L4 - Muscle and Nervous Tissue

Question 1

What is muscle tissue

Answer 1

Consists of elongated cells (muscle fibres) that use energy from the hydrolysis of ATP to generate force

Question 2

Function of muscle tissue

Answer 2

Producs body movements, maintains posture and generates heat

Question 3

What are the three types of muscle tissue

Answer 3

Skeletal muscle, cardiac muscle, smooth muscle

Question 4

What is the smallest skeletal muscle?

Answer 4

1.25mm stapedius in the ear - prevents hyperacusis

Question 5

What is the longest skeletal muscle?

Answer 5

Up to 60cm sartoroius - flexor, abductor, lateral rotator

Question 6

Is the control of skeletal muscle tissues voluntary or involuntary?

Answer 6

Voluntary

Question 7

What are the two types of filaments (myofilaments) in myofibrils?

Answer 7

Thin filaments: mostly actin (8nm diam)
Thick filaments: myosin (16nm diam)

Question 8

Describe the connective tissue of skeletal muscle (5 parts)

Answer 8

Epimysium - surrounds anatomical muscle
Perimysium - around fascicles
Endomysium - around muscle fibres (layer for capillaries/nerves)
Sarcolemma - cell plasma membrane
Sarcoplasm - cell cytoplasm

Question 9

What is the A band of the sarcomere?

Answer 9

All the thick filaments

Question 10

What is the I band of the sarcomere?

Answer 10

Thin filaments, but no thick filaments

Question 11

What is the H zone of the sarcomere?

Answer 11

Thick filaments but no thin filaments

Question 12

What is the M line of the sarcomere?

Answer 12

middle of sarcomere; middle line (holds thick filaments together)

Question 13

What is the Z disc of the sarcomere?

Answer 13

Passes through centre of I band, made up of actinins that link filaments of adjacent sarcomeres

Question 14

What is the function of titin in a sarcomere?

Answer 14

Links Z disc to M line; provides resting tension in I band, molecular spring

Question 15

What happens to the sarcomere when a muscle contracts?

Answer 15

The H zone and I bands get shorter
Z discs become closer together
A band stays the same

Question 16

What is the structure of cardiac muscle tissue

Answer 16

Striated, branched, single central nucleus with intercalated discs

Question 17

What do intercalated discs contain

Answer 17

Desmosomes which provide adhesion in contraction
Gap junctions for communication and rapid conduction

Question 18

Is the control of cardiac muscle tissue voluntary or involuntary

Answer 18

Involuntary

Question 19

Where is smooth muscle tissue located

Answer 19

In the walls of hollow internal structures (that contract/dilate)
e.g. intestines, blood vessel walls, iris of eye, reproductive, digestive, respiratory, urinary, skin erector pili

Question 20

Describe the structure of smooth muscle tissue

Answer 20

Short, small, spindle-shaped
Single central nucleus
Non-striated

Question 21

Is the control of smooth muscle tissue voluntary or involuntary?

Answer 21

Involuntary

Question 22

What do thin filaments and intermediate filaments connect to in smooth muscle tissue

Answer 22

Dense bodies

Question 23

What happens during contraction in smooth muscle tissue

Answer 23

Tension is transmitted to the intermediate filaments (don’t contract) and the cell twists as it contracts about these stable “rods”

Question 24

What is the function of the nervous system

Answer 24

Maintain homeostasis (along w/ endocrine system)
Initiates voluntary movements
Responsible for perception, behaviour and memory

Question 25

What is the receiving/input part of the neuron called, and what is the output portion of the neuron called?

Answer 25

Dendrites: the receiving/input part of the neuron Axon: carries the nerve impulse away from the neuron; output portion

Question 26

Describe multipolar neurons

Answer 26

Have 2 or more dendrites and a single axon All motor neurons are in this class

Question 27

Describe bipolar neurons

Answer 27

1 dendritic process and 1 axon Has cell body between axon and dendrite Related with special sense organs

Question 28

Describe unipolar neurons

Answer 28

The dendrites and axon are continuous Cell body is off to one side Most sensory nerves are unipolar

Question 29

Describe anaxonic neurons

Answer 29

Rare and function is poorly understood Cannot distinguish dendrites from axons

Question 30

Describe neuroglia

Answer 30

Found in both CNS and PNS Do not propogate action potentials, but can communicate Can divide, unlike neurons

Question 31

What are the different classifications of neuroglia

Answer 31

Astrocytes, Oligodendrocytes (ODC), Microglia, Ependymal cells

Question 31

What are the functions of neuroglia

Answer 31

Physical structure of nervous tissue Repair framework of nervous tissue Undertake phagocytosis Nutrient supply to neurons Regulate interstitual fluid in neural tissue

Question 32

Describe the structure of astrocytes

Answer 32

Star shaped; largest; most numerous of neurogolia Forms a syncytium network

Question 33

What is the function of astrocytes

Answer 33

Support and repair (scar) Communicate with neurons via 'gliatransmitters' Maintain environment around neuron by e.g regulating ions Maintains blood-brain barrier via endothelium

Question 34

What do Oligodendrocytes do

Answer 34

Form insulating multilayered meylin sheath (protein lipid layer) around CNS axons Can myelinate more than one neuron cell's axon

Question 35

What do microglia do

Answer 35

Resident cells of the brain that are phagocytic - protection

Question 36

What is the function of ependymal cells?

Answer 36

Produce cerebrospinal fluid (CSF) Lines the CSF filled ventricles in the brain and the central canal of the spinal cord CSF mechanical buffer; moves nutrients and waste

Question 37

Describe the structure of ependymal cells

Answer 37

Cuboidal cells containing both cilia and microvilli

Question 38

What are the two types of neuroglia in the PNS?

Answer 38

Schwann cells Satellite cells

Question 39

What is the function of Schwann cells?

Answer 39

Forms insulating myelin sheath around axons or can just support and surround several non-myelinated axons (Only one schwann cell per axon for myelination) unlike Oligodendrocytes

Question 40

What is the function of satellite cells

Answer 40

Surround neuron cell bodies Support and fluid exchange

Question 42

What are Purkinje fibres?

Answer 42

specialised muscle cells that conduct electrical activity around the heart. They have less myofibrils and more specialised “connexins” (gap junctions).