Cell Organelles/Signalling/Histology/Physiological Processes/Trauma&Shock Flashcards
Cells, shock
Explain the process of Proteosomal Protein Degradation.
E1 (U activating Enzyme) activates Ubiquitin (uses ATP)
U is passed from E1 to E2 (U conjugating enzyme) forming covalent, peptide bond.
E2+U complex is bound to E3 (ligase enzyme)
E3 finds target protein and transfers U from E2 to protein.
Proteosome binds and recycles U.
Protein enters Proteosome central canal and is broken into peptides.
Explain the process of Lysosomal Degradation of proteins.
Proteins are phagocytosed by lysosome
Lysosomal Enzymes are activated by acidic environment in lysosome
Enzymes (hydrolase, lipase, protease), break down substance
What proteins are targeted by proteosomal degradation?
Proteins with short half life (typically Potent/toxic)
Dysfunctional proteins
Metabolic enzymes
What proteins are targeted by lysosomal degradations?
Long half-life proteins Membrane proteins (endocytosed) Extracellular proteins (receptor mediated endocytosis)
What proteins are synthesized by the ribosomes of the RER?
Secreted proteins
Plasma membrane
Lysosomes
What proteins are synthesized by free ribosomes?
Proteins for mitochondria, nuclease, cytoplasm.
Peroxisomes
What purpose does the Golgi Apparatus serve?
Labels proteins for destination using modifications, like glycosylation.
Proteins move from cis cisternae end -> medial -> trans, are packaged into vesicles, and sent to destination.
Describe the process of the addition of mannose-6-phosphate to hydrolase and its movement from the Golgi to the final destination.
Hydrolase travels from the RER to the Cis Cisternae of the Golgi.
Golgi glycosylates and modifies hydrolase by adding mannose-6-phophate.
Receptors in trans-membrane of golgi recognize M6P, and surround hydrolase enzymes, forming vesicle.
Vesicle binds endosome
How would a neutrophil appear on a histological stain?
Multi-lobed nucleus
pale, lilac stained granules
How would a monocyte appear on a stain?
Large kidney shaped nucleus
No granules
How would a eosinophil appear on a stain?
Bi-lobed nucleus
Many red-orange staining granules
How would a basophil appear on a stain?
Bi-lobed (obscured by granules)
Abundant dark purple cytoplasmic granules
How would a lymphocyte appear on a stain?
Large, round nucleus
No granules
What is the purpose of a signal peptide?
It is recognized by signal recognition peptide (SRP) which guides the peptide to the signal peptide receptor on the RER. Signal peptide is then fed through the translocon (pore) in RER
What are the stages in blood clot formation?
Vasoconstriction
Platelet Plug formation
Coagulation
What causes platelet plug formation?
Vessel damage = collagen exposure -> platelets stick to collagen -> platelets release thromboxane A2 -> Ta2 causes more vasoconstriction and increases platelet clumping -> plug is formed
What occurs in the 3rd step of blood clot formation?
Coagulation; clotting involves cascade of enzymatic reactions (intrinsic/extrinsic pathways, and the common clotting pathway) that result in an insoluble fibrin mesh
What causes the initiation of the intrinsic clotting pathway?
Blood comes in contact with exposed collagen cells. Collagen activate clotting factor 12, which initiates cascade leading to activation of clotting 10, it combines with factor 5 to produce prothrombinase
What causes the initiation of the extrinsic clotting pathway?
Tissue trauma causes release of tissue factor (F3) into blood -> tissue factor leads to activation of Factor 7 (VII), which causes the activation of factor 10 (X)
Common Pathway is thus begun
What begins the stages of the common clotting pathway?
Enzyme prothrombinase (F10) converts prothrombin into thrombin Thrombin converts soluble fibrinogen into insoluble fibrin
What helps the fibrin strands stick to each other?
Factor 13 (Fibrin Stabilizing Protein) helps fibrin strands stick to each other forming fibrin mesh Fibrin mesh covers plug and traps platelets and blood cells.
What is clot retraction?
Platelets within platelet plug contract pulling on fibrin strands together, forming tightly sealed patch
What dissolves a clot?
Plasmin
What are the types of shock?
Septic, Hypovolaemic, Cardiac, Spinal/ Neuro, Anaphylactic
What is an abrasion?
Superficial/deep scraping to skin (dragging)
Bleeding not typically an issue
Wound is cleaned, dressed,
More severe abrasion may be scrubbed (in OR) to prevent tattooing of wound
What is tattooing of a wound?
When debris is stuck under skin surface, causing discolouration of the skin.
What is degloving?
Skin and blood supply are cut off
Major trauma, typically of limbs and digits
What’s an incised wound?
From sharp object
Slashing, or stabbing
Clean edges, depth needs to be considered and investigation of underlying damage
What’s a laceration?
Skin is split due to blunt force trauma
Causes tissue bridging, irregular edges
Legal and forensic implications
Irrigate, clean, close (glue, steristrips, staples, sutures)
What are bites?
Small entry wound, possible deep penetration
Typically from animals (Human Blood Borne Viruses)
Irrigation, delay closure
Differentiate between the intrinsic and extrinsic clotting mechanisms.
Intrinsic is initiated by exposure of collagen, much longer, involves more factors
Extrinsic is tissue factor (thromboplastin) released by damaged tissue activates Factor 7
Explain what an Activated Partial Thromboplastin Time (APTT) Assay is and its clinical relevance.
Clinically, APPT helps diagnose clotting issues involving the intrinsic pathway (Haemophilia A/B, Van Willebrand Disease).
How could you determine if there are problems with the common pathway of clotting?
Utilize tests looking at clotting with no calcium or phospholipid, and activated factor 10, if clotting occurs, issue is not with common pathway. This helps diagnose problems with common clotting pathways (i.e. Liver problems impacting thrombopoiesis (prothrombin production) and fibrinogen production).
What is Prothrombin time (PT Time) used to assess?
Measure of the integrity of extrinsic and final common pathway cascades
Slow Prothrombin time can indicate liver problems, Vitamin K deficiency, presence of blood thinners
How does warfarin reduce blood clots?
Vitamin K Oxide Reductase Inhibitor,
Competes with Vitamin K therefore inhibiting the Vit K carboxylation of clotting factors (2,7,9,10) in the liver, so they aren’t activated for coagulation.
Can be reversed by giving Vitamin K
How does Vitamin K aid in coagulation?
Aids in the maturation of certain clotting factors needed in the clotting cascade (factors II (prothrombin), VII, IX, X, Protein C).
What are the 3 types of bleeding?
Capillary (slow ooze)
Arteriole (pulsing, deep red)
Venus (constant, bright red)
What are the parameters of; blood volume, total % blood loss, pulse rate, blood pressure, respiratory rate, urine output, and mental status of a Class 1 Hypovolemic Shock?
Volume: <750mL %: Less than 15% Pulse rate: <100bpm Blood Pressure: normal Resp. Rate: 14-20 Urine output: >30mLs/hr Mental Status: normal
What are the parameters of; blood volume, total % blood loss, pulse rate, blood pressure, respiratory rate, urine output, and mental status of a Class 2 Hypovolemic Shock?
Volume: 750-1500mL %: 15-30% Pulse rate: >100bpm Blood Pressure: normal Resp. Rate: 20-30 Urine output: 20-30 mLs/hr Mental Status: mild anxious
What are the parameters of; blood volume, total % blood loss, pulse rate, blood pressure, respiratory rate, urine output, and mental status of a Class 3 Hypovolemic Shock?
Volume: 1500-2000mL %: 30-40% Pulse rate: >120bpm Blood Pressure: decreased Resp. Rate: 30-40 Urine output: 5-15 mLs/hr Mental Status: anxious
What are the parameters of; blood volume, total % blood loss, pulse rate, blood pressure, respiratory rate, urine output, and mental status of a Class 4 Hypovolemic Shock?
Volume: >2000mL %: >40% Pulse rate: >140bpm Blood Pressure: decreased Resp. Rate: >40 Urine output: negligible Mental Status: confused
What stops platelets in blood from clotting regularly?
Nitric Oxide and Prostacyclin inactivate and prevent platelet from binding the endothelial lining
What causes vascular spasm?
Endothelin- When endothelial cells are damaged, they release endothelin, which binds receptors on smooth muscles causing contraction.
Myogenic Mechanism- any injury to smooth muscle causes contraction
Nociceptors Activation- neural receptors cause SM contraction
What 2 proteins in the plasma membrane of a vessel work to prevent coagulation?
- Heparin sulphate on plasma membrane promotes protein anti-thrombin 3 binding to F2/10, inactivating thrombin, and factor 10
- Protein Thrombomodulin on plasma membrane binds protein thrombin (factor 2) which activates Protein C, causing degradation of factor 5 and 8.
How does the Von Willebrand Factor contribute to platelet plug formation?
Carries factor VIII while inactivated, preventing degradation. Thrombin will initiate its VIII release allowing for progress of intrinsic clotting pathway.
Also, VWF contains specific receptor that binds the Glycoprotein 1b on platelets, which activates the platelet to secrete ADP, thromboxane A2, serotonin, helping with platelet aggregation.
What 3 proteins are secreted from activated platelets?
ADP- Bind and activate platelets
Thromboxane A2- Bind and activate platelets, bind smooth muscle causing contraction/vasoconstriction
Serotonin- Bind smooth muscle causing contraction/vasoconstriction
What protein allows platelets to bind to one another?
Fibrinogen binds the Glycoprotein 2b/ 3a receptors on each platelet, allowing them to adhere.
Von Willebrand Factor also allows platelet-platelet/surface linking
What is the first factor involved in intrinsic pathway of coagulation?
Factor 12 interacts with negative charge on the Phosphatidyl serine on platelet surface, resulting in F12 activation.
In the Intrinsic pathways, what is the activation cascade after Factor 12 is activated?
Factor 12 activates Factor 11 -> F11 activates F9 -> Factor 9 forms complex with Factor 8 (need platelet factor 3 and Calcium) -> 9/10 complex activates Factor 10 -> Common pathways
What is another name for Factor 2?
Thrombin
What is the cascade pathways for the common coagulation pathway?
F10 reacts with F5 -> activates prothrombin activator -> Prothrombin activator activates Factor 2 -> F2 (thrombin) converts fibrinogen (F1) to insoluble fibrin-> Fibrin with helps of F13 forms cross-links
What is the cascade pathways for the extrinsic coagulation pathway?
Damaged tissue cells produce activated Factor 3 -> F3 activates Factor 7 -> F7 activates Factor 10
How long do the extrinsic and intrinsic pathways take to happen typically?
Extrinsic- 30 seconds
Intrinsic- 4-5 min
How does liver status impact both Prothrombin time and APPT time?
Early stage liver failure, PT is slowed
Late stage liver failure slows both APPT and PT
What pathologies impact the intrinsic pathway of coagulation?
Haemophilia A and B
Von Willebrand Disease
What is the 4th stage in Haemostasis
Clot retraction and repair
What happens in clot retraction and repair?
Platelet contraction and myofibroblasts will pull endothelial cells back together
Platelets secrete Platelet Derived Growth Factor-will trigger proliferation of the smooth muscle lining and connective tissue patches (to regenerate collagen by fibroblasts)
Vascular Endothelial Growth Factor- regenerates endothelial lining
What occurs in Fibrinolysis?
TPA (Tissue Plasminogen Activator, or streptokinase) on endothelial surface converts Plasminogen to Plasmin
Plasmin breaks down fibrin mesh.
Plasmin releases D-Dimer when breaking down clots (used in diagnostics)
Why is fibrin mesh important?
Prevents platelet plug from dislodging and causing embolism elsewhere
What can Tissue Plasminogen Activator be used for?
Used in early stages of a stroke to promote breakdown of blood clots by increasing plasmin levels.
How does heparin work?
More heparin enhances binding of antithrombin 3 to Factor 2 (thrombin), preventing activation of thrombin and can also block factor 10 activation of prothrombin
How does aspirin work to thin the blood?
It prevents Thromboxane A2 formation, so we wont have binding/activation of platelets, or binding of smooth muscle causing contraction/vasoconstriction
What are some examples of hypovolemic shock?
- Bleeding; in the form of G.I. Bleed (perforated ulcer), Abdominal Aortic Aneurysm rupture, trauma, post-partum haemorrhage, ectopic pregnancy
- Non-Blood Fluid Loss; Diarrhoea, 3rd degree burns, vomiting, pancreatitis, Diabetic Ketoacidosis
How can you determine the type of fluid loss causing hypovolemic shock?
Complete Blood Count
High Haematocrit = non-blood fluid loss
Low Haematocrit = Blood fluid loss
How does fluid loss cause shock?
Volume decreases -> BP decline -> baroreceptors stimulate medullary centre to send out action potentials -> norepinephrine release causing vasoconstriction, increased constriction of heart (increased BP-tachycardia) -> more fluid loss -> hypoperfusion to organs
How can you treat hypovolemic shock?
Fluids- crystalloids (ringer’s lactate, normal saline)
Colloids (Albumin or Hetastarch)- stabilize osmotic pressure (control water leaving blood)
What cascade does a low blood pressure cause (including hormone cascades and kidney, adrenal gland, and pituitary gland)?
Low BP -> kidneys produce renin -> renin converts angiotensinogen to angiotensin 1 -> angiotensin 1 converted (by ACE from lungs) to angiotensin 2 -> AGT2 causes vasoconstriction and;
AGT2 -> adrenal cortex production of aldosterone -> works in kidneys to ^ reabsorption of salt/water)
AGT2 -> stimulates antidiuretic hormone release from pituitary gland to ^ kidney reabsorption of water.
What happens in cardiogenic shock?
Heart cant pump hard enough ->
Results in decreased circulating blood volume -> low BP -> Activation of Renin-Angiotensin-Aldosterone-Antidiuretic Hormone-System -> Tachycardia
What can cause cardiogenic shock?
Myocarditis (sometimes caused by enterovirus)
Multiple M.I.s
Aortic Stenosis
Arrhythmias (tachy (too fast) and brady)
How can blood loss impact the pH of the blood?
Low blood volume -> reduced oxygen delivery -> ^ anaerobic respiration -> lactic acid by-products -> ^ Hydrogen protons -> metabolic acidosis of blood
What happens in tension-pneumothorax obstructive shock?
Outer pleural parietal layer of lung is damaged, and allows air to move into the pleural sac (air moving to area of low pressure), which increases pressure, this pushes the lung and impairs lobes ability to expand-> high pressure can impact heart ability to pump -> low BP
Can be observed with increased Jugular Venous Pressure and can hear hyperresonance sound
What are some examples of an obstructive shock?
Tension Pneumothorax
Cardiac Tamponade
What is distributive shock?
“abnormal distribution of blood flow in the smallest blood vessels results in inadequate supply of blood to the body’s tissues and organs.”
Decreased tissue perfusion due to reduced BP caused by decreased systemic vascular resistance.
How does septic shock occur?
Bacteria in blood release toxins that damage endothelial cells -> causes release of prostaglandins, leukotrienes -> causes mast cells to release more leukotrienes, prostaglandins, proteases, histamine, cytokines -> ^ vascular permeability, vasodilation-> tissue fluid accumulates in tissue -> blood volume decline -> reduced BP
Complement enzymes are also activated by proteases (from mast cells), which results in increased permeability.
How would you treat septic shock?
Broad spectrum Antibiotics
Culture to determine what the cause is
Give fluids - crystalloids (saline, ringers lactate)
If not responding to fluids, give vasopressor to constrict vessels
What are the 3 types of biochemical signalling cells use?
Hormones, growth factors, neurotransmitters
What are the 3 types of extracellular receptors?
Ion-channel-linked, G-coupled protein receptors (serotonin, adrenaline), Enzyme linked (tyrosine kinase receptors activated by growth factors)
What clotting factors are dependent on vitamin k?
Factor 2, 7, 9, 10
What is the structure of haem?
4 subunits forming a α2β2 tetramer
Each subunit has a heme unit containing an iron atom
What does Acid-Fast stain look for?
Mycobacterium
What does Van Geison’s Stain look for?
ECM- Collagen and other connective tissue
What does Silver stain test for?
Proteins
What does PAS stain look for?
Complex carbohydrates and glycogen
What does Gram stain look for?
Peptidoglycan in Bacteria
What does Geimsa stain look for?
Protozoa and intracellular bacteria
