Tissues Of The Body Flashcards

0
Q

What different types of glands are there?

A
  • Simple

- Compound

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1
Q

Describe the difference between endocrine and exocrine.

A
  • Exocrine: glands with ducts

- Endocrine: ‘ductless glands’ secrete directly into the bloodstream.

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2
Q

What different types of secretions are there?

A
  • Mucous: mucus rich in mucins

- Watery and free of mucus secretions

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3
Q

What is a visceral and parietal pleura?

A
  • Visceral (inner)

- Parietal (outer)

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4
Q

What are the 4 layers of the intestinal lining?

A
  • Mucosa
  • Submucosa
  • External muscular layers
  • Serosa
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5
Q

What layers does the mucosa consist of?

A
  • Muscularis mucosae
  • Lamina propria
  • Epithelium
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6
Q

What is the Submucosa?

A
  • Layer of connective tissue bearing glands, arteries, veins and nerves
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7
Q

How are luminal contents moved along the intestine?

A
  • 2 layers of smooth muscle form Muscularis externa which create a peristaltic wave
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8
Q

What is exocytosis also known as and what is it?

A
  • Merocrine secretion
  • Membrane bound component approaches cell surface
  • Fuses with plasma membrane
  • Contents are released into extracellular space.
  • Membrane reforms.
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9
Q

What is Apocrine secretion?

A
  • Non membrane bound structure moves to cell surface
  • Contact and pushes up apical membrane
  • Apical cytoplasm surrounds droplet
  • Membrane surrounding droplet pinches off
  • Membrane added to regain SA
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10
Q

What is holocrine secretion and where is it found?

A
  • Disintegration of cell
  • Release of contents
  • Discharge of whole cell
  • ONLY in sebaceous glands
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11
Q

What is transepithelial transport?

A
  • Endocytosis at one surface
  • Transport vesicle shuttles across cytoplasm
  • Exocytosis at opposite end.
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12
Q

What is the function if the Golgi apparatus?

A
  • Sorting into different compartments
  • Packaging via condensation of contents
  • Glycosylation (addition of sugars to proteins and lipids)
  • Transport
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13
Q

What happens to the products of the Golgi?

A
  • Majority to secretory vesicles
  • Retained in cells for use (lysosomes)
  • Transported to plasma membrane (Glycocalyx)
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14
Q

What is Glycocalyx?

A
  • Sweet husk, proteoglycans, glycoprotein and glycolipids
  • Protection of epithelial cells
  • Intracellular communication
  • Intracellular adhesion
  • Intracellular adhesion
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15
Q

What are the different types of secretion control?

A
  • Nervous (sympathetic stimulation of adrenal medullary cells for adrenaline)
  • Endocrine (stimulates cortex of adrenal gland to secrete hormones)
  • Neuro-endocrine (nervous cells stimulate hormone secretion)
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16
Q

Give 3 examples of exocrine secretion.

A
  • Unicellular gland in jejunum and colon
  • Parotid glands
  • Submandibular glands
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17
Q

Give 3 examples of endocrine secretion.

A
  • Pancreas
  • Thyroid
  • Adrenal (suprarenal)
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18
Q

Where in the body can mucous membranes be found?

A

Linings of internal tubes that have contact with the exterior environment, e.g respiratory tract

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19
Q

Where is a serous membrane and where is it found?

A
  • Thin, two part membranes which line closed bodily cavities to secrete a lubricating fluid, to allow friction free movement of structures they surround.
  • Peritoneum (abdominal organs)
  • Pleural sacs (lungs)
  • Pericardial sacs (heart)
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20
Q

What are serous membranes composed of?

A
  • Simple squamous epithelium, secretes watery lubricating fluid
  • Thin layer of connective tissue.
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21
Q

What are the different types of biopsies and where on the body are they use?

A
  • Smear: cervix, buccaneer cavity
  • Curettage: endometrial lining of the uterus
  • Needle: brain, breast, liver, kidney, muscle
  • Direct incision: skin, mouth, larynx
  • Endoscope: lungs,intestine,bladder
  • Transvascular: heart, liver
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22
Q

What are the 3 main types of stain and what do they stain?

A
  • Haematoxylin - acidic components (nucleus/chromatin) blue/purple
  • Eosin - basic (cytoplasmic proteins, extra cellular fibres) pink
  • Periodic Acid Schiff - (glycoproteins, carbohydrates) magenta
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23
Q

How does processing of a specimen lead to shrinkage artefacts?

A
  • Dehydration, rehydration and dehydration again
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24
Q

Why do tissues need repair?

A
  • Preserves cell structure

- Prevents autolysis and putrefaction

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25
Q

What is an epithelium?

A
  • Sheets of contiguous cells, varying in origin, that line the inner surfaces and cover outer surfaces.
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26
Q

Where is the basement membrane found and what is it’s function?

A
  • Between epithelial tissues and connective tissue

- Strong flexible layer for cellular adhesion and a molecular filter.

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27
Q

Where are pseudostratified cells found in the body?

A
  • Upper nasal cavity
  • Ear
  • Upper respiratory system
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28
Q

Where are simple squamous cells found and what’s their roles?

A
  • Blood vessels (active transport by pinocytosis)
  • Mesothelium (to secrete for lubrication)
  • Alveoli (gas exchange)
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29
Q

What are stratified squamous’ role and where are they found?

A
  • Prevent wear loss, UV damages, abrasion
  • Skin
  • Vagina
  • Anus
  • Oesophagus
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30
Q

Where are cuboidal cells found, what are their roles?

A
  • Ducts of exocrine glands
  • Kidney tubules
  • Absorption, hormone secretion.
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31
Q

Where are columnar cells found and what are their roles?

A
  • Small intestine & colon (absorption, secretion & lubrication)
  • Stomach lining & gastric glands (secretion)
  • Gall bladder (absorption)
  • Uterus
  • Oviduct (transport)
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32
Q

What are transitional epithelium?

A
  • Layers of cells that have the ability to change shape from cuboidal (relaxed) to squamous (tense)
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33
Q

Where are transitional epithelium found and its role?

A
  • Bladder, ureters.

- Distension and protection of underlying tissues

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34
Q

How long does it take for skin cells to ‘die’?

A
  • 28 days.
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35
Q

Where are keratinised stratified squamous cells found and their roles?

A
  • Skin surface
  • Linings of surfaces exposed to the exterior.
  • Protection against abrasion & physical trauma
  • Prevents water loss, ingress of microbes.
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36
Q

Where are stratified columnar found?

A
  • Conjunctiva of eye

- Lining some large excretory ducts.

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37
Q

Where are stratified cuboidal cells found?

A
  • Lining ducts of sweat glands.
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38
Q

Where does glycosylation of proteins occur?

A
  • Golgi apparatus
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39
Q

What is the process of glycosylation?

A
  • Addition of sugars to proteins and lipids.

- Glycocalyx formation (intercellular communication, adhesion to substrates, contact inhibition)

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40
Q

What are the 4 ways of controlling secretion?

A
  • Neural control (sympathetic stimulation of adrenal medullary cells)
  • Hormone control (ACTH promotes secretion of adrenal cortex hormones (cortisol)
  • Neuro-endocrine (hypothalamus controls ACTH production)
  • Negative feedback (inhibition of production)
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41
Q

What is the limit of resolution?

A
  • The minimum distance between two points that still allow them to be individually resolved.
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42
Q

Why are electron microscopes better at resolving than light microscopes?

A
  • Shorter wavelength, better resolution

resolution is proportional to wavelength

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43
Q

What is heterochromatin?

A
  • Dark in colour, dense & unexpressed
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44
Q

What is euchromatin?

A

Light in colour, less dense and expressed.

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45
Q

What is a nucleolus?

A
  • Contains RNA for ribosome synthesis and assembly.
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46
Q

What is the role of the Rough Endoplasmic reticulum?

A
  • Synthesise proteins
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47
Q

What is the role of the SER?

A
  • Biosynthesis of lipids
  • Steroid production
  • intracellular transport
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48
Q

What is the role of the Golgi with respect to proteins?

A
  • Modify, sort and package proteins from the RER
  • Movement from Cis to the Trans side.
  • Secretion in vesicles or formed into lysosomes.
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49
Q

What is the role of peroxisomes?

A
  • Detoxification (eg alcohols)

- Production and utilisation of H2O2

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50
Q

What subunits make up the cytoskeleton and what is its overall role?

A
  • Microtubules
  • Microfilaments
  • Intermediate filaments
  • Allow for transport of cellular constituents
  • Maintain the shape & structure of the cell
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51
Q

What components form connective tissue?

A
  • Cells
  • Ground substance
  • Fibres: collagen, reticular, elastic
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52
Q

What is the role of ground substance?

A
  • Resistant to impact due to jelly like composition.
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53
Q

What are the roles of the 4 different types of collagen?

A

1: Fibres/fibre bundles
2: Elastic cartilage
3: Reticulum (fibres around muscle and nerve cells)
4: Present in basal lamina

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54
Q

What is the definition of connective tissue?

A
  • Forms continuum throughout the body, provides metabolic and physiological support, links epithelium, nerves and muscles.
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55
Q

Elastic fibres contain what two components?

A
  • Elastin

- Fibrillin (surrounds enfolded elastic fibres)

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56
Q

What is the role of fibroblasts?

A
  • Synthesises and secretes fibres and ground substance.

Important in wound healing and cells responsible for scar tissue

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57
Q

What are macrophages and their role?

A
  • Phagocytic, degrade foreign organisms and cell debris

Effectively a phagocyte but in connective tissue

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58
Q

What is the role of mast cells?

A
  • Abundant in granules eg. anticoagulant

- Mediate hypertension and allergic reactions.

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59
Q

What is the function of the extracellular matrix?

A

A hydrating gel.

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60
Q

What is the difference between dense and loose connective tissue?

A
  • Dense: more fibres, less ground substance.

- Loose: fewer fibres, more ground substance.

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61
Q

What’s the difference between irregular and regular dense tissue?

A
  • Irregular, fibres run in all different directions, can resist force in all directions.
  • Regular, fibres all run in the same direction, very strong in the direction they run, tendons.
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62
Q

Cells from cartilage are known as?

A
  • Chondrocytes
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63
Q

The extracellular matrix of cartilage contains a high ratio of GAGs, what does this allow?

A
  • Diffusion between chondrocytes and blood vessels.
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64
Q

What is the role of Hyaline cartilage?

A
  • Precursors to bone development by endochondral ossification.
  • Present in articulating surfaces (connects ribs to sternum, parts of the respiratory tract)
  • Calcifies with age.
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65
Q

What is fibrocartilage?

A
  • Mix of chondrocytes and fibroblasts.
  • Combination of dense regulator connective tissue and hyaline cartilage.
  • No surrounding perichondrium
  • Sites: intervertebral discs, articular discs of joints, meniscus of knee joint and pubic symphysis.
  • Shock absorber, resists shearing forces
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66
Q

What is elastic cartilage and its role?

A
  • Many elastic fibres in ECM giving elasticity and resilience.
  • Doesn’t calcify with age.
  • Sites: External ear, epiglottis, Eustuchian tube.
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67
Q

When adults damage chondrocytes how is it repaired?

A
  • Can’t undergo mitosis of chondrocytes, so deposition of fibrous scar tissue fills the area.
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68
Q

What are the 4 main parts of the bone?

A
  • Spongey bone (deeper and porous, highly vasculated)
  • Compact bone (dense, hard, outer layer, Haversian and Volksmann canals)
  • Periosteum (tough, vasculated, surrounds bone)
  • ECM (Collegenous fibres in calcified matrix)
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69
Q

What is caniliculi?

A
  • Cytoplasmic process, connecting osteocytes that allow the sharing of nutrients.
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70
Q

Outline the bone remodelling system.

A
  • Osteoclasts, ‘cutting cone’ release of H+ and lysosomal enzymes
  • Osteoblasts, form new bone.
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71
Q

What are the 3 main macroscopic appearances of the skin and what are they effected by?

A
  • Colour: UV exposure, location, ethnicity
  • Hair: Site, sex, ethnicity, age
  • Laxity: Age, UV exposure.
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72
Q

What is Vitiligo?

A
  • Autoimmune depigmentation of the skin.
  • Tends to be symmetrical.
  • More obvious on dark people.
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73
Q

What is Alopecia?

A
  • Autoimmune reaction causing loss of hair.

- Greater psychological effect on women.

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74
Q

What are the 4 strata of the skin?

A
  • Horny (corneum)
  • Granular
  • Prickle
  • Basal
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75
Q

What happens in each of the stratum of the skin?

A
  • Basal: Keratinocyte mitosis
  • Prickle: Lose ability to differentiate, keratins synthesised.
  • Granular: Lose plasma membrane, differentiate into corneocytes, keratins and other fibrous proteins are aggregated.
  • Horny: Flattened corneocytes.
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76
Q

What are Langerhans cells?

A
  • Mediate an immune response, they’re antigen presenting cells.
  • Dendritic cells of bone marrow origin.
  • Scattered through prickle layer.
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77
Q

What are melanocytes and their role?

A
  • Occurs at intervals in the basal layer.

- Produce melanin (darker people have the SAME number of melanocytes just produce more)

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78
Q

What is produced from hair follicles and what for?

A
  • Sebum
  • Lubrication
  • Waterproofing
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79
Q

What are sweat glands primarily for?

A
  • Thermoregulation.
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80
Q

Name 3 characteristics of the dermis and its components.

A
  • Tough
  • Vascular
  • Fibrous

-ECM, blood vessels, nerves, lymphatics, mast cells.

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81
Q

What is the main effect of Psoriasis?

A
  • Major protein, fluids and heat loss.
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82
Q

What’s malignant melanoma?

A
  • Cancer of melanocytes

- Can’t cure once penetrated the basal membrane.

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83
Q

What are the main functions of the skin?

A
  • Barrier
  • Sensation
  • Thermoregulation
  • Psychosexual communication.
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84
Q

What are the 3 types of Cartilage?

A
  • Hyaline
  • Elastic
  • Fibrocartilage
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85
Q

What does GAG stand for in reference to cartilage and what is its role?

A
  • Glycosaminoglycans

- Allows diffusion between chondrocytes and blood vessels.

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86
Q

Give 3 characteristics of Hyaline cartilage.

A
  • Matrix with proteoglycans
  • Single/small clusters (isogenous groups)
  • Precursor model for bones, so found in early foetal development (development by endochondral ossification)
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87
Q

Where is Hyaline cartilage found?

A
  • Shoulder
  • Elbow
  • Wrist
  • Feet
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88
Q

What are the characteristics of elastic cartilage.

A
  • Many elastic fibres in ECM. = elasticity and resilience.

- Doesn’t calcify with age

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89
Q

Where is elastic cartilage found?

A
  • External ear
  • Epiglottis
  • Eustuchian tube.
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90
Q

What are the characteristics of fibrocartilage and its role?

A
  • fibroblasts + chondrocytes
  • dense regular connective tissue + hyaline cartilage
  • Synthesise and secrete both ground substance and fibres found in ground substance.
  • Primarily responsible for scar tissue.
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91
Q

Where is fibrocartilage found?

A
  • Intervertebral discs
  • Articular discs of joints
  • Menisci of joints
  • Pubic symphysis
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92
Q

What does connective tissue compose of?

A
  • Extracellular matrix
  • Ground substance (jelly like)
  • Fibres (collagen, reticular, elastic)
93
Q

Is mesochyme totipotent, multipotent or specialised?

A
  • Multipotent
94
Q

What’s ground substance’s role?

A
  • Impact resistance.
95
Q

What are the roles of the 4 different types of collagen?

A
  • 1: Fibrils aggregate into fibres and fibre bundles
  • 2: Elastic cartilage
  • 3: Reticulin (Fibrils from fibres around muscle and nerve cells)
  • 4: Unique form only found in basal lamina of basement membrane
96
Q

What does elastic fibres consist of?

A
  • Elastin

- Fibrillin

97
Q

What is the role of white adipose?

A
  • Contains fat as a fuel reserve
  • Thermal insulation
  • Shock absorption
98
Q

What are the two forms of bone?

A
  • Cancellous (Spongey)

- Compact

99
Q

What is cancellous bone and where is it found?

A
  • Network of fine bony columns/plates
  • Strong and light
  • Spaces filled with bone marrow.
  • Epiphyseal areas (head of bones)
100
Q

What is compact bone?

A
  • Forms the external surfaces of bones

- 80% of body’s skeletal mass

101
Q

What is the difference between immature and mature bone?

A
  • Immature: osteocytes are randomly arranged

- Mature: osteocytes are arranged in concentric lamellae of osteons

102
Q

Which type of bone contains Haversian and Volksmann ‘s canals?

  • Spongey
  • Compact
  • Both
A
  • Compact
103
Q

Outline how new bone is formed.

A
  • Osteoblast surrounds new osteoid and therefore an osteocyte
  • Osteoblast moves from lumen to epithelium, deposits new osteoid and therefore new bone.
104
Q

How is a bone remodelled?

A
  • Cutting cone is formed by boring a tunnel through the bone by osteoclasts releasing H+ and lysosomal enzymes.
  • Osteoblasts deposit new osteoids.
105
Q

What is endochondral ossification?

A
  • Replacement of a pre-existing hyaline cartilage template by bone,
    (How most bones are formed)
106
Q

How is hyaline cartilage transformed into bone?

A
  • Mineralised
107
Q

Outline the formation of bone from Embryo to mature adult.

A
  • Embryo 5-6 weeks: Purely hyaline cartilage.
  • Embryo 6-8 weeks: Collar of compact bone appears in shaft.
  • Fetus 8-12 weeks: Central cartilage calcifies, Nutrient artery penetrates supplying osteogenic cells, primary ossification centre forms
  • Postnatal: Medulla changes to spongey bone & forms epiphyseal growth plates, epiphyses develop secondary ossification centres.
  • Prepubertal: Epiphyses ossify and growth plates continue to move apart = lengthening of bone.
  • Mature adult: Growth plates replaced by hyaline articular cartilage plates.
108
Q

Name the zones of epiphyseal growth plates from top to base.

A
  • Reserve cartilage
  • Proliferation
  • Hypertrophy
  • Calcified cartilage
  • Reabsorption
109
Q

Outline how growth plates induce growth.

A
  • Cells actively divide into columns
  • Enlargement, matrix compressed into linear bands between cell columns
  • Enlarged cells degenerate and matrix calcifies
  • Calcification
110
Q

What is intramembraneous ossification?

A
  • Within condensations of mesenchymal tissue, not by replacement of a pre-existing hyaline cartilage template.
  • Thickening not lengthening of bones.
111
Q

Where does intramembraneous ossification occur?

A
  • Flat bones:
  • Skull bones
  • Maxilla
  • Mandible
  • Pelvis
  • Clavicle
112
Q

What is oesteogenesis imperfecta, and what are the clinical signs?

A
  • Disorders if connective tissue.
  • Affects: skeleton, joints, ears, ligaments, teeth, sclerae and skin
  • Bowing of bones, easily fractured with limited physical stress, very thin bones.
113
Q

Where is growth hormone synthesised and stored?

A

Anterior pituitary gland.

114
Q

What are the conditions associated with excessive/insufficient GH during development?

A
  • Excessive: Gigantism via promotion of epiphyseal growth plate activity
  • Insufficient: pituitary dwarfism
115
Q

What signs are there of excessive GH in adults?

A
  • Increase of bone width by promoting compact bone growth.
116
Q

What are the main sex hormones in males & females

A
  • Males: Androgens

- Females: Oestrogen

117
Q

What is the effect early sex hormone production has?

And for later sex hormone production?

A
  • Retards bone growth due to premature closure (fusion) of epiphyses
  • Prolonged bone growth, epiphyseal plates persist in later life.
118
Q
  • What conditions do infants with THD (Thyroid hormone deficiency) have?
A
  • Permanent neurological & intellectual damage

- Short stature

119
Q

What is osteoporosis?

A
  • Incomplete filling of osteoclast resorption bays.
  • Mineralised bone is decreased in mass, no longer provides adequate support.
  • More susceptible to fracture.
120
Q

What are the risk factors associated with osteoporosis?

A
  • Genetic, peak bone mass is higher in black people
  • Insufficient Ca intake
  • Insufficient Ca absorption and Vit D
  • Exercise
  • Smoking
121
Q

How does Achondroplasia occur?

A
  • Decreased endochondral ossification
  • Inhibited proliferation of chondrocytes in growth plate cartilage
  • Decreased cellular hypertrophy
  • Decreased cartilage matrix production
122
Q

What is Achondroplasia?

A
  • Common form of short limbed disease (trunk normal)

- Normal mentation, average lifespan.

123
Q

What is rickets?

A
  • Childhood disease, bones don’t harden due to Vit D deficiency.
  • Insufficient Ca deposition for adequate bone rigidity
  • Bones are soft and malformed
  • Distortion of skull bone
  • Enlargement of costochondrial junctions of ribs.
124
Q

What is Osteomalacia?

What are the symptoms?

A
  • Adult version of rickets
  • Due to severe Ca deficiency or lack Vit D
  • Bone pain, back ache, muscle weakness.
169
Q

What is the peripheral blood count for the following:

  • 1) Hb
  • 2) RBC
  • 3) WBC
  • 4) Platelets
A
  • Hb: 130-160 g/l
  • RBC: 4.4-5.5x10^12 g/l
  • WBC: 7-11x10^9 g/l
  • Platelets: 150-400x10^9 g/l
170
Q

What is the RBC’s function?

A
  • Delivery of O2 to tissues
  • Carries haemoglobin
  • Maintain haemoglobin in reduced state
  • Maintain osmotic equilibrium
  • Generate energy (ATP)
171
Q

What are the characteristics of the structure of RBC?

A
  • Biconcave
  • Flexible
  • 8 micrometer diameter
172
Q

What is the function of haemoglobin?

A
  • Carries O2 from lungs to tissues
  • Carries CO2 between tissues and lungs
  • ## Haem molecule combines reversibly with O2 and CO2
173
Q

What are the roles of globin chains in haemoglobin?

A
  • Protect Haem molecule from oxidation
  • Confers solubility
  • Permits variation in O2 affinity
174
Q

When is erythropoietin produced?

A
  • Reduced pO2 detected in interstitial peritubular cells in kidneys
  • Increases production
175
Q

What does erythropoietin do?

A
  • Stimulates maturation and release of RBC from bone marrow.
  • Increased Hb
  • Increased pO2
  • Erythropoietin production falls (product inhibition)
176
Q

Where are platelets produced?

A
  • Megakaryocytes
177
Q

How is platelet production controlled?

A
  • Thrombopoietin
178
Q

What are the functions of platelets?

A
  • Adhesion to connective tissue
  • Aggregation with other platelets
  • Facilitate clotting by phospholipid membrane
179
Q

How does adhesion occur with platelets?

A
  • Damage to vessel wall
  • Exposure of underlying tissues
  • Platelets adhere via receptor and form platelet plug.
180
Q

How do platelets help with clotting?

A
  • Activates clotting cascade
  • Interacts with clotting factors VII, IX, X
  • Fibrin mesh traps platelets and RBC
181
Q

Outline the stages of neutrophil maturation

A
  • Myeloblast
  • Promyelocyte
  • Myelocyte
  • Metamyelocyte
  • Band
  • Neutrophil
182
Q

What are the roles of monocytes?

A
  • Migration to tissues: macrophages
  • Response to inflammation and antigenic stimuli
  • Diapedesis to tissues (migration through intact capillary walls to tissues)
183
Q

What do lysosomes contain?

A
  • Lysozyme
  • Interleukins
  • Chrachidoric acid
  • CSF
265
Q

What do the prefixes sarco- and myo- mean?

A
  • Sarco: flesh/muscle

- Myo: muscle

266
Q

What types of muscle are striated?

A
  • Skeletal

- Cardiac

267
Q

What type of muscle is non striated?

A
  • Smooth
268
Q

Where are skeletal muscle cells developed?

A
  • Mesoderm
269
Q

What types of skeletal muscle cells are there?

A
  • Red
  • White
  • Intermediate
270
Q

How do red skeletal muscle cells differ from white skeletal muscle cells in characteristics?

A
  • Red are richer in myoglobin & vascularisation
  • Smaller
  • Numerous mitochondria
  • Fewer neuromuscular junctions
  • Poorer in ATP-ase
  • Richer in oxidative enzymes
271
Q

What is the function of red skeletal muscle cells?

A
  • Act more slowly than white
  • Slow, repetitive and weaker
  • Fatigue slowly
272
Q

What is the function of white skeletal muscle cells?

A
  • Act fast and strongly

- Fatigue quickly

273
Q

What is the bone to muscle connection called?

What is the bone to bone connection called?

A
  • Tendon

- Ligament

274
Q

Where is the sarcolemma positioned?

A
  • Between collagen bundles and muscle fibre’s myofilaments
275
Q

In muscle fibres what is the A band, I band and H zone?

A
  • A band is areas of myosin (dark)
  • I band is areas of actin only (light)
  • H zone is areas of just myosin (between actin)
276
Q

When a muscle contracts what happens to the A band, I band and H zone?

A
  • A band remains the same
  • I band shortens
  • H zone shortens
277
Q

How is the actin, tropomyosin, tropanin complex formed?

A
  • Actin filament forms a helix
  • Tropomyosin molecules coil around the actin helix, reinforcing it
  • Tropanin complex is attached to each tropomyosin molecule
278
Q

How are myosin filament heads able to join to actin?

A
  • Increase in Ca ions, bind to TnC of tropanin, moves tropomyosin away from actin’s binding sites
  • Displacement allows for myosin heads to bind.
279
Q

How do myosin filaments cause contractions?

A
  • Myosin cross bridge attaches to actin myofilament,
  • Working stroke, myosin head pivots and bends as it pulls on actin filament, slides towards M line,
  • New ATP attaches to myosin head, cross bridge detaches,
  • ATP -> ADP + Pi, cocking of myosin head occurs.
280
Q

What is a neuromuscular junction and how does it work?

A
  • ‘Synapse’ between muscle and nerves
  • Axon terminal contains vesicles of acetylcholine (AcH)
  • Nerve impulse causes release of AcH
  • AcH binds to receptors on sarcolemma
  • Na channels open
  • Na depolarises muscle causing a Ca release from SR hence muscle contraction
281
Q

What’s an epimysium and a perimysium?

A
  • Epimysium: Outer layer of connective tissue lining the fibre as a whole
  • Perimysium: Outer layer of individual fibre bundles.
282
Q

Name some recognisable characteristics of cardiac muscle.

A
  • Striations
  • 1 or 2 centrally positioned nuclei per cell
  • Intercalated discs (electrical & mechanical coupling with adjacent cells)
  • Branching
  • Endomysium provides a rich blood supply (around individual fibres)
283
Q

In what orientation do T tubules of cardiac muscle lie?

A
  • ‘Around’ the fibre, i.e in register with Z bands, not with A-I band junction.
284
Q

What are the cells called that carry impulses across the heart?

A
  • Purkinje fibres, distal conducting cells.
285
Q

What are the characteristics of Purkinje fibres?

A
  • Abundant in glycogen
  • Sparse myofilaments
  • Extensive gap junction sites.
  • Conducts rapidly, enables ventricles to contract synchronised.
286
Q

What shape are smooth muscle cells?

A
  • Fusiform (spindle shaped with a central nucleus)
287
Q

True or false? (Smooth muscles)

  • Striated
  • No sarcomeres
  • No T tubules
  • Contraction still relies on actin-myosin interactions
  • Contraction is rapid and requires lots of ATP
  • Can only remain contracted for short periods of time
  • Can be stretched
A
  • False
  • True
  • True
  • True
  • False
  • False
  • True
288
Q

How are smooth muscles stimulated?

A
  • Nerve signals
  • Hormones
  • Drugs
  • Local concentrations of blood gases
289
Q

How does smooth muscle look?

A
  • Sheets
  • Bundles
  • Layers
290
Q

Where is smooth muscle commonly found and what is its primary role?

A
  • Vascular structures’ walls
  • GI
  • Respiratory tract
  • Genitourinary system
  • Modifies volume
291
Q

In what conditions would smooth muscle have a clinical significance?

A
  • Asthma
  • High bp
  • Atherosclerosis
  • Abnormal GI mobility
292
Q

What are myoepithelial cells and their roles?

A
  • Basketwork around secretory units of exocrine glands
  • Contraction assists secretion
  • Dilation of pupil in iris
293
Q

What are the roles of myofibroblasts?

A
  • Sites of wound healing,
  • Produce collagenous matrix
  • Wound contraction
  • Tooth eruption
294
Q

How do smooth muscles contract?

A
  • Thick and thin filaments are arranged diagonally, spiralling down long axis
  • Contracts in a twisting way
295
Q

Can skeletal muscles repair?

A
  • Yes
  • Mitotic activity of satellite cells (hyperplasia) after an injury
  • Satellites can fuse to existing muscle cells to increase mass
296
Q

Can cardiac muscles repair?

A
  • No

- Fibroblasts cause scar tissue

297
Q

Can smooth muscle repair?

A
  • Yes

- Mitotic activity

298
Q

What is atrophy?

A
  • Destruction -> replacement

- Muscle wastage

299
Q

What is hypertrophy?

A
  • Replacement -> destruction
  • Muscle size increase
  • More contractile proteins hence increase in fibre diameter
  • Metabolic changes: increase: enzyme activity for glycolysis, mitochondria, stored glycogen, blood flow
300
Q

What is disuse atrophy?

A
  • Loss of protein
  • Reduced fibre diameter
  • Loss of power
301
Q

What is denervation atrophy?

A
  • Signs of lower motor neurone lesions:
  • Weakness, flaccidity, muscle atrophy
  • Re-innervation within 3 months for recovery
302
Q

How is an action potential terminated?

A
  • Acetylcholinesterase
303
Q

What is myasthenia gravis?

A
  • Autoimmune destruction of end-plate & ACh receptors
  • Loss of junctional folds
  • Widening of synoptic cleft
304
Q

What are the symptoms and treatment of myasthenia gravis?

A
  • Fatigue and sudden falling (reduced ACH release)
  • Drooping eyelids, blurred vision
  • Affected by state of health and emotion
  • Acetylcholinesterase inhibitors
305
Q
  • Duchenno and Becker are types of what and what are they?
A
  • Genetic muscular dystrophies
  • Duchenno: absence of dystrophin
  • Becker: Deficiency of dystrophin
306
Q

What is DMD?

A
  • Protein abnormality
  • Muscle fibres tear themselves apart on contraction
  • Pseudohypertrophy (swelling) occurs before fat and connective tissue can replace muscle fibres
  • Contractures (imbalance between agonist and antagonist muscles)
307
Q

What treatment is there for DMD?

A
  • Steroid therapy

- Genetic research

308
Q

Give 5 examples of myopathies.

A
  • Inflammatory
  • Electrolyte imbalances
  • Thyrotoxicosis
  • Hypoparathyroidism
  • Channelopathies
309
Q

What is haemopoiesis?

A
  • Formation of blood cellular components.
310
Q

What are the peripheral blood counts for:

Hb, RBC, WBC & Platelets?

A
  • Hb: 130-160g/L
  • RBC: 4.4-5.5x10^12/L
  • WBC: 7-11x10^9/L
  • Platelets: 150-400x10^9/L
311
Q

What is the MCV function values?

A
  • 80-100 fl

- (Mean corpuscular volume)

312
Q

What is the function of RBC?

A
  • Delivery of O2 to tissues
  • Carries haemoglobin
  • Maintain haemoglobin in reduced state
  • Maintain osmotic eqm
  • Generate energy (ATP)
313
Q

What are the physical characteristics of RBC?

A
  • Biconcave, flexible disc 8micrometer diameter

- Microcirculation minimum diameter 3.5micrometer.

314
Q

What is the function of haemoglobin?

A
  • Carries O2 from lungs to tissues
  • Carries CO2 between tissues and lungs
  • Haem molecule combines reversibly with O2 and CO2
  • Globin chains: Protect Haem molecule from oxidation
    Confer solubility
    Permits variation in O2 affinity
315
Q

What is the role of Erythopoietin?

A
  • Reduced pO2 detected in interstitial peritubular cells in kidneys
  • Increase production of Erythropoietin
  • Erythropoietin stimulates maturation and release of RBC from marrow
  • Hb increase
  • pO2 increase
  • Erythropoietin production falls.
316
Q

How are platelets produced and what hormone controls this?

A
  • Megakaryocytes produce platelets
  • Cells increase in size and replicates DNA
  • Platelets ‘bud’ from cytoplasm
  • Controlled by Thrombopoietin
317
Q

What is the function of platelets?

A
  • Adhesion to connective tissue
  • Aggregation with other platelets
  • Phospholipid membrane to facilitate clotting
318
Q

How does adhesion occur with platelets?

A
  • Damage to vessel wall
  • Exposure of underlying tissues
  • Platelets adhere via vWF/receptor and form platelet ‘plug’.
319
Q

What role does platelets have in clotting?

A
  • Fibrin mesh formed by clotting factors

- Traps platelets and RBC.

320
Q

How does neutrophil maturation occur?

A
  • Myeloblast -> Promyelocyte -> Myelocyte -> Metamyelocyte -> Band -> Neutrophil
321
Q

What is the role of monocytes?

A
  • When migrate to tissues they become macrophages
  • Response to inflammation and antigenic stimuli
  • Diapedesis to tissues
322
Q

What is the contents of lysosomes?

A
  • Lysozyme
  • Complement
  • Interleukins
  • Crachiadoric acid
  • CSF
323
Q

What is the RES?

A
  • Reticuloendothelial system
  • Immune system containing Phagocytic cells
  • RES cells identify and mount an appropriate immune response to foreign antigens
  • Main organs: Spleen, Liver, lymph nodes
  • ECF travels via lymphatic to LN.
324
Q

What are the roles of eosinophils?

A
  • To mediate hypersensitivity reactions

- e.g asthma/skin inflammation

325
Q

What are basophils?

A
  • Dense granules

- Active in allergic reactions

326
Q

What are Beta cells’ functions?

A
  • Express antigen specific Ig
  • T cell interaction transforming to plasmablasts/memory cells within lymph nodes.
  • Plasmablasts migrate to marrow and form plasma cells (Ig production)
327
Q

What are T cells functions?

A
  • Migrate to thymus and undergo TCR arrangement
  • Differentiate into helper and suppressor
  • Helper cells induce proliferate and differentiation of T&B cells active macrophages
  • Suppressor has cytotoxic activity and induces apoptosis
328
Q

What are natural killer cells?

A
  • Recognise self

- Kill non self cell lines by lysis.

329
Q

What is the innate immune response?

A
  • Inbuilt immunity to resist infection
  • Natural immunity, present from birth
  • No memory
  • Not specific
  • Not enhanced by secondary exposure
  • Uses cellular and humoral response.
330
Q

What is the adaptive immune response?

A
  • Immunity established to adapt to infection
  • Specific or acquired immunity
  • Learnt by experience
  • Confers to pathogen specific immunity
  • Enhanced to secondary immunity
  • Memory
  • Cellular and hormonal response
331
Q

How does the body facilitate the removal of pathogens from the body? Give 5 examples.

A
  • Blinking
  • Coughing
  • Sneezing
  • Mucociliary escalator
  • Vomiting
  • Digestive enzymes.
332
Q

What is the role of inflammation mediators?

A
  • inflammation mediators increase the permeability of blood vessels at the site of infection to allow:
  • Release of antibodies, macrophages, neutrophils and lymphocytes.
333
Q

What are the cells involved with innate immunity?

A
  • Macrophages/monocytes: Phagocytosis/presentation to lymphocytes
  • Neutrophil/PMN: Phagocytic/antibacterial
  • Eosinophils: Anti-parasite
  • Basophils
  • Mast cells: protection of mucosal surfaces/allergy
334
Q

What is phagocytosis?

A
  • Active engulfment of particles into phagosomes.
335
Q

What are phagosomes?

A
  • Macrophages and neutrophils

- Those with the ability to destroy bacteria/extracellular viruses/immune complexes

336
Q

What are the roles of neutrophils?

A
  • Work best in anaerobic conditions which prevail in damaged tissue
  • Initiates inflammation.
337
Q

What is the role of macrophages?

A
  • Phagocytose microbial cells, damaged/unwanted cells
  • Release cytokines important in both types of immunity
  • Can generate lysosomes when needed.
338
Q

What do natural killer cells do?

A
  • Directly induce apoptosis in virus cells by pumping in proteases
  • Recognise and kill abnormal cells such as tumour cells.
339
Q

What is opsonisation?

A
  • The coating of a microorganism in antibodies/complement to make it recognisable as foreign to phagocytes
340
Q

What is the complement system?

A
  • Marking pathogens for destruction by covalently binding to their surface.
341
Q

What are the different stages of the adaptive immune system?

A
  • Recognition phase: Clonal selection and expansion, differentiation to effector cells
  • Activation phase
  • Effector phase: Elimination of pathogen
  • Decline homeostasis: apoptosis of T and B cells
  • Memory
342
Q

What are the 4 membranous layers protecting the brain?

A
  • Skull
  • Dura mater
  • Arachnoid mater
  • Pia mater
343
Q

What are the meninges?

A
  • Dura mater
  • Arachnoid mater
  • Pia mater
344
Q

What is the leptomeninges?

A
  • Dura mater and arachnoid mater together.
345
Q

What is the epineurium?

A
  • Sheaths for a whole nerve

- Interfascicular bands join adjacent nerve fascicles.

346
Q

What is the perineurium?

A
  • Sheaths a nerve fascicle.

- A fascicle is a group of axons.

347
Q

What is the endoneurium?

A
  • Sheaths individual axons
348
Q

What are the two types of nerve cells and how is it split?

A
  • Glia: 90%

- Neurone: 10%

349
Q

What are dendrites?

A
  • Specialisations of cell bodies

- Main role is to increase surface area of cell body.

350
Q

What is the difference between temporal and spatial summation?

A
  • Temporal summation: Summated with respect to time of arrival.
  • Spatial summation: Summated with respect to their location
351
Q

What is the function of an axon?

A
  • Summates all inputs to the neurone
  • Initiates action potentials & therefore neurotransmitter production
  • Communicates with follower cell
352
Q

How are neurotransmitters released and used as interneural communicators?

A
  • Action potential arrives along axon terminal
  • Opening voltage gated Ca channels
  • Ca diffuses into synaptic knob
  • Ca triggers synaptic vesicles containing neurotransmitters to fuse with presynaptic membrane
  • Neurotransmitter diffuses across synaptic cleft and binds to a receptor which in turn is bound to a Na channel
  • Na channels allow Na to diffuse into dendrite and create a new action potential
  • Acetylcholinease breaks down acetylcholine so no continuous firing of action potentials.
353
Q

What are the three classes of neurone?

A
  • Sensory
  • Motor
  • Relay/inter.
354
Q

What is the role of a sensory neurone?

A
  • Afferent pathway

- Receptor to CNS.

355
Q

What is the role of a motor neurone?

A
  • Efferent pathway

- From brain to muscles

356
Q

What are relay neurones?

A
  • Relay the information between sensory and motor neurones.