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BIOSCI 107 > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

Describe the general features of muscle tissue

A
  • elongated cells celled muscle cells/fibres or myocytes
  • cells use ATP to generate force
  • contraction allows for movements, posture, and heat
  • muscle makes up 50% of the body tissue mass
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2
Q

What are the types of muscle

A

Skeletal
Cardiac
Smooth

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3
Q

Describe Skeletal muscle

A
  • Roughly 650 skeletal muscle
  • Attached to bones via tendons
  • Long, cylindrical cells
  • Appear striated
  • Multinucleated (many peripheral nuclei pushed to the side)
  • Contraction under conscious control
  • Functions for motion, posture, heat, protection

Smallest: stapedius
Longest: Sartorius

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4
Q

Describe the stapedius

A

The smallest skeletal muscle - 1.25mm - in the body. Located in ear
Functions to modify intensity of sound by tensing bones
Important because some sounds could shake bones apart - e.g. while crunching
When you have Bell’s Palsy and facial nerve paralysed, the muscle doesn’t work due to nerves and therefore sounds are loud

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5
Q

Describe the Sartorius

A

The largest skeletal muscle - 60cm.
Cells are long as run the whole length
Involved when you externally rotate your hip e.g. when trying to look under your foot/shoe

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6
Q

What causes striations of muscle fibres

A

Highly organised arrangement of myofibrils within the cells

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7
Q

What are myofibrils

A

They more or less fill the cytoplasm (sarcoplasm) of the muscle fibre and extend its entire length within the cell

Composed of thin and thick filaments (myofilaments)

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8
Q

What are myofilaments

A

Filaments within the myofibrils
They do not extend the length of the muscle fibre, but arranged in sarcomeres

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9
Q

What are thin filaments made from

A

Mostly actin

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10
Q

What are thick filaments made form

A

Myosin

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11
Q

What is the sacromere

A

The basic functional unit of the myofibril

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12
Q

Where is the Epimysium

A

Fascia that surrounds the anatomical muscle

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13
Q

Where is the Perimysium

A

Around the fascicles (surrounds multiple collections of muscle fibres/cells)

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14
Q

What are fascicles

A

Groups of muscle cells

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15
Q

Where is the endomysium

A

Around collections of muscle fibres/cells

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16
Q

What is the sarcolemma

A

The actual cell
plasma membrane

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17
Q

What is the sarcoplasm

A

Muscle cell cytoplasm

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18
Q

What is the A band

A

The dark, middle part; contains all the thick filaments

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19
Q

What is the I band

A

The thin filaments, but no thick filaments

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20
Q

What is the H zone

A

The thick filaments, but no thin filaments

21
Q

What is the M line

A

The middle of sarcomere (holds thick filaments together)

22
Q

What are the Z discs

A

They pass through centre of I band (between sarcomeres) made up of
“actinins” – that link filaments of adjacent sarcomeres

23
Q

Describe Cardiac muscle

A

Striated
Branched
Single central nucleus
Involuntary contraction
Fibres join end-to-end through intercalated discs

24
Q

What do intercalated discs contain

A

Desmosomes - adhesion/binding in contraction
Gap junctions - communication, co-ordinated and rapid conduction

25
Q

Describe smooth muscle

A

Short, small, spindle shaped
Involuntary contraction
Non-striated (smooth) - but still have thin and thick filaments that attach to dense bodies
Single central nucleus
Located in the walls of hollow internal structures (blood vessels, intestines, skin)

26
Q

What are dense bodies made from

A

A major protein is actinin

27
Q

Name the three main functions of the nervous system

A

Sensory: detection of internal and external stimuli and transfer to CNS

Integrative: analysis and storing of information

Motor: stimulation of effectors (e.g. muscle and glands) through PNS i.e. motor here means “effector”

28
Q

What are the two types of cells in the nervous system

A

Neurons
Neuroglia

29
Q

What are neurons

A

Have a cell body
Have branched dendrites
Have axons
Longest cells in the body (up to 1m - spinal cord to toe)

Functions;:
Conscious and unconscious control

For our purposes:
Do not divide
High metabolic rate (die rapidly without O2)

30
Q

What are dendrites

A

They receive/input nerve impulses (action potentials) into the cell body

31
Q

What are axons

A

Outer portion of neutron
Carries the nerve impulse away from the neuron

32
Q

Name the four types of neurons

A

Unipolar
Bipolar
Multipolar
Anaxonic

33
Q

Describe multipolar neurons

A

Have 2 or more dendrites
Single axon
Most common neurons in CNS
All motor neurons are multipolar
Some of the longest (spinal chord to toe muscles)

34
Q

Describe Bipolar neurons

A

1 dendritic process (can branch at tip but not at cell body)
1 axon
Has cell body between axon and dendrite
Rare and small
Location: Special sense organs (sight, smell, hearing) relay information from receptor to neurons

35
Q

Describe unipolar neurons

A

The dendrites and axon are continuous
Cell body off to one side
Whole part from where dendrites converge (come together into 1) is called the axon
Most sensory nerves are unipolar
Very long (1m) like motor nerves CNS-toe tip.

36
Q

Describe anaxonic neuron

A

Rare and function poorly understood
Anatomy cannot distinguish dendrites from axons Found in brain and special sense organs

37
Q

Describe neuroglia

A

Smaller than neurons but more numerous
Found in both CNS and PNS
Make up ~50% the volume of the CNS (“glue”).

Do not propagate action potentials, but can communicate.
Can divide within the mature nervous system

Functions:
Physical structure of nervous tissue
Repair framework of nervous tissue
Undertake phagocytosis
Nutrient supply to Neurons
Regulate interstitial fluid in neural tissue.

38
Q

What are astrocytes

A

Star-shaped; largest; most numerous of neuroglia.

Syncytium network.

Support (have microfilaments) and repair (scar).

Communicate with neurons via ‘gliotransmitters’ e.g. glutamate

Maintain environment around neuron e.g. by regulating ions.

Maintain blood-brain barrier via endothelium.

Wrap around vessels and influence their permeability

39
Q

What are oligodendrocytes

A

Form insulating multilayered myelin sheath (protein lipid layer) around CNS axons.

Can myelinate more than one neuron cell’s axon.
Accelerate the action potential.

40
Q

What are microglia

A

They are phagocytic (resident
macrophages) - protection
Can be inactive or active

41
Q

What are Ependymal cells

A

Produce cerebrospinal fluid (CSF).
Line the Cerebrospinal Fluid (CSF)-filled ventricles in the brain and the central canal of the spinal cord.
These single layer of predominantly cuboidal cells have cilia (flow) and microvilli (sampling).
Located in ventricles and in other locations where CSF found.
CSF mechanical buffer; moves nutrients and waste

42
Q

What are the two different types of neuroglia

A

CNS neuroglia
PNS neuroglia

43
Q

Name the CNS neuroglia

A

Astrocytes
Oligodendrocytes
Microglia
Ependymal cells

44
Q

Name the PNS neuroglia

A

Schwann cells
Satellite cells

45
Q

Describe schwann cells

A

“PNS version of CNS oligodendrocyte”
Form insulating myelin sheath around axons or can just support and surround several non-myelinated axons.
(Note: One Schwann cell per axon for myelination but more axons/cell if just support).

46
Q

Describe the Satellite cells

A

They surround neuron cell bodies.
Support and fluid exchange
(equiv. to astrocytes in CNS).

47
Q

What are the axon terminals

A

The branch like things that come out of axons

48
Q

What are dendritic branches

A

The things that come together to form a dendrite

BIOSCI 107 (10 decks)

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