10.1 Introduction to body defences Flashcards
List the five components of the static barriers of the innate immune system
- Skin
- Mucosa
- Stomach Acid
- Tears
- Microbiome
List the four components of the soluble barriers of the innate immune system
- Antimicrobial peptides
- Complement
- Opsonins
- Cytokines
List the five components of the cellular barriers of the innate immune system
- Macrophages
- Basophils/mast cells
- Natural killer cells
- Neutrophils
- Dendritic cells
List the two types of cells involved in adaptive immune response
- T cells
- B cells
List the six classes of immune cells involved in the innate immune response
- Natural killer cells
- Neutrophils
- Basophil/Mast Cell
- Monocyte
- Macrophage
- Dendritic Cell
List the two types of T cells
CD4 and CD8
How do natural killer cells perform their function
Triggering apoptosis
Neutrophil function
Phagocytose bacteria and viruses
Basophil/mast cell function
Inflammatory response; degranulating and releasing inflammatory mediators
What do monocytes differentiate into?
Macrophages (which have similar function to neutrophils)
Dendritic cell function
Capture and present antigens to CD4 T cells
CD4 T cell differentiation and subsequent function:
- Differentiates into t helper cells
- Secretes cytokines to help others
CD8 mechanism of action
Kills via apoptosis (basically the NKCs of the adaptive response)
B cell differentiation and function
Become plasma cells which produce antibodies
List the functions of skin
- Protection (infection, injury)
- Immunity
- Sensation (touch, pain, etc.)
- Thermoregulation
- Water balance (sweat)
- Waste excretion (urea, uric acid, NH3)
- Vitamin D production
What are the three layers of the skin?
- Epidermis
- Dermis
- Hypodermis
What type of tissue is within the epidermis?
Stratified epithelium (predominantly keratinocytes)
Is the epidermis vascular or avascular?
Avascular (needs connective tissue in dermis)
From bottom to top, name the five layers of the epidermis
- Stratum basal
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum Corneum
Describe the structure and function of stratum basal
- Continuous layer of single columnar epithelial cells; constantly dividing
- Made of immature basal keratinocyte stem cells
- Ensures that above layers of the epidermis are produced
- Connected to basement membrane
Describe the structure and function of stratum spinosum
- “Pricke cell layer”: proteins of desmosomes for stretch and shock resistance
- Several layers
- Provides strength
Describe the structure and function the stratum granulosum
- Thin granular layer
- Cells contain keratin granules, and secrete keratin into extracellular space
Describe the structure and function the stratum lucidum
- Thin clear layer
- Only seen in thick skin (palms and soles)
- Filled with a clear, intermediate form of keratin called eleidin
Describe the structure and function the stratum corneum. What is the name of the process that results in constant replacement of these cells?
- Multiple layers of dead cells embedded in keratin
- Protective layer from environment
- Constant desquamation and replacement
What are the four types of cells in the epidermis?
- Keratinocytes
- Langerhans cells
- Merkel cell
- Melanocyte
Structure and function of langerhans cells
- Dendritic cell (antigen presenting)
- Ingest foreign particles, and carries them to lymph nodes to inform the immune system of invaders
Structure and function of melanocytes
- Produce melanin
- Reside in stratum basale
- Secrete melanosomes which travel toward the apical surface and protect DNA from photo damage
Effect of sun exposure on melanin production
Increases (i.e. tannning)
Structure and function of merkel cell. Where are they located in the skin?
- Nervous cell (mechanoreceptors)
- Respond to stretch or torque (particularly in highly sensitive structures)
- Long processes
- Reside in stratum basale of epidermis
Describe changes in keratinocytes as they move towards the skin surface
- Keratin production increases
- Cells flatten
- Nuclei go away (stratum granulosum)
- Layers of dead cells form stratum corneum
How long is the skin regeneration cycle?
~28 days
Does thick or thin skin cover most of the body?
Thin
How is thick skin different from thin skin?
- No hair follicles
- Contains stratum lucidum
- Thick stratum corneum
Which two structures interlock to form the corrugated border between the epidermis and the dermis? Why is this shape advantageous?
- Epidermal ridges
- Dermal papillae
- Increased surface area (both layers need each others)
- These ridges create fingerprints
What are the two layers of the dermis?
- Papillary
- Reticular
What type of tissue is in the papillary dermis?
- Loose connective tissue
What type of connective tissue/fibres is/are in the reticular dermis?
- Dense
- Thick collagen fibres provide strength
What is the hypodermis mainly made of?
Adipose
What is the function of adipose in the hypodermis?
- Insulation
- Energy storage
- Protection
List the accessory organs of the skin
- Hairs
- Nerves
- Sweat gland
What do nerves in the epidermis sense?
- Temp
- Touch
- Pain
- Pressure
What are the two types of sweat glands
- Eccrine
- Apocrine
Which type of sweat gland is more common in areas of abundant hair
- Aprocrine
Which section of the nervous system controls sweat glands
Autonomic (makes sense: involuntary)
Describe the structure of sweat glands
- Secretory portion (where sweat is produced by epithelial cells of exocrine gland)
- Duct portion (carries sweat)
How is sweat released differently in eccrine and aprocrine glands
Eccrine: directly onto surface
Aprocine: release through hair follicle
Functions of sweat glands
- Waste removal
- Thermoregulation
Function of hair/hair follicles
- Touch
- Thermoregulation
- Sensation
What two structures are most hair follicles associated with?
- Sebaceous glands
- Arrector pili muscles
