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F215:04 Responding to the environment > F215:04:08 Three types of muscle > Flashcards

F215:04:08 Three types of muscle Flashcards

1
Q

Describe the composition of muscles

A

composed of cells that are elongated to form fibres

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2
Q

Why do all muscles produce a force on contraction?

A

Because they contain filaments made of the proteins actin and myosin
These protein filaments operate to cause contraction of voluntary muscle

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3
Q

What are the 3 types of muscle?

A

involuntary
cardiac
voluntary

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4
Q

What is another name for involuntary muscle?

A

smooth muscle

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5
Q

What is voluntary muscle often known as?

A

striated or skeletal muscles

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6
Q

Why is smooth muscle not under voluntary control?

A

As it is innrvated by neurones of the autonomic nervous system

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7
Q

Describe the arrangement of the muscle cells and the action carried out by involuntary muscles in the walls of the intestine

A

Arrangement: Circular and longitudinal bundles
Action: Peristalsis- moves food along the intestine

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8
Q

What is peristalsis?

A

Where food is moved along the intestine

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9
Q

Describe the arrangement of the muscle cells and the action carried out by involuntary muscles in the Iris of the eye

A

Circular and radial bundles
Controls the light intensity of light entering the eye:
- Contraction of radial muscles dilates the pupil
- Contraction of circular muscle contricts the pupil

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10
Q

How does the involuntary muscle in the eye control the light intensity that enters the eye?

A
  • Contraction of radial muscles dilates the pupil

- Contraction of circular muscle contricts the pupil

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11
Q

Describe the arrangement of the muscle cells and the action carried out by involuntary muscles in the wall of the arteries and around arterioles; wall and cervix of the uterus

A

Circular bundles
Important in temp regulation, regulation of local blood pressure and the redirecting of blood to voluntary muscles during exercise:
- Contraction of muscle narrows vessel diameter so reducing blood flow
- Relaxatio causes dilation, increasing blood flow

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12
Q

How do involuntary muscles in the wall of the arteries and around arterioles carry out their role in temp regulation, regulation of local blood pressure and the redirecting of blood to voluntary muscles during exercise?

A
  • Contraction of muscle narrows vessel diameter so reducing blood flow
  • Relaxatio causes dilation, increasing blood flow
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13
Q

Why are muscle cells referred to as being ‘spindle-shaped’?

A

As they contain small bundles of actin and myosin and a single nucleus

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14
Q

How long and wide are muscle cells when in a relaxed state?

A

5um wide

500um long

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15
Q

What two characteristics do involuntary muscles have?

A

The contraction is relatively slow

The muscle tires very slowly

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16
Q

Where is cardiac muscle found?

A

it forms the muscular part of the heart

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17
Q

What are the 3 types of cardiac muscle?

A
  1. atrial muscle
  2. ventricular muscle
  3. Specialised excitatory and conductive muscle fibres
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18
Q

What is the difference between the contractions of atrial and ventricular muscles, and skeletal muscles (cardiac muscles)

A

atrial and ventricular muscles have longer durations of contractions

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19
Q

Describe the excitatory and conductive fibres in cardiac muscle

A

they contact feebly but control electronic impulses and control the rhythmic heartbeat

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20
Q

What controls the rhythmic heartbeat and regulate the rate of contraction?

A

The excitatory and conductive fibres

Neurones of the autonomic system which carry impulses to the heart

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21
Q

What is a myogenic type of contraction?

A

Cardiac muscle which is capable of stimulating contraction without a nerve impulse

22
Q

Where is the sinoatrial node found?

A

in the right wall of the atrium

23
Q

What does sympathetic stimulation do and what kind of muscle does it effect?

A

increases the rate of the heart

cardiac muscle

24
Q

What does parasympathetic stimulation do and what kind of muscle does it effect?

A

returns the heart muscle to its normal rate

25
Q

What is the sinoatrial node made up of?

A

specialised excitatory and conductive fibres

26
Q

What is the vital characteristic of the sinoatrial node?

A

It has self-excitation amd the electrical activity generated there immediately spreads into the atrial wall

27
Q

What separates the atria and ventricles in the heart and why is it necessary?

A

a layer of non-conducting fibres

so the electrical activity can only spread to ventricles at the AV node

28
Q

What does AV stand for?

A

atrioventricular

29
Q

What is the role of the AV node?

A

It conducts the activity to the ventricle tips via the Purkyne fibres

30
Q

Describe the composition of a cardiac muscle cell

A

they are made of many individual cells connected in rows

Separated by dark areas called intercalated discs, which are cell membranes

31
Q

What are intercalated discs?

A

Cell membranes that divide the individual cells in cardiac muscle fibres
They fuse in such a way that there are gap junctions with free diffusion of ions and so action potentials pass very easily and quickly between cardiac muscle fibres through the latticework of interconnections

32
Q

Why are there gap junctions between the individual cells in cardiac muscle fibres that fuse in a way that there are gap junctions between them?

A

To allow free diffusion of ions and so action potentials pass very easily and quickly between cardiac muscle fibres through the latticework of interconnections

33
Q

Describe the way in which muscle fibres contract

A

Its continuous throughout its life

it contracts powerfully without fatigue

34
Q

What is voluntary muscle necessary for?

A

the movement of the skeleton at joints

35
Q

Describe the makeup of voluntary muscle cells, including its size

A

100um in diameter
contains many nuclei
Each fibre is surrounded by a cell surface membrane called a sarcolemma

36
Q

What is a sarcolemma?

A

the cell surface membrane that surrounds each voluntary muscle fibre

37
Q

What is cell muscle cytoplasm known as?

A

Sarcoplasm

38
Q

Describe the organelles inside the sarcoplasm

A
  • Many mitochondria
  • Extensive sarcoplasmic reticulum
  • Number of myofibrils
39
Q

What are myofibrils?

A

contractile elements and each consists of smaller contractile units called sarcomeres
Within the myofibrils are two types of protein myofilaments- thin actin and thick myosin

40
Q

What are sarcomeres?

A

the smallest contractile unit of a muscle

Makes up myofibrils

41
Q

What are the two different types of protein myofilaments found in sarcomeres?

A

myosin and actin which run the length of the cell

42
Q

Describe the contractions of voluntary muscle

A

It contracts quickly and powerfully but fatigues quickly

43
Q

Describe the detail of the skeletal muscle, beginning with the muscle and ending with the myofibril

A 
muscle
tendon
bundle of muscle fibres
connective tissue
muscle fibre
myofibril
44
Q

Blood vessels such as arterioles contain circular smooth muscle. Contraction of this muscle constricts the vessel. Why do blood vessels not need longitudinal muscle to act against the circular muscle in order to cause dilation?

A

Circular muscles are needed in order to constrict the blood vessels; however, the dilation of the blood vessels is achieved by relaxation of the circular muscles only, because the pressure of the blood in the vessel dilates the vessel- effectively the force for dilation is derived from the pumping of blood by the heart

45
Q

Suggest the advantage of the electrical activity of the heart being able to pass from atria walls to ventricle walls only at the AV node

A

It is essential that the ventricles contract smoothly from the apex upwards, so if the electrical activity passed from atrial walls to ventricular walls, they would begin contracting from the top downwards

  • It is also essential to allow full contraction of atrial walls, pushing the blood into the ventricles before ventricular contraction begins
  • So the impulse only being able to pass via the AV node introduces a short delay which allows full atrial contraction before ventricular contraction begins
46
Q

What is the difference between involuntary, voluntary and cardiac muscle in terms of their appearance ?

A

involuntary: short spindle shaped cells, each with a single nucleus
Voluntary: Cells form long multinucleate fibres
cardiac: Cells form branched fibres with intercalated discs joining cells at their ends

47
Q

What is the difference between involuntary, voluntary and cardiac muscle in terms of contraction?

A

Involuntary: contracts slowly , fatigues slowly
Voluntary: contracts quickly, fatigues quickly
Cardiac: contracts quickly, does not fatigue

48
Q

What is the difference between involuntary, voluntary and cardiac muscle in terms of what controls their contractions?

A

Invol: Autonomic nervous system
Vol: Nervous system
Cardiac: Contraction is myogenic, autonomic nervous system controls the rate of contraction

49
Q

What is the difference between involuntary, voluntary and cardiac muscle in terms of what they are involved in?

A

Invol: movement of materials along internal tubes, e.g. gut and autonomic reflexes such as pupil dilation/constriction
Vol: Voluntary movements of bones of the skeleton about the joints
Cardiac: pumping blood round the body

50
Q

What is the difference between involuntary, voluntary and cardiac muscle in terms of its appearance under a microscope

A

Invol: unstriated
Vol: striated
Cardiac: striated

F215:04 Responding to the environment (14 decks)

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