Unit 1

Question 1

what is physiology?

Answer 1

the science of the function of living systems

Question 2

function vs process

Answer 2

function –> why
- why does the system exist
-why does the event occur
Process –> How
-how does a system work
- physiological mechanism

Question 3

what is homeostasis

Answer 3

• maintenance of a relatively stable internal environment around a set point

Question 4

local vs relex control

Answer 4

Local
- cells near site of change initiate response
reflex control
- cells at a distant site control response

Question 5

what is a response loop

Answer 5

stimulus, sensor, input signal, integrating centre, output
signal, target, response

Question 6

what are the types of feedback

Answer 6

• negative feedback- stabilizes variable
• feedforward control- anticipates change
• positive feedback- reinforces stimulus – not homeostatic

Question 7

what are electrical signals

Answer 7

• changes in membrane potential
• restricted to nerve and muscle cells

Question 8

what are chemical signals

Answer 8

• secreted into extracellular fluid by all cells
• responsible for most of the communication
• cells that respond to signals are called target cells

Question 9

what are the types of long range cell- cell communication

Answer 9

• endocrine
  -neural
• neuro endocrine

Question 10

what is endocrine communication

Answer 10

chemical (hormone) released into blood stream and distributed throughout body

Question 11

what is neural communication

Answer 11

electrical signal travels down neuron; reaches end and is translated to chemical signal (neurotransmitter) which transmits information to next cell

Question 12

what is neuro endocrine communication

Answer 12

electrical signal travels down neuron; reaches end and is secreted into blood

Question 13

what is a target cell

Answer 13

• Only cells that have receptors for that signal will respond to it
• signal molecule that binds to a particular receptor is its ligand
• Receptors are proteins that project to outside of the membrane, or are within the cell, in the cytoplasm
• Chemical properties of signal molecules (ligands) determine what type of receptor they will interact with

Question 14

what are the types of ligands and receptors

Answer 14

• water soluble = hydrophilic = lipophobic –> surface receptor
• water insoluble = hydrophobic = lipophilic –> intracellular receptor

Question 15

what are the types of membrane receptors

Answer 15

• ion channel
• enzyme coupled receptor
• G protein coupled receptor (GPCR)
• integrin receptor

Question 16

variation of signal pathways

Answer 16

• one ligand may have several different types of receptors
• receptors exhibit saturation, specificity, competition for their ligands (and molecules similar to their ligands)
• cells can change their response to signals by changing receptor number or sensitivity

Question 17

explain ligands having different receptors

Answer 17

• same signal can have different effects in different cell types

Question 18

explain how receptors exhibit saturation, specificity, competition for their ligands

Answer 18

• e.g. relative affinities of adrenergic receptors for epinephrine versus norepinephrine
  – e.g. agonists and antagonists competing with endogenous ligands

Question 19

explain how cells can change their response to signals by changing receptor number or sensitivity

Answer 19

• increase –> ↑ gene expression (up-regulation)
  – decrease –> internalize surface receptors (down-regulation)
  – change receptor sensitivity –> e.g. phosphorylation 19

Question 20

what is an agonist

Answer 20

• a molecule that is similar to the natural ligand and it activates the receptor

Question 21

what is an antagonist

Answer 21

• a molecule that is similar to the natural ligand but it does not activate the receptor (blocker)

Question 22

**Cholera**

Question 23

what are cannon’s postulates

Answer 23

• the nervous system has a role in maintaining ‘fitness’ of the internal environment (coordinates responses that regulate blood volume, blood pressure, osmolarity, body temp, …)
• some systems are under tonic control
• some systems are under antagonistic control
• one chemical signal can have different effects in different tissues

Question 24

what is tonic control

Answer 24

• regulates physiological parameters in an “up- down” fashion
• such as a neuron increasing or decreasing its firing rate

Question 25

what is antagonist control

Answer 25

• Antagonistic neurons control heart rate: some speed it up, while others slow it down
• Stimulation by sympathetic nerves increases heart rate
• Stimulation by parasympathetic nerves decreases heart rate

Question 26

Specificity of neural vs endocrine reflex

Answer 26

Neural:
- each neuron terminates on a single target cell or on a limited number of adjacent target cells
Endocrine:
- most cells of the nody are exposed to a hormone; the response depends on which cells have the receptor for the hormone

Question 27

nature of the signal of neural vs endocrine reflex

Answer 27

Neural:
- electrical signal that passes through neuron then chemical neurotransmitters that carry the signal from cell to cell. In a few cases signals pass from cell to cell through gap junctions
Endocrine:
- chemical signals secreted in the blood for distribution throughout the body

Question 28

speed of neutral vs endocrine reflex

Answer 28

Neural:
-very rapid
Endocrine:
- distribution of signal and onset of action are much slower than neural reflex

Question 29

duration of action of neural vs endocrine reflex

Answer 29

Neural:
- usually very short; responses of longer duration are mediated by neuromodulators
Endocrine:
- responses usually last longer than neural responses

Question 30

coding for stimulus activity of neural vs endocrine reflex

Answer 30

Neural:
- each signal is identical in strength
-stimulus intensity is correlated with increased frequency of signalling
Endocrine:
- intensity correlated by amount of hormone secreted