Bone is made up of several different tissues working together: ________, ________, dense connective tissue, epithelium, various blood forming tissues, adipose tissue, and nervous tissue.

Each individual bone is an ________; the bones and cartilage make up the skeletal system.

The skeletal system supports ________ tissues and provides attachment sites for ________; it serves as a structural framework for the body.

Many of the body's internal organs are protected by ________ coverings.

The skeletal system assists skeletal muscles to produce ________.

The skeletal system stores and releases minerals (e.g. calcium, phosphorus) to help maintain ________ homeostasis.

Hemopoiesis, blood cell formation, occurs in the ________ marrow of bones.

The yellow marrow of adult bones serves as a site of ________ storage.

Bone tissue is made up of widely separated cells surrounded by large amounts of ________.

The matrix of bone tissue consists of inorganic salts (e.g. hydroxyapatite, calcium carbonate) and ________ fibers.

The salts deposited in a framework of collagen fibers give bone its ________, while collagen fibers give bone its great tensile strength.

There are four principal types of bone cells: ________ cells, ________, osteocytes, and osteoclasts.

Osteogenic cells are ________ stem cells.

Osteoblasts are ________ cells.

Osteocytes are ________ bone cells that maintain its daily metabolism.

Osteoclasts are cells that ________ bone tissue.

Depending on size and distribution of spaces between the hard components, the regions of a bone may be categorized as ________ or spongy.

Compact bone contains ________ spaces and is the strongest form of bone tissue.

Compact bone is arranged in units called ________ or Haversian systems.

Spongy bone consists of an irregular lattice of thin columns called ________.

The spaces between the trabeculae in spongy bone can be filled with ________.

Spongy bone is precisely oriented along lines of ________, which helps bones resist stresses and transfer force without breaking.

Spongy bone makes up most of the bone tissues of the ________, flat, and irregular shaped bones, and forms most of the epiphyses of long bones.

What is the process of bone formation called?

At what stage of embryonic development does bone formation begin?

What is the only means by which a bone can increase in length?

What indicates that a bone has completed its growth in length?

Which cells are responsible for the ongoing replacement of old bone tissue with new bone tissue?

What is the major reservoir for calcium ions in the body?

What type of muscle tissue primarily moves the bones of the skeleton and is striated?

Which division of the nervous system controls skeletal muscles in a voluntary manner?

What muscle tissue forms most of the wall of the heart and is striated but involuntarily controlled?

Where is smooth muscle tissue primarily located in the body?

What is the ability of muscle tissue to respond to certain stimuli by producing electrical signals known as?

Which property of muscle tissue allows it to stretch without being damaged?

What is the basic functional unit of a myofibril in skeletal muscle tissue?

What is the plasma membrane of a muscle cell called?

What organelle in a muscle fibre stores calcium ions and triggers muscle contraction?

What type of filaments are directly involved in the contractile process of a muscle fibre?

What are the two types of muscle tissue mentioned?

How is skeletal muscle tissue characterized under a microscope?

Which division of the nervous system controls skeletal muscle tissue?

Where is smooth muscle tissue located?

How are cardiac and smooth muscle tissue regulated?

What are the four key functions of muscle tissue?

What is the ability of muscle tissue to respond to certain stimuli by producing electrical signals called?

What triggers action potentials in muscle tissue?

What is the ability of muscle tissue to contract forcefully when stimulated by an action potential called?

What is the ability of muscle tissue to stretch without being damaged called?

What is the ability of muscle tissue to return to its original length and shape after contraction or extension called?

What are the three layers of connective tissue that protect and strengthen skeletal muscle?

What is the plasma membrane of a muscle cell called?

What are the tunnel-like structures that extend from the surface toward the center of each muscle fiber called?

What is the fluid-filled system of sacs that encircles each myofibril called?

What are the contractile organelles of skeletal muscle called?

What is the basic functional unit of a myofibril called?

What is the name for the smaller structures found within myofibrils that include thin and thick filaments?

What are the three kinds of proteins that build myofibrils?

What are the two contractile proteins involved in muscle contraction?

What is the main function of myosin?

What protein covers the myosin-binding site on actin in relaxed muscle?

What regulatory proteins hold tropomyosin strands in place?

What is the model describing the process of muscle contraction called?

How do myosin heads attach to actin during muscle contraction?

What triggers the release of calcium ions during muscle contraction?

What is the repeating sequence of events that causes the filaments to slide during muscle contraction called?

What starts muscle contraction by increasing calcium ion concentration in the cytosol?

What is the relationship between the length of sarcomeres and the forcefulness of muscle contraction?

What is the synapse between a somatic motor neuron and a skeletal muscle fiber called?

What neurotransmitter is released into the synaptic cleft at the NMJ?

What happens when ACh binds to receptors on the motor end plate?

What triggers a muscle action potential in response to a nerve action potential at the NMJ?

Why is the neuromuscular junction usually near the midpoint of a skeletal muscle fiber?

ATP inside muscle fibers is enough to power contraction for only a few seconds; if exercise continues past that time, the muscle must make more ATP from ________________ or from ________________ or ________________ cellular respiration.

Creatine phosphate catalyzes the regeneration of new ________________ molecules when contraction begins.

Anaerobic cellular respiration involves a series of ATP-producing reactions that do not require oxygen and breaks down glucose to produce ATP through a process called ________________.

Muscular activity lasting more than 30 seconds depends on ________________ cellular respiration, which requires oxygen and produces ATP in the mitochondria.

Muscle fatigue can be caused by several factors, including inadequate release of calcium ions from the ________________, depletion of ________________, insufficient oxygen, depletion of glycogen and other nutrients, buildup of ________________, and failure of action potentials in the motor neuron to release enough ________________.

Oxygen debt refers to the added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise to restore metabolic conditions to the resting levels, such as restoring glycogen stores in the liver, resynthesizing creatine phosphate and ATP in muscle fibers, and replacing the oxygen removed from ________________.

The total force or tension that a single muscle fiber can produce depends mainly on the rate at which nerve impulses arrive at the ________________.

motor unit consists of a somatic motor neuron plus all the skeletal muscle fibers it stimulates, and all the muscle fibers in one motor unit contract ________________.

Motor unit recruitment is the process of increasing the number of active motor units, and the different motor units of an entire muscle are not stimulated to contract in unison; ________________ are recruited first with progressively stronger units added if the task requires more force.

Muscle tone is seen in skeletal muscle even at rest and is established by neurons in the brain and spinal cord that excite the muscle motor neurons; small groups of motor units are alternately active and inactive in a constant shifting pattern, which helps maintain skeletal muscle firm but is not strong enough to produce ________________.

Isotonic contractions involve the muscle changing its length while the tension remains almost constant, while isometric contractions involve the muscle not changing its length but the tension increases; most activities include both ________________ and ________________ contractions.

Slow Oxidative (SO) fibers are the least powerful type of muscle fibers and generate ATP mainly by aerobic cellular respiration; they have a slow speed of contraction, are very resistant to fatigue, and are adapted for maintaining posture and ________________ activities.

What type of contraction occurs when the muscle lengthens while under tension?

In an isometric contraction, does the muscle generate tension without changing length?

When does a concentric contraction occur?

Fast Oxidative-Glycolytic (FOG) Fibres contain large amounts of ________________ and many blood capillaries. They can generate considerable ATP by ________________ cellular respiration, giving them a moderately high resistance to fatigue; intracellular glycogen levels are high, so they can also generate ATP by ________________ glycolysis. They contribute to activities such as ________________ and ________________.

Fast Glycolytic (FG) Fibres generate the most powerful contractions; they have low ________________ content and relatively few blood capillaries and mitochondria. They contain large amounts of ________________ and generate ATP mainly by ________________. They contract strongly and quickly, but fatigue quickly. They are adapted for intense anaerobic movements of short duration such as ________________ or ________________.

The relative ratio of fast glycolytic and slow oxidative fibres in each muscle is genetically determined and helps account for individual differences in ________________. Those with a higher proportion of FG fibres often excel in activities requiring periods of intense activity (e.g. ________________, ________________), while those with higher percentages of SO fibres are better at activities that require endurance (e.g. ________________).

Endurance-type (aerobic) exercises (e.g. running, swimming) cause a gradual transformation of some FG fibres into ________________ fibres. Endurance exercises also result in cardiovascular and respiratory changes that cause muscles to receive better supplies of ________________ and ________________.

Exercises that require great strength for short periods produce an increase in the size and strength of FG fibres; the overall result is ________________.

Cardiac muscle fibres contract when stimulated by their own ________________ fibres. Mitochondria in cardiac muscle fibres are larger and more numerous than in skeletal muscle; cardiac muscle depends largely on ________________ cellular respiration to generate ATP and requires a constant supply of ________________.

Smooth muscle tissue is usually activated ________________ and is classified into two types: visceral (single unit) and multiunit smooth. Stimulation of one ________________ muscle fibre causes contraction of many adjacent fibres, but stimulation of one ________________ fibre causes contraction of the fibre only.

A relaxed smooth muscle fibre is thickest in the middle and tapers at each end; it contains both thick and thin filaments, but they are not arranged in orderly ________________ and therefore do not exhibit ________________. They lack transverse tubules and have only a small amount of ________________ for calcium storage.

Contraction of smooth muscle starts more slowly and lasts much longer; it can both shorten and stretch to a greater extent than other muscle types. Contraction and relaxation of smooth muscle involves a regulator protein called ________________ that binds to calcium. Calcium moves out of the cell slowly, delaying relaxation; the prolonged presence of calcium ions in the cytosol of smooth muscle fibres provides for smooth muscle ________________.

Smooth muscle fibres can stretch considerably and still maintain contractile function. When smooth muscle fibres stretch, they initially contract and develop increased tension, but within a minute or so the tension decreases. This is called the ________________ response, which allows smooth muscle to undergo great changes in length while retaining the ability to contract effectively.

Because mature skeletal muscle fibres have lost their ability to undergo ________________, growth after birth is mainly by hypertrophy (enlargement of existing cells). Skeletal muscle can regenerate only to a limited extent because it has some ________________ cells that divide slowly and fuse with existing fibres to assist muscle growth and repair.

Under certain circumstances, cardiac muscle tissue can regenerate; cardiac muscle fibres can undergo hypertrophy in response to increased ________________. Smooth muscle fibres can undergo hypertrophy as well, and certain fibres retain their capacity for ________________.