Part A Drag the appropriate labels to their respective targets. Reset Help Fenestrations Basement membrane Fenestrated capillary Tight junction Large intercellular cleft Endothelial cell Continuous capillary Red blood cell in lumen Sinusoid capillary Submit Request Answer
Part A Drag the appropriate labels to their respective targets. Reset Help Fenestrations Basement membrane Fenestrated capillary Tight junction Large intercellular cleft Endothelial cell Continuous capillary Red blood cell in lumen Sinusoid capillary Submit Request Answer
The Correct Answer and Explanation is:
To accurately place the correct labels in a diagram of different types of capillaries (continuous, fenestrated, and sinusoid), you must understand their structure and function. Here is the correct label placement for each feature, assuming a typical diagram showing all three types side by side:
Label Placement for Capillary Types:
- Continuous Capillary
- Tight junction → connects adjacent endothelial cells
- Endothelial cell → lines the interior of the capillary
- Basement membrane → surrounds the endothelial layer
- Red blood cell in lumen → located inside the capillary tube
- Fenestrated Capillary
- Fenestrations → small pores in the endothelial cells allowing rapid exchange
- Basement membrane → still intact, supporting the endothelial cells
- Sinusoid Capillary
- Large intercellular cleft → wide gaps between endothelial cells
- Sinusoid capillary → label placed on this entire capillary type
- Fenestrated Capillary and Continuous Capillary → labels go beside the respective vessels in the diagram
Explanation
Capillaries are the smallest blood vessels in the body and are critical for the exchange of gases, nutrients, and waste between blood and tissues. There are three main types of capillaries: continuous, fenestrated, and sinusoid, each adapted to specific functions and tissues.
Continuous capillaries are the most common and are found in muscle, skin, lungs, and the central nervous system. They are characterized by tight junctions between endothelial cells, which limit permeability. The basement membrane is continuous, and red blood cells travel within the narrow lumen. This type provides selective permeability, ideal for tissues requiring controlled exchange.
Fenestrated capillaries are found in organs requiring rapid exchange of substances, such as kidneys, intestines, and endocrine glands. They have fenestrations—small pores within endothelial cells—that increase permeability to small molecules and fluids. These capillaries still have a continuous basement membrane, which supports filtration without allowing large molecules to escape.
Sinusoid capillaries, found in the liver, spleen, and bone marrow, are highly permeable. They feature large intercellular clefts and an incomplete or absent basement membrane, allowing even cells and large proteins to pass through. This structure is essential for tissues involved in extensive molecular exchange or blood cell modification.
Labeling these components correctly aids in understanding how capillary structure relates to function. Knowing the distinctions among the three types helps in clinical and physiological contexts, such as diagnosing vascular permeability issues or targeting drug delivery.
