Untitled Flashcards Set

What are the three layers of the heart wall?

Epicardium, Myocardium, Endocardium.

What is the primary function of the myocardium?

Responsible for heart contraction.

According to Poiseuille’s Law, what factors influence the flow rate (Q)?

Pressure gradient (P), radius (r), viscosity (), and length of vessel (L).

How do small changes in radius affect blood flow according to Poiseuille’s Law?

Small changes in radius result in significant changes in flow.

What mechanism increases blood flow in blood vessels?

Vasodilation increases blood flow.

What shape do vein valves have, and what is their function?

Semilunar shape; they prevent backflow of blood.

How do vein valves work with muscle contractions?

They work with the skeletal muscle pump to return blood to the heart against gravity.

What is one anticoagulant function of endothelial cells?

Produce nitric oxide which causes vasodilation and acts as an anti-platelet.

What happens to endothelial cells when they are injured?

They release von Willebrand Factor (vWF) and Tissue Factor (TF) which activate platelets and initiate coagulation.

What is DVT and what is its biggest risk?

Deep Vein Thrombosis; biggest risk is Pulmonary Embolism (PE).

Where does B-cell development occur in lymphoid tissue?

In the bone marrow.

What are the primary lymphoid organs?

Bone marrow and thymus.

What type of T-cell selection occurs in the thymus?

Positive and Negative selection.

What is positive selection in T-cell development?

T-cells must weakly bind to self-MHC to survive.

What does negative selection in T-cell development mean?

T-cells binding too strongly to self-antigens are eliminated.

Describe the t-cell education pathway.

T-cells enter as double negative, become double positive, undergo positive selection, and exit as single positive CD4+ or CD8+ T-cells.

What are germinal center reactions responsible for?

Affinity maturation and class switching of B-cells.

What happens during affinity maturation in germinal centers?

B-cells mutate antibody genes to select for higher affinity antibodies.

What does class switching in B-cells refer to?

The process where IgM switches to IgG, IgA, or IgE based on cytokine signals.

What are splenic venous sinusoids?

Open, leaky capillaries in the red pulp of the spleen.

What happens to healthy RBCs in the spleen?

They squeeze through endothelial slits.

What occurs to old or damaged RBCs in the spleen?

They get trapped and are phagocytosed by macrophages.

What is the main regulatory factor of cardiovascular flow?

Poiseuille’s Law.

How do endothelial cells participate in blood clotting?

By expressing thrombomodulin and releasing vWF and TF.

What is the role of vein valves in venous circulation?

Prevent backflow of blood during muscle relaxation.

What are two secondary lymphoid organs?

Lymph nodes and spleen.

What are the three types of lymphoid tissue?

Primary, secondary, and tertiary lymphoid tissue.

What is the role of AIRE in T-cell development?

It promotes negative selection by allowing mTECs to present self-antigens.

Describe the role of T-cells in the immune system.

They are responsible for recognizing and responding to pathogens.

What does it mean if a T-cell is described as single positive?

It expresses either CD4+ (helper) or CD8+ (cytotoxic) but not both.

How do B-cells activate in response to antigens?

They bind antigens and present them to helper T-cells.

What is the outcome of B-cell activation in a germinal center?

They undergo proliferation and mutation, followed by selection for high-affinity clones.

What is the primary characteristic of the light zone in germinal centers?

Selection for high-affinity B-cell clones.

What happens to B-cells after undergoing class switch recombination?

They exit as memory or plasma cells.

What is the function of the skeletal muscle pump in the circulatory system?

Helps return venous blood to the heart.

How does vasoconstriction affect blood flow?

It decreases blood flow.

What is the clinical significance of venous valves?

They are crucial for preventing blood stasis and thrombosis.

In what location does T-cell positive selection occur?

In the cortex of the thymus.

What defines a tertiary lymphoid tissue?

It forms at sites of chronic inflammation or tumor presence.