3.1.2: transport in animals

Question 1

what is an open circulatory system?

Answer 1

the transport medium isn’t carried in vessels and is pumped straight from the heart into the body cavity of the animal i.e insects

Question 2

what is an example of an open circulatory system and how does it work?

Answer 2

in insects
- they don’t have blood but they have a fluid called haemolymph
- it is pumped out of the heart and and passes into the body cavity, haemocoel
- molecules are transferred between haemolymph and body cells then the haemolymph goes back to the heart

Question 3

what is a closed circulatory system?

Answer 3

the blood is enclosed in blood vessels and doesn’t come directly into contact with the body cells. substances leave and enter the blood by diffusion through the walls of the blood vessels

Question 4

what are 3 different components of blood vessels?

Answer 4

• elastic fibres: flexibility to stretch and recoil
• smooth muscle: contracts and relaxes, adjusting size of lumen
• collagen: structural support

Question 5

what do arteries do? give 2 examples

Answer 5

carry mainly oxygenated blood away from the heart to the tissues of the body
- pulmonary artery and umbilical artery

Question 6

what are arterioles?

Answer 6

they link arteries and capillaries together

Question 7

what are capillaries?

Answer 7

microscopic blood vessels that link the arterioles to the venules, forming an extensive network through the tissues and used for gas exchange

Question 8

what are the adaptations of the capillaries to effectively exchange gases?

Answer 8

• large surface area for diffusion in and out of blood
• total cross-sectional area is greater than the arteriole, slowing down blood flow, giving more times to exchange substances
• one cell thick wall so their is less distance for diffusion

Question 9

what do veins do? give 2 examples

Answer 9

they carry deoxygenated blood, apart from 2 veins, towards the heart from the cells
- pulmonary vein
- umbilical vein

Question 10

where does the inferior and the superior vena cava transport blood from?

Answer 10

• inferior = lower parts of the body
• superior = head and upper body

Question 11

why do veins have valves?

Answer 11

blood is travelling at a low blood so it is to prevent back flow of blood

Question 12

what do venules do?

Answer 12

link capillaries with veins

Question 13

what are the adaptations of the veins?

Answer 13

• one way valves to prevent back flow
• using the breathing movement as a pump. the pressure changes and the squeezing action moves blood towards the heart

Question 14

what are the components of blood?

Answer 14

• plasma
• platelet
• red blood cells
• white blood cells

Question 15

what are the 4 chambers of the heart and what are they separated by?

Answer 15

• right atrium
• right ventricle
• left atrium
• left ventricle
  the septum separates the right and left side

Question 16

what is the name of the valves that separate the atrium from the ventricle and the ventricles from the arteries?

Answer 16

• atrium and ventricle = atrio-ventricular valves
• ventricles and arteries = semi-lunar valves

Question 17

why is the human circulatory system a double pump system?

Answer 17

the heart pumps blood to the lungs (deoxygenated blood) and to the rest of the body (oxygenated blood)

Question 18

what journey does blood take starting with the vena cava?

Answer 18

• rest of the body
• vena cava
• right atrium
• atrio-ventricular valves
• right ventricle
• semi-lunar valves
• pulmonary artery
• lungs
• pulmonary vein
• left atrium
• atrio-ventricular valves
• left ventricle
• semi-lunar valves
• aorta
• rest of the body

Question 19

what is the equation for cardiac output (total volume of blood that the heart can pump each minute)?

Answer 19

stroke volume (the volume of blood pumped each time the ventricles contract) x heart rate

Question 20

what does the plasma in the blood do?

Answer 20

is the liquid that carries all the components of the blood: platelets (important in blood clotting), red blood cells (carry oxygen), white blood cells (immune response), hormones, albumin (maintains osmotic potential of blood)

Question 21

what is the function of blood (what it transports)?

Answer 21

• oxygen to and carbon dioxide from respiring cells
• digested food from small intestines
• nitrogenous waste products to excretory organs
• hormones
• food molecules from storage compounds to cells
• platelets to damaged areas
• cells and antibodies in immune response

Question 22

what is tissue fluid?

Answer 22

the site of diffusion between blood and body cells, providing cells with nutrients and oxygen while removing waste products and helps fight infection

Question 23

how does tissue fluid form?

Answer 23

at the arteriole end of capillaries:
- high hydrostatic pressure (force of heart pumping) forces fluid out of capillaries
- forms tissue around body cells
at the venule end of capillaries:
- hydrostatic pressure is lower
- proteins in blood exert a high oncotic pressure in capillaries
- water potential is lower in capillaries than in tissue fluid due to fluid loss
- some tissue fluid moves back into capillaries by osmosis

Question 24

how does lymph form?

Answer 24

• some tissue fluid doesn’t re-enter capillaries
• this drains into lymph capillaries = lymph
• passed through lymph nodes to filter pathogens
• eventually returned to blood

Question 25

what occurs during the cardiac cycle (diastole and systole)?

Answer 25

the events in a single heartbeat
- diastole = heart relaxes, atria and ventricles fill with blood. the volume and pressure of blood in heart build as heart fills but pressure in arteries is at a minimum
- systole = atria contract then ventricles. pressure inside heart increases and blood forced out right side to the lungs and from left to the main body. volume and pressure of blood in heart are low at end of systole and blood pressure in arteries is maximum