Muscular and Nervous Tissue-Section 1

Question 1

Structure of the Skeletal Muscle Tissue

Answer 1

Cynlindrical and striated.
Striations form from the alternating distribution of actin and myosin.
Multiple peripheral nuclei.
Individual fibres surrounded by perimysium (irregular connective). Many fibres form a fascicle surrounded by areolar endomysium. Muscle itself surrounded by epimysium (dense irregular connective tissue).

Question 2

Sarcomere Striations

Answer 2

A-band: Dark striation where myosin fibres are found.
H-zone: Less dark section of the A-band, where there is only myosin.
I-band: Light striation where only actin fibres are found.
M-line: Midpoint of the A band.
Z disc: Boundary of sarcomere-middle of I-band. Made of actinin and joined to actin by titin.

Question 3

Cardiac Muscle Structure

Answer 3

Striated. Has central nucleus. Sarcomeres joined by intercalated discs. Intercalated discs have desmosomes and gap junctions (to conduct electrical impulses to coordinate heart beats).

Question 4

Smooth Muscle Structure

Answer 4

Spindle shaped, non-striated with dense bodies on the surface and non-contractile fibres connecting them.
Thick and thin contractile fibres also connect non-adjacent dense bodies.
When contracting, contractile fibres contract and causes the muscle to widen as the cell bends around the noncontractile frame.

Question 5

Types of Neurons and Respective Functions

Answer 5

Sensory- Conducts information about sensory stimulus to CNS.
Integrative- Analysis of sensory stimuli and determining response.
Motor- Stimulates effectors to carry out a response.

Question 6

Multipolar Neuron

Answer 6

Cell body found on one end of axon with many dendrites. Other end of axon has a branched dendrite.
Very long and most numerous in CNS.

Question 7

Unipolar Neuron

Answer 7

Cell body off to one side of axon. Each end of axon splits into branched dendrites.
Usually sensory neurons and very long.

Question 8

Bipolar Neuron

Answer 8

Cell body found between axon and dendrite. Only one dendrite but can branch many times.
Used to relay impulses from sensory organ to sensory neuron.

Question 9

Anaxonic Neuron

Answer 9

Cell body with many dendrites and a short axon. Found in brain.

Question 10

Astrocytes (CNS)/ Satellite Cells (PNS)

Answer 10

Formed when several glial cells interlock to form a syncytium network.
Repairs, support (contains microfilaments), maintains environment around neurons, maintains blood/brain barrier by controlling permeability.
Regulates neuron growth and proliferation.
Communicates by gliotransmitters.
Satellite cells only surround cell bodies

Question 11

Oligodendrocytes/Schwann Cells

Answer 11

Form myelin sheath around axons of neurons in the CNS/PNS. Can myelinate many neurons at once.
Myelination increases speed of conduction.

Question 12

Ependymal Cells

Answer 12

Produces cerebrospinal fluid and lines ventricles containing said fluid in brain and central canal of spinal cord.
Mostly cuboidal with cilia and villi. Cilia move CSF and villi sample CSF.
CSF: Mechanical Buffer. Moves nutrients and waste.

Question 13

Microglia

Answer 13

Macrophages found only in the brain.

Question 14

Smallest and longest muscle

Answer 14

Smallest: Stapedius, 1.25mm. Stabilises stapes. Prevents hyperacusis.
Longest: Up to 60cm. Flexor, abductor and lateral rotator of hip, flexor of knee.

Question 15

Function of alpha Actinin

Answer 15

Found on the dense material of the Z-disc. Attaches to actin and titin.

Question 16

Function of Titin

Answer 16

Attaches to Z-disc and M-line. Maintains the position of thick filaments. Allows the sarcomere to return to original shape after stretching or contraction.