M3- Chapter 8 - Transport in animals Flashcards
Why do animals need a transport system?
- Metabolic demands are high, so diffusion over long distances isn’t enough.
- SA: V ratio gets smaller
- Molecules such as hormones or enzymes may be made in one place but needed in another.
- Food will be digested in one organ system, but needs to be transported to every cell for use in respiration.
- Waste products of metabolism needs to be removed from the cells and transported to excretory organs.
Types of circulatory systems
Open circulatory systems
Closed circulatory systems
Single circulatory systems
Double closed circulatory systems
Features of a circulatory systems
Liquid transport medium that circulates around the system.
They have vessels that carry the transport medium
They have a pumping mechanism to move the fluid around the system
Mass transport system
When substance are transported in a mass of fluid with a mechanism for moving the fluid around the body.
Open circulatory system
Few vessels to contain the transport medium.
It is pumped straight from the heart into the body cavity of the animal. The exchange takes place between the transport medium and the cells, because the haemocoel comes into direct contact with the tissues and the cells.
Then, the transport medium returns to the heart through an open-ended vessel.
What is an open body cavity?
A haemocoel
Where can you find open circulatory systems
Mainly invertebrate animals. In insects, the gas exchange takes place in the tracheal system. Insect blood is called haemolymph. It only transports food or waste products, not oxygen.
What is haemolymph
Insect blood
Explain haemolymph
It doesn’t carry any oxygen or co2, but only food, water and waste products.
How is the heart positioned in the body cavity of an insect?
It extends along the thorax.
Explain a closed circulatory system
The blood is enclosed in blood vessels and they don’t come in contact with cells.
Blood is under high pressures and it returns directly to the heart.
Substances leave and enter the blood through diffusion.
What animals have a closed circulatory system
Sea urchins, starfish, all vertebrate groups.
Explain single circulatory system
Blood flows through the heart and is pumped out to the body and then it returns.
Blood passes through 2 sets of capillaries before returning to the heart.
By passing through the 2 narrow vessels, the pressure drops, so the speed decreases. This decreases the efficiency of exchange processes.
What are the 2 sets of capillaries in a single circulatory system?
- Exchange of oxygen and carbon dioxide
2. Substances are exchanges between blood and the cells.
What is the one exception to the single circulatory system that actually have high efficiency?
Fishes.
Because of their countercurrent flow, they actually have a higher ability to take oxygen.
Their body weight is supported by the water in which they live and they don’t have to maintain their temperature reducing their demands.
Explain a double closed circulatory system
Involves 2 separate circulations.
1. Heart -> lungs -> heart
2. body -> heart
Blood travels twice through the heart for 1 circuit.
There is a high pressure as it only passes through 1 capillary network.
What are the main components of blood vessels?
Elastic fibres
Smooth muscle
Collagen
Elastic fibres
Stretch and recoil
Provides flexibility
Smooth muscles
Changes the size of the lumen
Collagen
Provides structural support and maintains the size and volume of the lumen.
Arteries and arterioles
They carry blood away from the heart.
Carry oxygenated blood except in pulmonary artery (expect in the umbilical artery).
What are the layers of an artery
Collagen
Muscle
Elastic
Endothelium
Function of endothelium cells?
Very smooth so it allows the blood to flow smoothly.
In arteries, what does the elastic fibres?
Recoil and return to original length and allow surges (pulse)
Explain arterioles
Link arteries and capillaries.
They have more smooth muscle and less elastin than arteries (less pulse surge)
Vasodilation
Smooth muscle in the wall of an arteriole relaxes.
Vasoconstriction
Smooth muscle in the wall of an arteriole contracts.
Capillaries
They link arteries with the venules.
The lumen is so small that the red blood cells have to go through it in a single file.
There are gaps made by endothelial cells that make up the capillary walls and are quite big.
Capillary adaptation
Large SA for diffusion
Higher cross sectional area than the arterioles supplying the blood. So the rate of the blood decreases. Hence, gaseous exchange can happen.
The walls are 1 cell thin.
The walls are also “leaky” to allow plasma and dissolved substance to leave the blood.
Veins and venules
Blood away from the cells to the heart.
They carry deoxygenated (excluding the pulmonary vein and the umbilical vein).
Many venules make a vein.
Difference between venules and veins
Venules are smaller in diameter.
Parts of a vein
Collagen
Muscle
Elastin
Endothelium
Adaptations that allow blood to flow against gravity
One way valves at intervals (flaps)
Bigger veins run between big active muscles so when they contract, the blood is forced up.
Breathing movements creates pressure changes, and forces the blood up.
What does blood consist of
Plasma (hormones, dissolved glucose, minerals, amino acids) Albumin Fibrinogen Globulins Red blood cells White blood cells Platelets
Albumin
Maintains osmotic potential in blood
Fibrinogen
Blood clotting
Globulins
Transport and immune system.
Platelets
Fragments of megakaryocytes found in red bone marrow.
What does blood transport
Oxygen Digested waste Hormones Nitrogenous waste Food molecules Platelets to damaged areas Cells and antibodies
What is tissue fluid
It is the place where diffusion occurs between blood and the cells. It has the same composition as the plasma, but without red blood cells and plasma proteins.
Hydrostatic pressure
The pressure in the capillaries from the arterioles from the surge of blood that occurs when the heart contracts.
Oncotic pressure
The tendency of water to move into the blood by osmosis. And it’s always 3.3kPa.
How do large plasma proteins affect osmosis.
They have a large solute potential, hence giving plasma a low water potential, so water has a tendency to move in from the surroundings, so increasing the plasma proteins, so increases the oncotic pressure.
What is the hydrostatic pressure on the arterial end?
4.6kPa.
What is the hydrostatic pressure on the venous end?
2.3kPa
Where does the fluid go on the arterial end?
Out of the capillary
Where does the fluid go on the venous end?
Enters the capillary
What is a lymph
Called lymph capillaries.It has less nutrients and oxygen than plasma tissue fluids and fatty acids.
Lymph - explanation
Fluid doesn’t always return back to the capillaries, but instead to the blood vessels into a system of blind-ended tubes called lymph capillaries. They join to form larger vessels, which transport by contracting muscles.
They have valves and the lymph return to the blood under the collar bone.
Lymph nodes
Along the lymph vessels are lymph nodes, which is where lymphocytes build up (antibodies).
Enlarged lymphocytes means that your body is fighting pathogens.
