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DEN1DSA > Week 10 > Flashcards

Week 10 Flashcards

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1
Q

What are the main components of blood?

A

Plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets.

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2
Q

What is the function of red blood cells (erythrocytes)?

A

To carry oxygen from the lungs to tissues and carbon dioxide from tissues back to the lungs.

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3
Q

What protein do red blood cells contain and what is its role?

A

Haemoglobin; it binds and transports oxygen and some carbon dioxide.

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4
Q

What is the structure of red blood cells and why is it important?

A

They are biconcave discs—this shape increases surface area for gas exchange and flexibility for moving through capillaries.

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5
Q

What do red blood cells lack and how long do they live?

A

They lack nuclei and mitochondria; they live about 120 days.

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6
Q

What is haematocrit?

A

The percentage of blood volume that is made up of red blood cells—normally about 45% (42% in females, 47% in males).

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7
Q

What is haemoglobin and what gives blood its red colour?

A

A protein in red blood cells with four O₂ binding sites; it contains iron, which gives blood its red colour.

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8
Q

What is the function of white blood cells (leukocytes)?

A

To protect the body against infection and aid immune responses.

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9
Q

What are the two major groups of white blood cells?

A

Granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes).

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10
Q

What are the key features of neutrophils?

A

Most abundant WBC (50–70%), perform phagocytosis, contain granules with hydrolytic enzymes.

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11
Q

What is the function of eosinophils?

A

Digest large pathogens and contribute to allergic and inflammatory responses.

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12
Q

What do basophils release and why?

A

Histamine (for vasodilation) and heparin (anticoagulant) during inflammation and allergic reactions.

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13
Q

What are monocytes and what do they become in tissues?

A

Large WBCs with U-shaped nuclei; they become macrophages that digest pathogens and activate immune cells.

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14
Q

What do lymphocytes do?

A

Destroy cancer/infected cells and coordinate immune responses. Include B and T cells.

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15
Q

What are platelets and where do they come from?

A

Cell fragments from bone marrow; not true cells.

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16
Q

What are the roles of platelets in the body?

A

Clotting, secreting vasoconstrictors, forming plugs, attracting immune cells, promoting healing.

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17
Q

What is plasma and what does it transport?

A

The liquid component of blood (55%); it transports proteins, nutrients, wastes, gases, and electrolytes.

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18
Q

What is the role of plasma proteins?

A

They maintain osmotic pressure, help clotting, and transport hormones and molecules.

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19
Q

Why must red blood cell (RBC) numbers remain within a homeostatic range?

A

Too few RBCs → reduced oxygen delivery (hypoxia).
Too many RBCs → increased viscosity → poor flow and risk of clotting.

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20
Q

What mechanism maintains RBC homeostasis?

A

A negative feedback loop involving the hormone erythropoietin (EPO).

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21
Q

What is erythropoiesis?

A

The production of red blood cells, stimulated by the hormone erythropoietin (EPO).

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22
Q

What organ primarily produces erythropoietin (EPO)?

A

The kidneys (and to a lesser extent, the liver).

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23
Q

What triggers increased EPO production?

A

A decrease in oxygen-carrying capacity of blood (hypoxia).

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24
Q

How does the negative feedback loop for RBC production work?

A

Low oxygen → kidneys detect hypoxia → ↑ EPO release → bone marrow stimulated → ↑ reticulocyte (immature RBC) production → ↑ RBCs in circulation → oxygen levels return to normal.

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25
What are reticulocytes?
Immature red blood cells released into circulation during increased RBC production.
26
What is the result of the EPO-driven feedback loop?
Restoration of oxygen-carrying capacity and maintenance of RBC numbers within normal limits.
27
What is haemostasis?
A fast, localised response that stops bleeding when a blood vessel is injured. It consists of three main steps: Vascular spasm Platelet plug formation Coagulation (clotting)
28
What happens during vascular spasm?
Vasoconstriction of the damaged vessel reduces blood flow and loss. This response is triggered by injury, pain, and inflammation and lasts 20–30 mins.
29
What initiates platelet plug formation?
Injury exposes collagen fibres beneath the vessel’s endothelium. Platelets adhere, become activated, and release ADP, serotonin, and thromboxane A2, attracting more platelets in a positive feedback loop.
30
What stabilises platelet adhesion?
Large proteins (like von Willebrand factor) form bridges between platelets and exposed collagen.
31
Why is coagulation necessary after platelet plug formation?
Platelet plugs are loosely held together—fibrin formation from coagulation reinforces and stabilises the clot for larger injuries.
32
What is the role of fibrin in coagulation?
Fibrin forms a sticky mesh that traps RBCs and platelets, solidifying the clot.
33
What are the two initial pathways in the coagulation cascade?
Extrinsic pathway – activated by tissue factor from damaged tissue. Intrinsic pathway – activated by internal vessel injury (e.g., damaged endothelium).
34
What is the common endpoint of both intrinsic and extrinsic pathways?
Activation of Factor X, leading to: Prothrombin → Thrombin Fibrinogen → Fibrin
35
What is clot retraction?
The fibrin mesh contracts, squeezing out fluid and tightening the clot for stability.
36
How is coagulation regulated to prevent excess clotting?
Protein C: degrades Factors Va and VIIIa Antithrombin: degrades thrombin and multiple clotting factors Plasmin: breaks down fibrin Prostacyclin: inhibits platelet activation Laminar flow: separates cells and plasma, limiting clotting at vessel walls
37
What are the two types of coagulation disorders?
Haemorrhage – too little clotting Thrombosis – too much clotting (e.g., DVT or pulmonary embolism)
38
What is clot retraction and why is it important?
Clot retraction is the process where a clot shrinks to stabilise and close a wound. Actin and myosin in platelets contract, pulling fibrin strands and squeezing out serum. Edges of the vessel are drawn together. PDGF stimulates smooth muscle and fibroblast division for tissue repair. Vascular endothelium promotes endothelial cell regrowth.
39
What is the serum in clot retraction?
Serum is plasma without clotting factors, squeezed out during clot retraction.
40
What is PDGF and what does it do?
Platelet-Derived Growth Factor. It stimulates tissue repair by promoting division of smooth muscle cells and fibroblasts at the injury site.
41
What is fibrinolysis?
The process of removing a clot once healing is complete. It prevents blood vessels from becoming blocked by leftover clots.
42
What is the main enzyme involved in fibrinolysis?
Plasmin, formed from plasminogen, digests fibrin and breaks down clots.
43
How is plasminogen activated?
Tissue plasminogen activator (tPA) is released from endothelial cells. Thrombin and Factor XII also help activate plasminogen.
44
What are antithrombotic drugs?
Medications that reduce the formation of blood clots to prevent thrombosis (clots that can block vessels or cause embolisms).
45
How does warfarin prevent clotting?
Inhibits Vitamin K epoxide reductase. Prevents Vitamin K from converting to its active form (Vitamin K hydroquinone). This blocks activation of clotting factors II, VII, IX, and X, reducing coagulation.
46
Why is Vitamin K important in clotting?
It’s required to activate clotting factors II, VII, IX, and X. Without it, blood cannot clot effectively.
47
How does aspirin inhibit clot formation?
Blocks the enzyme cyclooxygenase (COX-1). Prevents production of thromboxane A2, which promotes platelet aggregation and vasoconstriction. Result: fewer platelets are activated, reducing plug formation.
48
What is thromboxane A2 and why is it important?
A chemical released by platelets to enhance vascular spasm and promote aggregation. Aspirin blocks its production to reduce clot formation.
49
What are the two main branches of the immune system?
Innate immune defense and adaptive immune defense.
50
What is the role of the innate immune system?
It provides immediate, non-specific protection against pathogens and is always active.
51
How does the adaptive immune system protect the body?
It offers targeted, long-lasting, and antigen-specific protection, including immune memory.
52
How fast does the innate immune system respond to pathogens?
Very quickly—it acts as the first line of defense.
53
How fast does the adaptive immune system respond to pathogens?
More slowly, but with greater specificity and memory.
54
Is the adaptive immune response localised or systemic?
It is systemic, meaning it is not restricted to the initial site of infection.
55
Name two types of phagocytic innate immune cells.
Macrophages and neutrophils.
56
Which innate immune cells are involved in allergic responses and parasite defense?
Eosinophils, basophils, and mast cells.
57
What is the function of B-lymphocytes (B-cells) in adaptive immunity?
They produce antibodies and differentiate into memory cells.
58
What are the three types of T-lymphocytes in adaptive immunity?
Helper T-cells, cytotoxic T-cells, and regulatory T-cells.
59
What do helper T-cells do?
Activate other immune cells.
60
What is the role of cytotoxic T-cells?
They kill infected or abnormal cells.
61
What do regulatory T-cells do?
Suppress overactive immune responses.
62
What triggers the adaptive immune response?
The recognition of antigens, usually proteins or large polysaccharides on pathogens.
63
What type of white blood cells recognise antigens?
Lymphocytes (B cells and T cells).
64
What do B cells do when they encounter an antigen?
They produce antibodies (immunoglobulins) specific to that antigen.
65
What are antibodies?
Proteins produced by B cells that specifically bind to antigens.
66
How do antibodies help fight pathogens?
They neutralise pathogens, mark them for destruction, or activate the complement system.
67
Do T cells produce antibodies?
No, T cells do not produce antibodies.
68
What is the main function of T cells in the adaptive immune response?
They destroy infected or abnormal cells and regulate the immune response.
69
What are the three main functions of blood?
Transport (O2, nutrients, waste), regulation (temperature, pH, fluid), and protection (clotting, immunity).
70
What are the major components of blood?
Plasma (90% water, proteins) and formed elements (RBCs, WBCs, platelets)
71
What is the role of red blood cells (RBCs)?
Transport oxygen and carbon dioxide using haemoglobin.
72
How is red blood cell production regulated?
By erythropoietin (EPO), mostly from kidneys, in response to hypoxia.
73
What is the function of white blood cells (WBCs)?
Provide immune defense against infection; include neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
74
What are platelets and their function?
Cell fragments that help stop bleeding by forming a platelet plug; regulated by thrombopoietin.
75
What are the surface barriers in innate immunity?
Skin and mucous membranes, providing physical and chemical protection (e.g. lysozyme, acid).
76
Name key innate immune cells and their functions.
Phagocytes (engulf invaders), NK cells (kill infected/cancer cells), and mast cells (inflammation).
77
What is the role of inflammation?
Localised response to injury that helps eliminate pathogens and start repair (redness, heat, swelling, pain).
78
What are antigens in the adaptive immune system?
Foreign molecules (usually proteins) that trigger specific immune responses.
79
What do B cells do?
Produce antibodies for humoral immunity; differentiate into plasma and memory cells.
80
What do T cells do?
Helper T cells activate others; cytotoxic T cells destroy infected/abnormal cells; regulatory T cells limit immune response.
81
What are antibodies and their function?
Immunoglobulins that bind specific antigens to neutralise or destroy pathogens.
82
What are the three steps of hemostasis?
1) Vascular spasm, 2) Platelet plug formation, 3) Coagulation.
83
What happens during coagulation?
Clotting factors activate a cascade converting fibrinogen to fibrin, forming a stable clot.
84
What is clot retraction?
Platelets contract to tighten and stabilise the clot.
85
What is fibrinolysis?
Breakdown and removal of the clot via plasmin after healing.

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