week 9 (resp. + renal) Flashcards
(24 cards)
question: how does hemoglobin transport O2 to tissues?
- Hb passes respiratory surface -> high PO2 promotes formation of oxyhaemoglobin
⤷ Hb fully bound w/ O2 - Hb leaving the respiratory surface = very saturated w/ O2
- blood passes tissues w/ low PO2
⤷ O2 from Hb is released - forms deoxyhaemoglobin
explain: the oxygen equilibrium curve (general)
- relationship between percentage of oxygenated Hb and PO2
- as PO2 increases, more Hb binds to the O2 until 100% saturated
**read graph R to L
PLATEAU
- at lungs = Hb 100% saturated
-IVE SLOPE
- Hb decreasing in sat. as O2 leaves to enter tissues
- PO2 decreases
- going lower and lower on the graph = losing more and more O2 to the tissues -> PO2 lower
question: how much O2 is kept for venous reserve?
- 75%
⤷ working based on demands of the body
⤷ around PO2 = 40 mmHg
question: what makes the O2 equil. curve hyperbolic or sigmoidal?
HYPERBOLIC
- myoglobin
⤷ monomeric = only binds 1 O2 at a time
- graph plateau shifts more L (plateau for longer)
⤷ saves/reserves O2
SIGMOIDAL (normal equil. graph)
- hemoglobin
- Hb does cooperative binding
⤷ each O2 binding makes the next easier
⤷ slow binding at first -> grows faster exponentially
question: what makes the O2 equil. curve shift R?
BOHR SHIFT = right
- increase in PCO2
⤷ affinity decreases -> tissues get O2 more easily
⤷ Hb sat. decreases - decrease in pH
⤷ ex. exercise -> increases lactic acid -> decreases pH -> less saturated Hb bc more O2 going to tissue
⤷ improves O2 unloading at tissues - increase in T
⤷ improves O2 unloading at tissues - affinity decreases
question: how can phosphate and fetal Hb can affect Hb affinity?
PHOSPHATE
- ex. 2, 3-DPG -> decreasing affinity
- organic phosphate molecules = negative allosteric modifiers of O2 binding
- shifts curve to R -> decreases O2 affinity of Hb
FETAL
- fetus have diff. Hb than adults
⤷ 2 alpha, 2 gamma
- gamma holds O2 stronger
- higher affinity to O2
- insensitive to 2,3-DPG
name: ways to transport CO2 (3)
- dissolve
⤷ more soluble than O2
⤷ 10% gets dissolved - bound to Hb
⤷ forms carbaminohemoglobin
⤷ 30% - transported as bicarbonate + dissolved in plasma
⤷ 60%
explain: function of chemoreceptors in breathing
- central chemoreceptors
⤷ resp. to PCO2 and pH changes in CSF
⤷ in medulla - peripheral chemoreceptors
⤷ resp. to PO2, PCO2, and pH changes
⤷ in carotid and aortic arteries - receptors send sig. back to breathing central pattern generators (CPG)
question: how do the chemoreceptors signal CPG?
**overall = PO2 drops to 40 mmHG -> resp. rate increases 50-70%
- drop causes NT release from carotid sensors
- tells CPG to increase resp. rate to increase PO2 again
question: what stim. a resp. from chemoreceptors in resp. sys?
- decrease PO2
- increase PCO2
- increase H+ / decrease pH
question: how does respiratory performance decrease with age? with smoking?
- elastic tissue deteriorates -> decreased lung compliance and vital capacity
- chest mvt. can be restricted bc of arthritic changes
**decreases are severely accelerated by smoking
- smoking damage can be recovered by never the same as non-smokers
explain: anatomy of kidney and pathway for urine
- kidney has 2 layers
⤷ outer cortex
⤷ inner medulla - urine prod. by nephrons in renal pyramids of the medulla
- urine is collected by minor calyces which join to make major calyx
- urine leaves kidney via ureter and passes to bladder
- urine leaves body through urethra
question: what is a nephron? glomerulus?
- tubular struc. that produces urine
- millions to nephrons in body
- main vasculature = glomerulus
⤷ cluster of capillaries that perform first step of filtering blood
question: transcellular transport vs paracellular transport?
- trans = through cell, across membranes
- para = between cells
name: main transport processes in nephron (main processes of urine formation) (3)
-
glomerular filtration
⤷ bp forces water and solutes across wall of glomerular capillaries into capsular space
⤷ moving from blood stream into nephron -
tubular reabsorption
⤷ from inside nephron -> back to body
⤷ removal of water and solutes from filtrate
⤷ mvt. across tubular epithelium into peritubular fluid -> peritubular capillaries -> blood -
tubular secretion
⤷ from body -> to nephron
⤷ transport of solutes from peritubular fluid into tubular fluid
question: where does filtration, reabsorption, and secretion happen?
- filtration = glomerulus
- reabsorption = proximal tubule, loop of henle, distal tubule, collecting duct
- secretion = proximal and distal convoluted tubules
explain: cortical vs juxtamedullary nephrons
CORTICAL NEPHRONS
- short loops of henle
- in cortical area
- do most of the reabsorption and secretion
JUXTAMEDULLARY NEPHRONS
- long loops of henle
- in medulla
- involved in producing concentrated urine
name + explain: function of main nephron structures in order (5)
-
renal corpuscle
- produce filtrate
- has glomerulus, capsular space, efferent and afferent arterioles -
proximal convoluted tubule
- reabsorption of water, ions, organic nutrients -
nephron loop (loop of henle)
- more reabsorption
⤷ water in descending limb
⤷ Na and Cl ions in ascending limb -
distal convoluted tubule
- secretion of ions, acids, drugs, toxins
- variable reabsorption of water, Na and Ca ions -
collecting duct
- reabsorb water
question: how is blood filtered in the glomerulus?
- wall of glomerulus capsule has blood cells but lets liquids into lumen of glomerulus capsule
- glomerular capillaries are leaky
⤷ podocytes have pores to allow certain blood contents to flow from blood to capsule
⤷ prevents RBC, WBC, and plasma from going through
explain: path through glomerulus
- blood enters through arterioles (efferent or afferent)
- passes through glomerular capillaries
⤷ contents leak into lumen - filtrate leaves through proximal tubule
question: what is the glomerular filtration rate?
- 1200 mL blood passes glomerulus each minute
- glomerular filtration rate = amount of filtrate the kidney produces each minute
⤷ 1 day = 180 litres of filtrate - 99% filtrate is reabsorbed
question: what moves fluid and solute across capillaries?
- psi across the glomerular wall
- glomerular capillary hydrostatic psi
⤷ pushes inwards (favours filtration)
⤷ pushes water and solute out of plasma - bowman’s capsule hydrostatic psi
⤷ pushes outwards (opposes filtration)
⤷ pushes water and solute into plasma - blood oncotic psi
⤷ psi of osmosis to pull water back into glomerular capillaries
⤷ opposes filtration
explain: net hydrostatic pressure
- difference between glomerular hydrostatic psi and bowman capsule hydrostatic psi
NHP = GHP - BCHP
explain: filtration psi
- difference between net hydrostatic psi and blood oncotic psi
FP = NHP - BOP
