Animal Tissues and Organ Systems
Guided Reading Qs
(Reading 25.3, 29.1-29.4)
1. What is the fluid that bathes all cells, where exchange of solutes takes place?
2. Maintenance of salt concentration, pH, water balance…these are all part of maintaining the balance of
the internal environment of an animal. What do we call this maintenance of balance?
3. Describe negative feedback. And, write one or two examples for yourself in the body stating what
change in condition causes a response.
Negative feedback is a process in which an activity changes a specific condition in the internal environment, and when the
condition changes past a certain point, a response reverses the change.
Example: furnace with thermostat—thermostat senses the air temperature built in to the furnaces control system—when
the temperature is low, furnace turns on—when air is war, furnace turns off
4. How is positive feedback different from negative feedback?
Positive feedback systems spark a chain of events that intensify change from an original condition,
intensification eventually leads to a change that ends feedback. Positive feedback mechanisms are usually
associated with instability in a system.
How is childbirth an example of this?
During childbirth, a fetus puts pressure eon the wall of the uterus—pressure induces the production and
secretion of a hormone, oxytocin, that makes muscles cells in the wall contract—contractions exert pressure on
the fetus, and the wall to expand, and so on until it leaves the mothers body
5. Sections 29.1-29.4 discuss the four types of animal tissue. List the four:
—sheet like tissue of cells with little extracellular material between them
—consists of cells scattered within an extracellular matrix of their own secretions.
Bind, spate, and insulate other tissues. Most abundant in body
—the functional partner of bone (or cartilage) that helps move and maintain the positions
of the body and its parts
—composed of neurons and a variety of cells, collectively called neroglia, that
structurally and functionally support them
6. Compare and contrast exocrine and endocrine glands.
have ducts or tubes that deliver secretions onto a free epithelial surface—secretions
include mucus, saliva, tears, milk, digestive enzymes, and earwax.
have no ducts. They secrete their products, hormones, directly in to interstitial fluid.
The hormones diffuse into the bloodstream, which delivers it to target cells. The plasma membrane of
the target cell has receptors that bind the hormone.
7. Epithelial tissue has a free surface and a basement membrane surface that glues the tissue to
underlying connective tissue. How does something like stomach acid stay on the free surface and not leak
between cells and under the tissue?
The rows of proteins in
seal the membrane together