2018 resit Flashcards
Describe structure and function of the synaptic knob and motor end plate, and describe the events in the neuromuscular junction that lead to a muscle contraction.
- Synaptic knob is swollen end of axon terminal that contains Ach.
- Motor end plate is a region of sarcolemma that abuts the synaptic knob; it is highly folded thus has increased surface area allowing for more Ach receptors.
- It contains acetylcholinesterase that breaks down Ach.
- Synpatic transmission at neuromuscular junction begins when an action potential reaches the presynaptic terminal of a motor neuron.
- Which activates voltage dependent calcium channels to slow calcium ions to enter the neuron.
- Stimulates Ach-containing vesicles to fuse with presynaptic membrane releasing ACh molecules into synaptic cleft.
- Ach binds to nicotine acetylcholine receptors on the cell membrane of muscle fibres.
- Binding causes depolarisation of muscle fibre, causing a cascade that eventually results in muscle contraction.
The respiratory system contributes five key function.
Name and explain these functions.
- Gaseous exchange: absorption of oxygen and excretion of carbon dioxide.
- Olfaction: sense of smell by specialist nerve endings in the nasal cavity and transmitted to the brain via the first cranial nerve.
- Speech: via the vocal chords in the larynx
- Homeostasis: via the oxygen and carbon dioxide exchange
- Protection: from inhaled pathogens and irritating substances
List the cell types involved specifically in innate or acquired immunity.
Innate: neutrophils, eosinophils, basophils
Macrophages
Natural killer cells
Adaptive: B lymphocytes and T lymphocytes
The gross anatomy of the brain can be divided into three main areas: forebrain, midbrain and hindbrain.
Discuss the different functional roles of these three brain areas.
Forebrain: important role in controlling a number of functions including motor, higher functioning, speech, sensory perception including vision, auditory, memory.
Diencephalon - relay point between brain and periphery receives input from periphery and send out signals via autonomic nervous system and endocrine system.
Midbrain: important role in receiving inputs of auditory and visual system
Many nuclei contacting neurons controlling specific function
Hindbrain: co-ordination (cerebellum)
Reflex centres (medulla oblongata)
Arousal (reticular activating centre)
Outline features of the five white blood cells.
A. basophils - contain high concentration of heparin, histamine, leukotriens, serotonin, chemotactic factor and mediates the hypersensitivity reaction; bind IgE antibody.
B. eosinophils - can phagocytose antigen-antibody complexes and inactivate leukotriene; cytoplasm contains a dense filamentous core of major basic protein - kills parasitic worms.
C. Neutrophils - are the first line of defence against microorganisms, especially bacteria; they are active phagocytes.
D. monocytes - ingest and remove tissue debris and infectious agents.
E. lymphocytes - two main types B and T cells - b cells produce antibodies and T cells destroy the body’s own cells that have themselves been taken over by viruses or become cancerous.
Briefly describe five physiochemical properties of a drug that would be investigated at the pre-formulation stage of development.
- Particle size - affects drug dissolution rate, bioavailability and stability - smaller particles dissolve faster enhancing absorption.
- Stability; physical and chemical - ability of drug to remain chemically and physically stable under various environments which is vital for safety and efficacy - helps identify suitable storage conditions and packaging
- Crystal properties including polymorphism - different polymorphism have different physical and chemical properties - identifying the most stable and effective form is crucial
- Solubility and pH dependence of solubility - ability of drug to dissolve in solvent and is crucial for drug absorption and bioavailability - poorly soluble drugs may have limited therapeutic effectiveness
- pKa log P - indicator of a drug’s lipophilicity affecting drug absorption, distribution and ability to cross cell membranes
What are the key differences in pH in the fasted and fed state and explain the impact these differences would have on the solubility and subsequent absorption of a basic small molecule drug?
1.Fasted state low gastric pH
2. Fed state gastric pH rise 3. from 1.2-1.5 to around 3.0-5.0
4. Basic drug solubility drop
5. As it is less acidic and a smaller percentage of the population is protonated
6. If a drug is not in solution it cannot be absorbed
7. Therefore potentially better to take it fasted with all else equal
8. More chime and bile acids in the fed state
9. Poorly soluble drugs solubilised.
Discuss the mechanisms of the immune response against viruses.
- immune system has an innate and adaptive immune response against viruses
- Innate immune repose: Toll like receptors bind to viral DNA and RNA;
- and induce the production of type 1 interferon;
- Type 1 interferon then drives the proliferation and differentiation of NK cells;
- Activated NK cells kill virus infected cells.
- Adaptive immune response: B-cell mediated immunity mechanisms: a) neutralisation of viral particles by antibodies,;
- b) opsonisation by antibodies;
- c) activation of complement by antibodies
- T-cell mediated immunity mechanisms: CD8 cytotoxic T cells bind to infected cells expression MHC 1-viral peptide complexes and kill the infected cells through mechanisms of cytotoxicity
- Cd8 cytotoxic T cell also release the cytokine interferon gamma which have anti-viral functions.
