Animal Transport Flashcards
Describe an open circulatory system?
Blood is not always held within the blood vessels and can circulate through the body cavity so that cells are immersed directly in the blood.
How does an open circulatory system work in insects?
In insects it is achieved by a dorsal tube- shaped heart found under the upper surface of the insect. The heart will pump blood towards the head by peristalsis; it re-enters the heart through pores called ostia
Describe the open circulatory system of a locus?
.Blood bathes in the tissues directly
.Little control over direction of circulation
.No respiratory pigment
.Blood pumped at low pressure in to a fluid filled cavity - the haemocoel
How do locus’ get their blood back to their head and heart?
Movement of muscles and valves assist
Why is an open circulatory system not appropriate for a larger more active animal?
Blood will flow at a low pressure through the body cavity and would therefore not be sufficient to supply the demand of the respiring cells in a larger more active animal
Describe a closed circulatory system?
.The blood is enclosed within the blood vessels
.Tissues are not in direct contact with the blood, a separate fluid called tissue fluid exits in the capillaries and bathes the cells.
.This allows the heart to pump at a higher pressure and therefore the blood can flow more quickly
What are the three advantages of a closed circulatory system?
- The blood flow can be directed to where it is needed, by vasoconstriction and dilation.
- The blood flow us more rapid and efficient
- More efficient delivery of oxygen and nutrients (glucose) and removal of waste products such as CO2
What type of circulatory system do fish have?
A single closed system
What is a single closed circulatory system?
The blood stays in vessels on a single pathway around the body. Blood only passes through the heart once, before returning to gills.
What is the route of the blood in a single closed system?
Heart
Gills
Body
Heart
Why do some mammals require a double circulatory system?
.They are endothermic (produce their own body heat)
.They have a high metabolic rate and high energy requirement
. They therefore require a large amount of glucose and oxygen and the removal of waste products such as CO2
Describe a double circulatory system?
A system consisting of a network of vessel which carry materials round the body in the blood, The heart pumps the blood and it goes twice through the heart.
What are the two component to a double circulatory system?
The Pulmonary system
The Systemic Circulatory system
What are the three advantages to a Double circulatory system?
- The heart increases the pressure after it has passed through the lungs, so the blood flows more quickly to the body tissues,
- More efficient delivery of oxygen and nutrients to body tissues.
- The oxygen supply to heart muscles better
Between the systemic and pulmonary system, which can carry blood at a higher pressure?
The systemic
What is the structure of the mammalian heart?
.A 4 chambered pump for both pulmonary and systemic circulatory systems.
.A double pump working synchronously keeping oxygenated and deoxygenated blood separated
Describe the characteristics of the cardiac muscle?
The cardiac muscle is myogenic and therefore beats from within the muscle itself to never gets tired.
What is the function on the Vena Cava?
Returns blood from all organs except the lungs
What is the function on the Right Atrium?
receives blood from the body organs and pushes it into the ventricle
What is the function on the Avioventricular (tricuspid) valve?
Stops blood flowing back into the atrium as the ventricle contracts
What is the function on the Right ventricle?
Receives blood from the atrium and pushes it into the lungs
What is the function on the Pulmonary Artery?
Distributes blood to the lungs
What is the function on the Aorta?
Distributes blood to all organs except the lungs
What is the function on the Aortic valve?
Stops blood flowing back into the ventricle as the ventricle relaxes
What is the function on the left ventricle?
Receives blood from the atrium and pushes it to the body
What is the function on the Atrioventricular (bicuspid) valve?
Stops blood flowing back into the atrium as the ventricle contracts
What is the function on the left atrium?
Receives blood from the lungs and pushes it into the ventricle
What is the function on the Pulmonary Vein?
Returns blood from the lungs
What is the first step of the cardiac cycle?
.Atria fill with blood from the Vena Cava and pulmonary vein (all chambers relaxed)
.Pressure in the atria rises
.Blood trickles into ventricles through the open atrioventricular valves (bicuspid and tricuspid valves)
What occurs in Atrial Systole?
When the walls of the atria contracts. The volume of the atria decreases and the pressure increases, blood enters the ventricles down a pressure gradient.
What occurs after Atrial Systole?
Atria empties as the rest of the blood is forced into the ventricles, through the Atrioventricular valves.
What occurs when the ventricles are full of blood?
.After a short delay to allow full contraction of the atria, the walls of the ventricles contract (ventricular systole). Atria relax.
.The walls of the ventricles contract from the bottom up, reducing the volume and increasing the pressure in the ventricles
What occurs to the atrioventricular valves after ventricular contraction?
They close to prevent backflow of blood
What causes the semi lunar valve to open?
The pressure in the ventricles is greater than the pressure in the aorta and pulmonary artery. This pushes open the semilunar valves (pulmonary and aortic valves) in the arteries.
What is the last step in the cardiac cycle?
.Blood is forced out of the heart into the aorta and pulmonary arteries
.Ventricles relax, pressure falls
.Semilunar valves shut
When do the Atrioventricular valves open?
The AV valves are open when the pressure above the valves is greater than below it.
.The atrioventricular valves opens when the pressure in the atrium is greater than the ventricle
When does the Semilunar valve open?
Semilunar opens when the pressure in the ventricle is greater than the artery
Why do the valves in the heart close?
To prevent backflow
What causes the lub-dub sound in the heart?
This occurs due to the closing of the atrioventricular valve followed by the closing of the semilunar valve
What is the pressure in the atria like? Why?
The atria have a thin muscle wall which exerts a small pressure to push blood into the ventricles
What is the pressure in the Right Ventricle like? Why?
The right ventricle has higher pressure than the atria, as it has to push blood to the lungs therefore the m muscle wall is thicker than the atria.
What is the pressure in the Left Ventricle like? Why?
The left ventricle has the highest pressure as it has to pump blood through the aorta to the rest of the body. This means that the muscle wall is up to 3 times thicker than the right ventricle.
Define Myogenic?
Muscle contractions initiated within the muscle itself
What is the Sino Atrial Node (SAN)? Where is it located?
.The heart’s internal pacemaker
.Located on the top right atrium
What is the function of the Sinoatrial node (SAN)?
It initiates the wave of excitation (electrical stimulation)
What is atrial systole and what causes it?
Atrial systole is when the walls of the atria contract simultaneously, this is caused by the wave of excitation.
What is the layer of non-conductive tissue called? What is its function?
The atrioventricular septum which prevents the wave spreading to the ventricles.
What happens to the wave of excitation after passing the atrioventricular septum?
The wave of excitation reaches the AVN (Atrioventricular node) and is delayed to allow the atria to complete contraction before ventricular systole.
After a brief pause at the Atrioventricular node what happens to the wave of excitation?
The wave of excitation then travels down highly conductive tissues in the septum called the bundle of His. As it reaches the apex it passes along the branching Purkinje Fibres up the walls of the ventricles, causing them to simultaneously contract from the bottom upwards: ventricular systole.
What is diastole?
When all the chambers of the heart simultaneously relax, the last stage of the cardiac cycle.
How can the electrical signal that passes through the heart be monitored?
Using an ECG (Electrocardiogram), this involves using detective electrodes on the skin.