B8 - Transport in animals Flashcards
What processes supply single-celled organisms with necessary substances? (5 points)
- Diffusion
- Osmosis
- Active transport
- Endocytosis
- Exocytosis
Why do multicellular organisms require specialized transport systems? (6 points)
- High metabolic demands
- Decreased SA:Vol ratio
- Long diffusion distances
- Molecules may be made in one place & needed in another
- Food digested in 1 organ & needs transporting to all cells used in respiration & metabolism
- Waste products of metabolism ned to be removed from the cells & transported to excretory organs
What is a mass transport system?
Transport of substances in a mass of fluid with a mechanism for movement
What is an open circulatory system? (2 points)
- Transport medium is pumped into the body cavity (haemocoel) with low pressure & comes into direct contact wiht the tissues & the cells.
- Transport medium returns tot he heart through an open-ended vessel.
What is haemolymph?
Insect blood that transports food and nitrogenous waste, not oxygen or carbon dioxide
What characterizes a closed circulatory system? (2 points)
- Blood is enclosed in vessels, pumped under pressure, and returns directly to the heart
- Blood doesn’t come into direct contact with body cells
What are single closed circulatory systems?
Blood flows through the heart once per complete circulation
What is the significance of a double closed circulatory system? (3 points)
- Blood travels twice through the heart for each circuit, allowing efficient transport.
- Once through the heart to the lungs to pick up oxygen and unload carbon dioxide
- Second time so the oxygenated blood is pumped arround the body.
What are the three main types of blood vessels? (3 points)
- Arteries
- Capillaries
- Veins
What is the function of elastic fibers in arteries?
- Provide flexibility, allowing vessels to stretch and recoil
- Enable them to withstand the force of the blood pumped out of the heart & stretch to take the larger blood volume
What is vasoconstriction?
- Contraction of smooth muscle in arterioles, reducing blood flow to capillaries
- Vasoconstriction : Narrows lumen, reducing flow.
What is the function of capillaries?
Exchange of substances between blood and tissue cells
How are capillaries adapted for efficient exchange? (3 points)
- Large surface area
- Thin walls (single endothelial cell thick)
- Slow blood flow
What do veins primarily carry & what are the exceptions to this rule ?
- Deoxygenated blood towards the heart
- Except pulmonary and umbilical veins
What adaptations help veins return blood to the heart? (3 points)
- One-way valves prevent blood backflow
- Muscle contractions squeeze the veins forcing the blood towards the heart
- Breathing movements of the chest acts as a pump
Fill in the blank: The transport medium in open circulatory systems is called _______.
haemolymph
True or False: The blood pressure in veins is higher than in arteries.
False
What is the main function of blood in the circulatory system? (8 points)
- Transport medium, it transports :
- Oxygen to, and carbon dioxide from, the respiring cells
- Digested food from the small intestine
- Nitrogenous waste products from the cells to the excretory organs
- Chemical messages (hormones)
- Food molecules from storage compounds to the cells that need them
- Platelets to damaged areas
- Cells and antibodies involved in the immune response.
List three components carried by plasma.
- Glucose
- Amino acids
- Hormones
What is the osmotic effect of plasma proteins?
Gives blood a relatively high solute potential.
What is tissue fluid?
Fluid that fills the spaces between cells and has the same composition as plasma, without red blood cells and plasma proteins.
What happens to hydrostatic pressure as blood moves through the capillaries?
It falls / decreases as fluid has moved out and the pulse is completely lost.
What is lymph?
Fluid that drains into lymph capillaries, similar in composition to plasma but with less oxygen and fewer nutrients.
Where does lymph eventually return to the bloodstream?
Right and left subclavian veins.
What role do lymph nodes play in the immune response?
Produce antibodies and intercept bacteria and debris.
What is the Bohr effect?
As the partial pressure of carbon dioxide rises, haemoglobin gives up oxygen more easily.
What is the shape of red blood cells (RBC) and why is it beneficial?
Biconcave shape increases surface area for gas diffusion.
What is the composition of haemoglobin? (2 points)
- Large globular protein
- Made up of four peptide chains, each with an iron-containing haem prosthetic group.
How does oxygen bind to haemoglobin?
Oxygen binds loosely, forming oxyhaemoglobin in a reversible reaction.
What happens during positive cooperativity in oxygen binding to haemoglobin? (3 points)
- The binding of one oxygen molecule makes it easier for subsequent molecules to bind.
- As the % saturation increases, it forms an S-shaped curve
- At the highest pO2 the curve levels out because all the haem groups are bonded to the O2 so the haemoglobin is saturated & cant take anymore
What is fetal haemoglobin’s advantage compared to adult haemoglobin?
Has a higher affinity for oxygen, allowing it to extract oxygen from maternal blood.
List the three ways carbon dioxide is transported in the blood.
- Dissolved in plasma (5%)
- Combined with amino groups in haemoglobin (10-20%)
- Converted into hydrogen carbonate ions (75-85%)
What enzyme catalyzes the conversion of CO2 and H2O to carbonic acid?
Carbonic anhydrase.
What is the role of the human heart ?
Pumps deoxygenated blood to the lungs to get oxygenated and oxygenated blood to the body.
What prevents the mixing of oxygenated and deoxygenated blood in the heart?
The septum in the inner dividing wall of the heart which prevents the mixing of deoxygenated and oxygenated blood.
What structure prevents backflow of blood in the heart?
Valves (bicuspis & trucuspid & semi-lumar)
What supplies the cardiac muscle with oxygenated blood?
Coronary arteries.
Fill in the blank: The heart is surrounded by _______ membranes.
inelastic pericardial
What happens when the right atrium contracts?
Forces blood into the right ventricle. (Artial systole)
What is the role of tendinous cords in the heart?
Ensure the valves are not turned inside out by pressure.
Where does deoxygenated blood enter the heart from the upper body?
Superior vena cava.
Where does deoxygenated blood enter the heart from the lower body?
Inferior vena cava.
What prevents backflow of blood into the atrium during right ventricle contraction ?
- The tricuspid valve
- The tricuspid valve closes when the right ventricle contracts, ensuring that blood flows in the correct direction.
What structures ensure that the heart valves do not turn inside out during contraction?
- The tendinous cords
- These cords anchor the valves to the heart muscle, preventing inversion due to pressure changes.
What type of blood is pumped from the right ventricle to the lungs?
- Deoxygenated blood
- The right ventricle pumps deoxygenated blood through the pulmonary artery to the lungs for oxygenation.
What valve opens between the left atrium and left ventricle as pressure builds in the atrium?
- The bicuspid valve
- Also known as the mitral valve, it allows oxygenated blood to flow into the left ventricle.
What is the function of the semilunar valves?
- Prevent backflow of blood into the heart
- These valves close to stop blood from returning to the ventricles after contraction.
How do the muscular walls of the left and right sides of the heart differ? (2 points)
- The left side has a thicker muscular wall
- This is necessary to pump blood throughout the entire body, unlike the right side which only pumps to the lungs.
What is the role of the septum in the heart?
- Prevents mixing of deoxygenated and oxygenated blood
- The septum is the wall that separates the left and right sides of the heart.
What happens to the septum after birth? (2 points)
- The gap closes to separate blood types
- This closure prevents mixing of deoxygenated and oxygenated blood in a healthy heart.
What is the duration of a single cardiac cycle in a human adult?
- About 0.8 seconds
- This cycle includes both diastole and systole phases.
What occurs during diastole?
- The heart relaxes and fills with blood
- Both the atria and ventricles fill with blood, leading to increased volume and pressure.
What occurs during systole? (2 points)
- The atria and ventricles contract
- This phase results in increased pressure and the ejection of blood from the heart.
What causes the ‘lub-dub’ sounds of the heartbeat?
- Closing of heart valves
- The first sound is caused by the closing of atrio-ventricular valves, and the second by the closing of semilunar valves.
What is the intrinsic rhythm of cardiac muscle?
- Around 60 beats per minute (bpm)
- This rhythm helps maintain a steady heart rate without excessive energy expenditure.
What initiates the heartbeat in the heart? (2 points)
- The sino-atrial node (SAN)
- The SAN generates electrical impulses that trigger atrial contraction.
What is the function of the atrio-ventricular node (AVN)?
- Imposes a slight delay before stimulating the bundle of His
- This delay ensures that the atria finish contracting before the ventricles start.
What does an electrocardiogram (ECG) measure?
- Electrical activity of the heart
- It records tiny electrical differences in the skin caused by heart activity.
What is tachycardia and when can it be clased as normal? (2 points)
- A rapid heartbeat over 100 bpm
- It can be normal during exercise or stress but may indicate electrical control problems if abnormal.
What is bradycardia and when can it be normal? (2 points)
- A slow heartbeat below 60 bpm
- It can be normal in fit individuals but may require treatment if severe.
What is atrial fibrillation and what does it result in? (2 points)
- An abnormal rhythm with rapid atrial contractions
- This condition results in ineffective pumping of blood due to irregular impulses.
Whats the Haldane Effect
- When hemoglobin is oxygenated, its affinity for CO₂ decreases.
- This promotes the release of CO₂ from carbaminohemoglobin and bicarbonate conversion, enhancing CO₂ excretion.
What are the 3 steps in the electrical control of the heart ?
- Sino-Atrial Node (SAN) initates heartbeat, causing atria to contract
- Atrioventricular Node (AVN) delays electrical impulse ensuring atrial contraction conpletes before ventricles contract
- Bundle of His & Purkyne Fibres conducts impulses to ventricles, triggeriing contraction from the apex upwards
