Transport In Animals Flashcards
(33 cards)
Why do multicellular animals need specialised transport systems?
High metabolic demands: More oxygen and nutrients are needed, and more waste is produced.
SA:V ratio decreases: Diffusion alone is insufficient.
Transport of molecules: Hormones and enzymes produced in one location are needed elsewhere.
Digested food: Needs to be transported to cells for respiration.
Waste removal: Metabolic waste must be transported to excretory organs.
What are the features of most circulatory systems? `
• Transport medium: Blood or haemolymph.
• Vessels: To carry the medium.
• Pumping mechanism: Moves fluid around the body.
• Mass transport: The bulk movement of fluid around the body.
What is an open circulatory system and its process
Definition: Blood is not always contained in vessels; it flows freely through body cavities.
1.Heart pumps blood into the haemocoel (open body cavity). 2. Blood is under low pressure and directly contacts tissues. 3. Blood returns to the heart via open-ended vessels. 4. Example: Insects and some molluscs.
What is haemolymph in insects?
• Insect blood that transports:Nutrients, Nitrogenous waste products, Immune cells (for disease defence)
•
Does NOT transport oxygen or CO₂ (gaseous exchange occurs in the tracheal system).
Blood flow cannot be varied to meet changing demands.
What is a closed circulatory system?
• Definition: Blood is enclosed in vessels and does not contact body cells directly.
1. Heart pumps blood under pressure → faster flow. 2. Blood returns directly to the heart. 3. Substances exchange via diffusion through capillary walls. 4. Blood flow can be adjusted by narrowing or widening vessels.
Most closed systems contain respiratory pigments (e.g., haemoglobin) to carry gases.
What are examples of animals with closed circulatory systems
- Echinoderms : sea urchins, starfish
- Vertebrates : including all mammals
- Cephalopod molluscs: octopus and squid
- Annelid worms: earthworms
What is a single closed circulatory system and it’s process
When blood flows through the heart once per complete body circuit
Occurs in fish and annelid worms
- Heart
- Gills (gas exchange)
- Body (substance exchange)
( and back to Heart)
Blood passes through two capillary networks
First set: gas exchange (oxygen and carbon dioxide)
Second set: exchange with body tissues
Low blood pressure: blood flow back to the heart is slow, limiting efficiency
Why are fish an exception to low activity in single circulatory systems
- Efficiency gaseous exchange: counter current mechanism; increases oxygen uptake
- Water buoyancy: reduces metabolic demand (less energy needed for support)
- No need to regulate body temp: low metabolic demands
so fish can be more activity despite having a single circulation
What is a double closed circulatory system and its process
Blood flows through the heart twice per complete body circuit Occurs
Occurs in mammals and birds
Two separate circulations:
1. Pulmonary circulation: heart - lungs - heart
2. Systematic circulation: heart - body - heart
Advantages:
- blood only passes through one capillary networks First per circuit - higher pressure and faster flow
- more efficient oxygen delivery
What are the main components of blood vessels
Elastic fibres: made of elastin, they stretch and recoil, providing flexibility
Smooth muscle: contracts or relaxes to control lumen size
Collagen: provides structural support to maintain vessel shape and volume
What is the function of the arteries
To carry blood away from the heart to the body tissues
Carry oxygenated blood EXCEPT
- pulmonary artery (carries deoxygenated blood to lungs)
- umbilical artery (carries deoxygenated blood to the placenta in pregnancy)
High pressure vessels due to blood pumped directly from heart
What are the structural adaptations of arteries
- thick walls with elastic fibres, smooth muscle and collagen
-elastic fibres: stretch during systole (heart contractions) and recoil during diastole (heart relaxation) maintaining blood pressure
- smooth endothelium: reduces friction, ensuring smooth blood flow
- pulse: arteries maintain a rhythmic pulse due to the hearts contractions
What are arterioles and their functions
They are small vessels linking arteries and capillaries
They are more smooth muscle and less elastin than arteries
- vasoconstriction: smooth muscle contracts, narrowing the lumen, reducing blood flow
- vasodilation: smooth muscle relaxes, widening the lumen, increasing blood flow
Regulates blood flow to specific organs
What are capillaries and what is their structure and function
Microscopic vessels linking arterioles and venules
They exchange substances between blood and tissues
- thin walls: one endothelial cell thick
- small lumen: erythrocytes pass through in a single file
- gaps between endothelial cells: allow substances to pass into tissue fluid
except in the CNS where junctions are tight)
How are capillaries adapted for efficient exchange
- large surface area: maximum es diffusion of substances between blood
- slow blood flow: total cross sectional area of capillaries: arterioles: slows blood flow so more nutrients, gases and waste can diffuse
- thin walls: single cell thick for a short diffusion pathway
What are venules and the function
They’re small vessels linking capillaries and veins
- thin walls: contain a small amount of smooth muscle
- several venules joint to form a vein
What are the functions of veins
- carry blood back to the heart
- carry deoxygenated blood except:
Pulmonary vein: carries oxygenated blood from lungs to heart
Umbilical vein: carries oxygenated blood from placenta to fetus in pregnancy - acts as a blood reservoir holding up top 60% of blood volume
- blood pressure in veins is low
What are the structural adaptations of veins
- wide lumen: reduces resistance to blood flow
- thinner walls: less muscle and elastic tissues compared to arteries
- smooth endothelium: reduces friction, allowing easy blood flow
- valves: prevent back flow and are open when blood flows towards heart and close when it tries to flow backwards
What adaptations help veins return blood to heart
Valves: prevent back flow
Skeletal muscle pump: veins run between large muscles (e.g legs) so muscle contractions compress the veins, pushing blood towards the heart
Respiratory pump: breathing movements change pressure in the chest which squeezes veins aiding blood movement towards the heart
What’s an aneurysm, where does it occur anf what are risk factors
A bulge or weakness in the blood vessel wall
Common locations: aorta or brain arteries
Risk factors: high blood pressure or changes in collagen:elastin ratio
What are possible treatments for an aneurysm
- Reduce blood pressure (medications like beta blockers reduce stress on vessel walls)
- Surgical intervention: inserting a stent or synthetic graft to reinforce the vessel
What are the main components of blood
Plasma (55%)
Yellow liquid containing:
• Water (main component).
• Dissolved glucose, amino acids, hormones, and mineral ions.
• Plasma proteins: Albumin (maintains osmotic potential), fibrinogen (clotting), and globulins (immune response).
Red blood cells (erythrocytes):
• Transport oxygen (via haemoglobin).
White blood cells (leucocytes):
• Immune response (e.g., phagocytes and lymphocytes).
Platelets:
Fragments of megakaryocytes involved in blood clotting.
Why might your lymph nodes be enlarged
Body is fighting off an invading pathogen
What are the main functions of blood
Transport:
oxygen to respiring cells
carbon dioxide to lungs
nutrients to cells
waste products to excretory organs
Platelets to damaged areas
Immune cells and antibodies to infection sites
Temperature regulation
Blood redistributes heat around the body
Maintains pH balance
Acts as buffer, minimising pH change
