12 Flashcards
chemoreception
when chemicals bind to chemoreceptors and activate action potential in sensory neurons
Gustation
Sense of taste
Olfaction
sense of smell
when odorants reach the mucous layer in the roof of nose they bind to membrane bound receptor proteins, activating
olfactory receptor neurons
axons from these neurons project up to the:
olfactory bulb
part of the brane where olfactory signals are processed and interpreted
olfactory bulb
intracellular peripheral membrane proteins closely associated with trans transmembrane signal receptors
G proteins
when G proteins are activated by a signal receptor they trigger the production of
second messenger
what are second messengers
-small, non protein signalling molecule or ion
-links the receipt of an extracellular signal to the production of an intracellular signal
3 steps of G-protein-coupled signalling
- a signalling molecule binds to its membrane receptor
- the associated G-protein exchanges GDP for GTP and splits into two parts
- the active G protein subunit activates a nearby membrane enzyme and catalyzes the production of a second messenger.
signal transduction in odorant receptors
- odorant binding to an odorant receptor causes conformational change in the odorant receptor protein
- this change in conformation activates G proteins which diffuses through the cytoplasm and activates adenylyl cyclase
- adenylyl cyclase converts ATP to cAMP.
- cAMP open cAMP gated Na/Ca2+ channels
- cAMP gated channels open and sodium and calcium flows in.
- calcium opens calcium gated cl channels causing efflux of Cl.
- neuron is depolarized
- sodium gated channel opens and sodium flows in generating action potential
each olfactory receptor neuron expresses __ type of odorant receptor
1
each odorant receptor respond to different odorants with varying affinity.
true
receptors of the same type project to distinct regions in the olfactory bulb called:
glomeruli
how does the brain identify specific smells?
by interpreting the intensity and pattern of activation of specific glomeruli
chemicals secreted into the environment and cause a physiological and behavioural change in members of the same species.
pheromones
pheromone receptors are localized in
vomeronasal organs (VNO).
sensory organs in the nasal region of some animals distinct from the olfactory bulb
vomeronasal organs
how to calculate the partial pressure of a gas
multiple the fractional composition of that gas by the total pressure exerted by the entire mixture.
pressure of a particular gas in a mixture of gases is called
partial pressure
it is harder to breathe at high altitudes because
the partial gradient between the atmosphere and your lung is small
_______ states that the rate of diffusion of a gas depends on 5 parameters
Fick’s law of diffusion
the five parameters in fick’s law of diffusion
- solubility of gas
- temperature
- surface area for diffusion
- differences in partial pressures across the gas exchange surface
- thickness of the barrier in diffusion
Rate of diffusion =
k x A x (P2 - P1)/D
k = diffusion constant
A = area for gas exchange
D = distance of diffusion
Five major steps of gas exchange
- Ventilation
- diffusion at the respiratory surface
- Circulation
- Diffusion at the tissues
- Cellular respiration
ventilation
movement of air through a specialized gas exchange organ
Diffusion at the respiratory surface
where oxygen moves from the air or water into the blood and CO2 moves from the blood into the air or water.
Circulation
transport of dissolved CO2 and O2 throughout the body via the circulatory system
Diffusion at the tissues
O2 moves from blood into tissues and CO2 moves out if the tissues into blood.
Cellular respiration.
the cell’s use of O2 to produce co2. leads to high Co2 and low o2 levels in the tissues
respiratory system
collection of cells, tissues, and organs responsible for gas exchange.
ram ventilation
when fish force water through their gills by opening their mouths
the stiff flap over fish gills is called
operculum
most fish ventilate by
opening and closing their mouths and operculum to create a pressure gradient
structure of gill
gill filaments extend from each gill arch and each gill arch contains thousands of sheet like gill lamellae
structure of lung in the order that each component branches out
Trachea
bronchi
bronchioles
alveoli
alveoli consists of (from the air side to the blood side)
- a thin aqueous film
- epithelium of alveolus
- extracellular matrix material(ECM)
- the wall of a capillary
humans ventilate their lungs by
changing pressure within their chest cavity.
change in volume of lung is caused by a downward motion of a thin muscular sheet called the:
diaphragm
each lung is surrounded by a pleural sac which is composed of
two layers of cells with small space between them
inhalation
during inhalation, the diaphragm moves down and the pressure in the chest cavity is lowered, causing the lungs to expand and air to move in.
exhalation
as diaphragm relaxes, the chest cavity volume decreases, and air is exhaled.
- passive process driven by the elastic recoil of the lungs and chest wall as the diaphragm and rib muscle relax.
- it can become energy demanding during exercise
functions of brain stem
information relay, autonomic control of the heart, lungs, digestive system.
the mammalian rate of breathing is controlled by the
medullary respiratory centre
how does the body deal with increased CO2 conc
Increased CO2 react with water in the blood and cerebrospinal fluid to form carbonic acid H2CO3, which dissociates in to H+ and bicabonate ion HCO3. the release of hydrogen ions lowers the blood and CSF pH, which is sensed by specialized chemoreceptors which stimulate CNS control centers to increase breathing rate.
blood is a fluid connective tissue consisting of cells in a watery extracellular matrix called:
plasma
the blood is composed of
plasma
platelets
white blood cells
red blood cells
Platelets
cell fragments that minimize blood loss.
white blood cells
part of the immune system
red blood cells
transport of CO2 and O2
red blood cells contain an oxygen carrying molecule called
hemoglobin
composed of four polypeptide chains, each of which binds to a non protein group called heme
hemoglobin
each heme contains an iron ion that can bind to an
oxygen molecule
the oxygen-hemoglobin equilibrium curve plots the
percentage saturation of hemoglobin vs the partial pressure of oxygen in tissues
decreases in pH alter hemoglobins conformation and causes a ___ shift in the hemoglobin curve
right
temperature increase decrease oxygen affinity and causes a _____ shift
right
fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin therefore
more oxygen is needed to supply tissues
______ _______ in red blood cells catalyzes the formation of carbonic acid from carbon dioxide in water.
carbonic anhydrase
CO2 that diffuses into red blood cells is converted to
bicarbonate ions and protons.
most CO2 is transported in blood in the form of
bicarbonate ions
parietal cells have a high concentration of the enzyme _____ ______ and ______
carbonic anhydrase, mitochondria
where is carbonic anhydrase found?
in red blood cells
importance of red blood cells for two reasons
- the protons produced by the carbonic anhydrase reaction induce the Bohr shift, which makes hemoglobin more likely to release oxygen.
- the Pco2 in blood drops when CO2 is converted to bicarbonate, favouring entry of CO2 into red blood cells
proton generated from the conversion of co2 to bicarbonate binds to ______
hemoglobin
diffusion of CO2 out of the alveoli
- hydrogen ions leave their binding sites on hemoglobin
- hydrogen ions react with bicabonate to form CO2
- CO2 diffuses into the alveoli anf is exhaled from the lungs
reactions to synthesize HCO3 occur in the:
RBC
HCO is exchanged for Cl in the plasma at the ____
tissues
Cl is exchanged for HCO3 in the plasma at the ____
alveoli
