3.2 - Transport In Animals Flashcards
What is the circulatory system?
The circulatory system is what uses blood to carry oxygen, carbon dioxide, glucose, hormones and antibodies around mammals
What are the 4 types of circulatory systems?
- Single
- Double
- Open
- Closed
What is a single circulatory system?
It is when the blood only passes through the heart once for each complete circuit of the body
What is a double circulatory system?
When the blood passes through the heart twice for each complete circuit of the body
Describe a fishes circulatory system.
The heart pumps the blood to the gills to pick up oxygen and then it goes through the rest of the body delivering oxygen before returning to the heart
Describe a mammals circulatory system.
The right side of the heart pumps blood to the lungs to pick up oxygen, then the blood goes from the lungs to the left side of the heart. It then pumps it to the rest of the body before going back to the heart
What is the name of the system that sends the blood to the lungs?
The pulmonary system
What is the name of the system that pumps blood to the rest of the body?
The systematic system
What is the advantage of the double circulatory system?
It gives the blood an extra push so the blood travels faster around the body without losing pressure so oxygen is delivered quicker
What is a closed circulatory system?
It is when the blood is enclosed in blood vessels
What is an open circulatory system?
When the blood isn’t enclosed in blood vessels all of the time, instead it flows freely in the body cavity
Describe a vertebrates closed circulatory system.
The heart pumps blood into the arteries that then branch out into capillaries. Substances then diffuse from the blood to the capillaries into body cells, then the veins take the blood back to the heart
Describe an invertebrates open circulatory system.
The heart contracts in a wave pumping the blood into a single main artery which opens up into the body cavity. The blood then flows around the insects organs gradually making its way back to the heart segment through a series of valves
What does an insects circulatory system transport around the body?
Nutrients and hormones
Oxygen is supplied through the tracheal system
How is an insects heart different to a mammals?
An insects heart is in segments that has valves to control the blood entering rather than being split into chambers
What are the 5 types of blood vessels?
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
What is the function of arteries?
Carry blood from the heart whilst maintaining a high pressure
What are the 3 layer in veins and arteries and what are they made of?
- Tunica intima(inside) = Endothelium
- Tunica media(middle) = Elastic fibres and smooth muscle
- Tunica externa(outside) = Collegan fibres
Describe the structure of an artery.
- Thick muscle layer
- Elastic tissue in the wall to stretch and recoil
- The endothelium is folded which allows the artery to expand
- Small lumen
Describe how the structure of arterioles differs from arteries.
Similar structure but there is less elastic tissue as the smooth muscle allows them to expand or contract to control blood flow
Describe the structure of capillaries.
They are made of endothelium which is 1 cell thick
Describe the structure of venules.
Thin wall that contains muscle cells
What is the function of the veins?
They take blood back to the heart under low pressure
Describe the structure of a vein.
- Wider lumen
- Little elastic and muscle tissue
- Thin endothelium
- Valves to stop blood flowing backwards
Why is the pulmonary artery different to normal arteries?
The pulmonary artery carries deoxygenated blood to the lungs, not oxygenated blood
Why is the pulmonary vein different to normal veins?
The pulmonary vein carries oxygenated blood to the heart from the lungs, not deoxygenated blood
What is tissue fluid?
It is the fluid that surrounds the cells in tissues.
Describe the formation of tissue fluid.
- At the start of the capillary bed the hydrostatic pressure inside the capillaries is greater than the hydrostatic pressure in the tissue fluid which forces the fluid out into the space around the cells
- As the fluid leaves the hydrostatic pressure in the capillaries reduces, so the hydrostatic pressure is lower at the end of the capillaries
- At the venule end of the capillaries the water potential is lower than the water potential in the tissue so the oncotic pressure is higher than the hydrostatic pressure which causes 90% of the water to re-enter the capillaries through osmosis
What happens to the 10% of tissue fluid that doesn’t re-enter the capillaries?
The extra tissue fluid returns to the blood through the lymphatic system
Describe what happens in the lymphatic system.
- The remaining tissue fluid goes into the lymphatic system through the lymph capillaries, so the tissue fluid is now known as lymph
-The valves in the lymph vessels stop the lymph from going backwards as it gradually makes it way move towards the main lymph vessel in the thorax where it returns to the blood near the heart
What components are in blood?
- Red blood cells
- White blood cells
- Platelets
- Proteins
- Water
-Dissolved solutes
What components are in tissue fluid?
- Water
- Dissolved solutes
- Very few white blood cells, only enter when there is an infection
- Very few proteins, most plasma proteins are too big to fit through the capillary walls
What components are in lymph?
- White blood cells
- Water
- Dissolved solutes
- Proteins, only antibodies
Why are red blood cells only in the blood?
They are too big to go through the capillary walls
When are platelets pressent in tissue fluid?
Only pressent when the capillary is damaged
Where are the atrioventricular valves?
Between the atrium and the ventricle
Where are the semi-lunar valves?
They link the ventricles to the aorta and the pulmonary artery
What do valves do?
They stop blood from flowing the wrong way by closing after the blood has passed through
What cause the valves to open and close?
- The valve opens when there is a high pressure behind it
- The valve closes when there is a high pressure in front of the valve
What are the 3 stages of the cardiac cycle
- Atrial systole
- Ventricular systole
- Diastole
What happens is atrial systole?
Both the right and the left ventricle contract together which causes the blood to be pushed into the ventricles stretching the wall ensuring they fill with blood through the atrio-ventricular valve.
Footnote
Only a small amount of pressure due to the thin walls
What happens in ventricular diastole?
The left and right ventricles contract together pushing the blood through the semilunar valve and out of the heart. The pressure above the valve causes it to open.
Footnote
Contraction starts at the apex of the heart causing the blood to be pushed up
What happens in diastole?
The muscular wall of all 4 chambers are relaxed allowing blood to flow into the atria from the valves. This causes the blood in the atria to be higher than in the ventricles so the atrio-ventricular valve is forced open allowing blood through the
Footnote
Elastic recoil allows the volume in the chambers to increase.
How do you calculate cardiac output?
Cardiac output = heart rate x stroke volume
Footnote
Heart rate = bpm
Stroke volume = volume of blood pumped during a heart beat in cm3
What word can be used to describe the heart muscle?
Myogenic
What does myogenic mean?
It has its own mechanism to coordinate the contraction of the chambers it id not controlled by any other part of the body
How is a heartbeat generated?
- The sink-atrial node, SAN, initiates a wave of excitation at regular intervals, 55-80 times per minute
- The wave of excitation spreads over the walls of both atria along the membrane causing the cardiac muscle to contract
- The wave of excitation reaches the atrio-ventricular node and there is a short pause
- It then goes down the pukyne tissue and runs to the apex before going up the bundle of his causing the ventricles to contract from the bottom upwards
Where is the SAN located?
Top right of the atrium
Where is the atrio-ventricular node located?
At the top of the septum (thick muscle in between the left and right chambers)
How are heart rates recorded?
Using ECG traces
What are the letters used on ECG traces to identify parts of a heart beat?
P,Q,R,S,T
What does the P represent on an ECG trace?
It represents the contraction of the atria
What does the QRS complex on an ECG represent?
The contraction of the ventricles
What does the T on an ECG represent?
The relaxation of the ventricles
What does tachycardia look like on an ECG?
The gap between the P and T traces are closer together
What does brachycardia mean and look like on an ECG?
A slow heartbeat rate, below 60 bpm. So the gaps between the P and T traces are further apart than normal
What is an eptopic heartbeat and what does it look like on an ECG?
When the atria contracts earlier also know as an ‘extra beat’. It makes the P trace look like a step rather than just a small bump
What is fibrillation and what does it look like on an ECG?
It is an irregular heartbeat, it has completely lost its rhythm. This means the ECG is a mess compared to normal, it will have extra bumps in places it shouldn’t.
