TOB Flashcards
0
Q
State the meaning of the term tissue?
A
A group or later of cells that performs a specific function
1
Q
How many mm in 100,000 nm?
A
0.1 mm
How many um?
2
Q
Explain the value of histology in diagnosis
A
Gold standard of diagnosis
Final proof of a disease and can determine the appropriate treatment
3
Q
What is histology
A
The study of the structure of tissues by means of a special staining techniques and light electron microscopes
4
Q
What technique involves the removal of a small piece of tissue from an organ or part of the body for microscopic examination?
A
Biopsy
5
Q
List 6 common biopsy techniques, and give examples of tissues that can be sampled by each method.
A
Endoscopic. Intestine, lung, bladder
Direct incision. Close to surface. Skin, mouth, larynx
Needle. Liver, kidney, brain, breast, muscle
Transvascular, liver, heart
Cutterage, endometrial lining of uterus surface
Smear, cervix
6
Q
In biopsys why does tissue need to be fixed?
A
To preserve the cellular structure. Prevents autolysis (destruction of itself by its own enzymes) and putrefaction
7
Q
name 2 common fixatives
A
Glutaraldehyde
Formaldehyde
8
Q
Describe the process of fixing in biopsy
A
Fixation of a fresh sample
Dehydration with ethanol
Clearing with xylene or toluene
Embedding in wax at 56 degrees
9
Q
How do you process a sample embedded in wax for viewing under a microscope?
A
Thin section into of the wax block Rehydration. With water and ethanol and xylene Staining Dehydration Mounting Microscope
10
Q
How are shrinkage artefacts formed?
A
Dehydration by ethanol
And then rehydration by ethanol water and xylene
11
Q
When is the stain PAS used. Periodic acid Schiff reaction,
A
Carbohydrates. E.g. Glucose, starch, glycogen , ribose (ATP, FAD, NAD) Statins
Glycoproteins
Stains pink
12
Q
When is haematoxin and eosin stain used?
A
Haematoxin stand acidic componants, purple and blue
E.g. DNA chromatin. And RNA
Eosin, stains basic components pink.
E.g.mcyroplasmic proteins and extracellular fibre.
13
Q
Describe and explain advantages of phase contrast
A
Uses two light waves,
Keeps cell alive
14
Q
Dark field.
A
In light and electron microscopy
Excludes in scattered beam from the image,
Therefore field around specimen (no specimen to scatter beam) is dark
Used to detect syphilis or malaria
15
Q
Fluorescence.
A
Target molecule of interest with fluorescent stain. Can Use multiple different stains on the sample so can test for multiple things at once
Can detect undetected uv Rays
16
Q
Confocal
A
Eliminates out of focus flair.
Used in living specimens
17
Q
Define epithelial
A
Sheets of continuous cells that cover the external surface of the body, internal spaces that open to the exterior and interior spaces
18
Q
Name the three locations where mesothelium are located.
A
Cavities Pleural sac Pericardial sac Peritoneal Blood vessels
19
Q
Give examples of open cavities in the body where epithelia are located.
A
Digestive
Respiratory
Urgogenital tract
20
Q
Where is the basement membrane (basal lamina) located?
What is its function?
A
In between epithelial cells and subtending connective tissue
Function: cellular and molecular filter, and a strong flexible layer for epithelial cells to adhere to
Also surrounds cells, e.g. Muscle fibres
Underneath sheets of epithelial cells
Separates 2 sheets of cells
Made of collagen, glycoproteins, to make a thin extracellular matrix
21
Q
Name a purpose of reticular fibres (type 3 collagen)
A
Used in connective tissue in lymphoid organs and adipose tissue
22
Q
How do we classify epithelia?
A
Simple/stratified
Shape
23
Q
Give an location of simple squamous epithelia
A
Lining of blood vessels, pulmonary alveoli, Bowmans capsule, middle ear Functions. Thin so good for diffusion, Lubrication Barrier Active transport by pinocyctosis.
24
Location and function of simple cuboidal epithelia
```
Functions. Absorption and conduit (exocrine)
Locations:
Ducts in Exocrine glands
Thyroid follicles
Kidney tubules
```
25
Simple columnar (& with micro villi)
Functions: absorption, secretion, lubrication, transport
Stomach lining, small intestine, colon
Nucleus positioned basally
Micro villi to assist absorption in GI.
26
Stratified squamous (non keratinized)
Resists abrasion and trauma, reduces water loss
| Oesophagus, vagina, oral cavity
27
Stratified squamous keratinized
Waterproof, no nuclei as dead,
Skin surface
Protects against uv, water, abrasion, microbes
28
(Simple) pseudo stratified
Secretion, absorption,mp article trapping and secretions, mucous secretion
Lining of nasal cavity, trachea and bronchi
Epididymis
Can have cilia
29
Stratified transitional
Distends when full. Protects tissue from toxic chemicals
Bladder
Ureters
30
Explain the reason for different rates of renewal at each type of epithelium
Cell renewal rate is high and In most epithelia is occurs regularly
It is Different in different locations e.g. Bladder every 4-5 days and epidermis every 28. Some don't change after puberty
31
Name three surface specialisations of epithelium. And describe how their structure is related to its function
Microvilli, apical extensions that greatly increase the SA for absorption in the intestines
Stereocillia, very long microvilli. Surface or ductus deferens and epidermis
Cilia. Beat in consecutive waves. Lining of trachea and Fallopian tubes
32
Give examples of when epithelial cells would regenerate or be replaced
Regeneration would occur in skin wound healing
Replacement of surface cells on skin
Renewal of uterine lining cells after menstuation
33
Describe metaplasia .
| Give an example
Epithelial cells that have the capacity to change from one type of epithelial cells to another
E.g. In heavy smokers. Pseudo stationed columnar epithelium of respiratory tract can change to stratified squamous
34
Describe neoplasia
In disease, e.g. Cancer, changes may occur in epithelia giving rise to a tumour (neoplasm) - a carcinoma
35
Where is the glomerulus located? And what is its function
Network of blood capillaries within renal corpuscle
| Primary site of blood filtration in the kidneys.
36
What cell is located in the darker staining region of the kidney cortex?
Its function is to filtrate the blood?
The renal corpuscles.
| Comprises of renal tubule (Bowmans capsule) surrounded by glomerulus
37
Why is DNA acidic ( roughly)
you compare the structures of phosphoric acid (Figure 1) and a short strand of DNA (Figure 2), you’ll see that in the latter, two protons of phosphoric acid are replaced by carbon atoms either in, or attached to, the five-membered ring.
In chemical terms, such a group is called a phosphate diester. The remaining proton is now quite acidic, and is relatively easily lost, thereby giving DNA its acidic character.
Indeed, under neutral conditions, DNA is deprotonated at this site, and the oxygen atom bears a negative charge. Despite the fact that DNA does contain many basic groups, their basic properties are masked somewhat because of the fact that they hydrogen bond with each other to form base pairs. Hence it’s the acidic part of the molecule that dominates, and that is why we know DNA as an acid.
38
Describe what a gland is
An epithelial cell or aggregate of cells specialised for secretion.
39
Name the type of gland that secretes substances directly into the blood stream. And give an example
Endocrine.
E.g. Adrenal glands
Cords (adrenal cortex)
Follicles (thyroid)
Clusters (pituitary)
40
Give an example of an exocrine gland and state how they secrete
Secrete through ducts to epithelium and lumens of organs.
E.g. Goblet cells, parotid glands
Can be unicellular (release secretions mucus to surface epithelium) or multicellular (to underlying connective tissue).
41
Name the three types of secretion
Merocrine.
Apocrine
Holocrine
42
Describe Merocrine secretion
Sweat glands
Exocytosis
Secretion contained within membrane bound vesicle.
Fuses with plasma membrane
Makes plasma membrane larger
Contents released into extracellular space
Membrane retrieved and stabilises cell surface area.
43
Describe apocrine secretion and give an example
Lactation ,mammary glands
Non membrane bound structure, e.g. Lipid
Pushes against apical membrane and pinches off from the cell
Makes the plasma membrane smaller so more membrane is added
44
Describe holocrine secretion
The cell disintegrates and releases the contents
| Sebaceous glands
45
Describe endocytosis
Cell engulfs the material and takes it into the cell
46
Describe how material is transported across the epithelium
Coupling reaction between ends and exocytosis .
Engulfed by endocytosis.
Transport vesicle transports the material across the cell.
Secreted by exocytosis
47
What is the function of the Golgi apparatus and where do its products go?
Packages its contents through condensation
Adds sugars to proteins and lipids (glycosylation)
Secreted in vesicles
Some retained in the cell, e,g. Lysosomes
Some to plasma membrane (glycocalyx)
48
Why do we glycosylate some proteins and lipids?
To make more complex shapes for specific interactions in the glycocalyx.MORE SPECIFIC
For adhesion, mobility, communication,
49
How is secretion controlled
Negative feedback
Nervous
Endocrine
Neuro-endocrine
50
Where are goblet cells found, and what do they look like when Staines with alcian blue. What colour are they under haemotoxin and eosin?
Jejunum, intestinal epithelia, tubular glands in large intestine
Mucins stains vivid blue
Not stained,
51
Give an example of a compound serous exocrine gland.
Parotid gland, occurs in pairs- part of salivary glands
Located below and in front of each ear,
Enzymes are located in the cytoplasm of its acinar cells as zymogen granules
52
Give an example of a mixed, compound, tubule acinar gland and describe it
Submandibular glands
Serous, mucous and mixed acini
Large glands surrounded by connective tissue capsule, sends septa into the glands which divides it into lobes
Location : just below the mandible of either side of the neck. Release secretions (saliva) into floor of mouth
53
Are Most secretions of endocrine glands are stored intracellularly or extracellulary? Give an example of the most common type? And explain its function?
Most e doctrine glands the secretions are stored intracellularly.
For example the adrenal gland
Made up of the cortex and the medulla
54
What does each part of the adrenal cortex secrete?
Zona glomerulosa- aldosterone, mineralocorticoids
Zona fasiculata- glucocorticoid hormones e.g. cortisol,
Zona reticularis - androgens and (some glucocorticoids)
Adrenal medulla- catecholamine hormones: adrenaline noradrenaline
55
What does the parathyroid gland secrete? What does this stimulate?
Is the parathyroid gland exocrine or endocrine?
PTH secreted by chief cells
Stimulates osteoclasts to reabsorb bone and reduce calcium loss as urine
Promotes calcium uptake by gut
Exocrine
56
Give an example of gland that stores secretory products extracellulary in follicles
Thyroid gland
Follicles lined by glandular cells
Lots of capillaries
57
Name an organ with mixed endo and exocrine glands, and describe
Lies behind stomach and one end by curve of duodenum
Endocrine gland, islets of langerhans, scattered within exocrine tissue.
Exocrine, most of the tissue, closely packed secretory acini that drain into a highly branched duct system lined with simple columnar epithelium and goblet cells.
Secretes digestive enzymes into duodenum and hormones into bloodstream
58
What do the islets of langerhans secrete?
Insulin (alpha cells
Glucagon (B cells)
Somatostatin (delta)
59
What do the pancreatic acini secrete. The exocrine part of the pancreas
Pro enzymes:
- e.g. trypsinogen
Pancreatic amylase and lipase
60
How does cystic fibrosis affect the pancreas?
Mucus secretions become thicker which block the duct, preventing fat digestion (digestive enzymes not secreted, decreased lipase) and causing pancreatitis.
This is due to the mucus secretions contain too little water.
The CFTR gene causes a transmembrane regulator is effective which means that cl and Na ions are not transported effectively disrupting osmosis.
61
Give examples of mucous membranea and their functions
Line internal tubes that open to the exterior
Alimentary, (GI)
Respiratory
Urinary
Label on histology, the layers of the wall
Epithelia lining
Connective tissue (lamina propria)
Muscularis mucosae (ailmentsry tract, smooth muscle)
62
Name examples of serous membranes
```
Closed cavities, shiny look
Peritoneum (envelops abdominal organs)
Pleural sacs, lungs
Pericardial sacs
Mesothelium secretes lubricating fluid,
2 layers: mesothelium, and thin connective tissue,
```
63
What is connective tissue made up of (broadly)
```
Cells, including fibroblasts, defence cells, storage cells, and mesenchymal (undifferentiated)
Fibres, (collagen, elastin, reticulin)
Ground substance (protein, glycoprotein, gags, lipid, water)
```
64
What is connective tissue and what is its function?
Links together muscle nerve and epithelial tissue
Provides support in metabolic and physiological processes (diffusing medium)
Injury repair
65
What are mesenchyme cells and what can they develop into? Give an example of a connective tissue where they are found
From middle embryonic germ layer. Multi potent. E.g, in mucous connective tissue in umbilical cord
Form fibroblasts that secrete collagen found in ligaments, tendons, supporting tissues
Lipoblasts, fat cells
Chondroblasts, cartilage
Osetoblasts, bone
Myoblasts, skeletal muscle
66
Describe the extracellular matrix in connective tissue
```
Hyaluronic acid (GAG) with attached proteoglycan aggregates
Interwoven with collagen
```
67
Describe the types of collagen and their functions
Ty1: most common, Triple helix found in bundles. In skin, tendons, vascular, organs, bone
Ty2: cartilage
Ty3: reticulate in reticulum fibres. Supporting mesh in soft tissues e.g. Liver and bone marrow. lymphatic tissue
68
List three common cells found in connective tissue and their properties
Fibroblasts, lots of RER and secretory vesicles
Synthesis and secretion of ground substance proteins - Collagen, and glycoproteins
Macrophages. In loose connective tissue, from blood monocytes
Mast cells. Granules contain histaminses and heparin. Binds allegens
69
Describe and give locations and types of dense irregular connective tissue
Connects epithelial tissue of skin to underlying tissue
Irregular: interwoven bundles of collagen. Criss cross, to counter multidirectional forces.
E.g. Dermis of skin, periosteum around bone, perichonfium around cartilage.
Dermis, found below epidermis containing blood vessels, skin appendages (hair follicles, sweat glands, sebaceous glands) sensory neurones
70
Describe and give examples of dense gulag connective tissue
Parallel collagen fibres, more tensile strength
Tendons (muscle to bone) , ligaments (bone to bone), open neurones
Tendons have flattenend fibroblasts - looks like slender nuclei
Not striated and nuclei more squished than in muscle
71
Describe and give examples of loose connective tissue
Less closely packed fibres,
More ground substance and cells
E.g. Beneath epithelial surfaces, around blood vessels, nerves and lymph nodes. Used as packing
E.g. Mucous connective tissue
72
How does vitiligo form?
Autoimmune depigmentation
Less noticeable in whites
Often symmetrical
73
Describe three other skin diseases caused by variations in macroscopic structure of skin (hair ,thickness, colour, laxity, oiliness)
Alopecia areata (hair loss)
Uv induced, ageing, sunburn, cancer
Acne
74
Describe how the epidermis is formed
1) keratinocytes mitosis in basal layer
2) daughter keratinocytes move up to prickle cell layer and produce keratins
3) keratinocytes terminally differentiate into corneocytes, main cells of the stratum corneum
4) stratum corneum made up of layers of flattened corneocytes
Takes 30-40 days
75
List the main cells found in the epidermis
Keratinocytes
Melanocytes, in basal layer, produce melanin
Langerhans cells, in prickle cell layer, unction in immune response
76
Describe the dermo-epidermal junction (basement membrane zone) the dermis snd its constituents: cellular and extracellular
Cellular: fibroblasts, blood vessels, lymphatic vessels, mast cells, nerves
Extracellular matrix, collagen, ground substance, elastin
Basement membrane just below basal layer of epidermis
Below that is dermis: tough vascular layer of extracellular matrix
Blood vessels get bigger further down the dermis,
77
Describe main functions of the skin
Barrier
Sensation
Thermo regulation
Sociosexual communication
78
Describe psoriasis and how it forms
Cause unknown
Proliferation of basal layer into prickle cell layer therfore producing excessive stratum corneum cells
Social impact
79
Describe 4 other skin diseases aside from psoriasis
Allergic contact dermatitis: langerhans mediate
Malignant melanoma: Tumour of melanocytes
Vitiligo: autoimmune disease attacking melanocytes leading to depigmentations
Allopecia areata
80
Describe the composition of cartilage
No blood vessels
Extracellular matrix: GAGs with type 2 collagen (protein with gags attached and acid monomers interwoven with collagen)
Cells: chondrocytes, produce and maintain matrix
Matrix: solid firm a resilient to pressure
81
Describe the three main types of cartilage
Hyaline cartilage: extracellular Martix containing proteoglycans attached to hyularonic acid and type 2 collagen
Elastic cartilage: matrix withi proteoglycans and hyularonic acid and type 2 collagen. Also had elastic fibres
Fibrocartilage: similar matrix but with type 1 collagen.
82
What role does the perichondrum have and where is it located?
Surrounds cartilage (except at sites where cartilage meets)
It is a connective tissue containing fibroblasts that maintain the matix and gradualy transitions into cartilage and chondrocytes cells.
It is vascular so supplies nutrients to the chondrocytes
In articulating surfaces where there is no perichondrum, the chondrocytes calcify and harden.
They also have more type 3 collagen and has more extracellular matrix in between the two king bones,medics friction and resist compression.
83
Describe the characteristics of elastic cartilage
Elastic fibres in matrix
Doesn't calcify
Locations: three Es pinna of inner ear. Eustachian tube, epiglottis
84
Characteristics and location of fibrocartilage
```
Chondrocytes and fibroblasts
Dense regular type 1 collagen
No perichondrium
shock absorber
Locations: intervertebral discs, menisci of knee joint
```
85
describe the different types of bone
Cancellous, spongy: irregular network of trabecullae. Spaces filled with bone marrow
Compact hard outer layer, osteocytes arranged in concentric lamellae.
Has haversin and Volksmann canals that carry blood vessels, lymph, and nerves
Covered by periosteum (unless at articulating surfaces)
86
Describe the cellular structure of bone
Bone structure consists of concentric lamellae of the mature or inactive osteocytes. Join to other lamellae by canaliculi that provide s channel for ions and nutrients and form gap junctions.
They are lined by sheath of Neuman.
Lamellae arranged around haversin Canada's that communicate with Volksmann canals.
Periosteum
Perichondrium
87
How does the cellular company's of compact and cancellous bone differ?
Cancellous bone is made of trabecullae which is arranged irregularly and allows for strength and lightness.
It doesn't have any haversin or Volksmann canals
88
Describe the four stages of fracture repair
1) clot and swelling: blood clot (heomotoma) when blood vessels break. Bone cells die athe the site which I leads to swelling.
2) Fibrocartilageonous callus: procalus of granulation tissue (capillaries and fibroblasts). Collagen holds it together
3) bony Callus formation. Hard callus and produces Cancellous bone, formed by ossification. Starts after a few days, continues for two months
4) bone remodelling: forms compact bone. Bulging material removed by osteoclasts.
89
Describe endochrondral ossification
```
Replacement of existing hyaline cartilage: e.g from foetus
Ossify at the epiphysial growth plates
Growth plates move apart
Occurs in most long bones
From cartilage to bone
```
90
Describe intermembrous ossification
Within mesenchymal tissue, not by replacing existing hyaline
Forms flat bones, e,f skull, pelvic, clavicle,
Thickens bones instead of lengthening
91
Describe the function of the three thypes of cells involved in ossification
Osteoclasts: break down bone
Osetoblasts: build up bone
Osteocytes: maintain bone
92
What is bone made of
Cells in calcified matrix
| Matrix: collagen and hydroxyapatite crystals (ca and pI)
93
Describe the cause and morphological features of androchronoplasia. And effect on society
Short limb dwarfism, normal intelligene
Caused by autosomal dominant point mutation
Affects fibroblast growth factor receptor
Reduces endochrondral ossification
Reduces chondrocytes in growth plate
Reduces cellular hypertrophy
Reduces cartilage matrix formation
80% born to parents without condition, new mutation.
94
Effects of a normal levels of growth hormone
Before puberty: high levels = gigantism. Epiphyseal growth plate activity promoted. Low levels = pituitary dwarfism
Adults: high = no epiphyseal plates so no effect on bone length. But does affect width. Promotes periosteum growth. Acromegaly (benign tumour)
95
Describe effects of abnormal levels of sex hormones
Affect ossification centre development
Androgens and oestrogens: sexual characteristic and stimulate pubertal growth spurt
Leads to retardation of bone growth at premature puberty, so epiphyseases close early
If fixing then keep growing and very tall
96
Describe the genetic basis of osteogenesis imperfecta. And it's risk to society
Affects type one collagen synthesis
Symptoms: brittle bones, fractures, abnormally curved, thin bones, hearing loss
More sever types: cause fractures on delivery = lethal
Deliberate injuries?!
Genetics: autosomal dominant,
Can be at risk of passing it on. Effect on mother of child dies at birth. The disease is progressive.m
97
Describe the importance of vitamin d in normal bone development
From diet or from uv light
Uv light: 2 hydroxyl action reactions, in liver and kidney
Increases ca absorption by small bowel and promotes remodelling by mineralization
98
Describe features of bones affected by rickets
Bones don't harden, soft, malformed,
Not enough calcium deposits caused by lack of vitamin d Therfore not stimulating uptake
Common in immigrant Asian population, need more vitamin d,
99
Describe osteomalacia
In adults caused by calcium or vitamin d deficiency
Symptoms: bone pain, back ache, muscle weakness,s trabecullae in cancellous bone has non mineralised bone (osteoid) covering its surface= weakened
100
Describe osteoporosis and its effect in society
Metabolic bone disease, depletion of bone mass.
Leads to bone marrow washing out
Type 1: post menopause women, due to increases osteoclasts after oestrogen withdraws
Type 2: elderly. Decreased osteoblast function
Risk factors: reduced calcium intake and absorption. Bed rest and lack of excercise increased bone loss.
White women at highest risk
101
Where is bone marrow located and name the two types
In the spaces of cancellous bone. And the central cavity
Which is found at ends of bones and in centres of bones
Red marrow: blood cell formation (Haemopoiesis)
Yellow marrow: formation of adipose tissue
102
How are tears in adult cartilage repaired
No mitosis, differentiated
So repaired by fibrous scar tissue
Bone can repair
103
Give the histological differences in the three types of muscle
Skeletal: striated, multiple peripheral nuclei (edge), voluntary control
Cardiac: striated, short fibres, single central nucleus, in voluntary, intrinsic rhythm,
Smooth: non striated, single central nucleus, involuntary, local stimuli,
104
Describe skeletal muscle
Location:
How power output varies
C
Pectoralis major muscles, biceps, rector femoris
Long fibres, length of the muscle and insert into the connective tissue e.g. Tendons
Power output depends on number of fibres and increased excercise increases volume, hypertrophy not number of fibres
105
Describe the cellular contents of a muscle cell
Cell made of many myofibrils, mitochondria (sarcosomes), sarcoplasmic reticulum and nuclei.
Grouped together and surrounded by sarcolemma
Muscle cell- nuclei
106
Describe cellular structure of muscle
Muscle fibres of myofibrils wrapped by sarcolemma are surrounded by and joined by connective tissue endomysium
Grouped together in s fasicle wrapped by perimysium
Fasicles and blood vessels grouped to form the muscle
All wrapped by the thickest connective tissues, epimysium
Joins to tendons and then bone
107
How are muscles connected to the body
Connected to tendons by myotentional junctions
Extrinsic muscles insert muscle into bone or cartilage e.g, tongue
Intrinsic muscles, not attached to bone, but to collagen and matirix of connective tissue
108
Describe smooth muscle
Long spindle shaped cells with a few central nuclei
Slow sustained contractions using actin and myosin interactions
Locations: walls of GI (mid Oesophagus to anus) and respiratory tracts (trachea to alveolar ducts). Walls of ducts and glands. Arteries and veins
In exocrine glands can assist secretions due to myoepithelial cells forming basket work around secretory units. Stimulated by calcium ions
Myofibroblasts assist in wound healing, produce collagen matrix. Contract by actin and Mysore
Stimulated by autonomic nervous systems (neurotransmitter in synaptic cleft)
109
Describe how mature muscle repairs from tears
Skeletal: cells can't divide, tissue regenerated using satellite cells undergo hyperplasia (mitosis) and fuse together with muscle cells to increase mass (Hypertrophy)
Cardiac: no regeneration, fibroblasts invade, divide and produce scar tissue
Smooth: retain Mitotic activity, produce new cells. Muscle cell wall thickens
110
Describe cardiac muscle,
Involuntary
No distinct myofibrils, continuous muscle
Has intercalated discs at z band level joining the fibres together
Weaker vertical discs forming gap junctions for electrical coupling
T tubules at z band (at a band? In skeletal)
Purkinjie fibres
111
Describe Purkinjie fibres
Purkinjie fibres carried in myocardial cells and have glycogen, extensive gap junctions, conduct action potentials rabidly causing ventricles to contract. Sparse myofilaments
Action potentials generated in sinoatrial node, pass through to av node to ventricles
112
Describe myofibril structure and their componants
Myofibrils made of myofilaments
Myofilaments are thin (actin) or thick (myosin) 2:1.... (Actin shorter so thinner)
Actin made of tropomyosin and troponin (2:1 so on ends)
Myosin made of myosin molecules,in rod like structure with heads (middle one)
113
Describe the sliding filament model of muscle contraction(4steps)
Ca ions bind to troponin c receptor on actin. Releasing tropomyosin and uncovers active site
Myosin heads bind to the active site releasing ADP and PI and pulls actin towards it
Atp attaches to myosin and releases the actin
Head returns back to normal
114
How is contraction stimulated (7steps)
Initiation: nerve impulses travel through neuromuscular junction
Impulse releases acetylcholine (AcH) into a synaptic cleft=
depolarises sarcolemma in muscle
Na channels open = repolarization of sarcolemma (outside of fibre) which changes t tubule conformation
Ca released into sarcoplasm
Binds to TnC subunit of troponin
Contraction cycle
AcH inhibited by acetylcholinesterase
115
How do the muscle fibres respond to excercise
Metabolic adaptation: e.g cardio
More mitochondria, larger z band, more t tubules/wider?
Hypertrophy: weights, stimulates protein syntheis = fatter fibres
116
How does skeletal muscle develop
Myoblasts from myotonic stem cells
| Fuse to form a myotube
117
Describe how atrophy can occur
Disuse : bed rest. Disuse, loss of proteins loss of fibre diameter
Age, after 30 yrs, harder to generate heat
Denervation atrophy: lack of nerve supply leads to atrophy, due to lack of stimulation,
118
Describe myasthenia gravis
Neuromuscular junction disorder
Autoimmune destruction of end plate AcH receptors
Leads to loss of the junctional folds that provide wells for the receptors and increase SA. = slower muscle contractions
Symptoms: tired. Falls, drooping eyelids, can't hold arm out
Treatment: acetylcholinesterase inhibitors, immune suppressants, thymectomy
119
Give an example of other substances that can effect the neuro muscular junctions
Toxins e,g, boutalism
| Affects AcH release
120
What affect do inorganic phosphates have on muscle
Muscles stay contracted as not producing acetylcholinesterase
Leads to suffocation
121
Describe the condition of duchenne muscular dystrophy and how it occurs
X linked recessive
Progressive disorder affecting proximal muscles
Muscles tear themselves apart on contraction because the cell membrane doesn't move with the muscle, stays and is torn.
Releases creatine phosphate - measure
Causes swelling before repaired
Imbalance between antagonistic and and atomistic muscles. Early signs
Steroid therapy
122
Describe malignant hyperthermia
Autosomal dominant
Caused by sudden raised intercellular ca levels e.g. Allergic reaction to anaesthetics
All muscles contract leading to hyperthermia and rapid temp increase: can be lethal.
Use lots of oxygen. Oxidative phosphorylation occurs rapidly and increases co2 levels
123
What componants make up the CNS
Connects brain and spinal cord
| Neurones (nerve cells) and neurogilla (oligodendrocytes, microbial, astrocytes)
124
What is nissl substance and where is it found
Stacks of RER cisternae used for protein synthesis.
Found in neurones around the cell body
Basophillic
125
Describe the structure of a neurone and nerve cell body (perikaryon)
```
Nissl substance
(Dendrites) receive stimuli from neurones/environment
Nucleus containing chromatin
Golgi apparatus
Axon, conducts nerve impulses. From cell body to other cells
Myelinated or unmyelinated.m
Thicker is quicker
Myelinated -= white matter
```
126
What cell myelinates axons in the cns?
Oligodendrocytes a type of neurogilla
| Myelinate up to 250 axons at a time
127
Describe multipolar neurones and name two other types of neurone
Multipolar neurones means that cells have over two processes, over 2 dendrites to an axon
Bi polar - 2 processes
Pseudo unipolar neurones- fusion of part on a dendrite and the axon
128
List the other neurogilla cells in the CNS
Astrocytes: form the Bbb, help transfer nutrients and waste products between neurone and blood
Oligodendrocytes
Ependeyma: line ventricles and central canal of spinal cord
Migrogila: immune cells and phagocytes.
129
How does a neuron respond to axon being severed
Proximal end seals up and prevents leakage. Forms s nerve stump
Distal end breaks away and dies and is degenerated
Cell body puffs up with increased contents and nucleus moves to the margins: chromatolysis
130
Dscribe the general structure and location of the pns
Cranial and spinal nerves
Bundles of nerve fibres in fasicle supported by connective tissues
Have nerve cells, and neurogilla: scwhaan cells, satellites and microgila
Consists of afferent (impulse to CNS)
Or efferent (CNS to effect on effector ) pathways
131
Describe the process of myelination
In the CNS unmyelinated axons are covered with the cytoplasm of a scwhaan cell. 1 cell for several axons
Myelination
Scwhaan cell winds around axon,
Compacted for insulation
Show poorly in histology. Need osmium tetroxide
132
What is a ganglion and how does is it different in The sympathetic and parasympathetic nervous systems
A collection of cell bodies, occurs where the pre ganglionic and post ganglionic cells meet
In Sympathetic there is a Short pre and long post
paraSympathetic there is long pre and Short post
133
What neurotransmitters are involved in the sympathetic nervous system
Pre ganglionic: acetyl choline and nictionic receptors
| Post ganglionic: noradrenaline and adenoreceptors
134
Neurotransmitters involved in parasympathetic nervous system
Pre ganglionic: AcH and nicotinic
Post ganglionic: AcH and muscarinic
Apocrine blocks muscarinic
135
Describe the somatic nervous system and is it part of the afferent or efferent pathways
Efferent
Under voluntary control
E.g. Rem sleep
136
Describe the autonomic nervous system, part of the efferent pathway
Involuntary, maintains essential life functions
Maintains homeostasis by regulating systems continuously.
Promotes excretory mechanisms, effector organs include: visceral organs, smooth muscle, secretory glands
Sympathetic or parasympathetic.
137
Describe the sympathetic nervous system
Tiger, fight flight
Expends energy
Blood to muscles and heart
Thoracolumbar division
Short Pre ganglionic neurone cell body in the CNS, secrete AcH to a nicotinic receptor on the second neurone
Post ganglionic neurone releases noradrenaline to adenoreceptors on the Effector organs
Ejaculation
138
Describe the parasympathetic nervous system
Lower heart rate
Promote digestion and bodily functions
Nerves from brain via cranial nerves and spinal cord: cranio sacral division
Pre ganglionic secretes AcH and has nicotinic receptors.
Post ganglionic secretes AcH and has muscularinic receptors on the effector organ
Erection
139
What is heomopoiesis
The formation of blood cells from haemopoietic stem cells
Proliferation: stem cell divides into 2: one to replace existing and one that differentiates
Differentiates to a myeloid blast:(RBC,WBC, platelets) or lymphoid blast (immuno response cells)
Cytokines (hormones) control which type.
140
Which cytokines are used to control differentiation to red blood cells and how is it controlled
Which cytokines is used to differentiate to platelets (thrombocytes)
Erythropoietin to rbc (erythrocytes)
Low Partial pressure of oxygen (hypoxia) in kidney stimulates erythropoietin.
More mature erythrocytes means more Hb carried and more oxygen can be transported
Thrombopoietin stimulates platelets
141
List the 5 types of white blood cells and what their functions are, where they're formed
Signalled by damaged tissue
Formed in bone marrow by multipoint haemopoietic stem cells but can mature elsewhere
Neutrophils- phagocytosis
Eosinophils - phagocytosis and allergy response,
Basophils- allergies, histamine
Monocytes- become macrophages, phagocytosis
Lymphocytes- natural t killer cells, form plasma cells,
142
What is the function of the reticuloendothelial system.
Port of immune system containing phagocytotic cells e.g. Monocytes, macrophages, microgila
Respond to foreign antigens
Found in speed and liver: through blood
And lymph nodes through extra cellular fluids
143
Describe erythrocytes
```
Rbc
2 alpha
2 beta chains
Bioconcave disc
Each molecule has one haem
Carries O2 to tissues and co2 to lungs
Lasts 120 days
```
144
Describe reticular cells
Synthesise reticular fibres
| Direct t and b lymphocytes in lymphatic tissue
145
Function and structure of platelets
```
Small blue particles, no nucleus
Produced by megakaryocytes
Contains fibrinogen, ADP and ca
Controlled by thrombopoietin
Used in clotting cascade
Adheres to damaged cell walls and aggregates together
Lasts 10 days
```
146
How does the structure of a RBC enable them to accomplish their functions
Long lifespan
Shape, and flexibility facilitates passage through microcirulation (3.5 um) rbc = 8um.
4 golgin chains, each carrying a haem molecule that can bind 1 molecule of O2
Therfore 4 molecules per euryrocyte
147
How are erythrocytes broken down?
When dying or dead they are engulfed by macrophages
Broken down into bilirubin and transported to the liver where it is passed on in the bile to the large intestine to be removed in feces as stereobilin or on the kidney to be removed in urine as urobilinogen
Transferrin also made which is used in erythropoises
148
Describe the first barrier to infection and how it works
Epithelia are the first barrier
Selectively permeable, natural antibiotics
Clear pathogens: tears, digestive enzymes, blinking, hairs, coughing, vomiting,gut movement
149
Describe the immune response, an overview
```
Pathogen breaks epithelial barrier
Activated epithelial cells
Chemokines and cytokines produced, stimulate natural killer cell activation
Permeabilised endothelium
Cells and fluid migrate to the area
Oposonisation and phagocytosis occurs
```
150
Describe the uses of antibodies
Neutralization, by preventing binding to epithelia
Oponisation: coating microorganism with antibodies so recognisable as foreign by phagocytes
Complementary activation,
151
Describe the innate immune response and list what cells are involved
Non specific and natural. Present from birth
Monocytes: phagocytosis and form macrophages
Macrophages: phagocytosis enhanced by opsonisation. Adaptive role as well as an antigen presenting
Eosinophils: allergy response
Basophils: allergy response
Mast cells: allergy response
Neutrophils: phagocytosis and antibacterial
Natural killer cells: recognise and kill abnormal cells e,g, tumours. Induce apoptosis in infected cells, pump proteases through their pores.
152
Describe the functions of neutrophils in inflammatory response
```
1st event
Not in healthy tissues,
Specialised for anaerobic
After activation it can't synthesis more granules of lysosomes , death
Bacteria bind to neutrophil receptors
```
153
Describe the humoral componants of innate immunity
Transferrin and lactoferrin: deprive microorganism of iron
Interferons: inhibit viral replication
Lysozymes: breaks peptidoglycan bacterial cell walls
Antimicrobial peptides
Fibronectin: opsonises bacteria
Complement: destruction of microorganism
TNF alpha: suppress viral replication, activates phagocytes
154
Describe the complement system
Group of proteins that mark pathogens for destruction by covalent lay binding.activates early
155
Describe the adpadive immune response cellular componants
T cells: t helper (lymphocytes) , activated when cd4 binds to specific antigen on APC. Clones itself and produces active t helpers and t memory cells
T killer: release perforin,
B cells: (bone marrow) form plasma cells and memory cells when activated by t helper cells. Release cytokines
Plasma cells then produce specific immunoglobulin
156
Describe the humoral response of the adaptive immune response
Cytokines: promote differentiation and proliferation of lymphocytes
Perforin: destroy cell walls
Antibodies: neutralisation, opsonisation , complement activation
157
Describe the main differences between innate and adaptive immunity
Innate, present from birth, non specific, not enhanced by 2 exposure, poorly effective without adaptive and triggers and amplifies adaptive
Adaptive: develops after exposure, specific to pathogen, memory cells poorly effective without innate, antibodies reflect infections that individual has been exposed to,
158
Describe the process of immune response after antigen exposure
Clonal selection
Colonial expansion
Differentiation to effector cells: t helper cells and cytotoxic t killer cells
Antibody producing cells
Humoral and cell mediated immunity to eliminate antigen
T and B cell apoptosis
Memory seeding
159
Describe the main differences between prokaryotes and eukaryotes
Prokaryotes: bacteria and archea (eukaryotes = fungi and Protozoa)
No membrane bound organelles
One chromosome not many
No introns
30&50s=70s ribosomes (eukaryotes 40&60=80)
Peptidoglycan cell wall
M RNA very easily broken down (more stable in eukaryotes)
160
What is an infection
The establishment of an organism on or in a host
| It's multiplication causes damage or dysfunction to the host
161
Which is more powerful a light or electron microscope? And what levels do they show
Electron microscope is more powerful. Looks at organelles within a cell. And bacteria and viruses etc
Light microscope looks at cells within tissues
162
Name the two stains that can be used to stain microbes
Acid fast: mycobacteria e.g. Tb and leprosy
Gram stains: quick, and can detect and classify most bacteria
163
Describe the process of a gram stain
Positively charged crystal violet binds to negative cell ports
Iodine added
Decolorisation with acetone or methanol. This affects the negative bacteria as can't get through positive cell wall
Red stain added. Affects the gram negative bacteria trying it red
Gram positive stays blue/purple
164
What does haemotoxin stain
| And eosin
Acidic
Stains nucleus, RNA, chromatin purple
Eosin stains proteins pink
Basic
165
List some shapes of bacteria
```
Cocci,
Rods
Bacilli
Coco acidly
Curved, spiral , filaments
Spores, granules
Flagellae, capsize
```
166
Describe the difference between gram positive and gram negative bacteria
Thicker peptidoglycan cell wall in gram positive bacteria. More receptive to antibiotics
Gram negative: thinner wall, broken down and pores form during decolourisation.
Impermeable lipid based bacterial outer membrane
167
Describe the basic features of viruses
Single or double stranded RNA or DNA NOT BOTH
no genes, to code for proteins etc so translates inside host proteins to produce viral proteins
Enveloped (contain lipids) or non enveloped ( no lipids)
168
Describe the two types of RNA that can be found in viruses
Sense or antisense
Sense: serves as mRNA and can be translated to proteins
Antisense: can't be translated e,g, Ebola
169
Describe the differences between enveloped and non enveloped viruses
Enveloped are easier to destroy by heat and pH. And survive less well outside cells.
The envelope wraps around the capsid
170
Describe the function of the capsid in viruses
Made of capos meres
Pretences the nucleic acid
Can attach to host cell
Can be helical or icosahedral
171
How can viruses be diagnosed and detected
Cell mediated response, after a week
Test blood for antigens and wbc
Or more expensive: PCR molecular testing of their genomes
172
Name 2 enveloped DNA viruses
Hepatitis b
| Small pox
173
Non enveloped viruses containing dna
Papilloma Virus (cervical cancer and warts) HPV
174
enveloped viruses containing RNA
```
Rubella
Rotavirus
HIV
MMR
Ebola
```
175
Non enveloped viruses containing RNA
Polio
Hepatitis a
Colds
176
List the four stages of development of a viral disease
Acute (instant affect)
Subacute (in between stage e.g. Ebola starts with flu symptoms) can be at risk to community therfore must inform
Chronic
Latent e.g. Herpes
177
How does a virus infect and replicate in a host cells
Host cell must have compatible machinery, there is a host range that the virus can replicate in. Must have a suitable receptor
The virus spreads in nerves through nervous system and blood to organs
The virus binds to the receptor at the cells ligand on its capsid or envelope
178
What effect does a virus have on the host ce,,
```
Death
Cytoplasmic effects: visable
Inclusion bodies,
Synctia formation, giant multinucleated cells
Chromosome damage
Inhibition of host cell protein
```
179
Can viruses cause cancers
Dna viruses can cause cancer, retroviruses.
| Turn on cellular oncogenes causing uncontrollable proliferation
180
Are the t tubules in line with the a band or the z band in cardiac muscle? Which is it for skeletal?
Cardiac: z bands
Skeletal: a-I bands
181
Describe the histological features of the salivary glands: the parotid, sublingual and submandibular glands
Parotid: serous glands (stained pink) secrete watery enzymes
Sublingual: majority are mucous cells, mucous poorly stains under H&E
Submandibular: mixed serous and mucous glands
182
```
State whether these glands are exocrine, endocrine or mixed
Salivary
Thyroid
Parathyroid
Adrenal
Unicellular glands (jejunum / colon)
Pancreas
```
```
Salivary: exocrine
Thyroid: endocrine
Parathyroid: endocrine
Adrenal: endocrine
Unicellular glands (jejunum / colon): exocrine
Pancreas: mixed
```
183
Give examples of gram positive cocci
Staphylococcus : e.g. Staphylococcus aureus- skin infections, respiratory diseases
Streptococcus: e.g. Streptococcus pneumoniae - pneumonia, meningitis
184
Give examples of gram negative cocci. And a description
Neissaria , diplo cocci
Neissaria meningitidis: meningitis , normal flora in nasopharynx
Neissaria gonnorrhaea: gonnorrea (coffee bean shaped)
185
Give examples and description of gram positive bacilli
Clostridium, anaerobic, spore forming,
Clostridium perfringens: rod shaped. Food poisoning, decaying vegetation, anaeorobic infections
Clostridium difficile: spindle shaped. Spores survive extreme conditions e.g alcohol. Can cause diahorrea if in colon
186
Describe gram negative bacilli
Eschericia e.g. Coli. Rod shaped. Gut flora, food poisoning, E. coli
Salmonella spp.rod. Typhoid, food poisoning
Shigella. Rod. Shigellosis. Dysentery
Pseudomonas aeruginosa. Cocci bacili. Skin flora. Cross infections
Legionella spp. In water
Helicobacter pylori. Stomach ulcers/cancer. Natural
Bacteriodes . Anaerobic, aero tolerant. Process complex molecules. Resistant to antibiotics
187
Describe bacteria that cannon be gram stained
Myobacterium (tuberculosis or leprae)
Wax coating. Tb (needs lots of oxygen, therfore affects respiratory)
Chlamydia spp. Blindness
