Muscle and Cardiovascular System

What is the terminology used to refer to muscles in general? Muscle cells?

"Myo" refers to muscles in general, and "sarco" refers to muscle cells

What is the definition of muscle?

A collection of tissues that support the body and enable it to move, thermoregulate, and transport materials. Some muscles may be controlled voluntarily, whereas others act involuntarily.

Considering the anatomy of skeletal muscle, define the epimysium.

A fibrous connective sheath (covering) that surrounds a well-defined group of muscle cells.

In regards to skeletal muscle actions, what is the term synergist used to describe? A fixator?

A synergist is a muscle that contracts at the same time as an agonist and assists it in carrying out it's action. A fixator muscle stabilizes joints to allow other movements to take place.

What is the difference between a tendon and an aponeurosis?

A tendon is a fibrous connective tissue band that are a continuation of epimysium and attach muscles to bones. An aponeurosis is a sheet of fibrous connective tissue which helps attach muscle to muscle or muscle to bone.

Describe the difference between the ADductor and ABductor muscles?

ADductor muscles (inward movers) help keep the front legs under the animal, they pull the limb towards the midline of the body. ABductor muscles (outward movers) pull the muscle away from the midline and flexes a joint.

What are the two primary protein filaments that are responsible for contractions?

Actin, which attaches to the Z lines and extend towards the center of the sarcomere but don't meet. Myosin, appear to "float" in the middle of the sarcomere and don't connect to the Z lines.

In regards to skeletal muscle actions, what is the term agonist (or prime mover) used to describe? An antagonist?

An agonist is a muscle, or muscle group that directly produces a desired movement. An antagonist is a muscle or muscle group that directly opposes the action of an agonist.

Why is the wall of the right ventricle thinner than the wall of the left ventricle?

Blood from the right ventricle doesn't have very far to go, it gets pumped into pulmonary circulation; whereas the left ventricle has the most work to do pumping blood into systemic circulation through the aorta and to the rest of the body.

What are skeletal muscles composed of?

Bundles of muscle fibers called fasicles.

How are the atria identified on the outside of the heart?

By their auricles, they are blind pouches that come off the main part of the atria and look like ear flaps.

What is the fibrous connective tissue called that surrounds each myofiber?

Endomysium

What are the three layers of the wall of the heart?

Epicardium is the outermost layer (also called serous pericardium); myocardium is the middle and thickest layer made up of cardiac muscle, endocardium lies on the internal surface I of myocardium and made up of thin, flat simple squamous epithelium and forms the lining of the heart chambers.

Where is the heart located?

In the middle of the thoracic cavity in the mediastinum, the space between the two lungs.

In regards to the skeletal muscles of respiration, what are the functions of inspiratory & expiratory muscles?

Inspiratory muscles increase the sizeof the thoracic cavity when they contract and expiratory decrease the cavity.

What are the attachment sites called between cardiac muscle cells? Why are they important?

Intercalated discs; securely fasten cells together and transmit impulses from cell to cell to allow large groups of cardiac muscle cells to contract in a coordinated manner.

What are the muscles on the inside surface of the myocardium?

It is not smooth, it forms ridges and nipplelike projections called papillary muscles that are covered by the endocardium.

What are the two membranes of the serous pericardium called?

Parietal layer which lines the pericardial sac, and the visceral layer which lies directly on the surface of the heart (also called the epicardium)

What is the space called that is between the two serous membranes and what is it filled with?

Pericardial space, it is filled with pericardial fluid which lubricates the two membranes and prevents friction as the rub together during contractions and relaxations

What is the fibrous sac called that contains the heart? What are it's two parts?

Pericardium; divided into the fibrous pericardial sac and the serous pericardium.

What is the name of the connective tissue that surrounds each fascicle?

Perimysium

What is the cell membrane of a muscle fiber called?

Sarcolemma

What are the general characteristics of the three types of muscle?

Skeletal is controlled by conscious mind and moves the bones of the skeleton so the animal can move around. Cardiac is found only one place in the body: the heart. It makes up the entire structure of the heart. Smooth carries out most of the unconscious, internal movements that the body needs to maintain itself in good working order. Found in GI tract, lungs, and moves fluids, food, water & secretions

What are the three types of Muscle Tissue?

Skeletal, Cardiac, and Smooth

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

The A bands are the darker, they are areas where the thick myosin filaments and thin actin filaments overlap. The I bands are the light bands, and made up of thin actin filaments.

What is a sarcomere and what are it's components?

The basic contractile unit of a myofibril. It runs from Z band to Z band. Composed of the protein filaments actin and myosin.

What are the two main inspiratory muscles?

The diaphragm (separates thoracic and abdominal cavity), and the external intercostal muscles (between ribs).

What are the two main sets of expiratory muscles?

The internal intercostal (rotates ribs backwards) and abdominal muscles.

What is the name of the structure that is a continuation of the myocardium that forms a wall between the two atria? The two ventricles?

The left and right atrium are separated by the interatrial septum and the left and right ventricles are separated by the interventricular septum which is a continuation of the interatrial septum. Together they form the atrioventricular septum.

What is the most prominent aponeurosis in an animal's body?

The linea alba, runs lengthwise between the muscles on an animal's ventral midline and connects the abdominal muscles from each side together.

What is the origin of a muscle? The insertion?

The origin is the more stable site of muscle attachment and generally moves less than the other. It does not move when the muscle contracts. The insertion is the site that undergoes most of the movement when a muscle contracts.

Muscles are usually named according to their physical characteristics, which are what?

Their action, their shape (deltoid), Their location (biceps brachii referring to brachium or upper arm), The direction of fibers, the numbers of heads (or number of attachment sites), and attachment sites (sternomastoid originates on the sternum)

Where are the cutaneous muscles located? What is their function?

They are in the connective tissue (fascia) just beneath the skin and have little or no attachment to bones. They are thin, broad, and superficial and serve only to twitch the skin.

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

They are large cells, not very wide but quite long. They have a thin overall threadlike or fiberlike shape, so they are usually called fibers. Instead of one nucleus they have many.

How are cardiac muscle cells different from skeletal?

They are much smaller and have only one nucleus per cell. They are longer than they are wide and often have multiple branches.

What are the pelvic limb muscles assist with? What are they often a good spot for?

They assist with locomotion, extensors and flexors. The gluteal and quadriceps are usually a good spot for Intramuscular (IM) injections.

What are the roles of the head and neck muscles?

They control facial expression, enable chewing, and move sensory structures such as the eyes and ears.

What do the muscles of the thoracic (front) limb assist with?

They function mainly in locomotion, mainly allowing the animal to walk and run and generally move around its environment.

What are the functions of the abdominal skeletal muscles?

They help support the abdominal organs, also help flex the back and other various functions such as straining, expulsion of feces from the rectum, urine from the bladder, a fetus from the uterus, and the process of vomiting and regurgitation. They also play a role in respiration.

List three structures found in the mediastinum. (besides the heart)

Trachea, esophagus, and lymph nodes.

What chambers are responsible for pumping blood out of the heart? Receiving blood into the heart?

Ventricles pump blood out, and Atria receive blood into the heart.

What is another name for skeletal muscle? Why is it called that?

Voluntary Striated Muscle, striated comes from its microscopic appearance they look striped and voluntary because they are under control of the conscious mind.