Physiology Flashcards
Main component of cell membrane
Phospholipids - Hydrophillic head and hydrophobic tail
What is Glycocalyx
A glycoprotein and glycolipid covering that surrounds the cell membrane of some bacteria
What is pulse pressure
The difference between systolic and diastolic blood pressure. Normally between 30-50 mmHg
How to measure mean arterial blood pressure
MAP = (2 * Systolic + Diastolic) / 3 (or)
MAP = Diastolic + 1/3 Pulse pressure;
70-105 mmHg is normal
Where is the cardiovascular control centre?
Medulla oblongata
Where are the baroreceptors located?
Arch of aorta and carotid sinus
What nerves pass on the signal from the barereceptors to the cardiovascular control centre?
Vagus nerve (10th) from aortic baroreceptors Herings nerve, branch of the Glossopharayngeal nerve (9th) from carotid baroreceptor
Mean arterial pressure formula
MAP = Cardiac output * SVR
Intrinsic control of stroke volume
Frank Sterling Mechanism
Receptors present on vascular smooth muscles
Alpha receptors
What is vasomotor tone?
Vascular smooth muscles are partially constricted at rest due to tonic discharge of sympathetic nerves causing a continuous release of noradrenaline
Ficks law of diffusion
Increasing the following has the following effects -
Concentration gradient - Increases diffusion
Surface area of membrane - Increases
Lipid solubility - Increases
Molecular weight - Decreases
Distance - Decreases
What happens in hypertonic conditions?
Cells lose water and shrink
What happens in hypotonic conditions?
Water diffuses into cells; they swell
Characteristics to determine kind and amount of material transported
Specificity
Saturation
Competition
Forms of carrier mediated transport
Facilitated diffusion (No energy) Active transport (Energy expended) - Can be primary or secondary
Types of secondary active transport
Symport - Solute and ion supplying driving force (typically Na) move in same direction
Antiport - Solute and ion supplying force move in opposite direction
Where is the temperature control centre?
Hypothalamus
What are the hypothalamic controls?
Anterior - Activated by warmth
Posterior - Activated by cold
Skin arteriole response to told
Vasoconstriction - Blood flow to skin decreased
What’s responsible for electrical properties of membrane
Unequal distribution and selective movement through plasma membrane
What pump creates the Na/K gradient
The Na/K channel pumps 3 Na out of the cell for 2 K in
At resting potential, what is the membrane more permeable to
K+
Why is the inside of membrane more negative
Due to large intracellular negatively charged protein
What ions are present outside and inside the membrane
Sodium (Na+) and Chlorine (Cl-) on the outside
Potassium (K+) and Anionic protein (A-) inside
Equilibrium and membrane potential
ENa = +60mV, Ek= -90mV and Em = -70mV
Importance of membrane potential
Generate action potential, muscle contraction, secretion of Insulin from pancreatic Beta-cells
Why is membrane potential less negative than equilibrium potential for Potassium
Due to slow constant influx of Sodium
What is homeostasis
Arrest of bleeding and maintenance of vascular patency
Primary vs secondary homeostasis
Primary - Formation of platelet plug
Secondary - Formation of fibrin clot
How are platelets formed
By ‘budding’ or breaking away from Megakaryocytes
What does endothelial wall damage release
Collagen is exposed and Von Willebrand Factor release
What is Thrombocytopenia
Reduced numbers of Platelets
Formation of fibrin clot
Prothrombin is converted to Thrombin via factor Xa. Thrombin then converts fibrinogen to fibrin
How does Fibrinolysis work
Tissue Plasminogen Activator (tPA) converts Plasminogen to Plasmin. Plasmin degrades Fibrin into Fibrin Degradation Products
Name some naturally occurring anticoagulants
Serine protease inhibitors, Protein C and Protein S
What is Thrombomodulin
Integral membrane protein that is a cofactor for Thrombin. Reduces blood coagulation by converting Thrombin to anticoagulant enzyme from procoagulant enzyme. This forms an anticoagulation complex consisting of Protein C and S. This inhibits factors V, VIII
What is arterial thrombosis rich in
Platelet rich thrombus, white in colour
Stroke vs unstable angina/MI
Stroke is thrombosis in cerebral arteries whereas unstable angina/MI is coronary arteries
What is venous thrombosis rich in
RBC and fibrin rich, red in colour
Treatment of arterial vs venous clots
Arterial clot - Antiplatelet such as Aspirin
Venous clot - Anticoagulant such as Heparin/Warfarin
Virchows triad
Stasis, Endothelial injury, Hypercoagulability
