3.2 Transport in animals Flashcards
What are the two types of circulatory systems?
Open or closed.
Define a closed circulatory system
Blood is confined in blood vessels only.
Give examples of organisms that have a closed circulatory system
Fish and Mammals
Give examples of organisms that have an open circulatory system
Insects
What are the two types of closed circulatory systems?
Single closed circulatory system or Double closed circulatory system.
Define single closed circulatory system
Consists of a heart with two chambers, meaning the blood passes through the heart once for every circuit of the body.
Define double closed circulatory system
The heart has four chambers and blood passes through the heart twice for every circuit of the body
What are some advantages of a double circulatory system?
Delivers oxygen and nutrients quickly to the parts of the body where they are needed.
What are some disadvantages of an open circulatory systems?
-Blood pressure is low and blood flow is slow
-Circulation of blood may be affected by body movements or lack of body movements
What are some advantages of the a closed circulatory system?
-Higher pressure so that blood flows more quickly
-More rapid delivery of oxygen and nutrients
-More rapid removal of carbon dioxide and other wastes
-Transport is independent of body movements
What is the function of arteries?
To move blood away from the heart to the rest of the body
Describe the structure of arteries.
-Thick walled to withstand high blood pressure,
-Contain elastic tissue which allows
them to stretch and recoil thus smoothing blood flow,
-Contain smooth muscle which
enables them to vary blood flow,
-Lined with smooth endothelium to reduce friction and ease flow of blood
What is the function of arterioles?
They feed blood into the capillaries
Describe the structure of arterioles.
Have thinner and less muscular walls.
What is the function of capillaries?
The site of metabolic exchange
Describe the structure of capillaries.
-Only one cell thick for fast exchange of substances
What is the function of venules?
Connect blood from the capillaries into the veins
Describe the structure of venules.
Larger than capillaries but smaller than veins
What is the function of veins?
Carry blood from the body to the heart.
Describe the structure of veins.
-Contain a wide lumen to maximise
volume of blood carried to the heart, -Thin walled as blood is under low pressure,
-Contain valves to prevent back-flow of blood, no pulse of blood meaning there’s little elastic tissue or smooth muscle as there is no need for stretching and recoiling
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.
What is Blood plasma, and what does it contain?
Plasma is the fluid portion of the blood, it contains dissolved substances such as oxygen, carbon dioxide, minerals, glucose, amino acids, hormones and plasma proteins.
Also contains red blood cells (erythrocytes) White blood cells and fragments called platelets.
How is tissue fluid similar to blood plasma?
Contains dissolved oxygen and carbon dioxide, but does not contain many blood cells or plasma proteins.
How is tissue fluid formed?
-At arterial end, blood has high hydrostatic pressure.
-The pressure pushes blood fluid out of capillaries through capillary wall. The fluid can leave through tiny gaps between cells and capillary walls.
-Blood cells and platelets too big to be pushed out of capillary
-Tissue fluid surrounds body cells, so exchange of gasses can happen through plasma membranes
How does tissue fluid return to the blood?
-The blood pressure at venous end of the capillary is much lower,
-allows some of the tissue fluid to return to the capillary carrying carbon dioxide and other waste substances into the blood
What happens to tissue fluid that doesn’t re-enter the blood
-Some tissue fluid is directed into another tubular system: The lymphatic system
-This drains excess tissue fluid and returns it to blood via subclavian vein in chest.
What is the fluid called thats found in the lymphatic system and what is it composed of?
Called Lymph, similar in composition to tissue fluid. Contains more lymphocytes, as they are produces in lymph nodes.
What are Lymph nodes?
Swellings found at intervals along the lymphatic system which have an important part to play in the immune response.
How does the oncotic pressure have an affect on movement of fluid in capillaries?
-Oncotic pressure of blood tends to pull water back into the blood (has a negative figure)
-Oncotic pressure of the tissue fluid pulls water into the tissue fluid.
Where are the atrio-ventricular valves and what is their function?
Valves between the atria and the ventricles
What is the function of the semilunar valves
Valves that prevent blood reentering the heart from the arteries.
What type of muscle is found in the walls of the heart?
Cardiac muscle.
Which side of the mammalian heart pumps oxygenated blood to the body?
The left side.
Which side of the mammalian heart pumps de-oxygenated blood to the lungs?
The right side.
Describe the external features of the mammalian heart.
-Made of dark red muscle called Cardiac muscle
-Atrium above ventricles
-Coronary arteries on the surface of heart
-At top of heart is tubular blood vessels, veins that carry blood into the atria
What is the function of coronary arteries?
Supply oxygenated blood to the heart muscles
What happens when the coronary arteries are constricted?
Reduces the delivery of oxygens and nutrients such as fatty acids and glucose. This may cause Angina or a heart attack
Describe the four chambers of the heart.
-Two upper chambers are atria, receive blood from major veins.
-Two bottom chambers are ventricles
Describe the course of how deoxygenated blood flows through the heart.
-Deoxygenated blood from body flows through Vena Cava into right atrium
-Flows through Atrio-ventricular valves into ventricles.
-Deoxygenated blood leaves right ventricle through the Pulmonary artery to lungs through Semilunar valves
Describe how oxygenated blood flows through the heart.
-Oxygenated blood from the lungs flows through Pulmonary veins into left atrium
-Down to ventricles through Atrio-ventricular valves
-Oxygenated blood leaves left ventricle through Aorta to body through Semilunar valves
Where are the Tendinous cords in the heart and what are their functions?
-Tendinous cords are attached to the valves , they prevent the valves from turning inside out when the ventricle walls contract.
Where is the Septum in the heart and what are their functions?
Septum separates the ventricles from each other
-This ensures oxygenated blood in the left side and deoxygenated blood in the right side are kept separate.
How does cardiac muscle create blood pressure?
Cardiac muscle contracts, creates pressure in the blood, higher the pressure created in the heart , further it will push the blood
Describe the structure and function of the Atria.
-Muscle of atrial walls are thin
-Because these chambers do not need to create much pressure.
-Function: receive blood from the veins and push it into the ventricles
Describe the structure and function of the Right ventricle.
-Walls are thicker than walls of atria, enables right ventricles to pump blood out of the heart.
-RV pumps blood to lungs, does not need to travel far
-High blood pressure could damage alveoli
Describe the structure and function of the Left ventricle.
-Walls are 2-3x bigger than that of the right ventricle
-Blood from left ventricle is pumped through the aorta and needs sufficient pressure to overcome resistance of the systematic circulation.
Describe the structure of Cardiac muscle.
-Fibrous branches
-Numerous mitochondria between muscle fibrils (Myofibrils)
-Muscle cells separated by intercalated discs
-each cell has a nucleus that is divided into contractile units called sarcomeres.
What is the cardiac cycle and why is is needed?
The muscular walls of the chambers in the heart contracting in a coordinated sequence, allows heart to fill with blood before pumping it away.
What are the three stages of the cardiac cycle?
-Atrial systole
-Ventricular systole
-Diasystole
Describe Atrial systole.
-Both atrias contract together,
-Small increase in pressure is generated
-Helps to push blood into the ventricles and stretch walls
Describe Ventricular systole.
-Both right and left ventricles pump together.
-Contraction starts at apex (base) of the heart
-Blood is pushed into the arteries.
Describe Diastole.
-Muscular walls of all four chambers relax
-Elastic recoil causes chambers to increase in volume
-Allowing blood to flow in from veins
Name the two types of valves found in the heart.
-Atrioventricular valves
-Semilunar valves
Describe the action of Atrioventricular valves opening.
-During diastole, ventricular walls relax
-Causes pressure in ventricles to decrease more than the atria
-Blood in atria pushes AV open
-Blood flows into ventricles
Describe the action of Atrioventricular valves closing.
-Valves remain open while atria contract, close when they relax
-Closure caused by swirling action in blood around valves when ventricle is full
How do atrioventricular valves remain closed during ventricular systole with help of tendinous cords?
-Pressure of blood increases in ventricles
-When pressure rises above the atria, blood moves upwards
-Movements fill valve pockets and keeps them closed
-Tendinous cords attached to valves stop them from turning inside out
-Prevents back flow of blood
Describe the action of Semilunar valves opening.
Ventricular systole raises blood pressure in ventricle,
-once pressure in ventricles are higher than that of the arteries the SV open
-Blood is forced out of the ventricles in a powerful spurt
Describe the action of Semilunar valves closing.
-Diastole causes ventricular walls to relax
-causes pressure in ventricles to decrease
-pressure drops below those in the arteries, SV closed by blood in the pockets of valves
What creates the pulse we can feel?
The pressure wave of the left SV closing
How does the structure of artery walls play a large part in creating an even flow for the tissues?
-Have a lot of elastic tissue
-Blood leaves heart, walls stretch
-Pressure in aorta drops as blood leaves
-Elastic recoil of walls help to maintain BP
-Further blood travels, more BP drops
-Pressure gradient between Aorta + Arterioles causes blood flow towards tissues.
How is the heart described as Myogenic?
-As it can initiate its own contraction
-Could cause inefficient pumping (Fibrillation)
What are the two nodes in the heart?
Sino-atrial node, (SAN)
Atrio-ventricular node, (AVN)
How is a contraction initiated ?
-Top of right atrium is SAN, which generates electrical activity.
-The SAN initiates a wave of excitation at regular intervals
-SAN also called Pacemaker
How are atria excited?
-Wave of excitation spreads across atria
-Travels along membrane
-Causes cardiac muscle to contract
-Causes Atrial systole.
How does the Wave of excitation pass through to the ventricles?
At the top of inter-ventricular septum is the AVN
-AVN delays Wave of excitation so atria can finish contracting
-After delay wave is sent down the Bundle of His which divides down to the separate ventricles.
How are ventricles excited?
-Excitation passed to the Purkyne tissue at base of ventricles
-Excitation spreads over walls of ventricles
-Causes muscles to contract
-Contract from base upwards
-Pushes blood up to the arteries.
What does an Electrocardiogram (ECG) monitor?
-The electrical activity of the heart
Describe an ECG trace of a healthy person.
-Series of waves labelled P,Q,R,S,T
-Wave P shows excitation of atria
-QRS complex indicates excitation of ventricles
-Wave T shows diastole.
Name 4 heart conditions that can be identified by looking at an ECG.
-Bradycardia
-Tachycardia
-Atrial fibrillation
-Ectopic heartbeat.
How to identify Bradycardia?
If an ECG shows someone having a slow heart rate
How to identify Tachycardia?
If an ECG shows someone having a fast heart rate
How to identify Atrial fibrillation?
If an ECG shows someone’s Atria beating more frequently than ventricles, and there is no clear P wave
How to identify Ectopic heartbeat?
If an ECG shows someone has earlier ventricular beats.
What is the name of the left Atrioventricular valve?
Bicuspid valve
What is the name of the right Atrioventricular valve?
Tricuspid valve
What is the name of the left Semilunar valve?
Aortic valve
What is the name of the right Semilunar valve?
Pulmonary valve
When do the SV valves open?
When Ventricular pressure becomes higher than the arteriole/aortic pressure
When do the SV valves open?
When Arteriole/aortic pressure becomes higher than the ventricular pressure.
When do the AV valves close?
When the Ventricular pressure becomes greater than the atrial pressure.
When do the AV valves open?
When the Atrial pressure becomes greater than the Ventricular pressure
What creates the Lub sound in the heart?
The sound of the atrioventricular valves closing (Tricuspid and Bicuspid valves)
What creates the Dub /pulse sound in the heart?
The sound of the Semilunar valves closing (Aortic and pulmonary valves)
Where is the protein Haemoglobin found?
In red blood cells (Erythrocytes)
What is formed when haemoglobin takes up oxygen?
Oxyhaemoglobin
Describe the structure of haemoglobin.
-Made up of 4 subunits
-Each subunit contains a polypeptide chain and a haem group
-haem group contains a single iron molecule
-Haem groups have a high affinity for oxygen.
How many oxygens can a haem group attract?
a haem group can attract 1 oxygen molecule
How many oxygens can a haemoglobin molecule carry?
4 oxygens
Describe the route oxygen takes when it is transported.
O2 passed into blood as it passes into alveoli
-O2 enter Red blood cells
-Become associated to haemoglobin
-Blood carries oxygen from lungs back into heart, before travelling around body
Why do cells around the body require oxygen?
For aerobic respiration
How is oxygen transported from blood into respiring cells?
Through dissociation
Where does dissociation occur?
-In tissues where (pO2) partial pressure is low
When does association occur?
-In the lungs where (pO2) partial pressure is high
How is the concentration of oxygen measured?
Measured by the relative pressure that it contributes to a mixture of gases called the Partial pressure of oxygen
What is the unit used to measure the partial pressure of oxygen?
Kpa
Describe the curve that haemoglobin associated with oxygen can create on a graph.
Creates an S-shaped curve,
-Called the haemoglobin-dissociation curve
What happens when the partial pressure for oxygen is low?
-Haemoglobin does not readily associate with oxygen molecules
Why does Haemoglobin not readily associate with oxygen molecules at lower pO2
-Because haem groups that attract oxygen are in the centre of the haemoglobin molecule, making it difficult for oxygen to reach them.
-This creates a low saturation of haemoglobin associated with oxygen
What happens to haemoglobin association to oxygen as the pO2 starts to increase?
-One oxygen molecule enters the haemoglobin molecule and associates with one of the haem groups
-This changes the shape of the haemoglobin molecule, which allows more o2 to enter the haemoglobin molecule and associate with other haem groups easily.
What is the change in the haemoglobin molecule shape called when the first oxygen binds?
A Conformational change
How is Fetal haemoglobin different from adult haemoglobin?
-Has a higher affinity for oxygen
-Curve on a graph is to the left compared to adult haemoglobin
Why must fetal haemoglobin have a higher affinity for oxygen?
-Must be able to associate with o2 in an environment where the pO2 may be low
-E.g placenta
Define the term Affinity.
A strong attraction
Define the term dissociation.
Releasing oxygen from oxyhaemoglobin
Define the term fetal haemoglobin.
Type of haemoglobin usually found only in the fetus
Describe how Co2 is transported.
-Co2 transported in three ways to the lungs for excretion
1- 5% dissolved in plasma
2- 10% combines with haemoglobin to form Carbaminohaemoglobin
3- 85% in form of hydrogencarbonate ions(HCo3-)
What is formed when Haemoglobin is combined with Carbon dioxide?
A compound called Carbaminohaemoglobin
How is Carbonic acid formed?
-Carbon dioxide diffuses into RBC.
-CO2 combines with water to form Carbonic acid.
What enzyme catalyses carbonic acid formation?
Carbonic Anahydrase
What is the molecular formula of carbonic acid formation?
CO2 +H2O = H2CO3
How are Hydrocarbonate ions formed from carbonic acid?
-Carbonic acid dissociates to release hydrogen ions and hydrogencarbonate ions
What is the molecular formula of Hydrogencarbonate ion formation?
H2CO3 = HCO3 + H
Describe how and why the chloride shift occurs.
Negative Hydrogencarbonate ions diffuse out of RBC,
-To maintain the charge in the RBC, negative Chloride ions diffuse into the RBC
-Called the Chloride shift
How is haemoglobinic acid formed after the chloride shift?
-Hydrogen ions are taken out of solution by associating with haemoglobin
-This produces Haemoglobinic acid
-This prevents the charge inside the RBC becoming acidic (acts as a buffer)
How is carbon dioxide released during the dissociation of Oxyhaemoglobin?
-Oxyhaemoglobin dissociates, sends oxygen to respiring tissues,
-Allows haemoglobin to bind with hydrogen ions, forming Haemoglobinic acid
-Due to over exertion in the tissues, they release carbon dioxide
What is the effect an increasing concentration of Carbon dioxide has on Haemoglobin?
The Bohr effect
In detail, what happens during the Bohr shift?
-CO2 enters RBC, forming carbonic acids
-Releases hydrogen ions
-This affects pH, making cytoplasm more acidic
-Tertiary structure of haemoglobin changes, reduces affinity for oxygen
-More Oxygen from oxyhaemoglobin released to tissues
What happens to the haemoglobin dissociation curve when there is an increase in CO2?
The Bohr shift, shifts downwards and to the right as more oxygen is released where co2 is produced during respiration.
