Unit 2.3 - Adaptions for transport

Question 1

What do mammals rely on when moving substances throughout their bodies?

Answer 1

mass flow - the bulk movement of substances from one place to another due to differences in pressure

Question 2

What provides the most important means of mass flow in animals?

Answer 2

blood vascular system

Question 3

what is an open circulatory system?

Answer 3

where blood is not confined to vessels but can freely flow over the tissues

Question 4

what type of circulatory system do mammals have?

Answer 4

closed circulatory system which consists of the heart, arteries, arterioles, capillaries and veins

Question 5

what does the arteries do?

Answer 5

carry blood away from the heart
thick muscular wall
elastic tissue
relatively small lumen
blood = carried at a high pressure

Question 6

what does the capillaries do?

Answer 6

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

Question 7

what does the veins do?

Answer 7

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

Question 8

what is special about a closed system?

Answer 8

blood can be maintained at a much higher pressure than in an open circulatory system and there is much more control over its distribution.

Question 9

what is vasodilation?

Answer 9

vessels can be widened

Question 10

what is vasoconstriction?

Answer 10

vessels can be narrowed, allowing the blood to be shunted to areas where it is most needed

Question 11

what is a double circulatory system?

Answer 11

where blood passes through the heart twice in each complete circuit of the body

Question 12

pulmonary circulation?

Answer 12

transports blood from the heart to the lungs and back to the heart again

Question 13

systemic circulation?

Answer 13

transports blood from the heart to all other parts of the body and back again

Question 14

what does every organ have?

Answer 14

major artery which supplies it with blood and most have a major vein which carries blood back to the heart

Question 15

What 3 ways are the pressure gradients produced by?

Answer 15

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

Question 16

what do valves do?

Answer 16

they prevent backflow of the blood

Question 17

What are some points about the heart?

Answer 17

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

Question 18

Where does the heart lie?

Answer 18

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 .

Question 19

what does the pericardium do?

Answer 19

protects the heart from overexpansion caused by an elastic recoil, where the heart = beating very fast

Question 20

What is the heart made of?

Answer 20

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

Question 21

what is the heart seperated by?

Answer 21

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