Ch 32: The Internal Environment of Animals: Organization and Regulation Flashcards
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.
to excite
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.
receptors
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.
axons
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.
pathway
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.
immediate
Hormone responses may be initiated by….
….organic molecules or ions, nervous system stimulation, or other hormones.
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.
ADH, oxytocin
Lipid-soluble hormones CAN pass through the cell membrane. They bind to the receptor in the cell cytosol to initiate response. Name 2 examples.
estradiol, testosterone
What are the effects of epinephrine on a liver cell?
On smooth muscle cells?
On skeletal muscle cells?
blood glucose levels are increased
blood vessels dilate increasing flow to skeletal muscle
blood vessels to intestines decrease
Is epinephrine water or fat-soluble?
water-soluble
Negative feedback turns off a response. Name an example of this in the body.
secretin signaling –>
low pH in duodenum –>
S cells of duodenum release secretin –>
circulates in the blood, arrives in the pancreas, elicits release of bicarbonate
Positive feedback amplifies a response. Example of this is oxytocin signaling.
Suckling stimulates release of oxytocin
Oxytocin causes smooth muscle in the mammary glands, which causes milk release
Aldosterone (a lipid-soluble hormone) affects only a small number of cells in the body because….
….only its target cells contain aldosterone receptors.
An animal is a ________ if it controls an internal variable and a ________ if it allows an internal variable to vary with external changes.
regulator
conformer
Define homeostasis.
Homeostasis is the maintenance of a steady state despite internal and external changes.
Characteristics of endotherms:
generate heat through metabolism
stable body temp (regulator)
requires a lot of energy (food)
**
Characteristics of ectotherms:
gain heat from environment (mostly)
adjust body temp through behavior (e.g. basking in the sun)
requires less energy (food)
** Animals can just both mechanisms to some extent.
Describe skeletal muscle.
(unbranched vs branched; striated vs unstriated, etc.)
Unbranched fibers
Striated
Attached to bones
Control voluntary movements of body
Describe cardiac muscle.
(unbranched vs branched; striated vs unstriated, etc.)
Branched
Striated
Found in the heart, regular contraction of the heart
Describe smooth muscle.
(shape; striated vs unstriated, etc.)
Spindle-shaped cells
Unstriated
Found in the digestive tract, vessels, bladder.
Cause contraction of other internal organs
Cardiac muscle is the only muscle composed of ________ fibers.
branched
What type of epithelium would you expect to find covering a surface subject to physical forces?
Stratified epithelium consists of multiple layers; this thickness provides a protective barrier.
What type of epithelial tissue, found in the intestines, absorbs nutrients?
Simple columnar epithelium, such as that found lining the intestines, is specialized for absorption and secretion.
Which of these tissues, found in the lungs, permits gas exchange by diffusion?
Simple squamous epithelium is a thin single layer of cells that allows for diffusion.
What type of epithelial tissue lines kidney tubules?
The simple cuboidal cells of kidney tubules allow for both secretion and absorption.
How does connective tissue differ from the other three major tissue types?
Connective tissue often consists of relatively few cells embedded in an extracellular matrix.
What describes loose connective tissue?
Loose connective tissue is a packing material that serves, for example, to hold organs in place.
Cartilage is found _____.
At the ends of long bones, such as the femur, there is a cartilage cap.
What is the connective tissue specialized for transport?
Blood
What is the first thing that happens when body temperature increases above normal body temperature?
The thermostat in the hypothalamus activates cooling mechanisms.
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.
enzymatic
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.
homeotherm
Which of the following is reabsorbed in the proximal tubule, leading to a reduction in the overall filtrate volume?
interstitial fluid
solutes
urea
water
solutes
water
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
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.
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
ascending limb of the loop of Henle
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
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.
True or False?
The collecting duct becomes more permeable to water when the kidneys are in water-conservation mode.
True
True or False?
The collecting duct concentrates urine by actively reabsorbing NaCl.
False; it concentrates urine by movement of water rather than by movement of ions.
True or False?
Reabsorption of water and solutes in the proximal tubule reduces the volume of the filtrate
True
True or False?
Regulated changes in the epithelium of the loop of Henle allow the kidney to operate in water-conservation mode.
False
What is a poikilotherm?
An organisms which allows its body temperature to fluctuate.
What is a homeotherm?
An organism that keeps its body temperature constant.
What is an endotherm?
Ectotherm?
An organism which produces its own heat.
An organisms which relies on heat from its environment.
What are the 4 mechanisms by which all animals lose and gain heat?
radiation
evaporation
convection
conduction
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.
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).
free water concentration
In their mechanism of action, a difference between lipid-soluble and water-soluble hormones is that….
…lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA.
In a physiological system operating with positive feedback, a change in a variable will _______ rather than reverse the change.
amplify
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.
uric acid
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?
The cells of the fish will absorb too much water, and the fish will die.
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.
hypotonic
The movement of substances from the blood into the proximal tubule is known as _____.
secretion (?)
As filtrate moves down the loop of Henle, the surrounding interstitial fluid becomes _____ concentrated than the filtrate, so _____ leaves the filtrate.
more
water
The most abundant solute in urine is _____.
urea
Glucose is removed from filtrate by _____.
active transport
Antidiuretic hormone (ADH) makes the _____ permeable to water.
collecting duct
