Ch 32: The Internal Environment of Animals: Organization and Regulation

Question 1

The signaling molecules broadcast throughout the body by the endocrine system are called hormones (from the Greek horman, which means “__ ______”). Different hormones cause distinct effects, and only cells that have receptors for a particular hormone respond.

Answer 1

to excite

Question 2

Depending on which cells have ________ for that hormone, the hormone may have an effect in just a single location or in sites throughout the body. It takes many seconds for hormones to be released into the bloodstream and carried throughout the body. The effects are often long-lasting, however, because hormones can remain in the bloodstream for minutes or even hours.

Answer 2

receptors

Question 3

In the nervous system, signals called nerve impulses travel to specific target cells along communication lines consisting mainly of extensions called _____. Nerve impulses can act on other neurons, on muscle cells, and on cells and glands that produce secretions.

Answer 3

axons

Question 4

Unlike the endocrine system, the nervous system conveys information by the particular _______ the signal takes. For example, a person can distinguish different musical notes because each note’s frequency activates neurons in the ear that connect to slightly different regions of the brain.

Answer 4

pathway

Question 5

The two major communication systems of the body differ in signal type, transmission, speed, and duration. All these differences reflect adaptation to different functions. The endocrine system is especially well adapted for coordinating gradual changes that affect the entire body, such as growth, development, reproduction, metabolic processes, and digestion. The nervous system is well suited for directing ________ and rapid responses to the environment, such as reflexes and other rapid movements. Although the general functions of the endocrine and nervous systems are distinct, the two systems often work in close coordination, as we will explore shortly.

Answer 5

immediate

Question 6

Hormone responses may be initiated by….

Answer 6

….organic molecules or ions, nervous system stimulation, or other hormones.

Question 7

Water-soluble hormones do NOT pass through cell membranes. They instead bind to receptor on cell surface to initiate response inside the cell. Name two examples of these.

Answer 7

ADH, oxytocin

Question 8

Lipid-soluble hormones CAN pass through the cell membrane. They bind to the receptor in the cell cytosol to initiate response. Name 2 examples.

Answer 8

estradiol, testosterone

Question 9

What are the effects of epinephrine on a liver cell?
On smooth muscle cells?
On skeletal muscle cells?

Answer 9

blood glucose levels are increased
blood vessels dilate increasing flow to skeletal muscle
blood vessels to intestines decrease

Question 10

Is epinephrine water or fat-soluble?

Answer 10

water-soluble

Question 11

Negative feedback turns off a response. Name an example of this in the body.

Answer 11

secretin signaling –>
low pH in duodenum –>
S cells of duodenum release secretin –>
circulates in the blood, arrives in the pancreas, elicits release of bicarbonate

Question 12

Positive feedback amplifies a response. Example of this is oxytocin signaling.

Answer 12

Suckling stimulates release of oxytocin

Oxytocin causes smooth muscle in the mammary glands, which causes milk release

Question 13

Aldosterone (a lipid-soluble hormone) affects only a small number of cells in the body because….

Answer 13

….only its target cells contain aldosterone receptors.

Question 14

An animal is a ________ if it controls an internal variable and a ________ if it allows an internal variable to vary with external changes.

Answer 14

regulator
conformer

Question 15

Define homeostasis.

Answer 15

Homeostasis is the maintenance of a steady state despite internal and external changes.

Question 16

Characteristics of endotherms:
generate heat through metabolism
stable body temp (regulator)
requires a lot of energy (food)

Answer 16

**

Question 17

Characteristics of ectotherms:
gain heat from environment (mostly)
adjust body temp through behavior (e.g. basking in the sun)
requires less energy (food)

Answer 17

** Animals can just both mechanisms to some extent.

Question 18

Describe skeletal muscle.

(unbranched vs branched; striated vs unstriated, etc.)

Answer 18

Unbranched fibers
Striated
Attached to bones
Control voluntary movements of body

Question 19

Describe cardiac muscle.

(unbranched vs branched; striated vs unstriated, etc.)

Answer 19

Branched
Striated
Found in the heart, regular contraction of the heart

Question 20

Describe smooth muscle.

(shape; striated vs unstriated, etc.)

Answer 20

Spindle-shaped cells
Unstriated
Found in the digestive tract, vessels, bladder.
Cause contraction of other internal organs

Question 21

Cardiac muscle is the only muscle composed of ________ fibers.

Answer 21

branched

Question 22

What type of epithelium would you expect to find covering a surface subject to physical forces?

Answer 22

Stratified epithelium consists of multiple layers; this thickness provides a protective barrier.

Question 23

What type of epithelial tissue, found in the intestines, absorbs nutrients?

Answer 23

Simple columnar epithelium, such as that found lining the intestines, is specialized for absorption and secretion.

Question 24

Which of these tissues, found in the lungs, permits gas exchange by diffusion?

Answer 24

Simple squamous epithelium is a thin single layer of cells that allows for diffusion.

Question 25

What type of epithelial tissue lines kidney tubules?

Answer 25

The simple cuboidal cells of kidney tubules allow for both secretion and absorption.

Question 26

How does connective tissue differ from the other three major tissue types?

Answer 26

Connective tissue often consists of relatively few cells embedded in an extracellular matrix.

Question 27

What describes loose connective tissue?

Answer 27

Loose connective tissue is a packing material that serves, for example, to hold organs in place.

Question 28

Cartilage is found _____.

Answer 28

At the ends of long bones, such as the femur, there is a cartilage cap.

Question 29

What is the connective tissue specialized for transport?

Answer 29

Blood

Question 30

What is the first thing that happens when body temperature increases above normal body temperature?

Answer 30

The thermostat in the hypothalamus activates cooling mechanisms.

Question 31

Thermoregulation is the maintenance of the body’s temperature within a tolerable range. All animals regulate their body temperatures to a certain extent, but some animals maintain a more constant temperature than others. The maintenance of body temperature is critical for physiological and biochemical processes, many of which rely on _________ activity.

Answer 31

enzymatic

Question 32

Animals can be described according to whether they generate their own body heat (endothermic) or gain most of their body heat from external sources (ectothermic). They can also be described according to whether they maintain a relatively constant body temperature (homeothermic) or allow their body temperature to fluctuate with the environment (poikilothermic).
The diagram below illustrates that animals are not strictly endotherms, ectotherms, homeotherms, or poikilotherms but rather that there is a continuum. Although birds and mammals are generally homeothermic endotherms (upper right in the graph), there is no fixed relationship between the source of body heat and the stability of body temperature. For example, the arctic shrimp is an ectotherm; yet it is also a ________ due to the fact that its environment’s temperature is relatively stable.

Answer 32

homeotherm

Question 33

Which of the following is reabsorbed in the proximal tubule, leading to a reduction in the overall filtrate volume?

interstitial fluid
solutes
urea
water

Answer 33

solutes
water

Question 34

Which of the following characteristics describes the thin segment of the ascending limb of the loop of Henle?

a. ) impermeable to H₂O, permeable to NaCl
b. ) permeable to H₂O, impermeable to NaCl
c. ) permeable to H₂O and NaCl
d. ) impermeable to H₂O and NaCl

Answer 34

a.) impermeable to H₂O, permeable to NaCl

The fact that the ascending limb of the loop of Henle is only permeable to NaCl allows the movement of ions into the renal medulla, thereby increasing the osmolarity of the interstitial fluid in the medulla. If water could also be reabsorbed in this part of the nephron, the osmolarity gradient of the medulla would not be established.

Question 35

In which section of the nephron does the filtrate have a higher osmolarity than the blood when it enters and lower osmolarity than the blood when it leaves?

ascending limb of the loop of Henle

descending limb of the loop of Henle

proximal tubule

distal tubule

Answer 35

ascending limb of the loop of Henle

Question 36

Which of the following contributes most significantly to the kidney’s high energy expenditure?

a. ) transport of water in the descending limb of the loop of Henle
b. ) transport of water in the collecting duct
c. ) transport of NaCl in the thick segment of the ascending limb of the loop of Henle
d. ) transport of urea in the collecting duct

Answer 36

c.) The transport of NaCl in the ascending loop of Henle requires energy because the ions are moved against the concentration gradient: from a lower concentration to a higher concentration.

Question 37

True or False?

The collecting duct becomes more permeable to water when the kidneys are in water-conservation mode.

Answer 37

True

Question 38

True or False?

The collecting duct concentrates urine by actively reabsorbing NaCl.

Answer 38

False; it concentrates urine by movement of water rather than by movement of ions.

Question 39

True or False?

Reabsorption of water and solutes in the proximal tubule reduces the volume of the filtrate

Answer 39

True

Question 40

True or False?

Regulated changes in the epithelium of the loop of Henle allow the kidney to operate in water-conservation mode.

Answer 40

False

Question 41

What is a poikilotherm?

Answer 41

An organisms which allows its body temperature to fluctuate.

Question 42

What is a homeotherm?

Answer 42

An organism that keeps its body temperature constant.

Question 43

What is an endotherm?

Ectotherm?

Answer 43

An organism which produces its own heat.

An organisms which relies on heat from its environment.

Question 44

What are the 4 mechanisms by which all animals lose and gain heat?

Answer 44

radiation

evaporation

convection

conduction

Question 45

In many birds and mammals, reducing heat loss from the body relies on __________ _______, the transfer of heat (or solutes) between fluids that are flowing in opposite directions. In their body, arteries and veins are located adjacent to each other.

Answer 45

countercurrent exchange

Question 46

Osmosis refers to the diffusion of water across a selectively permeable membrane, resulting in the net movement of water to the side with the lower ___ _____ ______________ (higher solute concentration).

Answer 46

free water concentration

Question 47

In their mechanism of action, a difference between lipid-soluble and water-soluble hormones is that….

Answer 47

…lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA.

Question 48

In a physiological system operating with positive feedback, a change in a variable will _______ rather than reverse the change.

Answer 48

amplify

Question 49

Birds, insects, and many reptiles excrete nitrogenous waste in the form of ____ ____, which reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce it.

Answer 49

uric acid

Question 50

You just received a freshwater aquarium as a gift and decide to add more fish. When you get to the pet store, you find that the most beautiful fish are saltwater animals, but you decide to buy them anyway. What will happen when you put your expensive saltwater fish in your freshwater aquarium?

Answer 50

The cells of the fish will absorb too much water, and the fish will die.

Question 51

The osmoregulatory problems of freshwater animals are opposite to those of marine animals. Freshwater fish are adapted to life in a _________ environment and have mechanisms to get rid of excess water absorbed into the body. Saltwater fish are adapted to the marine environment and have extracellular fluids that have a composition similar to seawater. Placing them in fresh water will upset their osmotic balance, and they may not have regulatory mechanisms that can compensate.

Answer 51

hypotonic

Question 52

The movement of substances from the blood into the proximal tubule is known as _____.

Answer 52

secretion (?)

Question 53

As filtrate moves down the loop of Henle, the surrounding interstitial fluid becomes _____ concentrated than the filtrate, so _____ leaves the filtrate.

Answer 53

more

water

Question 54

The most abundant solute in urine is _____.

Answer 54

urea

Question 55

Glucose is removed from filtrate by _____.

Answer 55

active transport

Question 56

Antidiuretic hormone (ADH) makes the _____ permeable to water.

Answer 56

collecting duct