Transport In Animals Flashcards
Why do large organisms need a transport system?
In large organisms, cells are further from each other, increasing the diffusion pathway and reducing the diffusion rate, making it too slow to supply all requirements.
How does surface area to volume ratio affect transport in animals?
Small animals have a large surface area to volume ratio, allowing more body surface for exchange. In contrast, large animals have a small surface area to volume ratio, resulting in less body surface for exchange.
What is the impact of metabolic activity on transport needs?
Active animals require good supplies of nutrients and oxygen to support energy and movement.
What are the features of a good transport system?
A good transport system includes a fluid to carry nutrients, oxygen, and waste (e.g., blood), a pump to create pressure, and exchange surfaces.
What is a single circulatory system?
In a single circulatory system, blood flows through the heart once for each circuit of the body.
Example: Fish - heart → gills → body → heart.
What is a double circulatory system?
In a double circulatory system, blood flows through the heart twice for each circuit of the body.
Example: Mammals - heart → body → heart → lungs → heart.
What is the term for blood going to the lungs?
Pulmonary circulation
What is the term for blood going to the body?
Systemic circulation
What is an advantage of the double circulatory system?
A heart can increase the pressure of blood after it passes through the lungs, allowing blood to flow under high pressure to the body.
What is an advantage of systemic circulation?
Systemic circulation can carry blood at a higher pressure than pulmonary circulation.
What characterizes an open circulatory system?
Blood circulates through the body cavity.
What is a disadvantage of the open circulatory system?
Blood pressure is low and blood flow is low.
How can circulation in an open circulatory system be affected?
Circulating blood may be affected by body movements.
What characterizes a closed circulatory system?
Blood is confined to blood vessels.
What is an advantage of a closed circulatory system?
Higher pressure allows blood to flow more quickly.
What is another advantage of a closed circulatory system?
It allows for rapid delivery of oxygen and nutrients.
What is a benefit of rapid removal in a closed circulatory system?
Rapid removal of CO2 and other waste products.
How does a closed circulatory system relate to body movements?
Transport is independent of body movements.
What do arteries do?
Arteries carry blood away from the heart.
Blood is at high pressure.
What are the characteristics of artery walls?
Artery walls are thick to withstand pressure.
Have collagen that provide strength
Endothelium is folded so allows it to stretch and recoil so no damage
The lumen is small to maintain high pressure because of the thick smooth muscle
What do veins do?
Veins carry blood towards the heart.
Blood is at low pressure.
What are the characteristics of vein walls?
Vein walls are thin since they do not need to stretch and recoil.
The lumen is large to ease the flow of blood and they contain valves to prevent backflow.
What is the function of capillaries?
Capillaries allow exchange of materials between blood and tissue.
They have thin walls to reduce diffusion distance.
What are the characteristics of capillary walls?
Capillary walls are thin, and the lumen is very narrow, allowing red blood cells to squeeze through.
The walls are leaky, allowing blood plasma to leave the blood.
What are arterioles?
Arterioles are small blood vessels that send blood from an artery to the capillaries.
Contraction of the muscle constricts the diameter of the arteriole, reducing blood flow.
What is the function of venules?
From capillaries, blood flows into venules, which then lead into veins.
What is blood plasma?
Blood plasma is the liquid component of blood that contains many dissolved substances such as hormones, carbon dioxide (CO2), and glucose.
What is tissue fluid?
Tissue fluid is similar to plasma but does not contain most of the cells found in blood. It surrounds the cells in the tissue and supplies them with oxygen and nutrients.
How is tissue fluid formed?
Tissue fluid is formed by plasma leaking from the capillaries, which carries dissolved substances into the tissue fluid through mass flow.
What happens at the arterial end of the capillary?
At the arterial end of the capillary, blood is at a high hydrostatic pressure, pushing blood fluid out of the capillaries through the capillary wall.
What does the fluid that leaves the blood consist of?
The fluid that leaves the blood consists of plasma with dissolved nutrients and oxygen. Red blood cells and platelets remain in the blood because they are too large to be pushed out.
What is the role of tissue fluid?
Tissue fluid surrounds body cells, allowing for the exchange of gases, where oxygen enters the cells and waste products like carbon dioxide leave.
What is the blood pressure at the venous end of the capillary?
It is much lower than at the arterial end.
What happens to some tissue fluid at the venous end of the capillary?
Some tissue fluid returns to the capillary, but some is directed to the lymph system.
What is the function of the lymphatic system?
It drains excess tissue fluid out of the tissues and returns it to the blood system.
What is the fluid in the lymphatic system called?
Lymph, which contains more lymphocytes as these are produced in lymph nodes.
What pushes fluid into capillaries?
The hydrostatic pressure of the tissue.
What pushes fluid into tissues?
The hydrostatic pressure of the blood.
What pulls water back into the blood?
The oncotic pressure of the blood.
What pulls water into tissue fluid?
The oncotic pressure of the tissue fluid.
What do the atria do?
The atria receive blood from major veins.
Where does deoxygenated blood flow?
Deoxygenated blood flows through the vena cava into the right atrium.
Where does oxygenated blood flow?
Oxygenated blood flows through the pulmonary vein into the left atrium.
What happens to blood from the atria?
From the atria, blood flows through atrioventricular valves into the ventricles.
What prevents the atrioventricular valves from turning inside out?
The valves are attached to tendinous cords which prevent them from turning inside out.
Where does deoxygenated blood leave the right ventricle?
Deoxygenated blood leaving the right ventricle flows into the pulmonary artery leading to the lungs.
Where does oxygenated blood leave the left ventricle?
Oxygenated blood leaving the left ventricle flows into the aorta.
What are the semi-lunar valves?
The semi-lunar valves are where blood leaves the heart.
Why do the atria have thin walls?
The atria have thin walls because the chamber doesn’t have to create much pressure.
Why does the right ventricle have thicker walls than the atria?
The right ventricle has thicker walls than the atria as it has to create higher pressure to overcome resistance to enable it to pump blood out of the heart to all parts of the body
Why is the left ventricle thicker than the right ventricle?
The left ventricle is 2 or 3 times thicker than the right ventricle as it pumps blood through the aorta and needs sufficient pressure to overcome systemic circulation.
What causes the ‘lub’ sound?
‘Lub’ is caused by the atrioventricular valves closing.
What causes the ‘dub’ sound?
‘Dub’ is caused by the semilunar valves closing.
What is the starting phase of the cardiac cycle?
The cardiac cycle starts at diastole when the atria and ventricles are relaxed.
What happens to blood during the cardiac cycle?
Blood flows into the atria, causing pressure to rise.
What occurs when atrial pressure exceeds ventricular pressure?
Atrial pressure being higher causes the atrioventricular valves to open, allowing blood to flow into the ventricles.
What happens during atrial systole?
The atria contract, pushing the remaining blood into the ventricles.
What occurs after ventricular systole begins?
Pressure in the ventricles rises rapidly.
What happens when ventricular pressure exceeds atrial pressure?
The atrioventricular valves close.
What happens to the semilunar valves during ventricular contraction?
The semilunar valves open, allowing blood to be pumped from the ventricles into the aorta and pulmonary artery.
What is the state of the atria during ventricular contraction?
The atria are relaxed.
What occurs during ventricular diastole?
Ventricular diastole occurs when the pressure in the ventricles is lower than in the aorta and pulmonary artery, causing the semilunar valves to close.
What is the relationship between atrial and ventricular pressures during the cardiac cycle?
Atrial pressure (AP) is greater than ventricular pressure (VP) during diastole, and vice versa during systole.
What is SAN also known as
Pacemaker
What is SAN?
SAN stands for Sinoatrial Node, which initiates a wave of excitation over the walls of both atria, causing them to contract.
What is the role of the Atrioventricular Node? And why is there a short delay
The Atrioventricular Node is located at the top of the interventricular septum and conducts the wave of excitation over the ventricles with a short delay.
Delay is so that the atria contracts fully
And so that the ventricles don’t contract to early
What follows the Atrioventricular Node in the conduction pathway?
After the Atrioventricular Node, excitation is carried away from the AVN to the Purkinje fibers by the Bundle of His.
What is the result of excitation spreading over the ventricles?
The wave of excitation spreads over the walls of the ventricles, causing them to contract. And it starts from the bottom upwards to push blood upwards
What does the P wave represent in an ECG?
The P wave shows atrial excitation.
What does the QRS complex represent in an ECG?
The QRS complex shows ventricular excitation.
What does the T wave represent in an ECG?
The T wave shows diastole.
What is bradycardia?
Bradycardia is defined as a slow heart rate.
What is tachycardia?
Tachycardia is defined as a fast heart rate.
What is an ectopic beat?
An ectopic beat is an early heartbeat.
What is fibrillation?
Fibrillation is characterized by lots of heartbeats.
What is the function of haemoglobin in oxygen transport?
Haemoglobin has a high affinity for oxygen
Oxygen binds to it in the lungs
Haemoglobin + oxygen → oxyhaemoglobin.
It is then transported where needed
What are the components of haemoglobin?
Haemoglobin has 4 subunits - polypeptide chains containing a haem group with iron (Fe).
Iron can attract and hold an O2 molecule.
How do oxygen molecules enter red blood cells?
O2 molecules diffuse into blood plasma to enter red blood cells, where they bind with haemoglobin.
This maintains a steep concentration gradient, allowing more O2 to enter blood from lungs.
What is the process called when oxyhaemoglobin releases oxygen?
The process is called dissociation.
Cells in body tissues need O2 for aerobic respiration.
What is the relationship between partial pressure of O2 and haemoglobin saturation?
As the partial pressure of O2 increases, the saturation of haemoglobin increases.
At high partial pressure of O2, haemoglobin has a high affinity for O2.
How does fetal haemoglobin differ from adult haemoglobin?
Fetal haemoglobin has a higher affinity for O2 than adult haemoglobin.
Foetal haemoglobin becomes more saturated with a low oxygen affinity
Placenta has a low partial pressure of oxygen
This increases the transfer of O2 across the placenta from maternal to fetal haemoglobin.
What would happen if fetal haemoglobin had very high affinity for O2?
If fetal haemoglobin had very high affinity for O2, it could prevent the unloading of O2 in the fetus.
What happens to CO2 released from respiring tissues?
It must be removed.
How is CO2 transported in the blood?
CO2 is transported in 3 ways: 5% dissolved in plasma, 10% combined with haemoglobin as carbaminohaemoglobin, and 85% in the form of hydrogen carbonate ions (HCO3-).
How is carbonic acid formed?
CO2 diffuses into red blood cells and forms carbonic acid by combining with water, catalyzed by carbonic anhydrase.
What happens to carbonic acid in red blood cells?
It dissociates to release H+ and hydrogencarbonate ions.
What is the chloride shift?
Hydrogencarbonate ions diffuse out of red blood cells while chloride ions diffuse in from plasma to maintain charge.
What effect do hydrogen ions have on red blood cells?
They cause the red blood cell to become acidic.
How does haemoglobin help with acidity in red blood cells?
H+ ions are taken out of solution by associating with haemoglobin to produce haemoglobinic acid, acting as a buffer.
What is the Bohr effect?
The Bohr effect describes the impact of increasing carbon dioxide concentration on hemoglobin.
How does carbon dioxide affect red blood cells?
CO2 enters red blood cells forming carbonic acid, which dissociates to release H+ ions.
This makes the cytoplasm more acidic
How does increased acidity affect hemoglobin?
Increased acidity alters the tertiary structure of hemoglobin, reducing its affinity for oxygen.
What is the result of hemoglobin’s reduced affinity for oxygen?
Hemoglobin is unable to hold as much oxygen, leading to less saturation when more CO2 is present.
What is the Bohr shift?
The Bohr shift refers to the rightward and downward movement of the hemoglobin dissociation curve.
What is the significance of the Bohr effect for actively respiring tissues ?
actively respiring tissues need more oxygen so the Bohr effect results in more oxygen being released where more CO2 is produced as there is less haemoglobin available to associate with O2
