Unit 2.3 - Adaptions for transport Flashcards
What do mammals rely on when moving substances throughout their bodies?
mass flow - the bulk movement of substances from one place to another due to differences in pressure
What provides the most important means of mass flow in animals?
blood vascular system
what is an open circulatory system?
where blood is not confined to vessels but can freely flow over the tissues
what type of circulatory system do mammals have?
closed circulatory system which consists of the heart, arteries, arterioles, capillaries and veins
what does the arteries do?
carry blood away from the heart
thick muscular wall
elastic tissue
relatively small lumen
blood = carried at a high pressure
what does the capillaries do?
miscropic
thin walled vessels which form networks in various parts of the body
walls consist of a single layer of endothelial cells + are devoid of muscle and elastic tissue
blood = carried under low pressure
what does the veins do?
carry blood towards the heart
veins have a thin muscle wall with little elastic tissue
lumen = relatively large and the blood = under low pressure
valves maintain a unidirectional flow of blood
what is special about a closed system?
blood can be maintained at a much higher pressure than in an open circulatory system and there is much more control over its distribution.
what is vasodilation?
vessels can be widened
what is vasoconstriction?
vessels can be narrowed, allowing the blood to be shunted to areas where it is most needed
what is a double circulatory system?
where blood passes through the heart twice in each complete circuit of the body
pulmonary circulation?
transports blood from the heart to the lungs and back to the heart again
systemic circulation?
transports blood from the heart to all other parts of the body and back again
what does every organ have?
major artery which supplies it with blood and most have a major vein which carries blood back to the heart
What 3 ways are the pressure gradients produced by?
by pumping action of the heart
contractions of skeletal muscles squeeze blood along veins
inspiratory movements of the thorax reduce the pressure inside the thoraic cavity which helps draw blood back to the heart
what do valves do?
they prevent backflow of the blood
What are some points about the heart?
capable of pumping blood continuously around the body, 24 hours a day without tiring
pumping action = vital importance to every living cell in the human body as it provides 02 + nutrients required for respiration whilst removing waste products at the same time
if human brain = deprived of blood, an individual loses consciousness within 3-5 seconds ; after 15-20 seconds the body begins to convulse; after a few minutes, parts of the brain may = permanently damaged
Where does the heart lie?
between the 2 lungs ; enclosed within a double layer of inelastic membranes which = the pericardium
fluid = secreted between the 2 membranes, allowing them to move easily over each other .
what does the pericardium do?
protects the heart from overexpansion caused by an elastic recoil, where the heart = beating very fast
What is the heart made of?
cardiac muscle, a type of muscle that is only found in the heart, myogenic - this never fatigues and does not tolerate a lack of oxygen or nutrients and quickly dies if the blood supply = cut off
what is the heart seperated by?
septum
each of the heart has 2 chambers : an upper atrium which receives blood from the vein and a ventricle which pumps blood to the arteries
