Case 8 Flashcards
(119 cards)
1
Q
Give a function of the epidermis
A
Waterproofs the skin and acts as barrier
Has keratinocytes here (produce keratin, a protective protein)
Merkel cells here, these detect fine touch and pressure
2
Q
What the layers of the epidermis?
A
Strateum Corneum Strateum Lucidium Stratum Granulosum Stratum Spinosum Stratum Basale
3
Q
What the the two types of epidermis, and where are they found?
A
Thick skin and thin skin
Thick skin on palms and soles, hairless
Thin skin everywhere else, has hair
4
Q
Thick epidermis has 4/5 layers of epidermis, while thin epidermis has all 5. True or false?
A
False, thick has all 5
5
Q
What type of cells makes up the epithelium?
A
Keratinised, stratified squamous (flattened, stacked)
All layers made from keratinocytes
6
Q
Which layer of epidermis is present in thick epidermis that isn’t present in thin?
A
Strateum Lucidium - clear layer of dead skin cells
7
Q
What is present in the Strateum Corneum?
A
- Keratin
- No nucleus
- Barrier function
- Corneodesmosomes: modified desmosomes that link adjacent cells in epidermis (adhesive structures)
8
Q
What is present in the Stratum Granulosum?
A
- Waterproof function
- Keratinisation of skin
9
Q
What is present in the Stratum Spinosum?
A
Keratinocyte maturation
10
Q
What is present in the Stratum Basale?
A
- Single layer of cuboidal cells and melanocytes
- Cells move from basale layer to surface
- As cells move up, migration, differentiation and apoptosis happens
11
Q
What is Sepsis?
A
A life threatening organ dysfunction caused by the disregulated host response to infection
12
Q
Which infection leads to Sepsis
A
Any infection
13
Q
Why has the definition of Sepsis changed in recent years?
A
Sepsis is rapidly acting (multi organ failure, septic shock, death)
If caught early, can be treated well
If caught a few hours later, can be fatal
Changed criteria for spotting sepsis, so it can be detected earlier
14
Q
What is bacteraemia?
A
Bacteria in blood
15
Q
What is infection?
A
Inflammatory response to microorganisms or invasion of
16
Q
What is septic shock?
A
As a subset of sepsis which particularly profound, circulatory, cellular and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone.
17
Q
Give the risk factors for sepsis
A
Very young or very old (under 1 or over 75)
Immunocompromised
Having a chronic disease like diabetes or cancer
18
Q
What bacteria cause sepsis?
A
- S.aureus
- pseudomonas S.pp
- E.coli
- Klebsiella
19
Q
Where can bacteria enter to cause infection?
A
- Respiratory tract (most common)
- Abdomen (after surgery)
- Bloodstream after wound
- Genitourinary tract (elderly more likely to get UTI’s)
- Skin infection
- Catheter related
20
Q
What are Langerhans cells?
A
Dendritic cells - migrate to lymph nodes upon activation
21
Q
Describe the layers of the skin
A
- Epidermis
- Dermis
- Hypodermis/subcutaneous
22
Q
What are the layers of the dermis?
A
- Papillary layer
- Reticular Layer
23
Q
What cells are present in the Papillary layer of the Dermis?
A
- Fibroblasts (make collagen)
- Adipocytes
- Blood vessels
- Phagocytes
- Lymphatic capillaries
- Nerve fibres
- Meissner Corpuscles (touch receptors)
- Dermal papillae, these are projections of dermis into Stratum Basale of Epidermis
24
Q
What is in the Reticular layer of the Dermis?
A
- Dense, irregular connective tissue (collagen and elastin)
- Well vascularized (blood supply)
- Rich sensory and sympathetic nerve supply
25
What is the function of the subcutaneous layer?
Connects the skin to underlying fascia (fibrous tissue) of bones and muscle
26
What structures are in the subcutaneous layer?
- Fat (though this varies in some areas) - for insulation and cushioning
- Well vascularised = blood vessels
- Loose, areolar connective tissue
27
What structure would you expect to find in the hypodermis of the head and neck that you wouldn't find in other parts of the body?
- Platysma (very broad muscle)
| - Muscles for facial expression
28
The clitoris, penis and eyelids have no adipose tissue is their hypodermis. True/False?
True
29
What accessory structures of the skin begin in the dermis?
Nails, endocrine glands, and hair
30
How is the surface area of the skin divided around the body?
Use the '9' rule
- Head is 9%
- Upper limb is 9%
- Lower limb is 18%
- Abdomen is 18% (abdomen and front of thorax, abdomen and back of thorax)
31
What are melanocytes?
Cells which produce melanin
| Specifically, cytoplasmic projections that transfer melanin granules (proteins) into granulocytes
32
Where are melanocytes found?
Basal layer of epidermis
33
What does melanin do?
Absorbs light/ UV-B = acts as protection for skin
| Needs to be stimulated by UV-B or ACTH (adrenocorticopic hormone, produced by pituitry gland and regulates cortisol)
34
Describe the mechanism of a Meissner Corpuscle
Mechanoreceptor (sensory, responds to mechanical pressure)
Stimulus (nudge)
- Meissner Corpuscle made of disks (specialised epithelial cells)
- disks move and Na+ can leak into disk below
- do this until bottom reached (where afferent nerve fibre is)
- Transmit Action Potential to afferent nerve fibre
- goes to CNS = response
- goes to efferent nerve fibre
*Meissner Corpuscles require constant changing stimuli
35
What is the function of a Meissner Corpuscle?
Detects 'light touch'
36
What is the function of a Pacinian Corpuscle?
Mechanoreceptor
| Detect vibration pressure in hairless skin
37
What is the structure of a Pacinian Corpuscle?
'onion' shaped, many rings of connective tissue built around nerve ending = reduces mechanical sensitivity of nerve ending
38
Describe the mechanism of a Pacinican Corpuscle
Significant stimuli (push from finger)
- layers begin spinning
- Na+ and other ions enter the ring
- Ions go to the middle of rings
- Reach afferent nerve fibre at centre
- AP generated
- Goes to CNS = response
39
Name all the infection types that S.aureus causes
- Toxin mediated
| - Suppurative (produce pus)
40
How does S.aureus cause disease from releasing toxins?
-S.aureus enter body
-Grow and colonise
-Release toxins
-Toxins acts as Superantigens (SAgs)
-Superantigens stimulate non-specific T cell response
-Polyclonal T cell and cytokine release
This is a defence mechanism against immune system
41
What are the toxin mediated diseases caused by S.aureus?
- Scalded skin syndrome (bacteria grows in dermal layers, skin falls off)
- Food poisoning
- Toxic shock syndrom
42
What are the suppurative diseases caused by S.aureus?
- Impetigo
- Empyema
- Pneumonia
- Osteomyelitis
- Endocarditis
- Septic arthritis
- Folliculitis
- Carbuncles
43
What is the treatment for septic arthritis?
Admission and IV antibiotics
44
What are the pathogenicity factors of S.aureus?
- Capsule
- Protein A
- Fibronectin binding protein
- Cytolytic exotoxins
- Panton-valentine leucocidin
- Superantigens exotoxins
45
How does the Capsule of S.aureus aid it in infection?
Prevents phagocytosis by protecting the bacteria from being engulfed
46
How does Protein A of S.aureus aid it in infection?
Surface protein originally found in the cell wall of the bacteria Staphylococcus aureus.
Binds to IgG = exerting anti-opsonisation effect
47
How does Fibronectin binding protein of S.aureus aid it in infection?
Aids binding to host cell
The protein is a cell-surface bound protein that binds to fibronectin (involved in general cell adhesion) and Fibrinogen (involved in clotting).
48
How do Cytolytic proteins of S.aureus aid it in infection?
- Produced from gram negative bacteria
| - Act as Haemolysins (lipids and proteins which break down cell walls of RBC’s) = destroy red blood cells
49
How does Panton-valentine leucodine of S.aureus aid it in infection?
- Beta pore forming toxins
| - Lyses Polymorphonuclear lymphocytes (immune cells)
50
What are the types of superantigens exotoxins?
- Enterotoxins (A,B,C,D,E,G)
- Toxic Shock Syndrom Toxins
- Exfoliatin toxins
51
What do enterotoxins do?
These are half of all S. aureus isolates cause vomiting and diarrheas
(This s. aureus grows in food)
52
What do Toxic Shock Syndrom Toxins do?
- Can happen in men and women
- Symptoms are: high temperature (fever) of 39C (102.2F),headache, chills, muscle aches, a sore throat and a cough, feeling and being sick, diarrhoea, a widespread sunburn-like rash, the whites of the eyes, lips and tongue turning a bright red, dizziness or fainting, breathing difficulties, confusion, drowsiness
53
What do Exfoliatin toxins do?
Blistering of the skin known as staphylococcal scalded skin syndrome, usually in infants.
54
What is MRSA?
Methicillin Resistant S. aureus (MRSA)
Antibiotic resistant strain of S.aureus
Common cause of nosocomial infections (hospital spread)
55
What is given to treat MRSA?
-Flucloxacillin will not work
-Give Glycopeptides e.g. Vancomycin
Weakens walls of bacteria, killing it
-Tetracycline
Different antibiotics needed means increase in cost and resources
56
What are PSMs?
```
Peptides of S.aureus
Allows bacteria to attach to cell walls
Cause neutrophils to lyse
Help biofilm formation
*Good target for drugs
```
57
How can bacteria enter the body?
- Skin breaks
- Catheter
- Surgical wound
- Immunocompromised = can't fight off infection
58
How does bacteraemia happen?
The biofilm forms
| Spores of this drops off into the blood
59
What is the first step in identifying Strep?
Blood culture
60
What would you expect to see in a blood culture of alpha haemolytic strep?
Haemoglobin changes colour
61
What would you expect to see in a blood culture of beta haemolytic strep?
RBC lysis
62
What would you expect to see in a blood culture of gamma haemolytic strep?
No change
63
What are the subgroups of beta haemolytic strep?
- Pyogenes (Group A)
| - Agalactae (Group B)
64
What bacteria species is beta haemolytic strep?
Gram positive cocci
65
What is the bacteria usually responsible for UTIs and uncomplicated wound infections?
Enterococcus
66
What is Strep Throat/Pharyngitis?
Inflammation of the pharynx =
| scratchiness in the throat and difficulty swallowing
67
What is the difference between viral and bacterial Pharyngitis?
```
Viral - can treat at home, will see red, swollen tonsils and throat
Bacterial - Need urgent care.
Swollen uvula, tonsils and throat.
White spots
Tongue is grey and furry
```
68
What is erysipelas?
| *What are the symptoms?
Bacterial infection of upper skin, caused by group A strep
*Symptoms: fever, chills, malaise, a red, swollen, and painful area of skin with raised edge blisters on the affected area
swollen glands
69
What is scarlet fever?
| *What are the symptoms?
Toxin mediated disease of group A strep
Rapidly fatal
*Symptoms: sore throat, fever, headaches, swollen lymph nodes, and a characteristic rash. The rash is red and feels like sandpaper and the tongue may be red and bumpy.
70
What is Necrotizing fasciitis?
| *What are the symptoms?
Flesh-eating disease, infection from group A strep that results in the death of parts of the body's soft tissue. It is a severe disease of sudden onset that spreads rapidly.
*Symptoms include red or purple skin in the affected area, severe pain, fever, and vomiting. Have to remove all of infected tissue
71
What diseases does group A strep cause?
```
Pharyngitis – Rheumatic fever
Impetigo
Scarlet fever
Erysipelas
Cellulitis
Necrotising fasciitis
Puerperal sepsis
Invasive group A streptococcal disease
Streptococcal toxic shock syndrome
Sepsis
```
72
Describe how group A strep spreads
- Germ is invasive and opportunistic, meaning infection happens when this germ is where it shouldn't be
- Inhaled through droplets or direct contact
- Reservoir is skin or nasopharynx
- Bind to pharyngeal mucosa through Protein Fm, Lipotechoic acid or M antigen (binds specifically to epithelial wall)
- Colonisation can be asymptomatic or symptomatic
73
What are the Pathogencity factors of group A Strep?
| *Describe what each factor does
-Streptolysin O and S
Lysis of Eukaryotic cells so bacteria can spread
-Hyaluronidase
Breaks down connective tissue
-Streptodornases
Breaks down DNA in lysed tissue/cells
-Streptokinase
Lysis of clots to allow spread of infection
-Pyogenic toxins
Superantigens (these trigger immune responses)
Responsible for many of the clinical manifestations e.g. scarlet fever
-C5A peptidase
cell-surface-localized serine protease that inactivates human C5a (neutrophil chemoattractant produced during complement activation) = inactivates complement
74
What is the danger of pharyngitis?
May develop Rheumatic fever and then Rheumatic heart disease
75
How is strep throat diagnosed?
FEVERPAIN Index
Rapid antigen test - use to determine whether it is viral or bacterial. Sample of mucus exposed to antibodies - positive result if there is a reaction.
76
What are the steps in the FEVERPain Index?
Fever over 38°C.
Purulence (pharyngeal/tonsillar exudate).
Attend rapidly (3 days or less)
Severely Inflamed tonsils
No cough or coryza (catarrhal inflammation of the mucous membrane in the nose)
1 point for each
77
What are the results of the FEVERPain index?
0 or 1 is associated with a 13% to 18% likelihood of isolating streptococcus.
A score of 2 or 3 is associated with a 34% to 40% likelihood of isolating streptococcus.
A score of 4 or 5 is associated with a 62% to 65% likelihood of isolating streptococcus.
78
What antibiotic should be given to someone with Pharyngitis/Strep throat?
*Is there a vaccine?
Phenoxymethylpenicillin - Penicillin or
Amoxicillin as alternative
*There is no vaccine
79
How does Rheumatic fever happen after strep throat?
-S. pyogenes has M protein on cell envelope
-This has a cross reaction with human cell surface proteins
= autoimmune reaction which causes symptoms
80
What are the symptoms of Rheumatic fever?
(1-5 weeks after streptococcal pharyngitis)
Fever
Rash
Carditis (inflammation of heart, can cause fibrosis of heart valves)
Arthritis
CNS manifestations (Sydenham chorea - rapid and involuntary movements of arms, legs and face.)
80% of symptoms increase within 10 weeks
81
What are the symptoms of Rheumatic Heart disease?
```
Permanent damage to cardiac valve tissue
Dizziness
Chest pain
Shortness of breath
Tiredness
Heart Failure
```
82
What is the likelihood of developing Rheumatic Heart disease?
1 in 3 with Rheumatic fever
83
What type of S.aureus is S. pneumoniae?
alpha haemolytic
84
What is the gram stain of S. pneumoniae?
Gram positive diplococci (in pairs)
85
S. pneumoniae is a part of flora. True/False?
True
86
What is meant by exogenous infection?
From outside agent e.g. droplet from carrier
87
What is meant by endogenous infection?
From within e.g. own flora ends up in place where it shouldn't during immunocompromised period
88
What diseases does S. pneumoniae cause?
Bacterial Pneumonia - Leading Cause of CAP
Otitis media – ear infections
Pnuemococcal Bacteremia – systemic infection (in blood), very invasive form
Pneumococcal Sepsis
Pneumococcal Meningitis – 2nd leading cause in UK
89
What are the Pathogenicity factors of S. pneumoniae?
-Capsule
Antiphagocytotic – invade innate immune system
-Pili
Enable attachment to cells of URT
-Choline binding protein
Facilitates binding to carbohydrate of cells in URT
-Autolysins – protein produced by strep
Facilitate breakdown of cell to allow release of pnuemolysin – damages eukaryote cells
-Pneumolysin – released when bacteria self destruct, helps bacteria around it
Breakdown of Eukaryotic cells
90
What is given to treat pneumococcal meningitis?
Penicillin
91
What are the beta lactam resistant strains of pneumoccal meningitis?
Cephalosporins
| Vancomycin
92
What is Prevanar 13?
Polyvalent vaccine introduced in 2010
| Protects against 13 strains that cause 96% of infections
93
Describe the mechanism of a Merkel cell
- Stimulus (light touch)
- NP (neucleopeptides) are released
- These go to the NP receptor
- Ion channels open
- Na+ enters cell
- Goes to afferent nerve = AP induced
- AP goes to CNS = response
- Goes to efferent nerve
* need sustained/constant stimulus
94
Describe the structure of a Merkel cell
- Specialised keratinocyte
- Oval shaped mechanoreceptors
- Vesicle pockets with membrane around them
95
Where are Merkel cells found?
In the stratum basale or papillary layer of thick skin (hairy and non hairy)
96
Where are Pacininan Corpuscles found?
In the dermis of glabrous/hairless skin
97
Where are Meissner's corpuscles found?
In the papillary dermis of tips of fingers and lips (non hairy skin)
98
What do Pacinian Corpuscles detect?
Vibration pressure
99
Where are Ruffini corpuscles found?
Between dermal papillae and hypodermis
100
What are Ruffini corpuscles?
Slowly adapting mechanoreceptors
101
What is the function of Ruffini corpuscles?
Detect skin stretch - this helps with finger coordination
102
Describe the mechanism of a Ruffini corpuscle
- Stimulus (from finger)
- Collagen shifts and is perturbed (Collagen is found in reticular dermis)
- Ion channels on nerve channels open up
- Na+ in extracellular matrix enters
- Ions go along afferent nerve fibres = AP
- AP goes to CNS = response
- efferent nerve
103
What are the 'ridges' on fingertips?
| *why do we have them?
These are our "fingerprints"
Dermal papillae that forms epidermal/papillary ridges
They are used to amplify vibrations, assist in gripping, improve surface contact in wet conditions
104
Name the two types of sweat glands
Apocrine
| Eccrine
105
Where are Apocrine sweat glands found?
Armpits and pubic area
106
Where are Eccrine glands found?
-All over body, highest in palms and soles
107
Where are Eccrine glands not found?
- Eardrum (tympanic membrane)
- Lip margins
- Nipples
- Inner surface of prepuce (foreskin), glans penis and labia minora
108
Describe the mechanism of Apocrine glands
- Secrete fatty sweat into gland tubule
- Emotional stress
- Tubule wall contracts
- Fatty secretion is excreted on skin
- Bacteria breaks down into odorous fatty acids = smell
109
Describe the function of Eccrine cells
Thermoregulation
| Cools the body down by secreting water onto skin
110
What does 'insensible water loss' mean?
Water lost through evaporation
111
What does the fluid secreted by Eccrine glands consist of?
99% water, NaCl, trace of other waste products
| The solution is hypotonic
112
What supplies the Eccrine and Apocrine glands?
Adrenergic fibres in the sympathetic nerves
113
Where are Apocrine glands found?
-Start in dermis
-Travel up and fuse with hair follicle
OR
-Directly onto skin
114
Where are Eccrine glands found?
- Start in dermis
| - Empties directly onto skin
115
Describe the structure of of an Eccrine gland
-Simple coiled structure
-Made of cuboidal secretory cells (find in low reticular layer and hypodermis /subcutaneous layer)
-Intraepidermal spiral duct
-Dermal duct with a straight and coiled portion (2 layers thick - stains darkly and cells are clustered)
-Secretory tubule coiled deep in dermis of hypodermis
(See figures)
116
What is the average amount of water lost to sweating?
300/400 ml
117
Describe the structure of an Apocrine gland
-Coiled structure
-Bigger than Eccrine
-Have a large lumen for moving a viscous fluid
-Secretory products are stored at apex of cell in secretory regions
(See figures)
118
Describe the mechanism of sweating
- Eccrine innervated by sympathetic post-ganglionic fibre
- Ach released and binds to receptors in membrane of clear eccrine gland cells
- Secretion of colourless solution by coil in SC (secretory compartment)
119
Where do the left and right coronary arteries branch from?
Ascending aorta
