Foundations of Biomedical Science Flashcards
What are intercalated discs?
Specialised cell junctions that connect cardiac myocytes end on end
Name the three cell junctions that connect cardiac muscle cells.
Fascia adherentes: link myofibrils between cells
Gap junctions: connect cells parallel to the myofibrils, facilitate coordinated contraction by electrically coupling cells
Desmosomes: connect at cell ends in between myofibrils
Name the three contractile cells
Myoepithethials: surround exocrine glands to squeeze out contents.
Myofibroblasts: pull wounds closed
Pericytes: surround capillaries and can contract to regulate local blood flow.
Name the three layers of connective tissue present in nerves
Epineurium: wrap whole nerve
Perineurium: wrap fascicles (bundles of axons)
Endoneurium: wrap individual axons
What colour do ganglion cell stain?
Dark blue
List 5 causes of acute inflammation
Certain infections Trauma Burns Foreign matter Infarction
Explain the vascular response to inflammation
Transient arteriole constriction > arteriolar then capillary and venular dilation (caused by histamine and NO) > increased vascular permeability > vasocongestion as blood become more concentrated with RBCs.
Four mechanisms for increases vascular permeability
Retraction of endothelial cells
Endothelial injury
Leukocyte-mediated vascular injury
Increased transcytosis
What are some examples of chemical, antimicrobial products produced as a part of innate immunity
Lysozyme - tears, oral cavity, skin: attacks cell wall Acid - stomach and vagina Bile salt - anus phospholipase A - eye, oral cavity DNA-ases and RNA-ases - skin defensins - gut and resp. tract
Name 4 way in which commensals aid innate immune protection
Compete for binding sites
Produce toxic metabolites
Produce bacteriocins / antibiotics
Induction production of antimicrobial products by epithelial cells through PAMPs
Describe the four effector functions of complement
Stimulate inflammation - increase blood flow, vasc. permeability and mast degranulation
Act as chemokines
Opsinise
Lyse
The three pathways of complement activation all result in…
Generation of C3 convertase which cleaves C3 leaving C3b bound to the microbial surface and releasing C3a
Briefly explain the three pathways of complement activation
Lectin pathway - Mannose-binding lectin (MBL) and ficolins recognise and bind carbohydrates on the pathogen surface (MBL is similar in structure to C1q so attracts other aspects of the activation cascade)
Classical pathway - antigen bound IgM or IgG activate the C1complex
Alternate pathway - spontaneous hydrolysis of C3 t o C3a and C3b - without factor H C3b can bind to pathogen surface which leads to the formation of C3 convertase.
What parts of the vertebrae make up the intervertebral foramen?
The pedicles of the inferior and superior of vertebrae.
What constitutes the spinal meninges?
Dura mater, arachnoid mater and pia mater
What three structures does the posterior ramus of the spinal cord innervate?
Capsule of the synovial joints
Deep muscles of the back
Skin of the back
Intervertebral discs are made up of which two components?
Outer, annulus fibrosus
Inner, nucleus pulposus
Describe the steps involved in the formation of the membrane attack complex
C3b binds C3 convertase - this cleaves C5 into C5a and C5b - C5b initiates the “late” events of complement activation in which a further set of complement proteins interact with C5b to form the MAC.
Explain the alternative pathway of complement activation
Spontaneous hydrolysis of C3 into C3a and C3b > C3b can bind to pathogen surface as the pathogen doesn’t have factor H > once C3b is on the surface, factors B and D can be recruited > formation of C5 convertase > formation of MAC
Explain the Classical pathway of complement activation
Ab on surface of pathogen can recruit C1q > this allows the recruitment of C1r > C1s can now be activated > leads to the breakdown of C4, C2 and C3
Explain the lectin pathway of complement activation
Mannan binding lectin attaches to mannose on microbes > captures MASP-2 and activates C4 > initiates series of reactions that also lead to the breakdown of C2 and C3
What PPRs do dendritic cells and phagocytes (eg macrophages) express, what do they recognise and what is the outcome of their activation?
TLRs, NLRs, C-type lectins
LPS, peptidoglycan, muramyl-dipeptide, beta-glucans etc
Cytokine production, phagocytosis, killing
activation of the adaptive immune response
What is the significance of MyD88 in the context of the immune response?
MyD88 is a member of the signalling pathway downstream from generally all TLRs that end in the activation of transcription factors for inflammatory mediators.
The spinal cord generally stops at … and becomes …
L2 and becomes Cauda equina
