Anatomy Test 6 (Muscular Tissue)

How many types of muscle tissue are there? What are they?

3 types of muscle tissue-

1. Skeletal

2. Cardiac

3. Smooth

Why do skeletal muscles have this name?

Because the function of most skeletal muscles is to move the bones of the skeleton

Are skeletal muscles striated?

Yes they are striated because alternating light and dark protein bands (striations) are visible when the tissue is examined under a microscope

In what manner do skeletal muscles work/what nervous control do they have?

They are voluntary muscles, which means that their activity can be consciously (voluntarily) controlled. The nervous control is in the somatic nervous system

What are skeletal muscles attached to?

They are most commonly attached to bones by tendons

What is the apperance of a skeletal muscle like?

It is a long cylindrical fibre with many peripherally located nuclei; unbranced; striated

Where are cardiac muscles only found?

They are found only in the heart, and form most of the heart wall

Are cardiac muscles striated?

Yes

What type of movement/nervous control do cardiac muscles have?

They have involuntary movements meaning it happens by itself and cannot be controlled. It is an autonomic division of the peripheral nervous system

What is the appearance of a cardiac muscle?

They are branded cylindrical fibres with 1 centrally located nucleus; intercalated discs join neighbouring fibers; striated

Where is smooth muscle tissue located?

Organ walls, airways, eye, blood vessels, and hair follicles

How does smooth muscle tissue get its name?

Because under a microscope, it appears nonstriated or smooth

Are smooth muscles striated?

No

What is the movement/nervous control of smooth muscles?

It is also involuntary and is controlled by part of the autonomic division of the peripheral nervous system

What is the structure of a smooth muscle?

The finer is thickest in the middle, tapered at each end, and has one centrally position nucleus; not striated; spindle shaped

How many functions do muscular tissues have? What are they?

5 functions-

1. Motion

2. Stabilize body positions

3. Movement of substances in body (blood, food, urine, semen)

4. Regulate organ volume (sphincters)

5. Thermogenesis

What type of muscular tissue helps with the function of motion/producing body movement?

Total body movement such as walking and running, and localized movements such as grasping a pencil, keyboarding, or raising your hand, rely on the integrated functioning of skeletal muscles, bones, and joints

What do skeletal muscles do in terms of stabilizing body positions?

Skeletal muscle contractions stabilize joints and help maintain body positions, such as when you are standing or sitting. Like postural muscles

What do postural muscles do in terms of stabilizing body positions?

Postural muscles contract continuously when you are awake

What is an example of skeletal/postural muscles stabilizing body positions?

The sustained contractions in neck muscles hold your head upright

What are sphincters?

Ringlike bands of smooth muscles that may prevent outflow of the contents of a hallow organ

What muscular tissues are involved in regulating organ volume?

Smooth muscles

How do smooth muscles regulate organ volume?

Sustained contractions of ringlike bands of smooth muscles called sphincters may prevent outflow of the contents of a hallow organ

How is temporary storage of food in the or urine in the urinary bladder possible?

Because smooth muscle sphincters close off the outlets of these organs

What muscular tissue helps move blood through the body’s blood vessels?

Cardiac muscles

How do cardiac muscles help move blood through the body’s blood vessels?

Cardiac muscle contractions in the wall of the heart pump blood through the body’s blood vessels 

What do smooth muscles do in blood vessels?

Contraction and relaxation of smooth muscle in the walls of blood vessels help adjust their diameter and thus regulate the rate of blood flow

What substances do smooth muscles move throughout the body?

Smooth muscle contractions also move food and substances such as bile and enzymes through the digestive canal, push gametes (sperm and oocytes) through the genital systems, and propel urine though the urinary system

What do skeletal muscle contractions indirectly promote in moving substances through the body?

Skeletal muscle contractions indirectly promote the flow of lymph plasma throughout the body and aid the return of blood in veins to the heart

What happens as muscular tissues contract?

They produce heat

What is the process called in which muscle contractions produce heat?

Thermogenesis

What is much of the heat released by muscle used for?

Much of the hear released by muscle is used to maintain normal body temperature

What is shivering? What does it do?

Involuntary contractions of skeletal muscles, known as shivering, can dramatically increase the rate of heat production

How many properties do muscular tissues have? What are they?

5 properties-

1. Excitability (irritability)

2. Conductivity

3. Contractility

4. Extensibility

5. Elasticity

What do the 5 properties of muscular tissues enable them to do?

The 5 properties of muscular tissue enables it to preform the 5 functions of muscular tissues and contribute to homeostasis of the body

What is excitability of muscular tissue a property of?

Both muscle and nerve cells

What is the ability of excitability of muscular tissue?

It is the ability to respond to certain stimuli by producing electrical signals called action potentials

What is produced during excitability?

An action potential

What are action potentials in muscles called?

Muscle action potentials

What are action potentials in nerves called?

Nerve action potentials or nerve impulses

How can action potentials travel along a cell’s plasma membrane?

Due to the presence of specific ion channels

How many types of stimuli trigger action potentials in muscle cells? What are they?

2 main types of of stimuli trigger action potentials in muscle cells-

1. Electrical

2. Chemical

Where do autorythmic electrical signals arise?

In the muscular tissue itself, as in the heart’s natural pacemaker

What are chemical stimuli in action potentials and wha are they released by?

Chemical stimuli, such as neurotransmitters released by neuron, hormones distributed by the blood, or even local changes in pH, can also trigger action potential in muscle cells 

What is conductivity in muscular tissues?

The action potential travelling down the membrane

What is contractility in muscular tissue?

The ability of muscular tissue to contract forcefully when stimulated by a nerve impulse. Is is also the ability to generate force

What is extensibility in muscular tissues?

The ability of muscular tissue to stretch, within limits, without being damaged

What limits the range of a muscles extensibility?

The connective tissue within the muscle limits the range of extensibility and keeps it within the contractile range of the muscle cells

What type of muscular tissue is subject to the most amount of stretching?

Smooth muscle tissue

What is elasticity in muscular tissue?

The ability of muscular tissue to return to its original length and shape after contraction of extension

What is each skeletal muscle and what is it composed of?

Each skeletal muscle is a separate organ composed of hundreds to thousands of skeletal muscle cells, also called muscle fibres (myocytes) because of their elongated shapes

What are skeletal muscle fibres called? Why?

Myocytes because of their elongated shape

What does cognitive tissue do in skeletal muscle tissue?

Connectie tissue surrounds muscle fibres and whole muscles, and carry the blood vessels and nerves that exert their effects on individual muscle fibres

What does a typical skeletal muscle consist of?

A muscle belly connected by tendons to the skeleton

What is the muscle belly of an organ?

The body

What is the reddish/meat-like appearance of muscular tissue

The reddish or meat-like appearance that we associate with muscular tissue arises from the large population of well-vascularized muscle fibres in the muscle belly

What are type of tissue are tendons?

They are glistening white dense regular connective tissue structures

What do tendons do?

They attach the muscle belly to bone

What are tendons usually, and what do they have/lack?

They are usually vascular, lack muscle fibres, and consist primarily of parallel arrangements of collagen fibres

What do tendons primarily consist of?

Parallel arrangements of collagen fibres

What are aponeuroses?

A broad flat muscle, or sheet like tendon like the tendon sheath

What is the muscle belly between?

It is found between tendons

What does the bulk of the muscle belly consist of?

Striated muscle fibers, but there is a lot more to it

What is surrounding each muscle fibre in smooth muscle?

Surrounding each muscle fibre is a thin wrapping of mostly reticular fiber called the endomysium

What does the endomysium help do?

It helps to bind the muscle fibres together, yet it is loose enough to allow them the move freely over one another

What does the endomysium carry?

Small blood vessels that supply the fibres with nutrients

What do groups of muscle fibres form?

Bundles wrapped in a thick layer of connective tissue

What is the muscle fibre bundle called?

A muscle fascicle, or a muscle fasciculus

What is covering the muscle fascicles?

A dense irregular connective tissue called the perimysium

What does the perimysium allow?

A certain degree of freedom of motion between neighbouring muscle fascicles and transmits blood vessels

What is around the periphery of the skeletal muscle?

A somewhat thicker covering of dense irregular connective tissue called the epimysium

What does the epimysium do?

It binds all the muscle fascicles together to form the muscle belly

What doe the muscle fibres in the belly of the muscle eventually do?

They eventually taper to round blunt ends, but the connective tissues associated with the fibres continue beyond the blunt ends to become the tendons of the muscle

What are the tendons of skeletal muscles?

They are a continuous mass of connective tissue that runs through the muscle as the endomysium, perimysium, and epimysium and emerges from the belly of the muscle as the tendons at either ends… Which makes your muscles so incredibly strong

At its junction with the bone, what is the surface tissue of the tendon like?

At its junction with the bone, the surface tissue of the tendon is continuous with the periosteum, while its deeper collagen fibres enter the bone to blend with the collagen of the bone extracellular matrix

When the various skeletal muscles of the body are further grouped, what are they protected by?

They are further grouped together and protected by  large dense irregular connective tissue sheets, called fascia

What do the fascia do?

They wrap around groups of muscles much like a sock encircles your foot

What are the connective tissue coverings of a skeletal muscle from superficial to deep?

Sarcolemma, epimysium, perimysium, and endomysium

What is the sarcolemma of a skeletal muscle?

It is the cell membrane of the muscle cell… the 1st layer

What is the sarcoplasm of a skeletal muscle?

It is the spaces between muscle fibres

How long are muscle fibres?

They are long cylinders, about 10-30cm long

What is the way of remembering the skeletal muscle layers?

Submarine Sandwich

What are the layers to the submarine sandwich?

The bread= the cell membrane of the muscle cell (sarcolemma)

The paper wrapping with extended flat ends= the first loose connective tissue layer (endomysium)

When multiple sandwiched are individually wrapped and then wrapped together in 1 big paper with the ends extended and flat= a fascicle (perimysium)… dense irregular connective tissue

When groups of sandwiches are wrapped into a bigger wrap with ends flat and extended= the epimysium

What are tendons formed by?

Connective tissue around muscles

What are the most important components of a skeletal muscle?

The muscle fibres

What is the diameter of a muscle fiber?

Mature muscle fibers range from 10 to 100 micrometers in diameter 

What are tendon fascicles?

All the ends of the paper in the submarine sandwich pulled down together… bundles of collagen fibers

What are tendon sheaths like?

They are like tubular bursae with a tendon down the middle

What do tendon sheaths do?

They reduce friction

Where are tendon sheaths found?

They can be found in the carpal tunnel

What is the carpal tunnel lined by?

The carpal tunnel is lined by a lining and covering called the synovial sheath which has synovial fluid

What is a ganglion cyst?

It is fluid filled and happens when the tendon sheath comes out

Where are the multiple nuclei of a skeletal muscle fibre located?

Just beneath the sarcolemma, the plasma membrane of a muscle fibre

What are T tubules?

Thousands of tiny tube-shaped invaginations of the sarcolemma, that tunnel in from the surface toward the centre of each muscle fibre

What are T tubules filled with? Why?

Because T tubules are open to the outside of the fibre, they are filled with interstitial fluid

What does the sarcolemma surround?

The sarcoplasm, they cytoplasm of a muscle fibre

What does the sarcoplasm include?

A substantial amount of glycogen

What is glycogen?

A storage molecule that consists of a chain of linked glucose molecules

What happens when a muscle requires energy and has already depleted its available glucose?

Glucose molecules from glycogen will be released and utilized for the synthesis of ATP