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Principles > Diversity of Cells and Their Function > Flashcards

Diversity of Cells and Their Function Flashcards

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1
Q

How is tissue preserved in as life-like a state as possible?

A

It is often “fixed”. usually this uses a chemical that cross-links proteins, such as formalin.

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2
Q

How do you impregnate the tissue with a support material and then investigate the tissue?

A

The tissue is dehydrated, put into organic solvent and placed in hot wax until it has fully penetrated the tissue.
Thin sections are cut on a microtome and put onto microscopic slides, the wax is washed out and the tissue rehydrated.

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3
Q

What substance is usually used as a support material?

A

wax

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4
Q

What happens when a tissue filled with support material is then rehydrated?

A

This produces distortions/changes from the original tissue and we term these artifacts (e.g. shrinkage)

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5
Q

What do the stains do when they are exposed to tissues?

A

They deferentially bind to particular types of moleculee.

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6
Q

What is the most common combination of stains used on tissues?

A

Haematoxylin and Eosin. often abbreviated to H&E

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7
Q

What is the role of haematoxylin?

A

This is a basic dye that has an affinity for acidic molecules and stains them purplish blue - e.g. the nucleus (remember what the A stands for in DNA) or ribosomes.

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8
Q

What is the role of Eosin?

A

This is an acidic dye that has an affinity for basic molecules and stains them pinkish red. Most proteins in the cytoplasm are basic and so the cytoplasm of a cell is usually stained pink or red.

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9
Q

What can be a problem with interpretation?

A

Remember when looking at sections that you are essentially seeing a slice of a 3D object in 2D.
E.g. a simple bent tube can produce all of these shapes when sliced thinly.

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10
Q

What are the 4 basic tissue types?

A 
Epithelium
Connective Tisue
Muscle
Nervous Tissue
Nearly all tissues and organs are made up of combinations of these 4 types.
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11
Q

What is the singular term for epithelium?

A

Epithelia

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12
Q

What is the role of epithelia?

A

They cover surfaces of the body or line hollow organs, and also form many glands.

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13
Q

How do epithelia occur?

A

THey occur as sheets of cells and vary widely in size, shape, orientation and function.

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14
Q

What is the role in connective tissue?

A

Connective tissue forms the framework of the body, but beyond that it has a dynamic role in the development, growth and homeostasis of tissue, and, via fat, in energy storage.

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15
Q

How do muscle cells create force?

A

They are specialized to generate force by contracting.

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16
Q

What does nervous tissue consist of?

A

It consists of neurons ad their supporting cells.

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17
Q

What is the role of nervous tissue?

A

Nervous tissue serves a control function and allows for rapid communication between different parts of the body.

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18
Q

Where are epithelia found?

A

They are found in a wide range of cell sizes and arrangements.
Epithelia can also form solid organs and glands e.g. the liver.
Surface epithelia cover or line surfaces, cavities and tubes e.g. the lining of the gall bladder.

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19
Q

What are the common features of epithelia?

A

Adhesion between epithelial cells is strong, thus forming sheet of cells, with a minimum of intercellular space. They are therefore perfect to cover surfaces and line body cavities.
All have, at their basal surface, a layer of extracellular matrix components, called a basal lamina (basement membrane), to which the cells are attached.
All are non-vascular. Nutrients from capillaries in underlying tissue must diffuse across the basal lamina.
The cells are usually polarized, that is the apical and basal ends of the cell differ.

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20
Q

Functions of epithelia

A

Mechanical barrier e.g. skin
Chemical barrier e.g.lining of stomach
Absorption e,g, lining of the intestine
Secretion e.g. salivary gland
Containment e.g. lining of urinary bladder
Locomotion (by cilia) e.g. oviduct
Minor functions include: sensation (neuroepithelium,e.g. taste buds) and contractility (myoepithelial cells)

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21
Q

What are the cell shapes of covering epithelia?

A

Squamous (flattened, like a fish scale)
Cuboidal (cube shaped)
Columnar (like a column, relatively tall and thin)

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22
Q

What are the number of layers that covering epithelia can have?

A 
"Simple" = One layer
"Stratified" = two or more layers
"Pseudostratified" = tissue appears to have multiple layers, but in fact all cells are in contact with the basal lamina.
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23
Q

What are the cell surface or tissue surface, specializations of covering epithelia?

A

Prominent microvilli (termed a “brush border”) (microfilaments in their core)
Cilia (core of microtubules)
Presence of layers of keratin proteins on the tissue surface (termed keratinized).

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24
Q

What specialized cell types are preset in covering epithelia?

A

goblet Cells (singe cell mucous glands)

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25
Q

What is the role of glandular epithelia?

A

They produce secretory products e.g. sweat, milk, hormones

26
Q

Where is the product secreted from in glandular epithelia?

A

Endocrine glands

Exocrine glands

27
Q

What is the role of endocrine glands in the glandular epithelia?

A

They secrete products towards the basal end of the cell (end sitting on basal lamina), then distributed by the vascular system throughout the body. Termed “ductless” glands although they have lots of capillaries.

28
Q

What is the role of exocrine glands in glandular epithelia?

A

They secrete product toward the apical end of the cell either into the lumen of an internal space, into a duct, or onto the body surface. Termed “ducted” glands

29
Q

What catagories is connective tissue subdivided into?

A

Soft connective tissue: Tendons, ligaments, mesentery, stroma of organs, dermis of the skin, etc.
Hard Connective tissue: Bone and cartilage
Blood and lymph: many authors consider blood and lymph as a specialized form of connective tissue.

30
Q

What does connective tissue consist of?

A

Extracellular matrix
Cells
The type of connective tissue is determined by the types and relative amounts of these two components

31
Q

What does the extracellular matrix in connective tissue consist of?

A

It consists of:
Fibres: colagen, reticular and elastic fibres
Ground substance: anamorphous, space occupying material made of huge unbranched polysaccharide molecules called glycosaminoglycans (GAGs), most of which are bound to proteins cores to form glycoproteins.
Tissue fluid

32
Q

What type of cells are present in the extracellular matrix?

A

Fibroblasts: widely distributed cells that produce and maintain the extracellular matrix.
Adipose cells: fat cells, found scattered in many connective tissues , but predominant cell in adipose tissue (fat)
Osteocytes: cells of bone
Chondrocytes: cells of cartilage

33
Q

What are the types of soft connective tissue?

A

Loose soft connective tissue

Dense soft connective tissue

34
Q

What is loose soft connective tissue composed of?

A

Loosely packed fibres separated by abundant ground substance. Cells are relatively plentiful.

35
Q

What is dense connective tissue composed of?

A

Densely packed bundles of collagen fibers. Can be dense regular CT if the fibers are aligned (e.g. tendon) or dense irregular CT if the fibre bundles run in many directions (e.g. dermis of the skin.

36
Q

What are the features of the hard connective tissue Cartilage?

A

strong, flexible, compressible, semi-rigid tissue.

Cartilage is avascular and receives nutrients from adjacent tissues by diffusion through its matrix.

37
Q

What causes the semi-rigid nature of the matrix in cartilage?

A

This comes from the highlyhydrated nature of teh ground substance (GAGs and proteoglycans)

38
Q

What are the three types of cartilage?

A

Hyaline, the most common
Elastic
Fibrocartilage.

39
Q

How is the type of cartilage defined?

A

By the extracellular matrix

40
Q

What are some of the places that Hyaline is found?

A

Articular surfaces
Trachea; rings
Costal cartilage
Epiphyseal growth plates

41
Q

What are the two types of bone that can be recognised through a long bone (limb bone) and how can they be recognised?

A

With the naked eye, 2 types of bone can be recognized.
An outer shell of dense cortical bone maes up the shaft (diaphysis)
Cancellous or trabecular bone occupies the ends of the bone (the epiphyses). Cancellous bone is a fine meshwork of bone that looks a bit like the inside of an Aero bar.

42
Q

Does bone remain the same throughput a person’s life?

A

Bone undergoes remodeling throughout life.

43
Q

How can you tell that bone is a living tissue?

A

Bone is penetrated by small canals (haversian canals) for blood vessels and nerves
It contains living cells called osteocytes.

44
Q

How are muscle cells highly specialized for the production of contractile force?

A

All cells contain some contractile fibres in their cytoskeleton, but in muscle cells the cytoplasm is packed with these fibres and the cells are highly specialised.

45
Q

How is force produced in muscle cells?

A

Force is produced by the movement of actin fibres over myosin fibres, with the aid of a number of accessory proteins.

46
Q

what are the types of muscle tissue?

A

smooth
Skeletal
cardiac

47
Q

What are other names for smooth muscle and why are those names and the name smooth muscle used?

A

It is also known as involuntary muscle (because it is not under conscious control) and Visceral muscle (because it is predominantly found in organs).
It is called smooth because it has no visible striations.

48
Q

What are indicators of smooth muscle?

A

The individual fibres are elongated, spindle-shaped cells with great range in length (20-200µm).
A cigar-shaped nucleus lies near the center of each fibre.

49
Q

Where would you find skeletal muscle?

A

It constitutes the muscles of the body that respond to conscious control.

50
Q

What are other names for skeletal muscle and why are none of these names entirely accurate?

A

Skeletal muscle can also be known as voluntary or striated muscle.
Some skeletal muscles are not always under the control of will and all striated muscles are not skeletal, e.g. cardiac.

51
Q

What are indicators of skeletal muscle?

A

The typical skeletal muscle fibre is a giant multinucleated, cylindrical cell. The fibres may attain considerable lengths (1 to 40 mm), with a diameter ranging from 10 to 100 µm.
Each fibre has many nuclei that are elongated and located at the periphery of the cell, just internal to the cell membrane, which in muscle cells is called sarcolemma.

52
Q

Where would you find cardiac muscle?

A

It forms the major part of teh walls of the heart chambers and origins of the great vessels.

53
Q

What are indications that the muscle is cardiac?

A

Like skeletal muscle, cardiac muscle has striations, however they are less prominent.
The fibres are much shorter than striated muscle (50-100µm) and branch to form a complex network.
Cardiac muscle cells have a single nucleus located near the centre of the fibre.
Intercalated discs, can be seen passing across the fibres at irregular intervals. These are the sites of end-to-end attachments between adjacent cells. Not surprisingly these contain multipe intercellular junctions to maintain mechanical integrity.

54
Q

what are indicators of nervous tissue?

A

It consists of neurons and support cells (glia).
Glia outnumber neurons by about 10:1 in the central nervous system.
Surrounded by connective tissue “coat” (Meninges for central nervous system (CNS) and Epineurium for peripheral nervous system (PNS))

55
Q

Neurons are very diverse but most fall into three types, what are these?

A

Multipolar is the most common.
Bipolar
Pseudounipolar.

56
Q

What are indicators of a multipolar neuron?

A

They have many dendrites and one axon

57
Q

What are indicators of a bipolar neuron?

A

They have one dendrite and one axon.

58
Q

What are indicators of a pseudounipolar neuron?

A

They have short processes which gives rise to an axon i both directions.

59
Q

What are the principle Glia of the CNS?

A

Astrocytes: support, ion transport induce blood brain barrier.
Oligodenrocytes: produce myelin in the brain and spinal cord.
Microglia: provide immune surveillance

60
Q

What are the principle glia of the PNS?

A

Schwann cells:produce myelin and support axons

Principles (57 decks)

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