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HUBS192 > HUBS192 > Flashcards

HUBS192 Flashcards

1
Q

Skin is the…

A

largest and most (only) visible organ of the body

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2
Q

What portion of body weight is skin?

A

16%

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3
Q

What surface area is skin?

A

1.5-2 square metres

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4
Q

What makes humans unique?

A

Our bare (not much hair), sweaty (lots of sweat glands) skin

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5
Q

What are the functions of skin?

A

Protect, excrete, maintain, produce, synthesise, store and detect

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6
Q

What does the skin protect?

A

Underlying tissues and organs against impact, abrasion, fluid loss and chemical attack

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7
Q

What does the skin excrete?

A

Salts, water and organic wastes by integumentary glands

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8
Q

What does the skin maintain?

A

Normal body temperature through either insulation or evaporative cooling as needed (thermoregulation)

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9
Q

What does the skin produce?

A

Melanin and keratin

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10
Q

What does melanin do?

A

Protect underlying tissue from ultraviolet radiation

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11
Q

What does keratin do?

A

Protect against abrasion and serves as a water repellent (hair and nails)

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12
Q

What does the skin synthesise?

A

Vitamin D3, a steroid that is subsequently converted into calcitriol, which is a hormone important to normal calcium metabolism

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13
Q

What does the skin store?

A

Lipids in adipocytes in the dermis and in adipose tissue in the subcutaneous layer

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14
Q

What does the skin detect?

A

Touch, pressure, pain, and temperature stimuli, and relay that information to the nervous system

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15
Q

What happens at the chemical level?

A

Atoms combine to form molecules

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16
Q

What happens at the cellular level?

A

Molecules interact to form cells that secrete and regulate extracellular materials and fluids

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17
Q

What happens at the tissue level?

A

Cells and extracellular materials and fluids combine to form tissues

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18
Q

What does epithelial tissue do?

A

Cover exposed surfaces, line internal passageways and chambers and form secretory glands

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19
Q

What does connective tissue do?

A

Fill internal spaces, provide structural support and store energy

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20
Q

What does muscle tissue do?

A

Contract to produce movement. Includes skeletal, cardiac and smooth muscle

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21
Q

What does nervous tissue do?

A

Conduct electrical impulses and carry information

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22
Q

What tissue is skin made of?

A

Epithelial, connective, muscle and nervous

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23
Q

What are the 3 layers of the skin?

A

Epidermis, dermis and hypodermis

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24
Q

What is in the cutaneous layer?

A

Epidermis and dermis

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25
Q

What is in the subcutaneous layer?

A

Hypodermis

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26
Q

What is the epidermis?

A

Stratified barrier, mostly keratinocytes ( cells with large amounts of keratin), no circulation (avascular)

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27
Q

What happens id a cut doesn’t go beyond the epidermis?

A

No bleeding

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28
Q

What is the dermis?

A

Protein fibres for strength and vascular (nourishes epidermis)

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29
Q

What is the hypodermis?

A

Adipose tissue- insulation

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30
Q

What is within the dermis?

A

Papillary layer and reticular layer

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31
Q

Describe the border between the epidermis and dermis

A

Has papule which increase surface area for nourishment

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32
Q

What are the layers of the epidermis?

A

Stratum corneum, Stratum lucid (in thick skin), stratum granulosum, stratum spinosum, stratum basale

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33
Q

What are the cells of the stratum corneum?

A

Dead dried out hard cells without nuclei which can be completely removed by strip-taping

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34
Q

What are the cells of the stratum granulosum?

A

Contain granules that promote dehydration of the cell, cross linking of keratin fibres. Waxy material is secreted into the intercellular spaces

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35
Q

What are the cells of the stratum spinosum?

A

Intercellular bridges called desmosomes link the cells together. The cells become increasingly flattened as they move upward

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36
Q

What are the cells of the stratum basal?

A

Columnar (tall) regenerative cells. As the basal cell divides and differentiates, a daughter cell migrates upwards to replenish layers above

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37
Q

What are simple epithelia?

A

Single layers of cells

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38
Q

What are the types of epithelia?

A

Squamous, cuboidal and columnar

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39
Q

What are stratified epithelia?

A

Multiple layers of cells

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40
Q

What type of epithelial cell is the epidermis?

A

Stratified squamous

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41
Q

What skin layers shed?

A

The epidermis and not the dermis

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42
Q

What protein fibres are in the dermis?

A

Collagen and elastin

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43
Q

Where is thick skin found?

A

Palms of hands and soles of feet

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44
Q

What are the characteristics of thick skin?

A

No hair, extra epidermal layer (stratum lucidum) for extra rigidity, stratum corneum much thicker but other layers the same

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45
Q

What happens to the epidermis in ageing?

A

Thinner and drier (less sebum and fewer active follicles)

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46
Q

What happens to the dermis in ageing?

A

Thinner (sagging and wrinkling), reduced collagen

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47
Q

What happens to skin repair in ageing?

A

Slower

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48
Q

What happens to cooling in ageing?

A

Impaired (less sweat/sweat glands)

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49
Q

What happens to pigmentation in ageing?

A

Less. Pale skin, grey hair

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50
Q

What is the relationship between smoking and skin ageing?

A

Smoking increases skin ageing

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51
Q

What does smoking do?

A

“reactive oxygen” damages collagen and elastin. vasoconstriction - nicotine increases vasopressin

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52
Q

Where is hair found?

A

All over the body (only prominent on the head) except palms of hands and soles of feet

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53
Q

What does hair consist of?

A

Hair shaft, hair follicle, arrector pili muscle and sebaceous gland

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54
Q

What happens when the arrector pili muscle contracts?

A

Causes the hair to raise

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55
Q

What does a sebaceous gland do?

A

Produce sebum which acts as a natural moisturiser/water repellent

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56
Q

Where is sebum produced more?

A

On the head, shoulders and face

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57
Q

What is lanolin?

A

Sheep sebum which is used in skincare

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58
Q

What is acne?

A

Blockage of hair follicles and infection

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59
Q

What does increased sebum do?

A

Increase the risk of acne

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60
Q

What are the two types of sweat glands?

A

Eccrine and apocrine

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61
Q

Where are eccrine glands?

A

Everywhere

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62
Q

What is the role of eccrine glands?

A

Thermoregulation

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63
Q

What is the role of apocrine glands?

A

Specialised

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64
Q

Where are apocrine sweat glands?

A

Situated deeper in the skin, release into base of the hair follicle

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65
Q

How are apocrine secretions described?

A

Oily

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66
Q

What are the 3 types of receptors?

A

Tactile, lamellar and bulbous

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67
Q

What receptor is deeper?

A

Lamellar are deeper than tactile receptors

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68
Q

What do nails do?

A

Protect fingertips and enhance sensation

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69
Q

What do sensory receptors require?

A

Deformation

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70
Q

What does high pigmentation do?

A

Protects from UV radiation

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71
Q

What does low pigmentation do?

A

Helps with vitamin D production

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72
Q

What does melanin pigment do?

A

Absorbs UV light to protect from UV damage (damage DNA)

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73
Q

Where is melanin produced?

A

In cells called melanocytes

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74
Q

How is melanin transported?

A

By melanosomes (vesicles) to the epidermal cells

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75
Q

Where are melanocytes found?

A

Only in the stratum basale

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76
Q

Do melanocytes shed?

A

No

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77
Q

Where are melanosomes found?

A

Throughout the epidermis

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78
Q

Do melanosomes shed?

A

Yes. With the keratinocytes

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79
Q

Where does the density of melanocytes vary?

A

Throughout the body but not between races

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80
Q

What is a mole?

A

Cluster of melanocytes

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81
Q

What causes a mole?

A

Overproliferation can be cause by sun exposure

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82
Q

What is a freckle?

A

Melanocytes overproducing melanosomes

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83
Q

What causes a freckle?

A

Overproduction triggered by sun exposure

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84
Q

What does more UV mean?

A

More pigment

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85
Q

What does less UV mean?

A

Less pigment

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86
Q

What is vitamin D deficiency?

A

Rickets

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87
Q

What is vitamin D essential for?

A

Normal calcium metabolism and strong bones

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88
Q

What does vitamin D deficiency also effect?

A

Mood

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89
Q

What is UV exposure in skin required for?

A

Vitamin D synthesis

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90
Q

Where is there a greater incidence of lightly pigmented skin?

A

At higher latitudes

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91
Q

What people are more susceptible to Vitamin D deficiency?

A

Highly pigmented people, particularly at extreme latitudes

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92
Q

What does New Zealand have one of the highest rates for worldwide?

A

Skin cancer

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93
Q

What proportion of NZers are pakeha (European descent, mostly British)?

A

Large proportion (74%)

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94
Q

What is the UV of NZ?

A

Intense (elliptical orbit of the sun, latitude, thin ozone)

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95
Q

What country also has high skin cancer rates?

A

Australia

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96
Q

What are the types of skin cancer?

A

Basal cell carcinoma and malignant melanoma

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97
Q

How is basal cell carcinoma described?

A

Common but relatively benign

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98
Q

Where does basal cell carcinoma originate?

A

In the stratum basale

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99
Q

Metastasis is ______ for basal cell carcinoma?

A

Rare

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100
Q

What is metastatis?

A

Breaking off and moving to and growing in another part of the body

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101
Q

How is Malignant melanoma described?

A

Rare but deadly if not treated

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102
Q

Where does malignant melanoma originate?

A

In the melanocytes (pigmented)

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103
Q

Malignant melanoma is ______ metastatic

A

Highly

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104
Q

What does the mortality rate of malignant melanoma depend on?

A

The tutor (thickness and depth as it is more likely to get into the circulatory system and cause damage to organs)

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105
Q

What is tattoo?

A

Artificial pigmentation (usually ink) deposited deep within the skin

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106
Q

Where is the ink of a tattoo deposited?

A

Into the dermal layer so it is effective and doesn’t shed

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107
Q

What is done with the tattoo ink?

A

It is captured inside the immune cells/scar tissue but not broken down

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108
Q

What happens to lymph nodes in tattoo?

A

They may become pigmented as the tattoo breaks down

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109
Q

What are the types of tattoo?

A

Trauma, decorative and cosmetic (e.g. eyebrows)

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110
Q

What is the Polynesian connections of tattoos?

A

Maori, ta moko

Samoan, Pe’a

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111
Q

What is meant by there is no perfect “one receptor - one function’ relationship?

A

Receptors can often respond to several different stimuli but will be most sensitive to a particular type

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112
Q

What are the types of receptors?

A

Free nerve endings, tactile (Merkel) discs, tactile (messier) corpuscles, lamellar (pacinian) corpuscles and bulbous corpuscles (Ruffini’s endings)

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113
Q

What is the most common receptors in skin?

A

Free nerve endings

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114
Q

What is the structure of free nerve endings?

A

Mostly unmyelinated small diameter fibres but also some small diameter myelinated fibres

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115
Q

Where are free nerve endings found?

A

Axon terminals branch into epidermis and detect lots of things

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116
Q

What do free nerve endings usually have?

A

Small swellings at distal ends called sensory terminals

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117
Q

What do sensory terminals have?

A

Receptors that function as cation channels»>depolarisation»>action potentials

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118
Q

What do free nerve endings respond to?

A

Mainly temperature (hot/cold), painful stimuli, some movement and pressure, some to itch (in response to histamine)

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119
Q

What do antihistamines do?

A

Block the receptors to the itch

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120
Q

What do some free nerve endings do?

A

Wrap around hair follicles (petririchial endings) acting as light touch receptors which detect bending of hairs

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121
Q

What are tactile (Merkel) discs?

A

Free nerve endings located in the deepest layer of the epidermis

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122
Q

What are tactile discs associated with?

A

Large disc shaped epithelial (Merkel) cells

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123
Q

How is communication between the tactile epithelial cell and nerve endings possible?

A

Via serotonin (5HT)

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124
Q

Where are tactile (Merkel) discs abundant?

A

In fingertips and they have very small receptive fields so good for two point discrimination

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125
Q

What are tactile (Merkel) discs sensitive to?

A

An objects physical features such as texture, shape and edges. Also fine touch and light pressure

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126
Q

Where are tactile (messier) corpuscles located?

A

In the papillary layers of the dermis between the epidermal ridges

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127
Q

Where are tactile (messier) corpuscles especially found?

A

In hairless skin (finger pads, lips, eyelids, soles of feet, external genitalia, nipples)

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128
Q

What is the structure of tactile (messier) corpuscles?

A

Encapsulated
Spiralling/branching unmyelinated sensory terminals surrounded by modified Schwann cells which don’t form myelin and then by a thin oval fibrous connective tissue capsule

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129
Q

What does deformation of the tactile (messier) corpuscle capsule trigger?

A

Entry of sodium ions into the nerve terminal&raquo_space;> action potential

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130
Q

What do tactile (messier) corpuscles sense?

A

Delicate ‘fine’ or discriminative touch, light pressure and low frequency vibration (20-80Hz)

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131
Q

What is delicate ‘fine’ or discriminative touch?

A

Sensitive to shape and textural changes in exploratory touch and movement of objects over the surface of the skin

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132
Q

Where are lamellar (pacinian) corpuscles found?

A

Scattered deep in the dermis and hypodermis

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133
Q

What is the structure of lamellar (pacinian) corpuscles?

A

Single dendrite lying within concentric layers of collagen fibres (secreted by fibroblasts) and specialised fibroblasts

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134
Q

What are the layers of collagen fibres in lamellar (pacinian) corpuscles separated by?

A

Gelatinous interstitial fluid

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135
Q

What is the dendrite in lamellar (pacinian) corpuscles isolated from?

A

Stimuli other than deep pressure

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136
Q

What happens when there is deformation of the capsule in lamellar (pacinian) corpuscles?

A

Pressure sensitive sodium channels are opened in the sensory axon. Inner layers covering the axon terminal relax quickly so action potential is discontinued (rapidly adapting)

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137
Q

What are lamellar (pacinian) corpuscles stimulated by?

A

Deep pressure (when first applied) and also vibrating because rapidly adapting

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138
Q

What is optimal stimulation frequency?

A

Around 250 Hz which is similar to frequency range generated upon fingertips by textures comprising off <1 micrometre

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139
Q

Where are bulbous corpuscles (Ruffini’s endings) found?

A

In dermis and subcutaneous tissue

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140
Q

What is the structure of bulbous corpuscles (Ruffini’s endings) ?

A

Network of nerve endings intertwined with a core of collagen fibres that are continuous with those of the surrounding dermis. Capsule surrounds the entire structure

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141
Q

What are bulbous corpuscles (Ruffini’s endings) sensitive to?

A

Sustained deep pressure and stretching or distortion of the skin

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142
Q

What are bulbous corpuscles (Ruffini’s endings) important for?

A

Signalling continuous states of deformation of tissues such as heavy prolonged touch and pressure signals

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143
Q

Where are bulbous corpuscles (Ruffini’s endings) also found?

A

In joint capsules where they help signal degree of joint rotation (proprioreception)

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144
Q

Where are bulbous corpuscles (Ruffini’s endings) in high density?

A

Around fingernails so may have a role in monitoring slippage of objects across surface skin

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145
Q

What do bulbous corpuscles (Ruffini’s endings) allow?

A

Modulation of grip

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146
Q

Where do arteries supply blood to?

A

Skin in the subcutaneous layer

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147
Q

Where do branches of arteries go?

A

Extend into the superficial layers and give rise to capillary loops which supply blood to the epidermis

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148
Q

What happens after blood is supplied to the epidermis?

A

It drains down into the venous plexus

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149
Q

What is also in the walls of arteries/blood vessels?

A

Smooth muscle that is under the control of the sympathetic nervous system

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150
Q

What are precapillary sphincters?

A

Bands of smooth muscle at the start of the capillary beds. Contracting muscles constricts blood vessels and reduces blood flow to the upper layers of the skin

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151
Q

What does noradrenaline act on?

A

The alpha 1 adrenergic receptors on the vascular smooth muscle of the skin

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152
Q

What happens after the alpha 1 adrenergic receptors on the vascular smooth muscle of the skin?

A

G- protein coupled receptors (GPCR’s) coupled to intracellular 2nd messengers lead to increase intracellular calcium ions and therefore constriction. Reduces skin blood flow

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153
Q

What happens when SNS activity is reduced?

A

Relaxation (dilation) of arteries to the skin causing an increase in skin blood flow

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154
Q

What is skin blood flow important in?

A

Thermoregulation and blood pressure control

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155
Q

What is the optimal core body temperature/ set point?

A

36.5-37.5

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156
Q

What happens when core body temperature gets too high?

A

Proteins denature and problems occur

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157
Q

What are the mechanisms for heat transfer?

A

Radiation, conduction, convection and evaporation

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158
Q

What does radiation cause?

A

Heat loss in the form of infrared rays

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159
Q

What objects will radiate infrared rays?

A

Any objects not at absolute zero temperature

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160
Q

What radiates heat?

A

As well as the body radiating heat, heat rays are also being radiated from objects towards the body

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161
Q

What happens when the body temperature is greater than the temperature of the surroundings?

A

More heat will be radiated from the body than to it

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162
Q

What is conduction?

A

Transfer of heat to objects or media which are in contact

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163
Q

What is conduction mainly lost to?

A

A lot more to air than to objects

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164
Q

What happens when the temperature of the air beside the skin becomes equal to the temperature of the skin?

A

Heat will stop being lost bu conduction unless the heated air moves away to be replace by cooler air (air convection)

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165
Q

What is convection?

A

Transfer of heat to air (or water) by conduction followed by the movement of air (or water) away from the skin which maintains the heat gradient for heat loss from the body

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166
Q

Why does a small amount of convection almost always occur?

A

Because of the tendency of heated air surrounding the body to rise

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167
Q

When does convection increase?

A

In wind/ running

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168
Q

What happens when water evaporates from the body?

A

The heat energy required to cause the water to evaporate is also lost

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169
Q

What happens when not sweating?

A

Water is still evaporated from the skin and respiratory tract

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170
Q

When is evaporation important?

A

When the temperature of the environment is greater than body temperature because it is the only method that heat can be lost by

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171
Q

Heat loss to water vs air

A

The body loses heat to water faster than air

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172
Q

What are the eccrine sweat glands innervated by?

A

The sympathetic nervous system

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173
Q

What do sympathetic cholinergenic nerves do?

A

Release ACH onto mAChR’s (GPCR’s)

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174
Q

What can some eccrine sweat glands do?

A

Be stimulated by adrenaline in the blood acting on beta receptors - ‘nervous sweating’ especially on palms and soles

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175
Q

What is involved in temperature regulation?

A

The preoptic area of the hypothalamus contains heat and cold sensitive neurons (central thermoreceptors)

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176
Q

What happens when body temperature increases?

A

If blood goes above the set point then the heat loss centre is activated

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177
Q

What happens when the heat loss centre is activated?

A
  • decreased SNS activation of alpha 1 receptors on skin blood vessels causes vasodilation
  • increased SNS cholinergic activation of mAChR’s on sweat glands causes sweating
  • Increased respiratory rate (evaporative heat loss increases)
  • behavioural changes
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178
Q

What happens when body temperature falls?

A

When blood goes below the set point the heat gain centre is activated

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179
Q

What happens when the heat gain centre is activated?

A

Blood vessels vasoconstrictor to make less blood go to the skin and lose less heat to the environment. Also countercurrent exchange

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180
Q

What is countercurrent exchange?

A

Cold blood coming back in veins which are in close proximity with arteries is warmed up by heat transfer from the arteries before it reaches the surface

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181
Q

What are the heat generating mechanisms?

A

Shivering, non-shivering thermogenesis and increased thyroxine

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182
Q

What is shivering?

A

Increased tone of skeletal muscles

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183
Q

What happens when tone rises above a critical level?

A

Shivering begins due to oscillatory contractions of agonist and antagonist muscles mediated by muscles spindles (stretch receptors)

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184
Q

What happens in non-shivering thermogenesis?

A

Increased sympathetic nerve activity and increased circulating adrenaline/noradrenaline from the adrenal medulla

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185
Q

What happens to the metabolism in non-shivering thermogenesis?

A

Increased cellular metabolism/metabolic rate

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186
Q

What also happens in non-shivering thermogenesis (particularly in infants)?

A

uncoupling of oxidative phosphorylation - heat produced instead of ATP (occurs in brown fat, particularly in infants)

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187
Q

What is increased thyroxine in response to?

A

TRH and TSH

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188
Q

What does increase thyroxine do?

A

Increases the basal metabolic rate

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189
Q

How long will it take for increased thyroxine take to begin in adult humans?

A

It may take several weeks of cold before the thyroid reaches new levels of thyroxine secretion

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190
Q

What are arrector pili muscles?

A

Smooth muscle innervated by SNS (alpha 1 receptors)

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191
Q

What do arrector pili muscles attach to?

A

The hair follicle and the upper dermis

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192
Q

What happens when arrector pili muscles contract?

A

The hair is pulled upright and the skin is dimpled where it attaches to the dermis (goosebumps). Also compresses sebaceous glands which lubricates the skin

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193
Q

What happens if you are a hairy mammal?

A

Goosebumps can trap a warm layer of air around the skin and make you look bigger, scarier and more formidable but it isn’t that useful for humans but can be a good example of physiological feedforward

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194
Q

Where are first degree burns?

A

Superficial - only involve outer layers of the epidermis

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195
Q

What is the appearance of first degree burns?

A

Red/pink, dry, painful, usually no blisters

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196
Q

What is an example of first degree burns?

A

Mild sunburn

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197
Q

What happens to the skin in first degree burns?

A

Remains a water and bacterial barrier

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198
Q

How long does it take for first degree burns to heal?

A

Usually 3-10 days

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199
Q

Where are second degree burns?

A

The epidermis and varying amounts of the dermis

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200
Q

What is the appearance of second degree burns?

A

Painful, moist, red and blistered

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201
Q

How long does it take second degree burns to heal?

A

Approximately 1-2 weeks

202
Q

What do second degree burns need?

A

Good dressings (absorptive initially)

203
Q

What do deeper second degree burns look like?

A

May include whiteish, waxy looking areas

204
Q

What happens to the hair follicles and sweat glands in deeper second degree burns?

A

The may remain intact

205
Q

What may happen to receptors in deeper second degree burns?

A

Some tactile receptors may be lost meaning they are less painful

206
Q

How long does it take for deeper second degree burns to heal?

A

Usually heal in 1 month but may have some loss of sensation and scarring

207
Q

Where are third degree burns?

A

Full thickness - extend into subcutaneous tissue and may include muscle and bone

208
Q

What is the appearance of third degree burns?

A

Varied colour from waxy white through to deep red or black. Hard, dry and leathery

209
Q

What is the pain like in third degree burns?

A

There is no pain because sensory nerve endings are destroyed

210
Q

What happens if third degree burns are more than a few centimetres?

A

They may require skin grafting

211
Q

How long do third degree burns take to heal?

A

Weeks to regenerate and scarring

212
Q

What must we know to find fluid replacement for burns?

A

The percentage of the total body surface area involved in second degree burns or more

213
Q

What percentage is the adult head?

A

9%

214
Q

What percentage are the upper limbs of adults?

A

9% each

215
Q

What percentage is the adult trunk?

A

36% (front and back)

216
Q

What percentage is the adult genitalia?

A

1%

217
Q

What percentage is the adult lower limb?

A

18% each

218
Q

What percentage is the child head?

A

15%

219
Q

What percentage is the child trunk?

A

32% (front and back)

220
Q

What percentage is the child upper limb?

A

9% each

221
Q

What percentage is the child genitalia?

A

1%

222
Q

What percentage is the child lower limb?

A

17% each

223
Q

What are complications of severe burns which directly relate to the skin function?

A

Dehydration and hypovolemic shock, infection/sepsis and hypothermia

224
Q

What are complications of severe burns which don’t relate to skin function?

A

electrolytes imbalances, hyper metabolism, gastrointestinal ulceration, renal failure and respiratory dysfunction

225
Q

What is the cardiovascular system made up of?

A

Organs

226
Q

What organs is the cardiovascular system made up of?

A

The heart, arteries, veins/lymphatics and capillaries

227
Q

What is the role of the heart?

A

Pump

228
Q

What is the role of the arteries?

A

Supply

229
Q

What is the role of the veins/lymphatics?

A

Drainage

230
Q

What is the role of the capillaries?

A

Exchange

231
Q

What are the organs made up of?

A

Vascular tissue

232
Q

What is vascular tissue made up of?

A

Connective tissues and cells

233
Q

What do the cells consist of?

A

Epithelia and muscle

234
Q

What do veins do?

A

Carry blood away from the capillaries

235
Q

What do capillaries do?

A

They are thin and exchange nutrients and gases in the blood to the target tissues

236
Q

What systems make up the cardiovascular system?

A

The blood vascular system and the lymphatic (vascular) system

237
Q

How is the blood vascular system described?

A

A closed supply and drainage system (continuous loop)

238
Q

How is the lymphatic (vascular) system described?

A

An open entry drainage system (one way)

239
Q

What are the two circulations in the blood and lymph vascular systems?

A

The pulmonary circulation and the systemic circulation

240
Q

What happens in the pulmonary circulation?

A

The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs for reoxygenation

241
Q

What happens in the systemic circulation?

A

The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body

242
Q

What happens with lymph?

A

Lymph which has left the capillaries and accumulated goes into the lymphatics and is returned to the vascular system. It passes lymph nodes which air present for immune surveillance

243
Q

What is the supply path?

A

Arteries only

244
Q

Where are major arteries situated?

A

To avoid damage (deep in the trunk, on flexor aspects of the limbs)

245
Q

What do important structures often receive?

A

Supply from two sources - two separate arteries (hands and brain)

246
Q

When do arteries change their name?

A

At each major branch

247
Q

What is found in the exchange network?

A

Capillaries of varying degrees of permeability

248
Q

What are the three types of capillaries?

A

Continuous, fenestrated and sinusoidal

249
Q

How permeable are continuous capillaries?

A

Controlled (tight)

250
Q

How permeable are fenestrated capillaries?

A

Leaky

251
Q

How permeable are sinusoidal capillaries?

A

Very leaky

252
Q

What are the 3 pathways for drainage?

A

Deep veins, superficial veins and lymphatics

253
Q

What do deep veins typically have the same name as?

A

Arteries beside them

254
Q

Where are superficial veins found?

A

Just below the dermis

255
Q

How do veins pump blood?

A

At low pressure and low velocity

256
Q

How do arteries pump blood?

A

At high pressure and high velocity

257
Q

How does the cross-sectional area of veins and arteries compare?

A

The cross-sectional area of veins is at least twice that of arteries

258
Q

Why is the cross-sectional area of veins twice arteries?

A

So the same volume of blood can be shifted per second. Supply = drainage

259
Q

What is the shape of the heart?

A

It is a blunt, cone shaped organ

260
Q

What is at the inferior end of the heart?

A

The apex

261
Q

How is the apex described?

A

Pointed

262
Q

What is at the superior end of the heart?

A

The base

263
Q

How is the base described?

A

Broad

264
Q

What does the heart sit in?

A

The mediastinum

265
Q

How is the heart positioned?

A

It is rotated to the left and the base tilted posteriorly to bring the right side of the heart to the anterior and the left side of the heart posterior

266
Q

How much of the heart sits to the left of the midline?

A

Two thirds

267
Q

Where is the base of the heart positioned?

A

Between ribs 2 and 3

268
Q

Where does a line from the middle of the clavicle (midclavicular line) reach?

A

The apex between ribs 5 and 6

269
Q

Where can the point of maximal impulse (PMI)/apex beat be measured?

A

Where the midclavicular line meets the apex

270
Q

What is the size of the heart?

A

Approximately the same as a closed fist

271
Q

What does the superior vena cava do?

A

Brings deoxygenated blood from the head, neck, chest and upper limbs to the right atrium

272
Q

What does the inferior vena cava do?

A

Bring deoxygenated blood from everywhere below the diaphragm to the right atrium

273
Q

What enters the right atrium through the coronary sinus?

A

Venous blood from drainage of the heart

274
Q

What do valves do?

A

Stop blood travelling backwards and insure unidirectional flow

275
Q

How many pulmonary veins are there?

A

4 (2 left and 2 right)

276
Q

What do the pulmonary veins do?

A

Bring oxygenated blood from the lungs to the left atrium

277
Q

What are atria?

A

Thin walled receiving chambers

278
Q

What does each side of the heart have?

A

An atrium and a ventricle

279
Q

What are the methods of entry into the right atrium?

A

Superior vena cava, inferior vena cava and coronary sinus

280
Q

What valve is between the right atrium and ventricle?

A

Tricuspid valve

281
Q

What is between the right and left ventricles?

A

The inter ventricular septum

282
Q

What is the first blood vessel in the systemic circulation?

A

The aorta

283
Q

What valve is between the left ventricle and the aorta?

A

The aortic (semilunar) valve

284
Q

What are the layers of the heart?

A

Endocardium, myocardium and epicardium + pericardium

285
Q

What is the endocardium?

A

The layer within the heart

286
Q

What is the myocardium?

A

The muscle within the heart

287
Q

What is the epicardium?

A

The layer upon the heart

288
Q

What is the pericardium?

A

The sac the heart sits in for pumping without damage

289
Q

What makes up most of the heart walls thickness?

A

The myocardium

290
Q

What part of the endocardium lines the border with the heart chamber?

A

The squamous epithelium (endothelium)

291
Q

What does the squamous epithelium (endothelium) do?

A

It is thin flat cells which forms exchange surfaces and prevents blood clotting

292
Q

What is also in the endocardium?

A

Loose irregular fibrous connective tissue (FCT), small blood vessels and purkinje fibres

293
Q

What does the loose fibrous connective tissue (FCT) do in the endocardium?

A

Support the endothelium

294
Q

What is the thickness of the left ventricle?

A

1.5cm

295
Q

What is the thickness of the right ventricle?

A

0.5cm

296
Q

Why is the right ventricle much thinner than the left ventricle?

A

Because it is a much shorter journey to the lungs than to the rest of the body

297
Q

What does the left ventricle need to do?

A

Produce more force which requires more muscle (myocardium)

298
Q

The volume of blood pumped from each ventricle is…

A

still the same per contraction

299
Q

What makes up the epicardium?

A

The visceral pericardium which is at the border of the pericardial space, large blood vessels and loose irregular FCT (adipose)

300
Q

What does the pericardium provide?

A

A protective layer

301
Q

The pericardium is …

A

non-stick for pumping without damage

302
Q

Where is the visceral layer of the pericardium?

A

Touching the heart

303
Q

Where is the parietal layer of the pericardium?

A

Outside

304
Q

What is between the visceral and parietal layers of the pericardium?

A

The pericardial space which has fluid within it for lubrication

305
Q

What is the pericardium described as?

A

A serous membrane (continuous)

306
Q

What does the pericardium consist of?

A

Fibrous pericardium, parietal layer, pericardial cavity and visceral layer

307
Q

What is the visceral layer part of?

A

The pericardium and the heart wall

308
Q

What valves does each side of the heart have?

A

A semilunar valve and an atrioventricular valve

309
Q

Where is the atrioventricular valve found?

A

Between the atrium and the ventricle

310
Q

Where is the semilunar valve found?

A

Between the ventricle and the outflow artery

311
Q

What is the function of atrioventricular valves?

A

To prevent blood returning to the atria during ventricular contraction

312
Q

What is the AV valve on the right side?

A

The tricuspid valve

313
Q

How many leaflets/cusps does the tricuspid valve have?

A

3

314
Q

What is the AV valve on the left side?

A

The bicuspid (mitral) valve

315
Q

How many leaflets/cusps does the bicuspid valve have?

A

2

316
Q

What is the filling phase called?

A

Diastole

317
Q

What is the squeezing phase called?

A

(ventricular) systole

318
Q

How is theAV valve during diastole?

A

Open to allow blood to drain into the ventricle

319
Q

How is the semilunar valve during diastole?

A

Closed to prevent blood from leaving the ventricle

320
Q

How is the AV valve in (ventricular) systole?

A

Closed to prevent blood flowing back into the atrium

321
Q

How is the semilunar valve during (ventricular) systole?

A

Open to allow blood to exit the ventricle

322
Q

What is the function of semilunar valves?

A

To prevent blood returning to ventricles during filling (diastole)

323
Q

What is the semilunar valve on the right side?

A

The pulmonary (semilunar) valve

324
Q

How many cusps does the pulmonary (semilunar) valve have?

A

3

325
Q

What does the pulmonary (semilunar) valve control?

A

Flow into the pulmonary circulation

326
Q

What is the semilunar valve on the left side?

A

The aortic (semilunar) valve

327
Q

How many cusps does the aortic (semilunar) valve have?

A

3

328
Q

What does the aortic (semilunar) valve control?

A

Flow from the left ventricle to the aorta

329
Q

When are semilunar valves pushed open?

A

As blood flows out of the heart

330
Q

When do semilunar valves close?

A

As the blood starts to backflow

331
Q

What is the size comparison of AV and semilunar valves?

A

Semilunar valves are much smaller than AV valves

332
Q

How is the AV leaflet described?

A

Large and flappy

333
Q

What would the AV leaflet do if there was nothing preventing it shutting?

A

It would slam shut

334
Q

What are papillary muscles?

A

Finger-like projections of the ventricular wall

335
Q

What do papillary muscles do?

A

Tension early in systole

336
Q

What are chordous tendineae?

A

Tendonous chords which are attached to the tip of the papillary muscle and the AV leaflet

337
Q

Where is the tension in the papillary muscle transferred to?

A

The chord tneidneae

338
Q

What do the papillary muscles and chordous tendineae do?

A

Allow the AV leaflet to slowly move into place when closing

339
Q

Where does the first branch of the systemic circulation form the aorta go?

A

Straight to the heart (oxygenated blood)

340
Q

Where is the right coronary artery found?

A

Running in a groove in the epicardium between the right atrium and ventricle (oxygenated blood)

341
Q

Where does the left coronary artery run?

A

It runs a small distance and then branches into the circumflex artery and anterior inter ventricular artery (oxygenated blood)

342
Q

What is the right side of the heart drained by?

A

The small cardiac vein (deoxygenated blood)

343
Q

What is the left side of the heart drained by?

A

The great cardiac vein (deoxygenated blood)

344
Q

Where do the small cardiac vein and great cardiac vein join?

A

At the coronary sinus at the posterior of the heart

345
Q

What does the coronary sinus do?

A

Drain deoxygenated blood into the right atrium

346
Q

What is the width of a capillary?

A

About the width of a red blood cell so the distance for diffusing substances to travel is minimised

347
Q

What features does cardiac muscle have?

A

It has features of smooth and skeletal muscle as well as cardiac muscle specific specialisations

348
Q

What is the function of cardiac muscle?

A

Beating of the heart

349
Q

Is cardiac muscle striated?

A

Yes, just like skeletal muscle but not smooth muscle

350
Q

How are the cells of cardiac muscle described?

A

Short, branced

351
Q

How wide are cardiac muscle cells?

A

Approximately 25 micrometres

352
Q

How many nuclei in cardiac muscle cells?

A

One (or occasionally 2) which is the same as smooth muscle but not skeletal

353
Q

How is the nucleus in cardiac muscle described?

A

Centrally positioned and oval shaped (in skeletal muscle the nucleus is pushed to the outsides)

354
Q

Where are cytoplasmic organelles in cardiac muscle?

A

Packed at the poles of the nucleus

355
Q

How are cardiac muscle cells connected?

A

By intercalated discs which are only found in cardiac muscle

356
Q

What volume of a cardiac muscle cell is mitochondria?

A

20%

357
Q

How are the sarcomeres arranged in cardiac muscle?

A

Irregular and branched (not linearly arranged as in skeletal)

358
Q

What are intercalated discs?

A

Regions between cardiomyocytes (cardiac muscle cells)

359
Q

What are the 3 junctions in intercalated discs?

A

Adhesion belts, desmosomes and gap junctions

360
Q

What do adhesion belts link?

A

Actin to actin via trasnmembrane proteins

361
Q

Where are adhesion belts found?

A

In the vertical portion and transfer force between cells

362
Q

What do desmosomes link?

A

Cytokeratin with cytokeratin

363
Q

What do gap junctions allow?

A

Electrochemical communication

364
Q

Where are gap junctions placed?

A

Parallel to the force of contraction because they are delicate junctions

365
Q

What does the conduction system of the heart actions do?

A

Greatly increase the efficiency of heart pumping

366
Q

What is the conduction system of the heart responsible for?

A

The co-ordination of heart contraction and atrioventricular valve action

367
Q

What alters the rate of conduction impulse generation?

A

Autonomic nerves

368
Q

What type of tissue is the conduction system of the heart?

A

Modified cardiac tissue, not nervous tissue

369
Q

Where does the conduction pathway of the heart begin?

A

At the superior aspect of the right atrium where there is a cluster of cells called the sinoatrial node

370
Q

Where does the conduction pathway go after the sinoatrial node?

A

Through the atrial chamber by internodal pathways

371
Q

Where do the internodal pathways reunite?

A

At the AV node which is the gateway into the ventricular chambers

372
Q

What comes after the AV node?

A

The AV bundle which goes down the inter ventricular septum into the tight snd left bundle branches

373
Q

What is the last part of the conduction system?

A

Purkinje fibres

374
Q

Where do purkinje fibres go?

A

They run up into the papillary muscles

375
Q

What do purkinje cells have?

A

Some peripheral myofibrils, mitochondria and glycogen

376
Q

Where is the nucleus of purkinje cells?

A

Central

377
Q

What junctions are found in purkinje cells?

A

Lots of gap junctions because involved in communication, some desmosomes and a few adhesion belts

378
Q

What portion of cardiac cells are purkinje cells?

A

1%

379
Q

What is the first artery in the pathway from the heart to the foot?

A

Ascending aorta

380
Q

What is after the ascending aorta?

A

Aortic arch

381
Q

What is after the aortic arch?

A

Descending aorta

382
Q

What is after the descending aorta?

A

Abdominal aorta

383
Q

What is after the abdominal aorta?

A

Common iliac artery

384
Q

What is after the common iliac artery?

A

External iliac artery

385
Q

What is after the external iliac artery?

A

Femoral artery

386
Q

What is after the femoral artery?

A

Popliteal artery

387
Q

What is after the popliteal artery?

A

Posterior tibial artery

388
Q

What is after the posterior tibial artery?

A

Plantar arch

389
Q

What arteries are in the thoracic cavity?

A

Ascending aorta, aortic arch and descending artery

390
Q

What arteries are in the abdominal cavity?

A

abdominal aorta, common iliac artery and external iliac artery

391
Q

Where is the popliteal artery sitting?

A

Posterior to the knee

392
Q

Where are the supply paths found?

A

Deep

393
Q

What is the first vein in the path from the foot to the heart?

A

Plantar venous arch

394
Q

What is after the plantar venous arch?

A

Posterior tibial vein

395
Q

What is after the posterior tibial vein?

A

Popliteal vein

396
Q

What is after the popliteal vein?

A

Femoral vein

397
Q

What is after the femoral vein?

A

External iliac vein

398
Q

What is after the external iliac vein?

A

Common iliac vein

399
Q

What is after the common iliac vein?

A

Inferior vena cava

400
Q

Where may drainage paths be found?

A

Deep and superficial

401
Q

What vein sits superficially?

A

Great saphenous vein

402
Q

Where is the great saphenous vein found?

A

Running the length of the leg in the hypodermis

403
Q

What is the longest vein in the body?

A

The great saphenous vein

404
Q

Where does the great saphenous vein join the femoral vein?

A

At the groin

405
Q

How many layers are in blood vessels?

A

3

406
Q

What are the 3 layers of blood vessels?

A

Tunica intima, tunica media and tunica adventitia

407
Q

What is the inner layer of blood vessels?

A

Tunica intima

408
Q

What is the middle layer of blood vessels?

A

Tunica media

409
Q

What is the outer layer of blood vessels?

A

Tunica adventitia

410
Q

What are the layers of the tunica intima?

A

Endothelium, sub-endothelium and internal elastic elamin

411
Q

What is the endothelium?

A

A simple squamous epithelium which lines the lumen of all vessels

412
Q

What does the endothelium act as?

A

A barrier between blood and the vessel wall which prevents clotting

413
Q

What is the sub-endothelium?

A

A sparse pad of loose FCT cushioning and supporting the endothelium

414
Q

What is the internal elastic lamina?

A

A condensed sheet of elastic tissue.

415
Q

How does the IEL compare in veins and arteries?

A

It is well developed in arteries and less developed in veins

416
Q

What is the major component of the IEL?

A

smooth muscle which is under involuntary control and autonomic tone

417
Q

What is the content of connective tissue in the tunica media?

A

Variable fibres of mainly elastin and collage

418
Q

What is the thickness of the tunica media proportional to?

A

Vessel diameter and blood pressure - thicker in arteries than veins

419
Q

What is the tunica adventitia composed of?

A

Loose FCT with a high content of collagen and variable amounts of elastin depending on the vessel

420
Q

What does the tunica adventitia have in larger vessels?

A

Vasa vasorum which are blood vessels that supply the blood vessels

421
Q

What is also found in the tunica adventitia?

A

Lymphatics and autonomic nerves

422
Q

What are the two types of arteries?

A

Elastic arteries and muscular arteries

423
Q

What do elastic arteries have?

A

More elastic tissue in the tunica media so that they are able to dampen the high pressure from the heart

424
Q

What is an example of an elastic artery?

A

Thoracic artery

425
Q

What do muscular arteries have?

A

Less elastin and more smooth muscle cells in the tunica media

426
Q

What is an example of a muscular artery?

A

Femoral artery

427
Q

What are arterioles?

A

Small arteries which are the last vessel in the supply path before the capillary bed

428
Q

What is the function of arterioles?

A

Act as the resistance vessels of the circulation - determine the blood pressure

429
Q

What is the function of capillaries?

A

Site of exchange between blood and tissues

430
Q

What are venules?

A

The first part of the collecting (drainage) system

431
Q

What do venules contain?

A

Monocuspid (one cusp/leaflet) valves to ensure that the blood doesn’t move backwards

432
Q

What are veins?

A

A low pressure, large volume transport system

433
Q

What do veins act to do?

A

Ensure one way (unidirectional) flow

434
Q

What type of vessels are veins?

A

Capacitance vessels which can hold accumulated blood if needed.

435
Q

Are capillaries capacitance vessels?

A

no

436
Q

Are arteries capacitance vessels?

A

no

437
Q

What is the structure of veins?

A

Irregular, flattened shape with large lumen and thin wall

438
Q

What do veins have?

A

Spare capacity meaning they can take up extra blood volume

439
Q

What are the layers of veins?

A

Intima, media and adventitia

440
Q

What is the media like in veins?

A

Much thinner than arteries - a few layers of smooth muscle (often in two distinct layers - circumferential and longitudinal)

441
Q

What is the adventitia in veins?

A

Often the thickest layer

442
Q

Where do deep veins sit?

A

With skeletal muscle either side of them

443
Q

What happens to deep veins when the muscle contracts?

A

It squeezes the vein and therefore pushes the blood up

444
Q

What stops blood flowing backwards in veins?

A

Valves

445
Q

When do varicose veins occur?

A

when veins dilate and so valve cusps no longer close properly allowing some blood to flow backwards

446
Q

What is the function of capillaries?

A

Site of exchange between blood and tissues

447
Q

What does the function of capillaries require?

A

Very thin walls, large total cross sectional area of capillary bed and slow and smooth blood flow

448
Q

How does the total area of capillaries compare to arterioles?

A

Much larger which means much slower blood flow

449
Q

What is found in a capillary?

A

Layer of endothelial cells, nucleus, red blood cells and intercellular (tight) junction

450
Q

What is the size of a red blood cell?

A

8-10 micrometres

451
Q

What is found in a capillary bed?

A

Terminal arteriole, precapillary sphincters, vascular shunt and post capillary venule

452
Q

What is the terminal arteriole?

A

The end of the supply netwokk

453
Q

What is included in the vascular shunt?

A

Metarteriole and thoroughfare channel

454
Q

What is the post capillary venule?

A

Start of the drainage network

455
Q

What are precapillary sphincters composed of?

A

Smooth muscle cells under involuntary control

456
Q

What are precapillary sphincters able to do?

A

Constrict and prevent blood flowing into the capillary bed

457
Q

What does the vascular shunt do?

A

Pushes blood straight from the supply to drainage without passing through the exchange network

458
Q

What are the 3 types capillaries?

A

Continuous, fenestrated and sinusoidal

459
Q

What are continuous capillaries?

A

Most widespread

460
Q

What are fenestrated capillaries?

A

Leaky

461
Q

What are sinusoidal capillaries?

A

Very leaky

462
Q

What is the diameter of continuous capillaries?

A

8-10 micrometres (single file flow of RBC)

463
Q

What is the most common form of capillary?

A

Continuous capillaries

464
Q

What do continuous capillaries also have?

A

A surrounding basement layer of extracellular tissue produced by the endothelial cells which the substances must also pass through

465
Q

what is the diameter of fenestrated capillaries?

A

8-10 micrometers (single file flow of RBC)

466
Q

What do fenestrated capillaries have?

A

Porous openings called fenestrations

467
Q

What is an example of fenestrated capillaries?

A

Glomerulus in the kidneys which filter the blood

468
Q

What is the diameter of sinusoidal capillaries?

A

30-40 micrometres (multiple RBC flow)

469
Q

What does the larger diameter of sinusoidal capillaries mean?

A

They are more likely to be involved in transport of nutrients and toxins rather than gases as RBC are further from the capillary wall

470
Q

What are the size of the openings in sinusoidal capillaries?

A

Larger than fenestrations

471
Q

How is the basement membrane in sinusoidal capillaries?

A

Incomplete

472
Q

What is an example of sinusoidal capillaries?

A

Liver sinusoids

473
Q

What are the methods of transport through capillaries?

A

Diffusion through membrane, movement through intercellular clefts, movement through fenestrations and transport via vesicles of caveolae

474
Q

What substances diffuse through the membrane?

A

Lipid soluble substances

475
Q

What substances move through intercellular clefts?

A

Water soluble substances

476
Q

What substances move through fenestrations?

A

Water soluble substances

477
Q

What substances move via vesicles or caveolae?

A

Large substances

478
Q

How do substances move through continuous capillaries?

A

Diffusion through membrane, movement through intercellular clefts and transport via vesicles of caveolae

479
Q

How do substances move through fenestrated and sinusoidal capillaries?

A

Diffusion through membrane, movement through intercellular clefts, movement through fenestrations and transport via vesicles of caveolae

480
Q

What capillary doesn’t require transport through the basement membrane?

A

Sinusoidal

481
Q

What is the lymph vascular system?

A

An open entry (drainage) system

482
Q

What are the functions of the lymph vascular system?

A

Drain, filter, screen and absorb

483
Q

What does the lymph vascular system drain?

A

Excess fluid and plasma proteins from tissues and returns them to the blood

484
Q

What does the lymph vascular system filter?

A

Foreign material from the lymph

485
Q

What does the lymph vascular system screen?

A

Lymph for foreign antigens and responds by releasing antibodies and activated immune cells

486
Q

What does the lymph vascular system absorb?

A

Fat from intestine and transports it to blood

487
Q

How does the lymphatic system commence?

A

As large, blind ending capillaries

488
Q

What does the lymphatic system do from the small intestine?

A

A special group of lymphatic vessels called lacteals drain fat-laden lymph into a collecting vessel called the cisterna chyli

489
Q

What do larger (thin wall) collecting vessels have?

A

Numerous valves to prevent backflow

490
Q

How are lymph vessels described?

A

Thin walled (thinner than veins and arteries), no RBC’s and has valves

491
Q

How is the body split when it comes to the lymphatic system?

A

The left side of the body and the right side of the body below the diaphragm are one section and the right side of the body above the diaphragm is another section

492
Q

What does the lymph from the left side of the body and the right side of the body below the diaphragm do?

A

Enter the thoracic duct and drain into the left subclavian vein

493
Q

What does the lymph from the right side of the body above the diaphragm do?

A

Enter the right lymphatic duct and drain into the right subclavian vein

494
Q

What does the small intestine virus contain?

A

A lacteal which drains to the cisterna chill and then to the thoracic duct

495
Q

Where are lymph nodes found?

A

Tend to be in clusters throughout the body but are also found separately

496
Q

What are some of the nodes in the body?

A

cervical, axillary and inguinal

497
Q

Where are cervical nodes?

A

In the neck

498
Q

Where are axillary nodes?

A

In the armpit

499
Q

Where are inguinal nodes?

A

In the groin

500
Q

What is found in the structure of a lymph node?

A

Afferent lymphatics, efferent lymphatics and lymphoid cells

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