Topic 5b - Circulatory systems

Question 1

Circulatory systems functions…

Answer 1

transport of gases & nutrient
transport of wastes
distributions of hormones
reg. of body temp
wound healing
protection from disease

Question 2

Heartbeat is …?

Answer 2

myogenic

Question 3

Where is cardiac cycle initiated?

Answer 3

right atrium (SA node) ‘pacemaker’ -> cells of atrium contract then signal -> ventricles

Question 4

What allows synchronous contraction of ventricles?

Answer 4

extensive nerve fibres (Purkinje fibres) beginning at apex of heart

Question 5

Components of blood…?

Answer 5

plasma
erythrocytes
white blood cells
platelets

Question 6

Plasma properties…?

Answer 6

90% water

dissolved proteins, nutrients, gases, wastes, hormones etc

Question 7

What are erythrocytes?

Answer 7

RBCs
contain haemoglobin (carry oxygen)

Question 8

How many RBCs formed per second?

Answer 8

25 million

Question 9

T or F - RBCs level is tightly controlled

Answer 9

true

Question 10

How are RBC levels tightly controlled?

Answer 10

mediated by erythropoietin

Question 11

If RBC low…? high…?

Answer 11

increased erythropoietin production -> ++ RBC prod.

decreased erythropoietin production -> decreased RBC prod.

Question 12

O2 deficiency…?

Answer 12

stimulates erythropoietin production by kidneys -> stimulates RBC prod. in bone marrow -> restored O2 level -> inhibits erythropoietin production by kidneys

Question 13

Different types of white blood cells…?

Answer 13

neutrophils
basophils
lymphocyte
eosinophil
monocyte

Question 14

What is a platelet?

Answer 14

pieces of large cells produced by megakaryocytes

Question 15

Blood clotting occurs…?

Answer 15

upon exposure to air

Question 16

How many cascades in clotting?

Answer 16

12 enzymatic reactions

• each step proceeds only after previous one is finished
• highly regulated cos of potentially disastrous results

Question 17

What does the final step in clotting involve?

Answer 17

thrombin (enzyme)

Question 18

Blood vessels damaged -> …?

Answer 18

1. vessel constricts reducing flow
2. exposes collagen -> activates platelets which stick & form plug
3. damaged cells & activated platelets release chemicals convert prothrombin -> thrombin
4. thrombin converts fibrinogen -> fibrin (insoluble fibres)
5. fibrin forms meshwork & seals cut vessel

Question 19

Layers that make up blood vessels…? outer to inner?

Answer 19

connective tissue
smooth muscle
endothelium
lumen

Question 20

Properties of capillaries…?

Answer 20

Thin & permeable to:

• gases
• nutrients
• cellular wastes

Question 21

When calf muscle is relaxed, vein valves are…? When muscle contracts…?

Answer 21

closed

bottom are closed & top open

Question 22

Properties of lymphatic system…?

Answer 22

returns plasma proteins & excess fluid back to blood stream

Question 23

How do lymph gradients work…?

Answer 23

1. Pressure forces fluid from plasma at arteriole end of capillary network
2. Extracellular fluid -> lymph vessels at venous ends of capillaries
3. Lymph -> larger lymph vessels & back to blood stream