Properties of Muscles

Question 1

Properties of Muscle: Electrical Excitability. (3 points)

Answer 1

Muscles can change due to external stimuli:

• electrical
• hormonal
• ion changes allowing for an action potential leading to contractions

Question 2

Properties of Muscle: Contractility.

Answer 2

Action potentials allowing for sarcomere’s to contract, muscles to move, thus moving bone.

Question 3

Properties of Muscle: Extensibility.

Answer 3

The ability to stretch.

Muscular tissue type determines how extensible it is.

Question 4

Define Spasticity.

Answer 4

Lack of muscular extensibility.

Question 5

Properties of Muscle: Elasticity.

Answer 5

The ability for muscle fibres to return to their original state without damage.
Plays an important role in extensibility of muscle.

Question 6

Properties of Muscle Fibres. (4 points)

Answer 6

Electrical Excitability, Contractility, Extensibility, Elasticity.

Question 7

Functions of Muscle: Movement

Answer 7

Muscular contraction pulls bone, allowing for the movement of joints and thus limbs.

Question 8

Functions of Muscle: Stabilising body positions.

Answer 8

Many muscles continually making small, not forceful contractions to ensure body positions are kept (e.g. posture).

Question 9

Functions of Muscle: Storage & Movement of substances within the body.

Answer 9

E.g. Calcium & blood. During respiration, circulation, and muscle contraction.

Question 10

Functions of Muscle: Heat Generation.

Answer 10

Heat is generated & released in muscular contractions to maintain core body temperature within homeostasis.
E.g. shivering to raise core body temperature.

Question 11

Functions of Muscle. (4 points)

Answer 11

Movement, Stabilisation of body positions,, Heat generation and Storage & Movement of substances within the body.

Question 12

Types of Muscular Tissue. (3 points)

Answer 12

Skeletal, Cardiac & Smooth muscle.

Question 13

Define “Striated” Muscle Tissue.

Answer 13

Organisation of myosin & actin, forming well-organised sarcomeres.
“Marked with long, thin, parallel streaks.”

Question 14

Describe properties of Skeletal Muscle. (3 points)

Answer 14

Striated.

Mostly voluntarily controlled muscle fibres - conscious contraction/relaxation,
nerves allow the muscle to send/receive electrical signals for an action potential to ensue, causing muscular movement.

Some involuntary muscular involvement.

Question 15

Describe properties of Cardiac muscle. (4 points)

Answer 15

Striated.

Solely located in heart/cardiac walls.

Involuntarily controlled muscular involvements.

Contains it’s own pacemaker (the Sinoatrial Node) which causes muscular movement outside the Central Nervous System.

Question 16

Describe properties of Smooth Muscle. (4 points)

Answer 16

Associated with the Gastrointestinal System & blood vessels.

Lacks striation that skeletal & cardiac muscle has. (also lacking the organisation of myosin & actin filaments that create sarcomeres)

Myosin & Actin filaments are present but not strictly organised.

Greater extensibility than skeletal & cardiac muscle.

Question 17

Aponeurosis

Answer 17

An amalgamation of tendons from several different types of muscle spread over a wide area.
Important in the anterior portion of the abdomen - no bones, so thicker, more protective portion of tendon is required.

Question 18

Dissections: Muscle belly

Answer 18

Dark/er brown

Question 19

Dissections: Tendons

Answer 19

Light/er, more white.

Shiny/glistening.

Question 20

Dissections: Neurovascular bundle

Answer 20

Wrapped in Connective Tissue.
1 nerve - axons are spread to different muscle cells.
1 artery.
1-2 veins.

Question 21

Describe the concept “Vena Comitans”.

Answer 21

2 veins surrounding the sides of an artery.

Question 22

Properties of: Muscle Belly.

Answer 22

Skeletal muscle cells are surrounded by differing levels of Connective Tissue (CT).

The CT comes together to form tendons.

Belly shape and strength is determined by it’s function (either thick & robust or wide).

Question 23

Properties of: Tendons.

Answer 23

Muscle to bone attachment.

Connective Tissue continues from muscle belly through to attach to bone.

Shape and strength are determined by tendon function - either rope-like (biceps brachii) or flat & expansive (rectus sheath of interior abdomen.

Question 24

Name the 2 Muscle Attachment Sites.

Answer 24

Origin (Proximal attachment) & Insertion (Distal attachment).

Question 25

Muscle attachment sites: Origin (Proximal attachment)

Answer 25

Tendon attaching to the more stable bone.

Proximal attachment site.

Question 26

Muscle attachment sites: Insertion (Distal attachment)

Answer 26

Tendon attaching to moveable bone.

Distal attachment site.

Question 27

Direction of muscle attachments.

Answer 27

Insertion usually pulls towards the origin.

Question 28

Muscle attachments: effect on joints.

Answer 28

Muscles cross over joints in order to have an effect on them.

Muscles can cross more than 1 joint. E.g. biceps brachii - 3 joint muscle (shoulder, elbow & proximal radioulnar joints).