Lecture 6: Locomotion

Question 1

Skeletal Muscle Tissue

Answer 1

Forms skeletal muscles, which attach to bones via tendons and contracts to cause locomotion and all other consciously controlled movements.
It is a voluntary muscle.
It is multinucleated.
It has striations

Question 2

Smooth Muscle Tissue

Answer 2

Occurs in the walls of hollow organs.
There are no striations
It is an involuntary muscle
It has 1 nucleus per cell.

Question 3

Cardiac Muscle Tissue

Answer 3

It is in the heart and it is used for pumping blood throughout the body and maintaining blood pressure.
It is an involuntary muscle.
It has one nucleus per cell.
It has striations

Question 4

Epimysium

Answer 4

It surrounds the entire muscle and it is on the outermost layer of the muscle.

Question 5

Perimysium

Answer 5

It is located beneath the epimysium and it surrounds the muscle fibres and the endomysium.

Question 6

Endomysium

Answer 6

Deepest layer in the muscle and it surrounds each individual myofibril.

Question 7

Sarcolemma

Answer 7

The plasma membrane of a skeletal muscle fibre. It is the site of action potential conduction, which triggers muscle contraction

Question 8

Myofibrils

Answer 8

Long cylindrical structures that lie parallel to the muscle fibre.
They attach to sarcolemma at their ends so as myofibrils shorten, the entire muscle contracts.
They are connected to each other by intermediate or desmin filaments that attach to the Z disc.

Question 9

Sarcomere

Answer 9

Functional Unit of skeletal muscles.
One of each is the space between 2 consecutive Z discs.
One contains an entire A band and two halves of an I band.

Question 10

Myofilaments

Answer 10

Smaller structures that myofibrils are composed of.
There are 2 main types: Thick filaments (Myosin) and Thin filaments (Actin)

Question 11

Thick Filament

Answer 11

Occurs only in the A band of the myofibril

Question 12

Thin filament

Answer 12

They attach to a protein in the Z disc called alpha-actinin.
They occur across the entire length of the I band and partway to the A band.

Question 13

H zone

Answer 13

Central region of the A band which looks slightly lighter than the rest of the A band.

Question 14

M line

Answer 14

Vertical line in the middle of the H zone.
This is where accessory proteins hold together thick filaments.

Question 15

Myosin

Answer 15

Component of thick filament.

Question 16

Actin

Answer 16

Main component of thin filament alongside troponin and tropomyosin.
Has binding sites for myosin attachment.

Question 17

Tropomyosin

Answer 17

Blocks the binding sites and prevents actin-myosin interactions when muscles are at rest.

Question 18

Troponin

Answer 18

Consists of three globular subunits:
One subunit binds tropomyosin.
One subunit binds actin.
One subunit binds Ca2+ ions.

Question 19

Axial Skeleton

Answer 19

Forms the central axis of the body.
Includes the bones of the skull, ossicles of the middle ear, hyoid bone of the throat, vertebral column, and the thoracic/rib cage.

Question 20

The skull

Answer 20

Consists of cranial bones, and facial bones.
Cranial bones form cranial cavity which encloses the brain and serves as an attachment site for muscles of the head and neck.
Facial bones provide cavities for the sense organs and serve as attachment points for facial muscles.

Question 21

Ossicles of middle ear

Answer 21

Transmit sound from the air as vibrations to the fluid-filled cochlea.

Question 22

Hyoid Bone

Answer 22

Lies below the mandible in front of the neck.
Acts as a movable base for the tongue and is connected to muscles of the jaw, larynx, and tongue.

Question 23

Vertebral/Spinal Column

Answer 23

Surrounds and protects the spinal cord.
Supports the head
Acts as an attachment point for ribs and muscles of the back and neck.
Consists of 26 bones (24 vertebrae, sacrum and coccyx.)

Question 24

Rib Cage

Answer 24

Consists of the ribs, sternum, thoracic vertebrae, and costal cartilages.
Encloses and protects the organs of the thoracic cavity.
Provides support for shoulder girdles and upper limbs
Serves as an attachment point for the diaphragm, muscles of the back, chest, neck and shoulders.

Question 25

Costal cartilages

Answer 25

Connect the anterior ends of most ribs to the sternum

Question 26

Appendicular Skeleton

Answer 26

Composed of the bones of the upper and lower limbs
Includes the pectoral/shoulder girdle which attaches the upper limbs to the body.
Also includes the pelvic girdle which attaches the lower limbs to the body

Question 27

Pectoral Girdle

Answer 27

Transfer force generated by muscles acting on the upper limb to the thorax.
Consists of clavicles in the anterior and scapulae in the posterior.

Question 28

Pelvic Girdle

Answer 28

Responsible for bearing the weight of the body and for locomotion.
It is securely attached to the axial skeleton by strong ligaments.
Has deep sockets with robust ligaments that securely attach to the femur.
Mainly composed of two large hip bones.

Question 29

Joint/Articulation

Answer 29

The point where 2 or more bones meet.
Responsible for movement and stability.

Question 30

Fibrous Joints

Answer 30

Bones are held together by fibrous connective tissue
There is no cavity or space present between the bones.
Most don’t move at all or are only capable of minor movements.

Question 31

Cartilaginous Joints

Answer 31

Joints in which bones are connected by cartilage.
Allow for very little/minimal movement.
Found at the joints between vertebrae.

Question 32

Synovial Joints

Answer 32

Only joints that have a space between the adjoining bones.
Space is called Joint Cavity and is filled with fluid which lubricates the joints and reduces friction allowing for greater movement.

Question 33

Angular Movement

Answer 33

Movements produced when the angle between the bones of the joint changes.
Flexion: When angle decreases
Extension: When angle increases

Question 34

Rotational Movement

Answer 34

Movement of a bone as fit rotates around its own longitudinal axis.

Question 35

Excitation-contraction coupling

Answer 35

Link between the action potential generated in the sarcolemna and the start of a muscle contraction.
Where electrical excitation of the plasma membrane leads to the activation of a muscle contraction.

Question 36

Motor Neuron

Answer 36

Conducts signals from brain/spinal cord to muscle

Question 37

Motor End Plate

Answer 37

The area of the sarcolemma on the muscle fibre that interacts with the neuron

Question 38

Synaptic Terminal

Answer 38

End of the neuron’s axon
Doesn’t contact the motor end plate

Question 39

Synaptic Cleft

Answer 39

Small space which separates the synaptic terminal from the motor end plate

Question 40

Sodium-Potassium ATPase

Answer 40

Uses cellular energy to move K+ ions inside the cell and Na+ ions outside.
Accumulates small electric charge, but a big concentration gradient.

Question 41

Neuron Action Potential

Answer 41

Cause the release of neurotransmitters from the synaptic terminal into the synaptic cleft, where they can diffuse across the synaptic cleft and bind to a receptor molecule on the motor end plate. The receptors are sodium channels that open to allow the passage of Na+ into the cell when neurotransmitter signal is received.

Question 42

Acetylcholine

Answer 42

Neurotransmitter released by motor neurons that binds to receptors in the motor end plate.

Question 43

Acetycholinesterase

Answer 43

Breaks down acetylcholine into acetylcholine and choline.
Resides in synaptic cleft.

Question 44

Transverse Tubules (T-tubules)

Answer 44

Extensions of the plasma membrane that reaches deep into the muscle fibre.

Question 45

Depolarization

Answer 45

Reduction of voltage difference between the inside and outside of the plasma membrane.