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Homeostasis is
the maintenance of a stable internal environment.
The maintenance of which of the following is not a part of homeostasis?
none of the above
Countercurrent exchange is
exchanging a component quantity (like heat) between two fluids with opposing flows
One of the uses of countercurrent exchange for a bluefin tuna is
heat transfer
The disadvantage in heat exchange for adjacent fluids moving in the same direction is that
once the gradient has disappeared, no further transfer can take place
As body temperature rises, the human body produces sweat as a means of cooling. This is an example of
negative feedback
Which of the following is true?
Endotherms maintain their body temperature through metabolic heat, while ectotherms must rely on the environment in order to regulate their temperature.
In general, since ectotherms derive most of their body temperature from environmental heat, they have much higher caloric needs than endotherms.
false
A set point
is the optimal value of a physiological variable.
Why is the regulation of contractions during labor considered a positive feedback loop?
Because oxytocin causes the uterus to contract, which causes more oxytocin to be released.
A heating/cooling system of a house is often used as an example to illustrate a feedback loop which is analogous to those found in animals. In this analogy, the temperature at which the thermostat is set represents the ________ and the thermostat itself represents the _____________.
set point, control center
What are the four main types of tissue in animals?
epithelial, connective, muscle, and nervous
Which of the following is a characteristic of epithelial tissue?
high rate of mitosis
Which type of epithelial tissue is in the alveoli of the lungs?
simple squamous
____________ epithelial tissue is composed of irregularly layered cells, which have microvilli on one side. They function in absorption
pseudostratified columnar
Epithelial tissues function in
all of the above

Epithelial tissues function in protection, permeability, and secretion.
The top of epithelial cells is exposed to air or fluid, while the bottom is
attached to a basement membrane.
Blood is considered a loose connective tissue.
false


Blood is considered a connective tissue, but it is not loose connective tissue.
Which of the following is true of fibroblasts?
Fibroblasts function in secreting proteins that form extracellular matrix.
Adipose tissue is also known as
fat tissue
Which of the following places is loose connective tissue most likely to be found?
all of the above

Loose connective tissues are found in a wide array of places in the body including in between muscles and bone, surrounding organs, and under epithelia.
When an animal gains weight with fat it adds fat stores to cells and adds adipose cells to fat tissue.
true
Blood and interstitial fluid are connective tissues.
true
Aponeuroses
connect muscle to muscle.
Connective tissue includes
all of the above

Connective tissue includes bone, adipose tissue, and lymph.
What are lacunae?
Lacunae are the small pockets in the matrix of cartilage.
What are the small tunnel-like pathways that lead out from blood vessels in bone in order to nourish osteocytes?
canaliculae
Which of the following is not a kind of cartilage?
chondrocartilage
The three major types of muscle tissue include:
smooth, cardiac, skeletal
Where would you most likely find striated muscle tissue?
attached to bone
Visceral muscles are found
surrounding the stomach.
Which of the following types of muscle tissue cannot be repaired if damaged?
cardiac muscle
Which statement regarding cardiac muscle is true?
It is striated like skeletal muscle.
The brain and spinal cord make up about _________ of the neural tissue in the body.
98%
Myofibrils are composed of which two kinds of microfilaments?

i. myosin (thick)
ii. myosin (thin)
iii. actin (thick)
iv. actin (thin)
i, iv


Myofibrils are composed of overlapping thick myosin filaments and thin actin filaments.


A sarcomere is
all of the above

A sarcomere is a group of overlapping actin and myosin filaments bordered by Z lines. It is the basic functional unit of the muscle.
According to the sliding filament model of muscle contraction:
neither type of filament contracts, the actin and myosin filaments slide together during muscle contraction.
Muscle contraction occurs when _________ interacts with __________.
actin, myosin
The thick fiber of the myofibril is composed of _________.
myosin
Human motion is the result of
muscles contracting to pull against bones.
Motor neurons stimulate muscle cells by
release of neurotransmitters from the synapse of the motor neuron.
The stimulation of the muscle cell by a neurotransmitter like acetylcholine causes __________ along the muscle cell.
depolarization
The critical calcium storage membrane in the muscle cell is the
sarcoplasmic reticulum.
In its relaxed state, the myosin heads are prevented from binding to the actin filaments by
tropomyosin.
__________ are extensions of the muscle cell plasma membrane that increse the surface area over which a depolarization spreads.
T tubules
True or false?

During muscle contraction, Ca2+ floods the cell, moving tropomyosin away from the binding site between myosin and actin.
true
The energy necessary for muscle contraction comes from
ATP bound to the myosin heads.
The ATP used in muscle contractions comes from
creatinine phosphate.
The attachment of the myosin head to the actin filament causes
the actin filament to slide to its contracted position as the myosin head returns to its original position
The strength of a contraction depends upon the
all of the above


The strength of contraction depends not only on the number of units contracted, but also the number of participating cross bridges (a function of muscle position prior to stimulation) and the availability of ATP. Without ATP available for hydrolysis, myosin-actin bonds cannot be formed.

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