This preview shows page 1. Sign up to view the full content.
Unformatted text preview: elastic and muscle tissue and a thin
outer layer of elastic connective tissue. In addition,
veins also have valves. 2. (a) Sinusoids differ from capillaries in that they
are wider and follow a more convoluted path
through the tissue. They are lined with phagocytic
cells rather than the usual endothelial lining of
(b) Capillaries and sinusoids are similar in that they
both transport blood from arterioles to venules. 3. (a) Leakage of fluid from capillaries produces
tissue fluid, which bathes the tissues, providing
oxygen and nutrients as well as a medium for the
transport (away) of metabolic wastes, e.g. CO2.
(b) Capillary walls are thin enough to allow
exchanges. No exchange occurs in arteries and
veins because the walls of arteries and veins are
too thick. 4. (a) Arteriolar end: Hydrostatic pressure predominates
in causing fluid to move out of the capillaries.
(b) Venous end: Increased concentration of solutes
and reduction in hydrostatic pressure at the
venous end of a capillary bed increases the
tendency for water and solutes to reenter the
capillary. 5. (a) Most tissue fluid finds it way directly back into the
capillaries as a result of net inward pressure at
the venule end of the capillary bed.
(b) Lymph vessels (which parallel the blood system)
drain tissue fluid (as lymph) back into the heart,
thereby returning it into the main circulation. Aging and the Endocrine System (page 103) 1. (a) Decrease in lean muscle mass (and consequent
increase in fat mass).
(b) Decrease in bone density (lower rate of bone
deposition). 2. After menopause, the ovaries stop responding to FSH
and LH, and estrogen levels decline. The pituitary
responds to the low estrogen levels by secreting
more FSH and LH in an attempt to stimulate estrogen
levels. (In premenopausal women, estrogen, and
LH and FSH secretion are regulated by negative
feedback mechanims). 3. Loss of bone mass. Arteries (page 107)
1. (a) Tunica externa
(b) Tunica media 2. (a) Thick, elastic walls are required in order to
withstand the high press...
View Full Document
This document was uploaded on 01/28/2014.
- Winter '13