A&P Test 3 Qz Qs/Review Slides

Between any two unfused vertebrae (cervical through lumbar), there is an intervertebral disc - except between C1 and C2. Give some reasons for the unique absence of a disc at that location.

- A disc cannot be located between the atlas and the axis because there is not place for a disc because the vertebral body is very small. - A function of discs is to provide limited motion of the vertebrae. There is not a disc between the atlas and axis so that the organism can ventrally flex the cervical region. Also, the absence of a disc between the atlas and axis provides for lateral flexion of the cervical region.

How does the regulation of blood calcium concentration exemplify negative feedback and homeostasis?

- A drop in plasma calcium concentration stimulates the secretion of parathyroid hormone, which works through several mechanisms to raise the calcium concentration. In correcting the initial change, this exemplifies negative feedback. - Low Ca increases PTH & Calcitriol: - STIMULUS: Low blood calcium levels. - RECEPTOR: Parathyroid glands detect low blood calcium levels. - CONTROL CENTER: Parathyroid glands release parathyroid hormone. - EFFECTORS: Effectors respond in the following ways: - BONE: PTH & Calcitriol act synergistically to increase activity of osteoclasts - KIDNEYS: PTH & calcitriol act synergistically to decrease calcium excreted in urine - SMALL INTESTINE: calcitriol increases absorption of calcium from small intestine. Blood calcium level rise and return to normal and homeostasis is restored

What are the advantages of a fused sacrum and coccyx?

- A fused sacrum and coccyx provide the structural support required for a human to sit and stand on two lower appendages. - This is because of the attachment of abdominal and lumbar muscles that are required for sitting and standing erect. - The fused sacrum and coccyx also provide shock absorption, protecting the spine.

All second-class levers produce a mechanical advantage greater than 1.0 and all third-class levers produce a mechanical advantage less than 1.0. Explain why.

- Mechanical advantage equals LE/LR. - In a second-class lever, the order of the lever components causes the effort arm to be larger than the resistance arm. This causes LE/LR to be greater than 1.0. The lever has, therefore, high mechanical advantage, high power, and low speed. - In a third-class lever, the effort arm is shorter than the resistance arm. This causes LE/LR to be less than 1.0. The lever has, therefore, low mechanical advantage, low power, and high speed.

Calcium phosphate crystallizes in bone as a mineral called: a. Calcium phosphate b. Calcitriol c. Calcidiol d. Hydroxapatite

D- Hydroxapatite

Which cells have a ruffled border and secrete hydrochloric acid? a. C cells b. Osteocytes c. Osteogenic cells d. Osteoblasts e. Osteoclasts

E- Osteoclasts