventricle
What are coronary arteries and why are these important?
The arteries over surface that supply oxygenated blood to heart muscle
If constricted causes restricted blood flow to heart muscle reduces delivery of oxygen and nutrients such as fatty acids and glucose
May cause angina or heart attack
Atrio-ventricular valves are?
Valves vetween atria and ventricles which ensure blood flow in correct direction
Semi lunar valves do what
Valves prevent blood reentering the heart from the arteries
Walls very thin
Don't need much pressure
Function to receive blood from veins and push it into ventricles
Thicker than walls of atria
Enables right ventricles to pump blood out of lungs
Left ventricle pumps deoxygenated blood to lungs
Alveoli in lungs very delicate and could be damaged by very high blood pressure
Walls of left ventricle can be two or three times thicker than right ventricle
Blood pumped out through aorta and needs sufficient pressure to overcome systemic circulation
Stages of cardiac cycle
Right and left ventricles pump together
Contraction starts at base of heart so blood pushed upwards towards arteries
Muscular walls of all four chambers relax
Elastic recoil causes chamber to increase in volume allowing blood to flow in from the veins
Right and left atria contract together
Muscle in walls is thin so only small increase in pressure is created by contraction
Helps to push blood into ventricles stretching walls and ensuring they are full of blood
Electric cycle of heart
Wave of excitement quickly spreads over walls of both atria
Travels along membrane of muscle tissue
As wave of excitation passes causes cardiac muscle cells to contact
How does the contraction of ventricles work?
After short delay wave of excitation is carried away from AVN, down specialised conducting purkyne tissue
Runs down I ventricular septum
At base of spectrum wave of excitation spreads out over walls of ventricles
As excitation spreads upwards from apex of ventricles causes muscles contract
Ventricles contract from base upwards
Pushes blood up towards major arteries at top of heart
What's special about cardiac muscle?
Muscles from atria and ventricles have own natural frequency
Atria muscle tends to contract at high frequency than ventricular tissue
Why is there a need for coordination of heart?
Property of muscle could cause inefficient pumping if contractions of chambers aren't synchillised (condition known as filbrillation)
What does the heart have to allow coordination?
Meaning of myogenic
Muscle that can initate its own contractions
Where is the SAN and what is its full name?
At top of the right atrium near point where vena cava empties blood into atrium is the sino-atrial node
What is the SAN
A patch of tissue that generates electrical activity
What does the SAN do?
Initates wave of excitation at regular intervals
How often in humans does it occur?
55-80 times a minute
Give another name for SAN
How can we monitor the electrical activity of the heart?
Using an electrocardiogram
What does using a ECG involve?
Attaching number of sensors to skin
Some of electricity activity generated by heart spreads through tissues next to the heart and outwards to skin
Sensors on skin pick up the electrical excitation created by heart and convert this into trace
What does the electrocardiogram have and what is it called?
A particular shape
What does wave P show on the ECG?
The excitation of the atria
What does wave QRS show on ECG?
Indictates excitation of ventricles
What does T show?
What is a slow heart called?
What is a fast rate called?
What is it called when atria beating more frequently than ventricles?
How can you spot atrial fibrillation?
No clear P waves seen
If a beat happens too quickly or too slow once in every few heartbeats?
What does the patient often feel with ectopic heartbeat?
Often feels as if a heartbeat has been missed
Slow heart rate
What's sinus rhythm?
Fast heart beat
What's atrial fibrillation?
Atria beating more frequently than ventricles
What's ectopic heartbeat?
A heart beat that happens once every few heartbeats that is too fast or too slow
What is oxygen transported in?
In erythrocytes (red blood cells) carried by the protein haemglobin
Write the word equation for haemoglobin and oxygen
Haemoglobin + oxygen -> oxyhaemoglobin
What is haemoglobin?
Complex protein with four subunits
What do these subunits consist of?
Polypeptide chain and haem (non-protein) group
Haem group contains 1 iron ion in form Fe2+
Iron Ions can attract and hold oxygen molecule
Haem group have high affinity for oxygen
How many oxygen can haemoglobin carry?
Each haem group can hold one oxygen molecule
How many haemglobin in erythrocytes?
28 million molecules
How many oxygen molecules can an erythrocytes carry?
Over a billion
Transport of oxygen
Oxygen absorbed into blood as passes alveoli
Oxygen molecules diffusing into blood plasma enter red blood cell
Become associated with haemoglobin
Takes oxygen molecules out of solution so maintains steel concentration gradient allowing more oxygen to enter blood from lungs and diffuse into cells
Meaning of affinity
Meaning of dissociation
Means releasing oxygen from oxyhaemoglobin
What is dissociation in terms of blood
Blood carries oxygen from lungs back to heart before travelling around body to supply tissues
In body tissues cells need oxygen for aerobic respiration
Therefore oxyhaemoglobin must be able to release oxygen
Ability of haemoglobin to associate and release oxygen depend on what?
Concentration of oxygen in surrounding tissues
What is the concentration of oxygen measured by and what's it called
Measured by relative pressure that contributes to a mixture of gases
Called partial pressure or oxygen tension
What is concentration of oxygen in haemoglobin measured in?
(kPa) units of predate
What's different between a normal liquid and blood?
You might expect concentration of oxygen absorbed into normal liquid to be directly proportional to oxygen tension in surrounding air so graph would be a straight line. This isn't the case for blood containing haemoglobin.
How can haemoglobin disassociate with oxygen
In a way that produces an S-shaped curve called haemoglobin dissociation curve
Why does it make this shaped graph?
At low oxygen tension, haemoglobin molecule doesn't readily associate with oxygen molecules because haem groups attract the oxygen are in the centre of the haemoglobin molecule making it difficult for oxygen to reach the haem group and associate with it.
Difficulty in combining first oxygen molecules account for low saturation level of haemoglobin at low oxygen tension
How does diffusion gradient change as the oxygen tension rises?
What happens as a result of a rise in the diffusion gradient?
Eventually one oxygen molecule enters haemoglobin molecule and associates with one of the haem group
Causes slight change in shape of haemoglobin molecule known as confirmational change
Allows more oxygen molecules to enter haemoglobin molecule and associate with other haem groups relatively easy
Accounts for steepness of curve as oxygen tension rises
What happens to graph as haemoglobin approaches 100% saturation?
Curve levels off creating s-shaped curve
What is mammalian haemoglobin well adapted at and how?
Transporting oxygen to tissues of a mammal
Oxygen tension found in lungs is sufficient to produce close to 100% saturation
Oxygen tension sufficiently low in respiring body tissues to cause more oxygen to dissociate readily from oxyhaemoglobin
How is fetal haemoglobin slightly different from adult haemoglobin
Fetal haemoglobin has a high affinity for oxygen than adult haemoglobin
How does the high affinity of fetal haemoglobin graphs compare to adult haemoglobin?
The oxygen dissociation curve is to the left of the curve for adult haemoglobin
Why is the affinity stronger in fetal haemoglobin compared to adult haemoglobin?
Fetal haemoglobin must be able to associate with oxygen in an environment where the oxygen tension is low enough to make adult haemoglobin release oxygen
How does the fetal haemoglobin get oxygen?
In placenta, oxygen tension is low
Fetal haemoglobin will absorb oxygen from surrounding fluid
Which reduces oxygen tension more
Oxygen diffuses from mothers blood which makes maternal haemoglobin release more oxygen.
What three ways is carbon dioxide transported to the lungs for excretion?
About 5% dissolved directly into plasma
About 10% combined with haemoglobin to form carbaminohaemoglobin
About 85% transported in the form of hydrogencarbonate ions (HCO3-)
How does hydrogencarbonate ions form?
Carbon dioxide in blood plasma diffuses into red blood cells
Combines with water to form a weak acid to form a carbonic acid
Reaction catalysed by enzyme
CO2+ H2O-> H2CO3
Carbonate acid dissociates to release hydrogen ions (H+) and hydrogencarbonate ions (HCO3)
H2CO3-> HCO3- + H+
What's chloride shift?
Hydrocarbonate ions diffuse out of red blood cell into plasma
Charge inside red blood cell is maintained by movement of chloride ions (Cl-) from plasma into red blood cell
What could the hydrogen ions building up in the red blood cell?
The contents of the red blood cell to become acidic
How is this prevented?
Hydrogen ions are taken out of solution by associating with haemoglobin to produce haemoglobinic acid (HHb)
Haemoglobin is acting as a buffer
What's a buffer?
A compound that maintains a constant pH
What does blood going into respiring tissue carry and what as?
Carries oxygen as oxyhaemoglobin
Where is partial pressure lower in the lungs or in the respiring tissues and why?
In the respiring tissue because oxygen has been used in respiration
What does this lower partial pressure in the respiring tissues result in?
The oxyhaemoglobin begins to dissociate and release oxygen to the tissues
What the oxyhaemoglobin dissociating mean in terms of carbon dioxide concentration?
The haemoglobin available to take up the hydrogen ions forming haemoglobinic acid where tissues are active there's more carbon dioxide released having a dramatic impact on the haemoglobin
What is the Bohr effect?
The effect that extra carbon dioxide gas in the haemoglobin has on the haemoglobin explaining the release of more oxygen
What's the first stage of the Bohr effect?
Carbon dioxide enters the red blood cells forming carbonic acid which dissociates to release oxygen
What's the second stage of the Bohr effect?
Hydrogen ions affect the pH of the cytoplasm making it more acidic
What's the third stage of the Bohr effect?
As with any protein changes in pH can affect the tertiary structure of the haemoglobin
Increased acidity alters the tertiary structure of the haemoglobin and reduces the affinity of the haemoglobin for oxygen
What's the fourth stage of the Bohr effect?
Haemoglobin is unable to hold as much oxygen
Oxygen released from oxyhaemoglobin to the tissues
What happens where more tissue is respiring?
More carbon dioxide
Therefore more hydrogen ions produced in red blood cell
So more oxyhaemoglobin will give up their oxygen and become haemoglobin
So haemoglobin become less saturated with oxygen
How is the haemoglobin dissociation curve different where there is more respiring tissue
Shifts downwards to the right