Circulatory System of a Mammal (Exchange and Transport) (UNIT2) Flashcards
Why do large organisms need a transport system?
With increasing size, the surface area to volume ratio decreases to a point where the needs of the organism cannot be met by the body surface alone. Specialised exchange surface needed.
What is the job of a transport system?
To absorb nutrients and respiratory gases and to remove excretory products. Take materials from cells to exchange surfaces and vice versa. MAterials have to be transported between exchange surfaces and environment. Also between different parts of organism.
What two factors does the presence of a specialised transport system depend on?
- SA:vol ratio
- How active organism is.
Lower SA:vol ratio and more active, more need for exchange system.
What are the 6 features of a transport system?
- Suitable medium to carry materials (blood) normally a liquid based on water- water readily dissolves substances.
- Form of mass transport in which transport medium is moved around in bulk over large distances.
- Closed system of tubular vessels containing transport medium and forms branching network.
- A mechanism for moving transport medium within vessels.
REQUIRES PRESSURE DIFFERENCE BETWEEN ONE PART OF SYSTEM AND ANOTHER.
2 ways:
+Muscular contraction either of body muscles or specialised organ.
+Plants use passive natural physical processes such as evaporation.
- Mechanism to maintain mass flow movement in ONE DIRECTION (valves)
- Means of controlling flow to suit changing needs of organism.
Outline the transport system in mammals.
Closed blood system, confined to vessels.
Heart (muscular pump) circulates blood.
DOUBLE CIRCULATORY SYSTEM.
Blood passes twice through heart for each complete circuit of body.
Why do mammals have a double circulatory system?
When blood passes through lungs, pressure is reduced. If was to pass straight to rest of body its low pressure would make circulation slow. Returned to heart to boost pressure. Substances delivered to rest of body quicker.
Why do mammals need substances delivered quickly?
High temperature so high rate of metabolism.
What are the three types of vessels in mammals circulatory system>
Arteries, veins capillaries.
What s the final journey of substances into the body and why is it rapid?
Into cells by diffusion. Large SA, short distance and steep diffusion gradient so rapid.
Leaving the aorta, what journey does blood take back?
OXYGENATED:
UP TO: head and neck
Upper limbs
DOWN TO: Hepatic arteries->LIVER
Stomach and intestines->hepatic portal vein->liver Renal artery->Kidneys
Lower limbs
DEOXYGENATED
DOWN TO:
Head and neck and upper limbs-> vena cava
UP TO:
Liver-> Hepatic vein->vena cava
Kidneys->renal vein->vena cava
Lower limbs->vena cava
VENA CAVA-> Right atrium->Right ventricle->Pulmonary artery->LUNGS->Pulmonary vein-> Left atrium->Left ventricle->AORTA
Arteries
carry blood away from heart and into arterioles.
Arterioles
Smaller arteries that control blood flow from arteries to capillaries.
Capillaries
Tiny vessels that link arterioles to veins
Veins
Carry blood from capillaries back to heart
Layers of arteries, arterioles and veins. (5)
- Tough outer layer- resists pressure changes from both within and outside
- Muscle layer- can contract and so control the flow of blood
- Elastic layer- helps to maintain blood pressure by stretching and springing back
- Thin inner lining (ENDOTHELIUM)- smooth to prevent friction and thin to allow diffusion.
- Lumen- not actually a layer but the central cavity of the blood vessel through which blood flows.