HUBS192 Lecture 13 - Composition and General Functions of Blood

Question 1

what are the general functions of blood?

Answer 1

1) transport
2) immune response
3) coagulation

Question 2

what does the blood transport?

Answer 2

• O2, water, nutrients
• CO2, waste products
• ions associated with pH and homeostasis
• heat
• hormones
• immune cells and coagulation factors

Question 3

how does the blood help with the immune response?

Answer 3

helps for fighting infection and production of the immune response
-largely done via white blood cells

Question 4

how and why does the blood coagulate?

Answer 4

• to prevent bleeding

- via platelets and “coagulation factors” in plasma

Question 5

what is blood volume proportional to?

Answer 5

blood volume is typically in proportion to lean body mass

Question 6

what is the composition of blood?

Answer 6

1) plasma

2) formed elements

Question 7

what is the approximate amount of plasma within blood in percentage?

Answer 7

55% (with a range of 46-63%)

Question 8

what is the main component of plasma?

Answer 8

water makes up over 90% of plasma

Question 9

what are the 3 components of plasma?

Answer 9

1) water
2) plasma proteins
3) other solutes

Question 10

what are platelets?

Answer 10

cell fragments that participate in clotting to stop bleeding

Question 11

what are the 3 formed elements of the blood?

Answer 11

1) platelets
2) white blood cells
3) red blood cells

Question 12

what is the function of white blood cells?

Answer 12

immune response and defence mechanisms that seek and destroy invading pathogens

Question 13

what is the function of red blood cells?

Answer 13

highly specialised cell that transports oxygen

-most common cell type

Question 14

what is hematopoiesis?

Answer 14

the formation of blood cells

Question 15

where is hematopoiesis initiated?

Answer 15

initiated in red bone marrow, with contains hemocytoblasts

Question 16

what are hemocytoblasts?

Answer 16

progenitors (origin) for all blood cells

Question 17

where are hemocytoblasts located?

Answer 17

located in the red bone marrow

Question 18

what is the signal that causes hemocytoblasts to differentiate into red blood cells?

Answer 18

stimulated by erythropoietin (EPO)

Question 19

what is another name for a red blood cell?

Answer 19

erythrocyte

Question 20

what is the shape of a red blood cell?

Answer 20

biconcave disc shape

Question 21

what is the function of red blood cells?

Answer 21

allows for efficient diffusion of gases (eg oxygen)

Question 22

what are 2 features of red blood cells?

Answer 22

1) large surface area to volume ratio

2) flexibility for movement through narrow capilaries

Question 23

what does a red blood cell contain a large amount of?

Answer 23

contains a large amount of haemoglobin (1/3) that uses iron as part of the heme structures to bind O2

Question 24

how many heme units does a red blood cell contain?

Answer 24

four heme units, so each haemoglobin can bind four oxygens

Question 25

what is a hematocrits or packed cell volume (PCV)?

Answer 25

the fraction of blood occupied by the red blood cells (determined by centrifuged blood separates into its main components

Question 26

what is the relationship between the haematocrit and the amount of exercise a person does?

Answer 26

a person who trains frequently will have a higher haematocrit number because they require more oxygen (more red blood cells)

Question 27

what is the haematocrit range for men?

Answer 27

0.40-0.54

Question 28

what is the haematocrit range for women?

Answer 28

0.37-0.47

Question 29

what is the name for a low haematocrit level?

Answer 29

anaemic

Question 30

what is the name for a high haematocrit level?

Answer 30

polycythemic

Question 31

what is the process of the generation of red blood cells?

Answer 31

• all blood cells derived from a common progenitor cell= hemocytoblasts
• RBC production stimulated by erythropoietin (EPO)
• requires iron to make haemoglobin

Question 32

what is the process of erythropoiesis at high altitudes?

Answer 32

reduction in RBCs causes a decrease in O2 delivery - sensed by the kidneys and then erythropoietin is released into the system stimulating the hemocytoblasts to make more RBCs that means more haemoglobin and more haemoglobin means more oxygen can be diffused from the lungs

Question 33

why do athletes train at high altitudes?

Answer 33

at high altitude there is less oxygen in the air therefore the body is effectively tricked into releasing more EPO and making more blood cells, therefore when performing at the normal altitudes they will have a larger oxygen carrying capacity

Question 34

what is the process of increasing performance for sport?

Answer 34

erythropoietin –> erythrocytes (red blood cells) –> increased O2 capacity –> increased performance

Question 35

what is EPO augmented by?

Answer 35

augmented by testosterone

-testosterone is a hormone that stimulates the erythropoietin (EPO) production

Question 36

what is the precursor cell for platelets?

Answer 36

megakaryocytes