Lecture Final

Question 1

Describe a skeletal muscle cell in terms of cell size, shape, number of nuclei, and appearance under the microscope

Answer 1

Skeletal muscle cells are huge, longer than they are wide. They can be several inches long. An
inch is equal to about 25 mm, or 25,000 μm, which is really large on a cellular scale. Despite being
so long, skeletal muscle cells are very thin (up to 80 μm in diameter) with an overall threadlike or
fiberlike shape. In fact, skeletal muscle cells are usually called skeletal muscle fibers rather than
skeletal muscle cells.Instead of having just one nucleus like most cells, skeletal muscle fibers have many. Large ones can have 100 or more nuclei per cell, all located out at the edge of the cell just beneath the sarcolemma (muscle cell membrane). This reflects their development from numerous primitive muscle cells that fused. Most of the volume of a skeletal muscle fiber is made up of hundreds or thousands of smaller myofibrils packed together lengthwise. The myofibrils are themselves composed of thousands of even tinier protein filaments. Prominent organelles between the myofibrils in a muscle fiber include many energy producing mitochondria, an extensive network of sarcoplasmic reticulum (similar to
the endoplasmic reticulum of other cells), and a system of tubules called transverse or T tubules
that extend in from the sarcolemma (cell membrane).

Question 2

What are the differences among a skeletal muscle fiber, a skeletal muscle myofibril, and a skeletal
muscle protein filament?

Answer 2

S.M. fibers are cells, very thin and up to several inches long
S.M. myofibril:smaller, hundreds or thousands make up fibers
S.M. protein filament: thousands compose myofibrils. Organelles are btw myofibrils

Question 3

Which contractile protein filaments make up the dark bands of skeletal muscle cells?

Answer 3

The large dark band (the A band) is made up of thick myosin filaments.

Question 4

Which contractile protein filaments make up the light bands of skeletal muscle cells?

Answer 4

The large light band (the I band) is made up of thin actin filaments. The dark line in the center of the I band is called the Z line. It is the attachment site for the actin filaments.

Question 5

Distinguish locations for epimysium, endomysium, and perimysium and what they cover?

Answer 5

Epimysium: Fibrous layer composed of tough collagen fibers. Surrounds fascicles
Edomysium: Composed of fine, reticular fibers. Surrounds each muscle fiber.
Perimysium:Composed of reticular fibers and thick collagen fibers. Surrounds fascicles.

Question 6

Know anatomic terms for muscle and what actually moves in contraction?

Answer 6

Cross bridges on the myosin filaments ratchet and pull actin filaments on both sides toward the center of myosin filaments, shortening all the end to end sarcomeres in a muscle fiber.

Question 7

What is a sarcomere and what are its components?

Answer 7

A sarcomere is the area from one Z line to the next Z line and is the basic contracting unit of skeletal muscle. Many sarcomeres lined up end to end form a myofibril. Each individual sarcomere in a myofibril only shortens slightly when the fiber is stimulated to contract, but when all the sarcomere contractions are added together, the muscle fiber shortens considerably

Question 8

What ion, released from the sarcoplasmic reticulum by a nerve impulse, starts the contraction
process in a muscle fiber?

Answer 8

Ca++

Question 9

What molecules in muscle act as the “batteries” to power the sliding of the actin and myosin
filaments?

Answer 9

Adenosine triphosphate (ATP)

Question 10

What molecules function as the “battery chargers?

Answer 10

Creatine phosphate (CP)

Question 11

If individual muscle fiber contractions obey the “all
or nothing law,” how does an animal control the
size and strength of its muscular movements?

Answer 11

Muscular movements are carefully controlled by the nervous system, which controls the number of muscle fibers it stimulates for a particular movement. Small, fine movements require only a few muscle fibers to contract. Larger, more powerful movements require contraction of many muscle fibers. The nervous system must predict how large and powerful a movement needs to be and must send the appropriate nerve impulses down to the appropriate muscle fibers in the target muscle or muscles. This is often referred to as the “muscle memory” necessary to skillfully perform activities such as knitting, shooting a basketball, or drawing a blood sample from an uncooperative cat.

Question 12

What is myoglobin and why is it important?

Answer 12

Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue. It stores and releases large quantities of O, when strenuous muscle contractions begin to deplete O2, it can resupplies the fiber.

Question 13

What is a neuromuscular junction and what happens there?

Answer 13

Sites where the ends of motor nerve fibers connect to muscle fibers. There is a very small space -synaptic space- btw end of fiber and sarcolemma (cell membrane) Nerve impulse causes the release of acetylcholine, which diffuses across synaptic space and binds to receptors on sarcolemma. Starts process that leads to muscle contraction.

Question 14

Why does an animal breathe heavily for a while after heavy exercise?

Answer 14

After heavy exercise, an animal needs more oxygen to convert lactic acid into glucose so that it
can be used again. Lactic acid is produced in muscle fibers during anaerobic metabolism as a
byproduct of glucose. Anaerobic metabolism begins when oxygen demand exceeds the supply

Question 15

Describe a cardiac muscle cell in terms of cell size, shape, number of nuclei, and appearance under
the microscope.

Answer 15

Small cells with single nucleus
Intercalated disks: attachments btw cardiac muscle cells allow transmission of impulses from cell to cell for coordinated contraction of lg groups of cells

Question 16

What are intercalated disks and why are they important to the functioning of cardiac muscle?

Answer 16

Intercalated discs are the firm end to end attachments between cardiac muscle cells. They are visible under the microscope as dark transverse lines between the cells. Intercalated discs are important because they securely fasten the cells together and transmit impulses from cell to cell to allow large groups of cardiac muscle cells to contract in a coordinated manner.

Question 17

Describe the effect of its nerve supply on the functioning of cardiac muscle.

Answer 17

The heart has a nerve supply that can modify its activity, but it is not needed to initiate the contractions of the cardiac muscle. We know from successful heart transplants that the heart’s nerve
supply is not essential to its function.

Question 18

What is the general effect of sympathetic nervous system stimulation on cardiac muscle?
Parasympathetic nervous system stimulation?

Answer 18

Sympathetic nerve fibers stimulate the heart to beat harder and faster as part of the fight or flight response when an animal feels threatened. Parasympathetic fibers do the opposite, in that they
inhibit cardiac function, thereby causing the heart to beat more slowly and with less force when thebody is relaxed and resting.

Question 19

Describe a smooth muscle cell in terms of cell size, shape, number of nuclei, and appearance under
the microscope.

Answer 19

Smooth muscle is found in large sheets of cells in the walls of some hollow organs (visceral
smooth muscle) and in small, discrete groups of cells (multiunit smooth muscle). Smooth muscle
cells are small and spindle shaped (tapered on the ends) with a single nucleus in the center. They
have a smooth, homogeneous appearance under the microscope because their filaments of actin and
myosin are not arranged in parallel myofibrils, as in skeletal and cardiac muscle. Rather, small
contractile units of actin and myosin filaments crisscross the cell at various angles and are attachedat both ends to “dense bodies” that correspond to the Z lines of skeletal muscle

Question 20

What are the main differences between visceral smooth muscle and multiunit smooth muscle?

Answer 20

Visceral smooth muscle is found in the walls of many soft internal organs, which are also known by the general name viscera. The cells of visceral smooth muscle are linked to form large sheets in the walls of organs such as the stomach, intestine, uterus, and urinary bladder. Fine movements are not possible with visceral smooth muscle; rather, it shows large, rhythmic waves of contraction. These contractions can be quite strong, as in the peristaltic contractions that move food along the gastrointestinal tract and the uterine contractions that push the newborn animal out into the world at parturition (birth). Visceral smooth muscle contracts without the need for external
stimulation. Whereas visceral smooth muscle is large and relatively powerful, multiunit smooth muscle is small and delicate. Instead of being formed into large sheets that function as a single large unit, multiunit smooth muscle is made up of individual smooth muscle cells or small groups of cells. It is found where small, delicate contractions are needed, such as in the iris and ciliary body of the eye, the walls of small blood vessels, and around small air passageways in the lungs. Also unlike visceral smooth muscle, contractions of multiunit smooth muscle are not automatic. They require specific impulses from autonomic nerves to contract

Question 21

Describe the effect of nerve stimulation on the functioning of visceral smooth muscle and multiunit smooth muscle

Answer 21

Visceral smooth muscle contracts without the need for external stimulation. Multiunit smooth muscle requires specific impulses from autonomic nerves to contract

Question 22

What is the general effect of sympathetic nervous system stimulation on visceral smooth muscle?
Parasympathetic nervous system stimulation?

Answer 22

Sympathetic stimulation decreases visceral smooth muscle activity, and parasympathetic
stimulation increases it.

Question 23

What are the main differences in the structures and functions of skeletal muscle, cardiac muscle, and smooth muscle?

Answer 23

Skeletal muscle cells are huge, longer than they are wide and thin. They can be several inches
long with many nuclei in each cell. Large numbers of muscle cells contract at the same time under
voluntary control. They are found all over the body and function to move bones and generate heat.
Cardiac muscle cells are much smaller than skeletal muscle cells and have only one nucleus per cell. They are not shaped like the long, thin fibers of skeletal muscle. Cardiac muscle cells are longer than they are wide and often have multiple branches. They are securely attached to each other end to end to form intricate, branching networks of cells. They are found only in the heart. Rather than large numbers of muscle cells contracting at the same time, as in skeletal muscle, cardiac muscle cells contract in a rapid, wavelike fashion. They can do this because the cells “communicate” with each other through the intercalated discs that connect them. This type of movement is important in allowing the heart to contract forcefully to eject blood to the body.
Similar to skeletal muscle, smooth muscle is found all over the body; however, it is under
involuntary control (for example, in blood vessels, viscera, and the eye). The cells are spindle shaped and each has a single nucleus. Smooth muscle exists as large sheets of cells that move in
wavelike contractions (visceral smooth muscle) or as distinct small groups of cells or individual cells
with fine control of action (multiunit smooth muscle). Because their contractile units are not
organized into regular, parallel sarcomeres, individual smooth muscle cells can shorten to a greater extent than skeletal or cardiac muscle cells.

Question 24

Know basics for smooth muscle from your reading. How is it influence by the parasympathetic
nervous system and the sympathetic nervous system?

Answer 24

Ok

Question 25

How do endocrine glands differ from exocrine glands?

Answer 25

Endocrine glands secrete tiny amounts of hormones directly into the bloodstream and not
through ducts. This feature differentiates them from exocrine glands, which secrete their products
onto epithelial surfaces through tiny tubes called
ducts

Question 26

In what ways are the functions and characteristics of the endocrine system similar to those of the
nervous system? In what ways are they different?

Answer 26

Both systems regulate body functions to maintain homeostasis. The endocrine system’s
reaction to stimuli is slow, whereas the reaction of the nervous system to stimuli is fast. The
endocrine system’s duration of effects is long, whereas the duration of effects of the nervous system is short. The target tissues for the endocrine system are virtually all body cells and tissues, whereas the target tissues for the nervous system are muscle and glandular tissues. The chemical messengers of the endocrine system are hormones, whereas the chemical messengers of the nervous system are neurotransmitters. The messenger producing cells of the endocrine gland are cells or modified neurons, whereas the messenger producing cells of the nervous system are neurons. Distance from chemical message production to the target for the endocrine system is long (via the bloodstream),whereas this distance for the nervous system is short (across the synaptic
space)

Question 27

What is a hormone target?

Answer 27

A cell that has receptors for a particular hormone is referred to as a target of that hormone.

Question 28

What is a hormone?

Answer 28

Chemical messengers produced by endocrine glands and secreted directly into blood vessels. Produce effects when they find specific receptors in or on cells.

Question 28

What hormones are anabolic steroid drugs related to?

Answer 28

Testosterone

Question 29

Why are kidney failure patients often anemic?

Answer 29

Because the kidneys produce the hormone erythropoietin that stimulates red bone marrow to increase rbc production

Question 30

How does a negative feedback system control the secretion of many hormones?

Answer 30

A gland produces its hormone as a result of stimulation by another hormone. When the level
of hormone from the first gland drops below needed levels, the second gland, the stimulating gland,produces more stimulating hormone, which stimulates the first gland to produce more of its hormone. The rising level of hormone from the first gland in the bloodstream eventually reaches the
level required in the body. Once that level is reached, the production of stimulating hormone by the second gland is turned down. This reduces the stimulation of the first gland, causing it to produce
less hormone. When the level of hormone from the first gland drops below what the body needs again, the second gland (stimulating gland) turns its production of hormone back up, which turns the production of hormone from the first gland back up, and the process continues.

Question 31

Through what mechanisms does the hypothalamus control the production or release of hormones from the pituitary gland?

Answer 31

Modified neurons in the hypothalamus secrete releasing and inhibiting factors into portal blood vessels. Specific for a particular anterior pituitary hormone.

Question 32

How do the hypothalamus’ effects on the anterior and posterior portions of the pituitary differ?

Answer 32

don’t know

Question 33

Why is the pituitary gland referred to as the “master endocrine gland?

Answer 33

The pituitary gland is often called the “master endocrine gland” because many of its hormones
direct the activity of other endocrine glands

Question 34

Name ALL 7 anterior pituitary hormones. Where are they produced?

Answer 34

Growth Hormone
Prolactin
Thyroid stimulating hormone
Adrenocoticotropic hormone
Follicle stimulating hormone
Luteinizing hormone
Melanocyte stimulation hormone

Question 35

Name ALL posterior pituitary hormones? Where are they produced?

Answer 35

Antidiuretic hormone
Oxytocin
Both produced in the hypothalamus and stored in the posterior pituitary.

Question 36

What stimulates the continued release of prolactin during lactation?

Answer 36

Once lactation has begun, prolactin production and release by the anterior pituitary gland continue as long as the teat or nipple continues to be stimulated by nursing or milking.

Question 37

What is one major effect of each hormone in question #9 (from reading/handout)
Example: Other than promoting growth in young animals, what are some of other effects of GH?

Answer 37

Growth hormone (GH) helps regulate metabolism of proteins, carbohydrates, and lipids in all of the body’s cells. The effect of GH on protein metabolism is to encourage the anabolism, or synthesis, of proteins by body cells. The effects of GH on carbohydrate and lipid metabolism are
linked. GH causes the mobilization (release) of lipids from storage in adipose (fat) tissue and their
catabolism (breakdown) in body cells for energy production. At the same time, it discourages the
cells from using carbohydrates, principally glucose, as energy sources. Because glucose is such an
important energy source for the body’s cells, a balance between GH and insulin is important to
maintain homeostasis of glucose levels in the blood

Question 38

What stimulates the continued release of prolactin during lactation?

Answer 38

Once lactation has begun, prolactin production and release by the anterior pituitary gland

Question 39

Do FSH and LH play important roles in male animals? If so, what are they?

Answer 39

Yes. In the male, FSH has an effect similar to one of its effects in the female. It stimulates
spermatogenesis, the development of male reproductive cells (the spermatozoa) in the seminiferous tubules of the testes. In the male, LH stimulates cells in the testes called interstitial cells
to develop and produce the male sex hormone testosterone. Therefore LH is sometimes called
interstitial cell stimulating hormone (ICSH) in the male

Question 40

Does ADH help promote or prevent the loss of large amounts of water in the urine? What effect would the inhibition of ADH release have on the body?

Answer 40

It helps prevent the loss of large quantities of water in the urine. Inhibition of ADH would cause more water to flow out of the body in the urine.

Question 41

What hormone plays an important role in helping an animal maintain its body temperature under
cold environmental conditions? How does it produce its effects?

Answer 41

Thyroid hormone. It does this through the calorigenic effect. The production of thyroid
hormone increases with exposure to cold temperatures. This response increases the body’s metabolic rate, which generates more heat. It also causes nutrients to be burned at a faster rate; so to prevent significant loss of body weight, animals housed outdoors in cold temperatures need to be fed morecalories than those kept in warmer temperatures.

Question 42

How do the clinical signs of hypothyroidism and hyperthyroidism relate to the normal functions of
thyroid hormone?

Answer 42

Because thyroid hormone influences the functioning of all cells, organs, and systems,
hypothyroidism affects the whole body. Clinical signs relate primarily to a slowing of the body’s
metabolism. Common clinical signs include alopecia (hair loss, usually bilaterally symmetrical),
dry skin, lethargy, reluctance to exercise, and weight gain without any increase in appetite. Affected animals often seek out sources of heat because deficient thyroid hormone levels cause the animal to have difficulty maintaining its body temperature. Most cases of hypothyroidism occur in middle age animals, but if it occurs in a young animal, dwarfism (impaired growth) and impaired mental development occur along with the other common signs.
Hyperthyroidism is most commonly seen in cats, although it is seen occasionally in dogs. Excessive
amounts of thyroid hormone speed up cellular metabolism all over the body. This results in signs
such as nervousness, excitability, weight loss, increased appetite, tachycardia (abnormally fast heart rate), vomiting, diarrhea, polyuria (excessive urine production), and polydipsia (excessive thirst).

Question 43

What two hormones play important roles in maintaining homeostasis of blood calcium levels in the body? Which one prevents hypercalcemia? Which prevents hypocalcemia?

Answer 43

Parathyroid hormone (PTH), also called
parathormone, and calcitonin. PTH helps prevent
hypocalcemia and calcitonin helps prevent hypercalcemia.

Question 44

What three groups of hormones are produced in the adrenal cortex? What are their effects?

Answer 44

don’t know

Question 45

How are the hormones of the adrenal medulla involved in the “fight or flight” response?

Answer 45

These effects of the fight or flight response are produced partly by direct sympathetic nerve stimulation of target tissues and partly by the epinephrine and norepinephrine released into the
bloodstream by the adrenal medulla. The adrenal medullary hormones circulate around the body,
helping to produce the whole body fight or flight effect. After the threat has passed, it takes the body
a while to come down from its excited state. This delay results from the epinephrine & norepinephrine circulating in the bloodstream. It takes some time for them to be metabolized and
removed from circulation.

Question 46

Which four hormones have a direct hyperglycemic effect in the body? What is the only hormone that
acts to lower the blood glucose level?

Answer 46

Growth hormone, thyroid hormone, glucocorticoid hormones, and glucagon. Insulin acts to lower the blood glucose level

Question 47

Which hormones are anabolic steroid drugs related to?

Answer 47

Testosterone

Question 48

How do the basic actions and purposes of estrogens and progestins differ?

Answer 48

Estrogens are responsible for the physical and behavioral changes that prepare the female for
breeding and pregnancy and signal the male that the time for breeding is approaching. Progesterone,
the primary progestin, helps prepare the uterus to receive the fertilized ovum and is necessary for
pregnancy to be maintained once the fertilized ovum implants in the uterus.

Question 49

Why are kidney failure patients often anemic?

Answer 49

The kidneys produce the hormone erythropoietin which stimulates red bone marrow to increase production of oxygen carrying RBCells

Question 50

Why do hormone like drugs generally have a high potential for undesirable side effects?

Answer 50

Because the production & effects of natural hormones are so interrelated, the therapeutic use of hormones and hormone like drugs can produce some potent and widespread problems, along w/beneficial effects. The amounts of hormones used therapeutically are usually very large compared with the normal physiological hormone levels in the body; therefore the potential for undesired side effects increases accordingly.