Transport in Animals Flashcards
what are reasons for transport systems in multicellular animals?
- small SA:V ratio so can’t rely on diffusion as substances won’t get to cells in the middle of the organism
- higher metabolic rate so diffusion wouldn’t be able to keep up with demand so transport systems are needed
what are the main components of a transport system in animals?
- transport fluid in which substances are transported(e.g. blood)
- vessels through which the fluid can flow
- heart
what are the two types of circulatory system?
open and closed circulatory system
components of an open circulatory system?
consists of a heart that pumps fluid called haemolymph through short vessels and into a large capacity called the haemocoel. in the haemocoel the haemolymph directly bathes organs and tissues enabling the diffusion of substances. when the heart relaxes the haemolymph is sucked back in via pores called osita.
open circulatory systems have low pressure.
components of a closed circulatory system?
blood is fully enclosed within blood vessels at all times. blood is pumped through vessels from the heart to capillaries around the body. and it has high pressure. the blood does not come directly into contact with the cells of the body. in a closed circulatory system, the transport fluid is enclosed within vessels at all times, whereas in an open one they are not always enclosed
what are the two types of closed circulatory systems?
single and double
What is a single closed circulatory system?
A circulatory system where blood flows through the heart once for each complete circulation of the body.
What is an example of an organism with a single closed circulatory system, and how does it function efficiently?
Fish have a single closed circulatory system, with blood passing through capillaries in the gills for gas exchange before circulating through the body.
How does a double closed circulatory system work?
Blood travels through the heart twice for each circuit – once to the lungs for oxygenation and once to the rest of the body.
Why do mammals and birds require double circulatory systems?
they are endothermic and require high metabolic rates, so efficient oxygen and nutrient delivery are essential to maintain body temperature.
Why do aquatic predators such as sharks rely on a single circulatory system?
Their gills efficiently extract oxygen from water, which allows them to maintain activity with a single circulatory loop.
adv and dis adv of single circulatory system
adv:
- less complex so no need for complex organs
dis adv:
- Blood pressure drops as it passes through the gill capillaries, reducing the rate of flow to the rest of the body. so activity level of the animal tends to be low
adv of double circulatory system
adv:
- It maintains a higher blood pressure and a faster flow of blood, enabling more efficient oxygen and nutrient delivery so allows organism to be more active.
What are the key components of blood vessels and their functions?
Elastic fibres – Stretch/recoil, maintaining flexibility.
Smooth muscle – Contracts/relaxes to control lumen size.
Collagen – Provides structural support, maintains shape.
What are the functions and structure of arteries and arterioles?
Function: Carry oxygenated blood away from the heart (except pulmonary & umbilical arteries).
Structure:
Thick walls with elastic fibers to handle pressure surges.
Smooth muscle controls diameter.
Collagen adds strength.
Arterioles are smaller arteries that control blood flow into capillaries.
How do capillaries facilitate exchange of substances?
Capillaries are microscopic vessels linking arteries and veins.
Diameter: ~7.5μm, only one red blood cell wide.
Function:
Thin walls allow diffusion of substances.
Slow blood movement aids exchange.
Single endothelial cell layer for efficient diffusion.
How do veins and venules return blood to the heart?
Function: Carry deoxygenated blood back to the heart (except pulmonary & umbilical veins).
Structure:
Thin walls with less muscle & elastic fibers.
Large lumen reduces resistance.
Valves prevent backflow.
Aiding Blood Flow:
Valves stop backflow.
Muscle contractions push blood upward.
Breathing movements create pressure changes that assist blood flow.
What is an aneurysm, and why is it dangerous?
Definition: Weakening in a blood vessel wall, leading to bulging.
Common locations: Brain & aorta.
Risk factors: High blood pressure, genetic disorders.
Research findings:
Aortic aneurysms occur in 1.8-5.1% of humans.
Lung artery aneurysms occur in 9.7% of humans.
Implications: Helps predict individuals at risk
What are the main components of blood and their functions?
Main Components:
Plasma – Carries nutrients, hormones, and proteins.
Red blood cells – Transport oxygen (contain hemoglobin).
White blood cells – Defend against infections.
Platelets – Help with blood clotting.
Blood Volume:
Plasma: 55% of blood.
Red blood cells: 45%.
White blood cells & platelets: <1%.
How is tissue fluid formed, and what forces are involved?
Plasma leaks out of capillaries, forming tissue fluid.
Forces Involved:
Hydrostatic pressure pushes fluid out.
Osmotic pressure pulls fluid back in.
Fluid Return: 90% is reabsorbed into the blood, while 10% enters the lymph system.
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What is lymph, and what does it do?
Definition: Tissue fluid that enters lymph capillaries.
Functions:
Returns excess fluid to blood circulation.
Contains white blood cells for immune defense.
Transports lipids from digestion.
What is the function of the lymphatic system?
The lymphatic system plays a major role in fluid balance and immune defense by returning excess tissue fluid to the bloodstream and fighting infections.
How is lymph formed?
Tissue fluid containing oxygen and nutrients is transported from the blood through the arteries to the capillaries.
Some tissue fluid is reabsorbed into the blood, while the rest drains into the lymphatic capillaries, forming lymph.
How is lymph transported through the body?
Lymph capillaries join to form larger vessels.
Body muscle movement helps push lymph through the vessels.
One-way valves (like those in veins) prevent backflow.
Lymph eventually returns to the bloodstream via the right and left subclavian veins (under the collarbone).
What are lymph nodes, and what do they do?
Lymph nodes contain lymphocytes that produce antibodies to fight infections.
They trap bacteria and debris, which are ingested by phagocytes.
They play a major role in the body’s defense mechanisms.
Why do lymph nodes sometimes become enlarged?
Enlarged lymph nodes indicate that the body is fighting an infection.
They accumulate lymphocytes to help combat invading pathogens.
Doctors check lymph nodes in the neck, armpits, stomach, and groin to detect infections.
What is the structure of haemoglobin?
Haemoglobin has four polypeptide chains, each bound to a haem prosthetic group containing an Fe²⁺ ion. It is a conjugated protein. So at any one time, there are 4 haem groups in haemoglobin.
What is haemoglobin called when it binds oxygen?
Oxyhaemoglobin. This reaction between haemoglobin and oxygen is reversible. Haemoglobin can both bind and release oxygen as needed.
What does an oxygen dissociation curve show?
The percentage saturation of haemoglobin with oxygen at different partial pressures of oxygen.
Why is the oxygen dissociation curve S-shaped?
Oxygen binding increases haemoglobin’s affinity for more oxygen.
What happens to haemoglobin’s affinity for oxygen at low partial pressures?
It is low, making it harder for the first oxygen molecule to bind.
How does binding the first oxygen molecule affect haemoglobin?
It changes haemoglobin’s quaternary structure, increasing affinity for more oxygen.
Why does the fourth oxygen molecule require a high partial pressure to bind?
Because most haem groups are already occupied, making binding less likely.
What is the approximate haemoglobin saturation in the alveoli?
Around 97% due to high partial pressure of oxygen.
Why does haemoglobin release oxygen in body tissues?
Tissues have a lower partial pressure of oxygen due to aerobic respiration.
What happens when haemoglobin unloads its first oxygen molecule?
The quaternary structure changes, decreasing the affinity for remaining oxygen molecules.
In highly active tissues (e.g., exercising muscles), how does haemoglobin behave?
It releases more oxygen due to very low partial pressures.
What gas is produced during aerobic respiration?
Carbon dioxide (CO₂).
ow does an increased partial pressure of CO₂ affect the oxygen dissociation curve?
It shifts the curve to the right.
hat is the effect of CO₂ on haemoglobin’s oxygen affinity?
CO₂ decreases haemoglobin’s affinity for oxygen.
What is the name of the effect where CO₂ reduces haemoglobin’s oxygen affinity?
The Bohr effect.
How does CO₂ affect haemoglobin saturation at a given oxygen partial pressure?
At high CO₂ levels, haemoglobin has lower oxygen saturation compared to low CO₂ levels.
Why does haemoglobin have a high oxygen affinity in the lungs?
Because the partial pressure of CO₂ is low in the lungs.
Why does haemoglobin unload more oxygen in active tissues?
Because active tissues have high CO₂ levels, lowering haemoglobin’s oxygen affinity.
What molecule does CO₂ form in the blood?
Carbonic acid (H₂CO₃).
What ion does carbonic acid release in the blood?
Hydrogen ion (H⁺).
How does H⁺ affect haemoglobin?
H⁺ binds to haemoglobin, changing its quaternary structure and lowering its oxygen affinity.
What is the overall effect of CO₂ on oxygen transport?
It promotes oxygen unloading in active tissues and oxygen binding in the lungs.
How is the fetal circulatory system linked to the maternal circulatory system?
In the placenta, fetal and maternal blood pass closely but do not mix. The maternal blood has higher oxygen levels, causing oxygen to diffuse across the placenta into fetal blood.
How is fetal haemoglobin different from adult haemoglobin?
Fetal haemoglobin has a higher affinity for oxygen than adult haemoglobin. This shift in the oxygen dissociation curve to the left increases oxygen transfer from maternal to fetal blood.
Why doesn’t fetal haemoglobin have an extremely high oxygen affinity?
If fetal haemoglobin had too high an affinity, it would not easily unload oxygen in fetal tissues. Instead, its affinity is only slightly higher than adult haemoglobin to allow proper oxygen delivery.
How does the structure of fetal haemoglobin differ from adult haemoglobin?
Fetal haemoglobin has two different polypeptide chains compared to adult haemoglobin due to differences in gene expression, giving it a higher oxygen affinity.
How does carbon dioxide affect oxygen transfer from maternal to fetal blood?
CO₂ from the fetus diffuses into maternal blood, lowering maternal haemoglobin’s oxygen affinity. Combined with fetal haemoglobin’s higher oxygen affinity, this makes oxygen transfer highly efficient.
How is carbon dioxide transported in the blood?
CO₂ is transported in three ways:
1. 5% dissolves directly in plasma.
2. 20% binds to haemoglobin, forming carbaminohemoglobin (a reversible reaction).
3. 75% is carried as hydrogen carbonate (HCO₃⁻) ions in plasma.
How does carbon dioxide form carbaminohaemoglobin?
CO₂ reacts with haemoglobin’s free amino groups, forming carbaminohaemoglobin. This occurs in high CO₂ areas (e.g., respiring tissues). In the lungs, where CO₂ is low, carbaminohaemoglobin breaks down, releasing CO₂ for exhalation.
How is carbon dioxide converted into hydrogen carbonate ions?
CO₂ reacts with water to form carbonic acid (H₂CO₃), catalysed by carbonic anhydrase in red blood cells. Carbonic acid then dissociates into hydrogen ions (H⁺) and hydrogen carbonate ions (HCO₃⁻), which diffuse into plasma.
What is the chloride shift and why is it important?
To balance the negative charge lost when HCO₃⁻ leaves the red blood cell, chloride ions (Cl⁻) diffuse in. This prevents charge imbalance and maintains cell function.
How does haemoglobin act as a buffer in blood pH regulation?
H⁺ ions from carbonic acid could lower blood pH. Haemoglobin binds to H⁺, forming haemoglobinic acid, preventing pH changes. This helps maintain stable blood conditions.
What happens to CO₂ transport in the lungs?
In the lungs, HCO₃⁻ diffuses back into red blood cells, swaps with Cl⁻ (reverse chloride shift), and recombines with H⁺ to form carbonic acid. Carbonic anhydrase breaks it down into CO₂ and H₂O, allowing CO₂ to diffuse into plasma and be exhaled.
What is the double circulatory system?
Mammals, including humans, have a double circulatory system.
Two circuits:
Pulmonary circulation – Oxygenated blood goes from the heart to the lungs and back.
Systemic circulation – Oxygenated blood is pumped from the heart to the rest of the body and back.
Key process:
Blood passes through the heart twice during each complete circuit.
What is the structure of the heart?
The heart is a four-chambered organ made of cardiac muscle.
Chambers:
Atria (top chambers): Thin-walled, receive blood.
Ventricles (bottom chambers): Thick-walled, pump blood.
Valves:
Atrioventricular (AV) valves:
Left: Bicuspid (mitral) valve
Right: Tricuspid valve
Semilunar valves: Prevent backflow (found in aorta & pulmonary artery).
The septum separates oxygenated & deoxygenated blood
How does blood flow through the heart?
Deoxygenated blood enters the right atrium via the vena cava.
It flows into the right ventricle, then is pumped to the lungs via the pulmonary artery.
In the lungs, blood gets oxygenated and returns to the left atrium via the pulmonary vein.
Blood enters the left ventricle, which pumps it to the body through the aorta.
The left ventricle has a thicker wall because it pumps blood to the whole body.
What are the coronary arteries and why are they important?
Coronary arteries branch off from the aorta and supply the heart muscle with oxygen.
A blockage in these arteries can cause coronary heart disease or heart attacks.
What happens during the cardiac cycle?
Diastole (Relaxation Phase)
The atria and ventricles relax, filling with blood.
AV valves open, semilunar valves close.
Atrial Systole (Atria Contracting)
Atria contract, pushing blood into ventricles.
Ventricular Systole (Ventricles Contracting)
Ventricles contract, forcing blood into the aorta & pulmonary artery.
Semilunar valves open, AV valves close to prevent backflow.
What causes heart sounds and how is heart activity measured?
Heart sounds (“lub-dub”)
“Lub” – AV valves close during ventricular contraction.
“Dub” – Semilunar valves close as ventricles relax.
Electrocardiogram (ECG) measures electrical activity of the heart, showing contractions & heart rhythm.
How does the heart maintain its rhythm?
Controlled by electrical signals in the heart, not nerves.
Sinoatrial Node (SAN): Pacemaker, initiates heartbeat.
Atrioventricular Node (AVN): Delays signal before sending it to the bundle of His & Purkinje fibres.
Purkinje fibres: Ensure coordinated contraction of ventricles.
What happens if there is a hole in the heart (septal defect)?
If the septum doesn’t develop properly, oxygenated & deoxygenated blood mix.
This causes poor oxygenation of the body.
Some people live with small holes unnoticed, but larger defects need surgery.
What are the main heart rhythm abnormalities and their characteristics?
Tachycardia: Heartbeat >100 bpm. Can be normal during exercise, fever, or stress. Persistent tachycardia at rest may need treatment.
Bradycardia: Heart rate <60 bpm. Can be normal in very fit people but may require an artificial pacemaker if severe.
Ectopic Heartbeat: Extra beats often felt as a missed beat. Usually harmless but can indicate issues if frequent.
Atrial Fibrillation: Rapid electrical impulses in the atria (up to 400/min). Many impulses do not pass through the AV node effectively, resulting in an irregular heartbeat and reduced pumping efficiency.
What is blood pressure, how is it measured, and what are typical values?
Definition: Pressure in the arteries due to ventricular contraction.
Systolic Pressure: Highest arterial pressure (ventricles contracting).
Diastolic Pressure: Lowest arterial pressure (ventricles relaxed).
Normal Adult Reading: ~120/80 mmHg (but can vary).
Hypertension: Persistently high blood pressure.
Hypotension: Abnormally low blood pressure.
Measurement: Commonly taken in the arm for consistency and ease.
