Tissues of the Body Flashcards
1
Q
Define epithelia.
A
- Sheets of contiguous tissue
- Varying embryonic origin
- Cover external surfaces & line internal surfaces
2
Q
How many days does it take for skin to be renewed?
A
28 Days
3
Q
How many days does it take for small intestine epithelia to be renewed?
A
4-6 Days
4
Q
What are the 4 regions of the epidermis in descending depth?
A
I remember it as SGPB, a more amusing one might be Horny Grannies Pickle Beetroot.
- Stratum Corneum (horny)
- Granular Layer
- Prickle Cell Layer
- Basal Layer
5
Q
What are the 6 layers of the wall of the oesophagus?
A
- Epithelium
- Lamina Propria
- Muscularis Mucosa
- Submucosa
- Muscularis Externa
- Adventitia
6
Q
What are the four layers of the ailmentary tract?
A
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
7
Q
What can needle methods of biopsy be used for?
A
- Brain
- Breast
- Liver
- Kidney
- Muscle
8
Q
What can a smear biopsy be used for?
A
- Cervix
- Buccal cavity
Everyone knows about cervical smears but it can also be used in the mouth for the exact same reason.
9
Q
What can curettage be used for?
A
Testing endometrial lining of uterus
10
Q
What can direct incision be used for?
A
- Skin
- Mouth
- Larynx
11
Q
What can endoscopic methods be used for?
A
Think about what you can see if you shove a pipe up or down the two orifices:
- Lung
- Intestine
- Bladder
12
Q
What can transvascular methods be used for?
A
- Heart
- Liver
13
Q
What do serous membranes consist of?
A
- Simple, squamous epithelium
- Connective tissue
14
Q
What does a mucous membrane consist of?
A
- Epithelium
- Lamina propria
- Muscularis mucosa
15
Q
What is a gland described as if it’s ducts branch?
A
Complex/compound
16
Q
What is a gland?
A
An epithelial cell/collection of epithelial cells specialised for secretion.
17
Q
What is an endocrine gland?
A
A ductless gland which secretes directly into the blood
18
Q
What is an exocrine gland?
A
A gland with ducts
19
Q
What is confocal microscopy?
A
Labelling of a tissue with multiple probes to produce a 3D render
20
Q
What is connective tissue?
A
- A tissue (group of cells)
- Mesodermal origin
- Consists of cells and protein fibers embedded in a chiefly carbohydrate ground substance
21
Q
What are the special molecules contained in mucous?
A
Mucins (high glycosylated polypeptides) which stain badly in H&E
22
Q
What is Dark Field microscopy and why is it used?
A
Don’t include the unscattered light from beam so it can be used to view live and unstained samples
23
Q
What is PAS and what does it stain?
A
Periodic Acid-Schiff stains carbohydrates and glycoproteins magneta
24
Q
What is Phase Contrast and why is it used?
A
The interference effects of combining two light waves to enhance the image of unstained cells
25
What is the basement membrane?
The thin, flexible, acellular layer between the epithelial tissue and connective tissue
26
What is the benefit of glycosylation and where does it occur?
Branching sugars are added in the golgi and are responsible for interactions such as:
- Inhibition
- Communication
- Adhesion
27
What is the definition of the term biopsy?
The removal of a small part of an organ for microscopic examination
28
What is the function of the basement membrane?
- Provides surface for epithelia to adhere to
- Cellular and molecular filter
- Penetration into it gives an indication of cancer prognosis
29
What is the meaning of the word tissue?
A collection of cells specialised for a particular function
30
What is the purpose of ground substance?
- Acts as a lubricant
| - Barrier to pathogens
31
What is transepithelial transport?
When a molecule is too large to be taken though a membrane it is endocytosed into a vesicle and then exocytosed
32
What parts of a tissue does H&E stain?
- Haematoxylin stains acidic components in the nucleus purple/blue
- Eosin stains alkaline components in the cytoplasm pink
33
What two components make up the extracellular matrix?
Fibers and ground substance
34
Where can endocrine glands be found?
- Thyroid
- Pancreas
- Adrenal
- Parathyroid
35
Suggest some places where exocrine glands can be found?
- Goblet cells (unicellular glands) in Jejunum
- Submandibular
- Parotid
- Pancreas
36
Where can the protein elastin found?
Dermis of the skin
37
Which areas in the body are simple squamous epithelia located?
- Loop of Henle
- Bowman's capsule of Kidney
- Mesothelium
- Endothelium
- Alveoli
38
Which areas of the body are keratinised stratified squamous epithelia located?
-Skin
39
Which areas of the body are non-keratinised stratified squamous epithelia located?
- Buccal cavity
- Vagina
- Anus
- Oesophagus
- Surface of cornea
40
Which areas of the body are simple columnar epithelia located?
- Lining of the stomach
- Small intestine
- Uterus
- Oviducts
- Gallbladder
- Ductuli Efferents of testis
41
Which areas of the body are simple cuboidal epithelia located?
- Surface of the ovary as a barrier
- Thyroid follicles
- Kidney tubules
42
Which areas of the body are simple pseudostratified epithelia located?
- Lining of nasal cavity
- Trachea
- Bronchi
- Eustachian tube
- Epididymis
43
Which areas of the body are stratified transitional epithelia located?
Urinary bits:
- Ureters
- Bladder
- Calyces of kidney
44
Which fixatives are commonly used to fix tissues?
Glutaraldehyde and formaldehyde
45
Which type of secretion has vesicles in cell but not when released?
Merocrine (exocytosis)
46
Which type of secretion has vesicles pinched off from the cell membrance?
Apocrine
47
Which type of secretion involves the entire cell being released and disintegrating?
Holocrine
48
Why are shrinkage artefacts commonly created?
The dehydration and rehydration in slide preparation
49
Why is histology important?
- Provides gold standard of diagnosis
| - Inform what specific type of treatment to give a patient
50
What is histology?
The study of the structures of tissues by means of special staining techniques combines with light and electron microscopy
51
Why do tissues need to be fixed?
- Macro molecules are cross linked, preserving cellular structure
- Prevents autolysis
- Prevents putrefaction
52
Describe keratinocyte differentiation.
1) Keratinocyte mitosis occurs in BASAL layer
2) Daughter keratinocytes move into prickle cell layer where terminal differentiation occurs meaning the cells can no longer divide
3) Then in the granular layer cells lose plasma membrane and become corneocytes
4) FInally in the stratum corneum they are flattened corneocytes
53
Where are melanocytes found?
Basal cell layer of epidermis
54
What do melanocytes produce?
Melanin N.B. More melanin production leads to darker skin - not more melanocytes
55
Where are Langerhans cells found?
Prickle cell layer of the epidermis
56
What is the function of Langerhans cells?
Specialised to present antigens to T lymphocytes to mediate immune response
57
Where is the epidermal basement membrane located?
Occurs at the dermo-epidermal junction below the basal layer of the epidermis
58
What 5 cell constituents make up the dermis?
- Fibroblasts
- Blood vessels
- Lymphatic vessels
- Mast Cells
- Nerves
59
What are the components of the extracellular matrix in the dermis?
- Ground Substance
| - Fibres (Type 1 collagen, elastin etc.)
60
List the 4 types of skin appendage
- Hair Follicles
- Nails
- Sebaceous glands
- Eccrine and apocrine sweat glands
61
What are the 4 main functions of skin?
- Barrier
- Sensation
- Thermoregulation
- Psychosexual communication (whey!)
62
What are the three histological forms of muscle?
- Skeletal
- Cardiac
- Smooth
63
Which two histological forms of muscle are striated?
- Cardiac
| - Skeletal
64
What is the thick filament called?
Myosin
65
What is the thin filament called?
Actin
66
Outline the 5 stages of the sliding filament model of muscle contraction, starting with attachment.
- Attachment of the myosin head to the actin molecule
- Release of the myosin head when ATP binds
- Cocking of the myosin head due to hydrolysis of ATP
- Force generation as the myosin weakly binds and the phosphate is released leading to the power stroke
- Reattachment of the myosin head to the actin
67
How does calcium allow for the binding of myosin to actin?
- Increased amounts of calcium bind to the TnC part of troponin
- Conformational change moves tropomyosin away from the actin binding site
- This displacement allows for the binding of myosin to the actin site
68
Describe the mechanism of innervation of muscle and excitation contraction coupling. (6 points)
- Action potential arrives at the pre synaptic neurone causing influx of Ca2+
- Causes vesicles containing acetylcholine to fuse with membrane and release Ach
- Binds to nicotinic receptors (nAch receptors) on the motor end plate
- Binding leads to depolarisation of the sarcolemma by an influx of sodium
- Proteins in T tubule change conformation causing calcium to be released from the terminal cisternae into the sarcoplasm
- Ca2+ binds to Tnc on troponin casuing contraction
69
Which connective tissue surrounds the entire muscle?
Epimysium
70
Which connective tissue surrounds the muscle fascicle?
Perimysium
71
Which connective tissue is inside each fascicle?
Endomysium
72
Where do skeletal muscle fibres interdigitate with tendon collagen bundles?
Myotendinous junction
73
What do many fascicles make up?
Muscles
74
What do myofilaments make up?
Myofibrils
75
What are muscle fibres made of?
Myofibrils
76
What are fascicles made of?
Muscle fibres
77
How can skeletal muscle be repaired?
Tissue regenerates by the mitotic activity of satellite cells which fuse with muscle cells to increase mass
78
Cardiac muscle cannot be regenerated, what happens instead?
Fibroblasts invade, divide and lay down scar tissue
79
Which muscle cells retain their mitotic activity?
Smooth muscle
80
Which six features could distinguish cardiac muscle from other types of muscle?
- Branching
- Centrally placed nucleus (doesn't occur in skeletal)
- Intercalated discs
- Adherens type junctions
- Striations (don't occur in smooth)
- Purkinje fibres
81
Which type of muscle has the T tubules in line with Z lines?
Cardiac muscle
82
What is the function of gap junctions?
Electrical coupling
83
Which type of muscle has the T tubules in line with A-I band junction?
Skeletal muscle
84
What shape are the cells of smooth muscle?
Spindle-shaped (fusiform)
85
What type of muscle has no sarcomeres or T Tubules?
Smooth muscle
86
What are the benefits of smooth muscle?
- Contraction is more sustained
- Contraction requires less ATP
- Capable of being stretched
87
What are the features of Purkinje fibres?
- Abundant glycogen
- Sparse myofilaments
- Extensive gap junction sites
- Rapid conduction of action potentials
88
What is the function of Purkinje fibres?
They transmit action potentials to the ventricles from the atrioventricular node
89
What is it called when more muscle is destroyed than created?
Atrophy
90
What is it called when more muscle is created than destroyed?
Hypertrophy
91
What is another name for sensory neurones? What is their function?
Afferent neurones carry impulses to the central nervous system
92
What is another name for motor neurones? What is their function?
Efferent neurones carry impulses away from the central nervous system
93
What type of connective tissue is an entire nerve surrounded by?
Epineurium
94
What type of connective tissue is a nerve fascicle surrounded by?
Perineurium
95
What type of connective tissue is a single axon cell surrounded by?
Endoneurium
96
What are neurones with multiple dendrites known as?
Multi-polar
97
What are neurones with one axon and one dendrite known as? Where are they usually found?
Bi-polar neurones usually found in the retina of the eye
98
What are neurones with one axon only known as? Give an example of one type.
Unipolar - the primary sensory neurone
99
What is the sleeve of Schwann cells surrounding peripheral nerves called?
Neurolemma
100
What are the gaps between Schwann cells called?
Nodes of Ranvier
101
Which histological stain is commonly used to detect the myelin sheath? Why?
Osmium tetroxide as the myelin sheath is predominately lipid which is soluble in most of the common staining techniques.
102
In the CNS what maintains the myelin coating?
Glial cells called oligodendrocytes
103
Which nervous system nervous system contains myelinated (CNS) and unmyelinated (PNS) neurones?
Autonomic (involuntary) nervous system
104
Which nervous system contains myelinated neurones only?
Somatic (voluntary) nervous system
105
What type of neurotransmitter do excitatory neurones release?
Release glutamate/aspartate neurotransmitter
106
What type of neurotransmitter do inhibitory neurones release?
Release of glycine/GABA neurotransmitter
107
How does demyelination relate to a slowing of conduction velocity?
The impulse can no longer jump from Node of Ranvier by saltatory conduction and therefore cannot be propagated as quickly meaning the impulse moves slower
108
What is the name for the nerve cell body?
Perikaryon
109
What are the 4 main features of the perikaryon?
- Nucleus
- Nucleolus
- Nissl substance (aggregation of RER)
- Dendrite
110
What is the function of astrocytes? Where are they found?
Astrocytes are found in the blood brain barrier of the CNS and assist in the transfer of nutrients/waste
111
What is the function of oligodendrocytes? Where are they found?
Maintenance of the myelin sheath in the CNS
112
What is the function of microglia? Where are they found?
The microglia are important in immune and inflammatory responses in both the CNS and PNS
113
What is the function of satellite cells?
Physical support of peripheral neurones
114
The autonomic nervous system is made up of which two neurones?
Pre-ganglionic and post-ganglionic
115
Why is the sympathetic nervous described as having a thoraco-lumbar outflow?
Its cells begin in the thoracic and lumbar regions of the spinal cord
116
Why is the parasympathetic nervous described as having a cranio-sacral outflow?
Its cells begin in the cranial and sacral regions of the spinal cord
117
What are the relative sizes of the pre and post ganglionic nerve fibres in the sympathetic nervous system?
Short pre-ganglionic and long post-ganglionic
118
What are the relative sizes of the pre and post ganglionic nerve fibres in the parasympathetic nervous system?
Long pre-ganglionic and short post-ganglionic
119
What is the overall function of the sympathetic nervous system?
- Fight/flight/fright
- Diversion of blood to muscles
- Increase in heart rate
- Increase in blood pressure
- Reduced blood flow to skin and GIT
120
What is the overall function of the parasympathetic nervous system?
- Relaxed state
- Reduced heart rate
- Increased digestion
- Increased bodily functions
- Increased sleep
121
In the parasympathetic nervous system what type of transmitter is used in the pre ganglionic nerve fibre?
Cholinergic transmitters
122
In the parasympathetic nervous system what type of transmitter is used in the post ganglionic nerve fibre?
Cholinergic transmitters
123
In the parasympathetic nervous system what type of receptors do the post ganglionic neurones express?
Nicotinic receptors
124
In the sympathetic nervous system what type of receptors do the post ganglionic neurones express?
Nicotinic receptors
125
In the sympathetic nervous system what type of transmitter is used in the pre ganglionic nerve fibre?
Cholinergic transmitters
126
In the sympathetic nervous system what type of transmitter (mainly) is used in the post ganglionic nerve fibre?
Noradrenergic transmitters
127
In rare cases some post ganglionic transmitters of the sympathetic nervous system are not noradrenergic, what transmitter are they?
Cholinergic transmitters
128
Give two examples of cholinergic transmitters of the post ganglionic nerve fibres of the sympathetic nervous system.
- Perspiration
| - Ejaculation
129
Define the term “limit of resolution"
Limit of resolution is the minimum distance that two objects can be distinguished at.
130
What is the glycocalyx?
The cell ‘coat’ made up of oligosaccharide and polysaccharide side chains on the outside of the plasma membrane.
131
What are fibroblasts?
Synthesise and maintain extra-cellular materials. Synthesise collagen, elastic and reticular fibres and ground substance.
132
What are mast cells?
Near blood vessels containing granules (histamine and heparin). They release pharmacologically active molecules.
133
Where can reticular fibres be found?
- Form a delicate network around smooth muscle cells, certain epithelial cells, blood vessels, adipocytes and nerve fibres
- Make the structural framework around certain organs such as the liver, spleen, bone marrow and lymphoid organs.
134
What is ground substance made up of?
- Glycosaminoglycans (GAGs)
- Proteoglycans
- Glycoproteins
135
What gives elastic fibres their ability to stretch?
High lysine content
136
What type of connective tissue is blood?
Loose
137
Give some examples, other than blood, of loose connective tissue.
Forms the septa (walls) and trabeculae (rods) that make up the framework inside organs and adipose tissue.
138
What are the three major types of cartilage?
- Hyaline
- Elastic
- Fibrocartilage
139
What are the main features of mucous connective tissue? Where is it found?
- Large stellate fibroblasts (which fuse with similar adjacent cells), few macrophages and lymphocytes and soft ground substance full of hylauronic acid-Loose connective tissue
- Only found in the umbilical cord and subdermal CT of the embryo.
140
Where is areolar connective tissue found? What type of connective tissue is it?
Loose connective tissue found:
- Deep under the skin
- Submucosa
- Below the mesothelium of the peritoneum
- With adventitia of blood vessels
- Surrounding the parenchyma of glands
141
What is areolar connective tissue made up of?
- Fibroblasts
- Macrophages
- Some mast cells
- Collagen fibres are the most abundant
- Elastin fibres also present.
142
What type of tissue is adipose tissue?
Loose connective tissue
143
What type of tissue is reticular tissue? Where is it found?
Loose connective tissue found in:
- Liver
- Kidney
- Spleen
- Lymph nodes
- Bone marrow
144
Name two places in the body where you could find dense regular connective tissue?
- Ligaments
| - Tendons
145
What are ligaments made up of?
Dense regular connective tissue - Collagen fibres interspersed with fibroblasts
146
What is the main histological difference between ligaments and tendons?
In ligaments collagen is less regularly arranged than in tendons.
147
Describe the histological structure of tendons.
- Collagen fibres interspersed with flattened fibroblasts in bundles -> fascicles
- Fasiciles have endotendineum (loose CT) inside and held together by peritendineum. A fibrous sheath surrounds the whole tendon
148
What is the benefit for the skin of havind dense irregular connective tissue?
Has Interwoven bundles of collagen which counteracts multi-directional forces
149
What is the benefit for a tendon of having dense regular connective tissue?
Fibre bundles orientated in parallel to provide maximum tensile strength which means huge strength in one direction
150
What is the main histological difference between loose and dense connective tissue? Why?
Dense CT has close packing of fibres with fewer cells and less ground substance. This allows it to achieve mechanical support and transmit forces
151
What are entrapped chondroblasts known as?
Chondrocytes
152
What is the function of the chondroblasts?
Secrete the matrix which entraps the cells
153
What is cartilage made up of?
- Organic substances
- Mesenchymal cells
- Collagen type I fibres
- Ground substance (protein, glycoprotein, glycosaminoglycans, lipids and water)
154
What is the cartilage often surrounded by? What is this made up of?
Perichondrium (dense irregular connective tissue) made up of:
- Outer Fibrous layer
- Inner cellular (chondrogenic) layer
155
What is the foetal skeleton made up of?
Hyaline cartilage
156
What are the two remnants of the hyaline cartilage (that made up the foetal skeleton) in the child?
- Growth plates
| - Articular cartilage
157
What is the main type of collagen in hyaline and elastic cartilage? Why?
Type II Collagen for firm and flexible support
158
What is the main type of collagen in fibrocartilage? Why?
Type I Collagen (in bundles) for mechanical strength and rigidity and Type II Collagen
159
Which type of cartilage has no perichondrium?
Fibrocartilage
160
Where can hyaline cartilage be found?
- Respiratory passageways
- Articulating surfaces of long bones
- Anterior ends of the ribs
- Foetal skeleton
161
Where can elastic cartilage be found?
- Pinna of ear
- Epiglottis
- Auditory tubes
162
Where can fibrocartilage be found?
- Intervertebral discs
- Menisci of the knee
- Pubic symphysis
163
What are the main functions of bone?
- Support
- Protection
- Mineral storage
- Haemopoiesis.
164
Describe the two different types of bone.
- Compact (dense) bone made up of vertical osteons with horizontal Volkmann's canals and vertical Haversian canals
- Cancellous (spongy) bone
- Meshwork of trabeculae filled in with marrow
165
What are the two colours of marrow and what is their respective function?
- Red: red blood cell synthesis
| - Yellow: contains adipose tissue
166
Which hormone stimulates osteoclasts to reabsorb bone matrix leading to calcium in the blood?
Parathyroid hormone
167
What is the hardness and rigidity of bone due to?
The interaction between collagen and inorganic salts
168
What three types of cells are found in bone?
- Osteoblasts – synthesise organic bits of cells, make bone + produce osteoid matrix.
- Osteocytes – found in the lacunae cavities, maintaining bone and are formed when osteoblasts are entombed
- Osteoclasts – large multinucleated cells from monocytes that digest bone.
169
What are the two types of ossification called? What do they give rise to?
- Intramembranous - flat bones created from loose connective tissue/mesenchyme
- Endochondral - most skeletal bones, made from the hyaline cartilage of foetus
170
Describe the process of endochondral ossification
- Cartilage is reabsorbed and replaced with bone (e.g. long bones)
- Begins at the primary centre in the shaft (diaphysis) and later at each end (epiphysis – secondary centre)
- Growth in length is at epiphyseal growth plates
171
Describe the process of intramembranous ossification
- Begins as highly vascularised loose connective tissue
- Mesenchymal cells differentiate into osteoblasts surrounded by collagen fibres and ground substance
- Osteoblasts secrete uncalcified matrix (osteoid) and then become osteocytes
172
Describe the cellular processes involved in bone repair following a fracture.
1) Big ole' hole in the bone and rupture of blood vessels supplying it - bone cells start dieing
2) Inflammatory cells invade that mess and form a huge haematoma (blood out of a vessel) - we refer to this as a pre-callus and it's now got lots of cytokines and growth factors floating in it
3) Osteoblasts, chondroblasts and fibroblasts start creating a soft callus with bits of bone, cartilage and connective tissue in it
4) This soft callus is converted into a hard (bony) callus via endochondral ossification to make a solid lump of bone
5) The final stage is remodelling where bits of bone are cut away and the bone is shaped by tendons pulling the bone until it matches the contours of the surrounding bone until it fully heals
-
173
What is the transit time of a keratinocyte from basal layer to stratum corneum during keratinocyte differentiation?
30-40 days
174
Describe the microstructure and organisation of muscles in order of size.
- Fascicles
- Muscle fibres (cells)
- Myofibrils
- Myofilaments (actin and myosin)
175
What metabolic changes accompany hypertrophy?
Need more energy (ATP) and more oxygen:
- Increased enzyme activity for glycolysis
- Increased mitochondria
- Increased stored glycogen
- Increased blood flow
176
An increase of muscle mass from work performed against load results in what? What is this described as?
More contractile proteins, increase in fibre diameter - Hypertrophy
177
What is the benefit of the rapid conduction of the action potentials down Purkinje fibres?
Enables the ventricles to contract in a synchronous manner
178
In general terms outline the process of haemopoiesis
- Proliferation: Starting with a stem cell, the cell divides into two. One to replace the original stem cell (self-renewal) and one that differentiates.
- Differentiation of haemopoietic progenitor (under influence of cytokine) to form either a myeloid blast (RBC, WBC, platelets) or a lymphoid blast (immunoresponse cells)
179
What causes differentiation to red blood cells?
Erythropoietin
180
What causes differentiation to platelet cells?
Thrombopoietin
181
What is the main driver of erythropoiesis?
Partial pressure of O2 - if it's low it stimulates increase in erythropoietin
182
Name the 5 types of white blood cells that circulate in the blood and lymphatic system. What type of nucleus does each have?
- Neutrophils (Multi-lobed nucleus)
- Eosinophils (Bi-lobed)
- Monocytes (Kidney shaped)
- Basophils (Bi- or Tri-lobed)
- Lymphocytes (Deep staining)
183
What is the structure of erythrocytes?
- Biconcave disc
- 4 globin chains (2α & 2β)
- Each molecule carries a haem
184
What is the function of erythrocytes?
Carries O2 to tissues and CO2 to the lungs
185
What is the structure of reticular cells?
Synthesise reticular fibres and surround them with cytoplasm
186
What is the function of reticular cells?
Direct the T and B lymphocytes to specific regions with the lymphatic tissues
187
Describe the core structure of platelets.
- Small round blue particles
- Produced by megakaryocytes in the bone marrow
- Cytoplasm contains α fibrinogen, Von Willebrand’s factor and dense (ADP and Ca2+) granules
188
Describe the core function of platelets.
- Clotting cascade
| - Adhere to damaged cells walls and aggregate together
189
What is the function of eosinophils and neutrophils?
Phagocytosis
190
What is the function of basophils?
Mediate acute inflammatory reactions using heparin and histamine
191
Describe the main function of monocytes.
- Migrate through the blood and become macrophages when leaving the blood in many organs of the body
- When they become mature macrophages they are capable of phagocytosis and interacting with T cells
192
Name the seven humoral components of the innate immunity system and briefly describe what each of them do?
- Transferrin/Lactoferrin deprive microorganisms of iron
- Interferons inhibit viral replication
- Lysozymes breakdown peptidoglycan in bacterial cell walls
- Antimicrobial peptides do what they say on the tin
- Fibronectin – opsonises bacteria and promotes their phagocytosis
- Complement causes destruction of microorganisms directly/with the help of phagocytic cells
- TNF-α suppresses viral replication and activates phagocytes
193
Name the five cellular components of the innate immunity system and describe what each of them do?
- Macrophages (monocytes when they are in the blood) – phagocytosis and antigen presentation to lymphocytes.
- Neutrophils – Phagocytic and anti-bacterial
- Eosinophils – Anti-parasite and allergic response
- Basophils & Mast Cells – Allergic response
- Natural Killer Cells – Recognise and kill abnormal cells, e.g. tumours
194
Name the three humoral components of the adaptive immunity system and describe what each of them do?
- Cytokines – Promote the differentiation and proliferation of lymphocytes
- Perforin – Released by T killer cells and destroy cell walls
- Antibodies – Protect host by neutralisation (prevents binding to epithelia), opsonisation and complement activation (enhances opsonisation and lysis)
195
Name any TWO cellular components of the adaptive immunity system and describe what each of them do.
- T Helper – Become activated when CD4 binds to a specific antigen on the MHC/antigen complex of an APC (antigen presenting cells). Once activated, it clones itself to form active T-helper cells and T-memory cells
- T Killer – Released when cell is already infected
- B Cells – Divide to form plasma cells and memory cells when activated by T-helper cells and release cytokines
- Plasma cells produce specific immunoglobulin for non-self antigen.
196
Suggest THREE of the features of innate immunity which make it different to adaptive immunity.
- Present from birth
- Non-specific
- No "memory"
- Not enhanced by secondary exposure
197
What is haem component of haemoglobin broken down in to? Where does this take place
- Bilirubin
| - Formed in the reticuloendothelial cells of the liver, spleen, and bone marrow.
198
Describe the function of the liver in bilirubin metabolism.
Glucuronidation - liver reacts bilirubin with a solubilizing sugar called glucuronic acid
199
Describe the excretion of bilirubin after it reacts with glucuronic acid and is excreted in the bile.
- Bile goes through the gall bladder into the intestines where the bilirubin is changed into a variety of pigments (importantly stercobilin and urobilinogen)
+ Stercobilin excreted in the faeces (white faeces)
+ Urobilinogen excreted via the kidneys (brown urine)
200
What are the meninges?
The system of membranes which envelops the central nervous system
201
What are the three layers of meninges?
You have to PAD the brain, so from inner to outer:
- Pia mater
- Arachnoid
- Dura mater
202
What are the 5 layers of stomach?
- Epithelium
- Gastric Mucosa
- Muscularis Mucosa
- Submucosa
- Muscularis Externae
203
Describe the process of opsonisation with relation to phagocytosis.
Phagocytosis is enhanced by the coating of antibodies or complement on an infected cell to render it recognisable as foreign (opsonisation).
