The "black structures" are what?
Osteoblasts
Osteocytes within lacunae
Osteoclasts
Central (Haversian) canal
The Correct Answer is B
A. Osteoblasts: Osteoblasts are bone-forming cells found on the surface of bone tissue. They secrete bone matrix but are not housed within lacunae.
B. Osteocytes within lacunae: The black structures represent osteocytes, which are mature bone cells located inside small spaces called lacunae. These cells maintain the bone matrix and are arranged concentrically around central canals, forming osteons.
C. Osteoclasts: Osteoclasts are large, multinucleated cells responsible for bone resorption. They are found on bone surfaces in resorption bays, not within lacunae.
D. Central (Haversian) canal: The central canal is a large, open passageway in the middle of an osteon that contains blood vessels and nerves. The black dots are much smaller and represent lacunae housing osteocytes, not the canal itself.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Epidermis: The outermost layer, thin and avascular.
B. Hypodermis: The deepest layer, composed mainly of adipose tissue, lying beneath the dermis.
C. Stratum basale: A sublayer of the epidermis, not a full skin layer.
D. Dermis: The dermis lies beneath the epidermis and above the hypodermis. It is composed of connective tissue and contains blood vessels, lymphatic vessels, nerves, sweat glands, sebaceous glands, and hair follicles.
Correct Answer is D
Explanation
- Normal female (46,XX): Would show 23 pairs of chromosomes without any extra copies. This karyotype has an extra chromosome 21.
- Male with Down syndrome (47,XY,+21): Would show one X and one Y chromosome in the 23rd pair, not two X chromosomes.
- Normal male (46,XY): Would show 23 pairs with no trisomy, and the sex chromosomes would be XY.
- Female with Down syndrome (47,XX,+21): In this karyotype, chromosome 21 appears as a triplet (Trisomy 21), which is diagnostic of Down syndrome. The 23rd pair shows two X chromosomes, confirming the individual is female. Therefore, the correct interpretation is a female with Down syndrome.
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