Skin is very tough but extremely sensitive. Explain how some structures in the skin allow it to withstand a vigorous pinch and tug, while other structures allow it to detect the presence of a mosquito on your arm
What will be an ideal response?
Skin's toughness comes from the durability of the epidermis and the reticular layer of the dermis. The many dead keratinocytes superficially and the desmosomes that link keratinocytes help withstand trauma. Tougher still is the collagenous dense irregular tissue of the dermis. Sensitivity comes from the many light touch cutaneous receptors. The hair follicle receptors can detect when a hair has been bent by the landing of an insect on the arm.
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Small areas of the myocardium contracting chaotically is called
A. bradycardia. B. tachycardia. C. flutter. D. fibrillation.
Which of the following statements best describes interstitial growth of cartilage?
A) Unspecialized cells from mesenchyme develop into chondrocytes, which divide and form cartilage. B) Chondrocytes in the lacunae divide and secrete matrix, allowing the cartilage to grow from within. C) Growth occurs in the lining of the long bones. D) Fibroblasts give rise to chondrocytes that differentiate and form cartilage.
Which of the following descriptions of a blood sample is most accurate?
A. The ratio of red blood cells to white blood cells would be about 1:1. B. Platelets are usually present in higher numbers than red blood cells, but lower numbers than white blood cells. C. Most of the cells that can be identified are red blood cells, with much fewer white blood cells. D. White blood cells, usually much smaller than red blood cells, are represented in much lower numbers than platelets.
Which of the following will occur with a decrease in the ECF volume?
A. increase in GFR B. increase in angiotensin II levels C. increase in natriuretic peptide levels D. increase in free H2O clearance E. increase in fractional excretion of Na+