Chapter 5: Transport in animals

Question 1

Describe the process of a heartbeat?

Answer 1

Sino-atrial node (pacemaker) initiates the wave of excitement which spreads through atrium walls. Walls start contracting to same rhythm. Wave of excitation goes to atrioventricular node (rest of muscle not conductive) After 0.1 second delay the wave travels down the Purkyne tissue and septum. Ventricles contact and send the wave up their walls from the apex squeezing out blood toward arteries

Question 2

Explain what happens at atrial systole?

Answer 2

Atrium fills up with blood, atrioventricular valve currently closed, when pressure gets so high the valves open and the atrium walls contract and push the blood into the ventricles

Question 3

Explain what happens at ventricular systole?

Answer 3

Semi lunar valves closed, 0.1 second delay after atrium walls contract the ventricles contract. As pressure gets higher in ventricles the atrioventricular valves close and the semi lunar valves open. Ventricles contract and push blood upwards

Question 4

Why do we need transport systems?

Answer 4

Our bodies are too large to rely on diffusion alone. Too metabolically active so require energy, nutrients and oxygen transported right away

Question 5

Explain what happens during ventricular diastole?

Answer 5

Atria and ventricles relax, semi lunar valves shut as pressure is now low, blood flows through veins and back to atrium to start refilling it

Question 6

Difference between an open and a closed circulatory system?

Answer 6

OPEN = Blood flows out of the arteries and not contained within the blood vessels and fills up the haemocoel (insects have this)
CLOSED = Blood is always enclosed within blood vessels

Question 7

How do insects transport oxygen?

Answer 7

Arrangement of tubes called tracheae which go from the surface to the cells and tissues which require oxygen, spiracles are valves on the outside tracheae

Question 8

Double circulatory vs Single circulatory system?

Answer 8

DOUBLE = Passes through the heart twice to be able to pump the blood around quicker
SINGLE = Fish have these. Blood is pumped to the gills then rest of the body, only goes through heart once. Less efficient as lower pressure

Question 9

What is an artery?

Answer 9

Vessel that carries blood away from the heart, divides into smaller arterioles

Question 10

Capillaries join up with what?

Answer 10

Venules which then mega to form veins

Question 11

The three layers of an artery?

Answer 11

Inside to out - Tunica intima (smooth muscle) , tunica media (elastic fibres), tunic externa (collagen)

Question 12

Characteristics of an artery?

Answer 12

Large lumen for erythrocytes to fit through, lots of elastic fibres and strength to withstand high blood pressure, thickest walls

Question 13

What can arterioles do?

Answer 13

Contract to control the volume of blood flow

Question 14

Function of capillaries?

Answer 14

Take blood close to cells to allow for rapid transfer of substances between blood and cells. 1 cell thick to maximise gas exchange

Question 15

What is the point of veins having valves?

Answer 15

To prevent back flow of blood