Chapter 4: Tissue Level Of Organization: Tissues And Homeostsis Flashcards

1
Q

What are cell junctions?

A

Contain points between the plasma membranes of tissue cells.. Tightly packed into functional units

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2
Q

What are the 5 most important types of cell junctions?

A

Tight junctions, adherens junctions, desmosomes, hemidesmosomes, and gap junctions

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3
Q

What are tight junctions?

A

Weblike strands of transmembrane proteins that fuse to the outer surfaces of adjacent plasma membranes to seal off passageways between adjacent cells. E.g., cells of epithelial tissue that lines the stomach, intestines, and urinary bladder. Inhibit the passage of substances between cells.. prevents contents from these organs from leaking into blood and surrounding tissues

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4
Q

What are adherens junctions?

A

Dense layer of proteins on the inside of the plasma membrane that attaches to both the membrane proteins and the microfilaments of the cytoskeleton.The transmembrane proteins are called CADHERINS and join the cells. Form adhesion belts in epithelial cells. Helps epithelial surfaces resist separation during contractile activities like food moving through intestines

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5
Q

What are desmosomes?

A

Contains plaque and have transmembrane glycoproteins that extend into intercellular space between adjacent cell membranes and attach cells to one another (similar to adherens). But unlike adherens junctions, the plaque of desmosomes doesn’t attach to microfilaments but rather attaches to elements of the cytoskeleton called INTERMEDIATE FILAMENTS (consists of the protein keratin). Contributes to stability of cells and tissues. Common in cells that make up the epidermis and cardiac muscle cells. Prevents epidermal cells from separating under tension and cardiac muscle cells from pulling apart during contraction.

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6
Q

What are hemidesmosomes?

A

Resembles desmosomes but don’t link adjacent cells. Transmembrane glycoproteins are integrins rather than cadherins. On the inside of the plasma membrane, integrins attach to intermediate filaments (made of keratin). On the outside of plasma membrane they attach to the protein LAMININ which is in the basement membrane. Therefore, anchors cells to the basement membrane.

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7
Q

What are gap junctions?

A

Membrane proteins called CONNEXINS form tiny fluid-filled tunnels called CONNESNS that connect neighbouring cells. The plasma membranes of gap junctions are not fused together as in tight junctions but are separated by a narrow intercellular gap. Through the connexons, ions and SMALL molecules can diffuse from the cytosol of one cell to another. Transfer of nutrients and perhaps wastes in avascular tissues like the lens and cornea of the eye. Allows the cells in a tissue to communicate with one another. Enables nerve, muscle, and impulses to spread rapidly among cells.

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8
Q

What are the 3 differences between epithelial and connective tissue?

A

1) Epithelial cells have many cells tightly packed together so has little to no EC matrix. Connective tissue has a lot of EC matrix that separates cells. 2) Epithelial cells have no blood vessels and connective tissue does. 3) Epithelial cells almost always form surface layers and not covered by other tissue (except the epi lining of blood vessels)

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9
Q

Why are epithelial tissue located right next to connective tissue?

A

Since epi tissue lacks blood vessels and forms surfaces, it needs to be adjacent to blood vessel-rich connective tissue because it enables it to make exchanges with blood necessary to deliver O2 and nutrients and remove waste

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10
Q

What are the 3 main functions of epithelial tissues?

A

1) Selective barrier, 2) Secretory surface (releases products produced by cells onto its free surfaces), and 3) Protective surface

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11
Q

What is the apical, lateral and basal surface?

A

Apical is the most superficial epithelial layer. Faces the body surface, body cavity, lumen (interior space) of an internal organ, or tubular duct. Lateral surface faces the adjacent cells on either side. Basal surface is the deepest layer of cells. Adheres to EC materials like the basement membrane (so hemidesmosomes anchor epi to basement membrane)

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12
Q

What are the 2 layers of the basement membrane?

A

1) Basal lamina: Closer to epithelial cells. Contains proteins like laminin, collagen, glycoproteins, and proteoglycans… adheres to integrins in hemidesmosomes and therefore attaches epi cells to basement membrane. 2) Reticular lamina: Closer to the underlying connective tissue. Contains proteins and collagen produced by connective tissue cells called friboblasts.

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13
Q

What are some functions of the basement membrane?

A

1) Form a surface that epi cells migrate during growth/wound healing. 2) Restricts passage of large molecules between epithelium and connective tissue. 3) Participates in filtration of blood in kidneys

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14
Q

What are 2 types of epithelial tissue?

A

1) Covering and lining epithelium (outer surface of skin and some organs. Inner lining of blood vessels, ducts, body cavities, respiratory system, digestive system, urinary system, repro system). 2) Glandular epithelium (Secreting portion of glands… like thyroid, adrenal sweat glands).

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15
Q

Types f covering and lining epithelial tissue is classified according to these 2 characteristics:

A

1) Arrangement of cells in layers and 2) Cell shapes

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16
Q

What is simple epithelium?

A

Single layer of cells that function in absorption, secretion, diffusion, osmosis and filatration.

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17
Q

What is pseudostratified epithelium?

A

Multi layers of cells. Simple epithelium because all its cells rest on basement membrane. Cells that extend to apical surface may contain cilia… others (goblet cells) secrete mucus

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18
Q

What is stratified epithelium?

A

2 or more layers of cells that protect underlying tissues where there’s considerable wear and tear.

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19
Q

What are the 4 shapes of cells?

A

Squamous, cuboidal, columnar, and transitional.

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20
Q

What are squamous cells?

A

Thin so allows rapid passage of substances

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21
Q

What are cuboidal cells?

A

Tall and wide. Shaped like cubes and hexagons. Many have microvilli at their apical surface and function in secretion/absorption.

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22
Q

What are columnar cells?

A

Taller than they are wide… protects underlying tissue. Their apical surfaces may have cilia or microvilli. Often specialized for secretion and abosorption.

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23
Q

What are transitional cells?

A

Change shape. Like in organs that stretch like the urinary bladder (stretches to a larger size and then collapses to a smaller size).

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24
Q

Name different types of simple epithelium

A

Simple squamous epithelium, simple cuboidal epithelium, simple columnar epithelium (non ciliated and ciliated), and pseudostratified columnar epithelium (non ciliated and ciliated).

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25
Q

What are the types of stratified epithelium?

A

Stratified squamous epithelium (keratinized when surface cells are dead and hardened, non keratinized when surface cells remain alive), stratified cuboidal epithelium, stratified columnar epithelium, and transitional epithelium.

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26
Q

What is the function of glandular epithelium?

A

Secretion. A gland may consist of a single cell or group of cells that secrete substances into ducts, a surface or into the blood

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27
Q

What are the two types of glands?

A

Endocrine and exocrine

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28
Q

Two types of exocrine glands?

A

Unicellular and multicellular

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29
Q

What are unicellular glands?

A

Single cell exocrine glands. Goblet cells are important unicellular exocrine glands that secrete mucus directly onto the apical surface of a lining epithelium

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30
Q

What are multicellular glands? Examples?

A

Most exocrine glands. Composed of many cells. Examples include sudoriferous (sweat), sebaceous (oil) and salivary glands

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31
Q

What 2 criteria are multicellular glands based on?

A

1) Whether their ducts are branched or unbranched and 2) The shape of the secretory portions of the gland

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32
Q

What is a simple gland?

A

Duct not branched

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33
Q

What is a compound glad?

A

Duct branched

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34
Q

What is a tubular gland?

A

Glands with tubular secretory parts

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35
Q

What are acinar glands?

A

Glands with rounded secretory portions

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36
Q

WHat are tubuloacinar glands?

A

Glands with both tubular and rounded secretory parts.

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37
Q

Types of simple glands and examples of each

A

Simple tubular (ie glands in large intenside), simple branched tubular (ie gastric glands), simple coiled tubular (ie sweat glands), simple acinar glands (ie glands of penile urethra), simple branched acinar (ie sebaceous glands)

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38
Q

Types of compound glands and examples of each

A

Compound tubular (ie bulbourethral (Cowper’s) glands), compound acinar (ie mammary glands), and compound tubuloacinar (ie acinar glands in pancreas)

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39
Q

What are merocrine glands? Examples

A

Releases secretions from cell in secretory vesicles via exocytosis (ie salivary and pancreas). Most exocrine glands

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40
Q

What are apocrine glands? Example

A

Accumulate thier secretory product at the apical surface of the secreting cell. Then that portion of the cell pinches off by exocytosis from the rest of the cell to release the secretion (ie milk fats from mammary glands)

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41
Q

What are holocrine glands? Example

A

Accumulate secretory product in their cytosol. As the secretory cell matures, it ruptures and becomes the secretory product… secretions contain lots of lipids from plasma membrane and intracellular membranes. (Ie subaceous gland of the skin)

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42
Q

What are the many functions of connective tissues?

A

Binds together, supports and strengthens body tissues; protects and insulates internal organs; compartmentalizes structures like skeletal muscles; serves as major transport system within body (ie blood), primary location of stored energy reserves (ie adipose tissue) and main source of immune responses

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43
Q

What are the 2 things that the EC matrix consists of?

A

Fibres and ground substance. EC fibres are secreted by connected tissue cells and account for many of the functional properties of tissue and in controlling the surrounding watery environment via specific proteoglycan molecules.

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44
Q

What cells give rise to connective tissue?

A

Mesenchymal cells (embryonic cells)

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45
Q

What are immature cells called and name some examples?

A

-blasts. Fibroblasts (lose and dense connective tissue), chondroblasts in cartilage and osetoblasts in bone. Blast cells maintain capacity to divide and secret the EC matrix.

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46
Q

What are mature connective tissue cells called?

A

-cyte. Fibrocytes, chondrocytes, and osetocytes. They are involved in monitorying and maintaining the EC matrix

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47
Q

What are fibroblasts?

A

Large,flat, branching processes, numerous. Migrate through connective tissue secreting fribers and certain components of the ground substance of EC matrix

48
Q

What are macrophages ?

A

Develop from monocytes (type of WBC). Can engulf bacteria and cell debris via phagocytosis. Two types: Fixed (resides in a particular tissue) and wandering (can move throughout the tissue and gather at sites of infection/inflammation).

49
Q

What are plasma cells?

A

Develop from B lymphocytes. Secrete antibodies. Reside in connective tissue especially the GI and resp tracts. Also abundant in salivary glands, lymph nodes, spleen and red bone marrow

50
Q

What are mast cells?

A

Abundant alongside blood vessels that supply connective tissue. Produces histamine (a chemical that dilates small blood vessels as part of the inflammatory response), can also bind to, ingest and kill bacteria.

51
Q

What are adipocytes?

A

Adipose cells. Connective tissue cells that store triglycerides (fats). Found deep in skin and around the heart and kidneys

52
Q

What are leukocytes?

A

Not found in significant numbers in connective tissue. But can migrate from blood into connective tissue in response to certain conditions. Ie neutrophils and eosinophils

53
Q

What are the 2 components of the EC matrix?

A

1) ground substance 2) Fibres

54
Q

What is the ground substance of EX matrix?

A

Between cells and fibres. Can be fluid, semifluid, gelatinous or calcified. Supports cells, binds them together, stores water, provides a medium for exchange of substances between blood and cells . Plays an active role in how tissues develop, migrate, proliferate, and change shape and how they carry out metabolic functions.

55
Q

What are glycsaminoglycans (GAGs)?

A

Found in the ground substance. It is made up of a complex array of polysaccharides including hyaluronic acid, chondroitin sulfate, dermatin sulfate, and keratin. Except for hyaluronic acid, the GAGs are associated with proteins called proteoglycans (GAGs project from the proteins like brustles). GAGs trap water making the ground substance more jelly like

56
Q

What is hyaluronic acid?

A

Viscous slippery substance tat binds cells together, lubricates joints and helps maintain the shape of eyeballs.

57
Q

What is hyaluronidase?

A

WBCs and sperm cells and some bacteria produce it. It is an enzyme that breaks apart hyaluronic acid so causing ground substance of connective tissue to become more liquid. The enzyme helps WBCs move more easily throuh connective tissue to reach sites of infection and aids penetration of oocyte by sperm.

58
Q

What is chondroitan sulfate?

A

Present in ground substance. Provides support and adhesiveness in cartilage, bone, skin, and blood vessels.

59
Q

What is dermatin sulfate?

A

Present in ground substance. Occurs in skin, tendons, blood vessels and heart valves

60
Q

What is keratin sulfate?

A

Occurs in bone, cartilage, and cornea of eye

61
Q

What is adhesion proteins?

A

Links components of ground substance to one another and surface of cells. Present in ground substance

62
Q

What is fribronectin?

A

Binds to collagen fibres and ground substance, linking them together. Main adhesion protein in connective tissue. Present in ground substance too.

63
Q

What are the 3 types of fibres in the EC matrix?

A

Collagen fibres, elastic fibres and reticular fibres.

64
Q

What are collagen fibres?

A

Strong and resist pulling forces (tension), not stiff which allows tissue flexibility. Cosists of the protein collagen (most abundant protein in the body). Found in most types of connective tissue especially bone, cartilage, tendons (attaches muscle to bone) and ligaments (attaches bone to bone).

65
Q

What are elastic fibres?

A

Smaller than collagen. Branch and join together to form a fibrous network within connective tissue. Consists of the protein elastin surrounded by a glycoprotein fibrillin. Strong but can be stretched up to 150% of their relaxed length without breaking. Has elasticity (can return to original shape after stretching). In skin, blood vessel walls and lung tissue

66
Q

What are reticular fibres?

A

Collagen fibres arranged in bundles with a coating of glycoprotein. Provides support in the walls of blood vessels. Forms a network around the cells in some small tissues like areolar connective tissue (small space), adipose tissue, nerve fibres and smooth muscle tissue. Provides support and strength. Plentiful in reticular connective tissue which forms the stroma (supporting framework) of many soft organs (spleen and lymph nodes)

67
Q

What is loose connective tissue?

A

Fibres of loose connective tissue are loosely arranged between cells. Includes areolar connective tissue, adipose tissue and reticular connective tissue

68
Q

What is dense connective tissue?

A

Contains more fibres which are thicker and more densely packed but have fewer cells than loose connective tissue. 3 types.

69
Q

What is cartilage?

A

Dense network of collagen fibres and elastic fibres firmly embedded in chondroitin sulfate ( a gel-like component of the ground substance). Can endure lots more stress than loose and dense connective tissue. Resilient due to chondroitin sulfate (ability to assume original shape after deformation). Few cells and lots of EC matrix. No nerves or blood vessels in EC matrix. Chondrocytes occur within spaces called lacunae. Perchondrium surrounds the surface of most cartilage and contains blood vessels and nerves and is the source of new cartilage cells. Cartilage heals poorly because no blood supply. Precursor to bone, forms most embryonic skeleton.

70
Q

What is antiangiogenesis factor?

A

A substance that prevents the growth of blood vessels… this is why cartilage doesn’t have blood vessels because it secretes the antiangiogenesis factor

71
Q

What are the 3 types of cartilage?

A

Hyaline, fibrocartilage and elastic cartilage

72
Q

What is perichondrium?

A

A covering of dense irregular connective tissue on the surface of cartilage

73
Q

What is interstitial growth?

A

Growht from within tissue. Division of existing chondrocytes and continuous deposition of increasing amounts of ECM by the chondrocytes. As the chondrocytes synthesize new matrix they are pushed away from eachother and cartilage expands from within.

74
Q

What is appositional growth?

A

Growth at outer surface of tissue. Cells in inner cellular layer of the perichondrium differentiate into chondroblasts. Chondroblasts then surround themselves with ECM and become chondrocytes. Therefore the matrix accumulates beneath the perichondrium on the outer surface of the cartilage causing it to grow in width.

75
Q

What is bone tissue?

A

Cartilage, bones and joints make up the skeletal system (which supports soft tissues, protects delicate strcutures and works with skeletal muscles to generate movement). Bones store Ca, P, red bone marrow, produces blood cells, contains yellow bone marrow and stores triglycerides.

76
Q

What connective tissues make up bone?

A

Bone (osseous tissue), the periosteum, red and yellow bone marrow, and the endosteum (a membrane that lines with space within bone that stores yellow bone marrow).

77
Q

What is the basic unit of COMPACT BONE?

A

Osteon

78
Q

What are the 4 parts of each osteon in bone?

A
  1. Lamellae 2. Lacunae 3. Canaliculi, and 4. Central canal
79
Q

What is lamellae in bone?

A

Rings of ECM consisting of mineral salts (calcium and phophates( which give bone its hardness and compressive strength, and collagen fibres which give bone its tensile strength)

80
Q

What is lacunae in bone?

A

Small spaces between lamellae that contain osteocytes

81
Q

What is canaliculi in bone?

A

Project from lacunae. Networks of minute canals containing the processes of osteocytes. Provides routes for nutrients to reach osteocytes and wastes to leave

82
Q

What is the central canal in bone?

A

Contains blood vessels and nerves

83
Q

What is spongy bone?

A

Lacks osteons. Consists of thin columns of bone called trabeculae, which contains lamellae, osteocytes, lacanuae, and canaliculi. Space between trabeculae are filled with red bone marrow

84
Q

What are 2 types of liquid connective tissue?

A

Blood and lymph

85
Q

What is lymph?

A

ECM that flows in lyphatic vessels. Consists of several types of cells in a clear liquid ECM that’s similar to blood plasma but with less protein.

85
Q

What are membranes?

A

Flat sheets of pliable tissue that cover / line part of the body

86
Q

What are epithelial membranes? What are the main epi membranes?

A

Consist of an epithelial layer with an underlying connective tissue layer. Mucous membrane, serous membrane and cutaneous membrane

87
Q

What are mucous membranes?

A

Lines a body cavity that opens directly to the exterior. Examples: Digestive, respiratory and reproductive tracts. Consists of a lining layer of epithelium (which acts as a barrier to microbes and pathogens… tight junctions) and an underlying layer of connective tissue.

88
Q

What is the Lamina Propria?

A

Connective tissue layer of the mucous membrane that is areolar connective tissue. Supports epithelium, binds it to underlying structures, allows some flexibility of membrane, protects underlying structures, holds blood vessels in place, and is the vascular source for underlying epithelium. O2 and nutrients diffuse from the lamina propria to covering epithelium… CO2 and waste diffuse in other direction

89
Q

What is serous membrane? And what are its 2 layers?

A

Lines the body cavities tht don’t directly open to exterior (ie thoracic and abdominal cavities). Covers organs within the cavity. Areolar connective tissue covered by a MESOTHELIUM (simple squamous epithelium) which secretes serous fluid to lubricate organs so they can glide over one another). Has 2 layers: Parietal (attached to and lines the cavity wall) and visceral (covers and adheres to the organs within a cavity)

90
Q

What are cutaneous membranes? What are the 2 parts?

A

Aka skin. Covers the entire surface of the body. Consists of 2 parts: Epidermis and dermis.

91
Q

What does the epidermis consist of?

A

Keratinized stratified squamous epithelium.

92
Q

What does the dermis consist of?

A

Dense irregular connective tissue and arleolar connective tissue

93
Q

What are synovial membranes?

A

Lines cavities of freely movable joints (JOINT CAVITIES).Lines structures that don’t open to exterior (similar to serous). But unlike mucous, serous and cutaneous membranes, they lack epithelium and therefore are NOT epithelial membranes.

94
Q

What are synovial membranes composed of?

A

Synoviocytes which secrete some components of synovial fluid. Synovial fluid lubricates and nourishes the cartilage covering the bones at movable joints… contains machrophages that remove microbes and debris from joint cavity

95
Q

What is muscular tissue?

A

Has elongated cells called muscle fibres (or MYOCYTES) that can use ATP to generate force. Therefore, produces body movements, generates heat, maintains posture and provides protection.

96
Q

What are the 3 types of muscle tissue?

A

Skeletal, cardiac and smooth

97
Q

What are the 2 main cell types in nervous tissue?

A

Neurons and nerolgia

98
Q

What are neurons?

A

Neurons are sensitive to stimuli. They convert stimuli into electrical signals called nerve action potentials (nerve impulses) and conduct these action potentials to other neurons, muscle tissues or glands.

99
Q

What are the 3 parts of neurons?

A

Cell body (contains nucleus and other organells), dendrites (highly branched short cell processes/extensions that is the receiving or input portion of a neuron) and axons (single thin cylindrical process that may be very long. Output portion of a neuron. Conducts nerve impulses toward another neuron or tissue).

100
Q

What is the neuroglia?

A

Do not generate or conduct nerve impulses

101
Q

What is electrical excitability?

A

Neurons and muscle fibers exhibit it. It’s the ability to respond to certain stimuli by producing electrical signals (ie action potentials).

102
Q

What are action potentials?

A

Can travel along the plasma membrane of a neuron or muscle fibre due to the presence of specific voltage-gated ion channels. When action potential occurs in a muscle fibre the muscle fibre contracts

103
Q

What are neurotransmitters?

A

The chemical substance released when an action potential forms in a neuron. Allows neurons to communicate with other neurons, muscle fibres or glands

104
Q

What is the parenchyma?

A

Cells that makeup the functioning part of tissues and organs

105
Q

Epithelial cells have a continuous capacity for renewal. How?

A

Stem cells. They divide to replace damaged cells. The reside in protected locations in the epithelium of the skin and GI tract. Stem cells in red bone marrow continually provide new red and white blood cells and platelets.

Hepatocytes and endothelial cells in blood vessels are mature differentiated cells that undergo cell division

106
Q

What are satellite cells?

A

In skeletal muscle tissue. They do NOT divide rapidly enough to replace muscle fibres.

107
Q

Describe the renewal capacity of nervous tissue?

A

Has the poorest capacity for renewal. Stem cells in the brain normally don’t undergo mitosis to replace neurons

108
Q

What is needed for tissue regeneration?

A

Restoration of an injured tissue / organ depends if parenchymal cells are active in the repair processes. If parenchymal cells accomplish repair, tissue regeneration is possible.

109
Q

What if fibroblasts of the stroma are active in repair?

A

The replaced tissue will be connective tissue

110
Q

What is fibrosis?

A

Fibroblasts synthesize collagen and other ECM materials that aggregate to form scare tissue known as fibrosis… so the original function of organs and tissues is impaired

111
Q

How is extensive tissue damage like a large open wound repaired?

A

Both connective tissue stroma and parenchymal cells are active in repair. Fibroblasts divide rapidly (new collagen fibres provide structural strength), blood capillaries also sprout new buds to supply healing tissue… these processes of creating an actively growing connective tissue is called GRANUALTION TISSUE… forms across a wound or surgical incision to provide a framework (stroma) that supports the epithelial cells that migrate into an open area and fill it

112
Q

What’s wound dehiscence?

A

The partial / complete separation of the outer layers of sutured incision.

113
Q

What are the causes of wound dehiscence?

A

Sutures placed too far apart, removed too early deep wound infection, age, chemo, coughing, straining, vomiting, obesity, smoking, use of anticoagulants

114
Q

What 3 factors affect tissue repair?

A

Nutrition, blood circulation, age

115
Q

How does aging affect epithelial and connective tissues?

A

Epithelial tissues get progressively thinner and connective tissues become more fragile leading to an increased incidence of skin and mucous membrane disorders, wrinkles, susceptibility to bruises, increased of bone density, higher rates of bone fractures and more episodes of joint pain and disorders

116
Q

How does aging affect muscle tissue?

A

Loss of skeletal muscle mass and strength, decline in efficiency of the pumping of the heart, decreased activity of smooth muscle containing organs (organs of the GI tract)