Flashcards in Physiology Deck (52)
What are the components of a phospholipid?
Hydrophobic tail + hydrophilic head
Bonds between phospholipids are strong. True/False?
Bonds are weak - explains the fluid nature of the membrane
Cholesterol contributes to which two aspects of the membrane?
Fluidity and stability
What are the 3 main types of proteins found on the membrane?
Transmembrane (channels, transporters)
The glycocalyx layer is formed by...
Short carbohydrate chains bound to proteins and lipids
What are desmosomes?
Adhering junctions that anchor cells together
What are tight junctions?
Join lateral edges of epithelial cells near their apical membranes
What are gap junctions?
Communicating junctions that allow movement of charge between adjacent cells
2 main factors that influence whether a particle can passively permeate the membrane
Lipid solubility (non-polar pass easily)
Diffusion is movement from ___ to ___ concn
High to low
Fick's law of diffusion describes the rate of net diffusion and is made up of...
Magnitude of concn gradient
SA available for diffusion
Lipid solubility and size/weight of substance
Distance over which diffusion must occur
Osmolarity is defined as...
The number of osmotically active particles present in a solution
How is osmolarity calculated?
Using molar concn (mM) and number of osmotically active particles (n)
150mM NaCl has osmolarity = ?
150 x 2 (Na+ and Cl-) = 300mOsm
A hypotonic solution will ____ in cell volume
Increase (needs mOre water)
Facilitated diffusion requires energy. True/False?
Active transport transfers a substance from high to low concn. True/False?
Low to high
_ Na+ out for every _ K+ in with regards to Na-K pump
Secondary active transport occurs by which 2 mechanisms? Define them
Symport (co-transport): solute and ion move in same direction
Antiport: solute and ion move in opposite directions
Membrane potential (Em) arises due to...
Separation of opposite charges across the membrane
At resting potential, the membrane is 100x more permeable to sodium than potassium. True/False?
100x more permeable to K+ than Na+
Em for K+ is approx...
Em for Na+ is approx...
Eion = 61log[ion]o / [ion]i
Membrane potential is much closer to the potential of Na+ ions. True/False?
Much closer to Ek+ due to greater permeablity of K+
Em for a typical nerve cell at rest = ?
GHK equation (used to calculate membrane resting potential)
Em = 61log x PK+[K+]o + PNa+[Na+]o / PK+[K+]i + PNa+[Na+]i
Which receptors control mean arterial BP? Where are the receptors, control centre + effectors located?
Baroreceptors, located in aortic arch + carotid sinus
Control centre: medulla oblongata
Effectors: heart + blood vessels
Normal range for MAP?
Formulae for calculating MAP?
MAP = [(2x diastolic) + systolic]/3
MAP = diastolic + [systolic - diastolic]/3
MAP = CO x TPR
MAP of at least __ mmHg is needed to perfuse coronary arteries, brain and kidneys
Firing rate in baroreceptors ____ when MAP increases
(sensitive to stretch: when you stretch them, firing increases)
Cardiac output (CO) is...
The volume of blood pumped out by each ventricle per minute (SV x HR)
Stroke Volume (SV) is...
Volume of blood pumped out by each ventricle per heart beat
Increasing contractile strength of the heart causes stroke volume to ____
Vasomotor tone is described as...
Vascular smooth muscle being constricted at rest
Normal blood glucose level
Around 5 mmol/l
In the absorptive + post-absorptive states, which hormones control [glucose]p
Insulin and glucagon
In emergencies, which hormone control [glucose]p
In starvation, which hormones control [glucose]p
In pancreatic islet cells, _ cells release glucagon, _ cells release insulin and _ cells release somatostatin
alpha, beta, delta
Insulin lowers [glucose]p by...
Stimulating uptake of glucose by muscle and fat cells
Activating liver enzymes to convert glucose into glycogen
Diabetics can increase GLUT4 expression by doing what?
Glucagon increases [glucose]p by...
Increasing glycogenolysis/inhibiting glycogen synthesis
Cortisol increases [glucose]p by...
Stimulating protein catabolism, lypolysis and gluconeogenesis
Core body temperature is about...
Basal metabolic rate is defined as...
The minimum amount of energy required to sustain body functions
Which receptors monitor body heat? Where are they, the control centre and effectors located?
Thermoreceptors, located in the hypothalamus and skin
Control centre: hypothalamus
Effectors: skeletal muscles, skin arterioles, sweat glands
The posterior hypothalamus is activated by cold. True/False?
Fever is temperature between...
Hyperthermia is temperature...