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FOUNDATION MEDICINE > Physiology COPY > Flashcards

Physiology COPY Flashcards

1
Q

What do membranes do?

A

Control exit and entry of waste products, they are selectively permeable.
-Maintain ion concentration gradients and participate in the joining of cells

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2
Q

What is the plasma membrane?

A

-Phospholipid bilayer
-Cholesterol
-Proteins
-Carbohydrates

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3
Q

What does cholesterol add to plasma membrane?

A

Fluidity and stability
-Stiffens the membrane

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4
Q

3 types of proteins in plasma membrane?

A

Integral
Transmembrane
Peripheral

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5
Q

Where are integral proteins in membrane?

A

Embedded in bilayer
-Receptors

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6
Q

What are names of transmembrane proteins and where are they?

A

Transporters/channels
-Extend through membrane

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7
Q

What is different about peripheral proteins compared to transmembrane and integral?

A

They do not penetrate the membrane

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8
Q

What makes up the glycocalyx?

A

Glycoproteins
Glycolipids

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9
Q

Functions of lipid bilayer?

A

Basic structure of membrane
Hydrophobic interior serves as a barrier
Responsible for fluidity

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10
Q

Function of carrier/transport proteins?

A

Span the membrane and are substrate specific

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11
Q

Where are docking marker acceptors?

A

Inner membrane surface

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12
Q

How do docking membrane acceptors work?

A

Interact with secretory vesicles leading to exocytosis of vesicle contents

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13
Q

How do receptor proteins work?

A

Bind specific molecules - lock & key

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14
Q

Types of cell adhesion molecules (proteins)?

A

Cadherins
Integrins

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15
Q

What do cadherins do? And what are they?

A

Hold cells within tissues together
Cell adhesion molecules

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16
Q

What do integrins do?

A

Span membrane acting as a link between extra and intra-cellular environments

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17
Q

2 Functions of carbohydrates?

A

-Serve as self identity markers enabling cells to identify and interact with one another (different cell types have different markers)
-Role in tissue growth

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18
Q

3 types of specialized cell junctions?

A

Gap junctions
Tight Junctions
Desmosomes

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19
Q

Desmosomes?

A

Adhering junctions that anchor cells together

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20
Q

Tight junctions?

A

Join lateral edges of epithelial cells near luminal/apical membrane

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21
Q

Gap junctions?

A

Communicating junctions that allow movement of charge carrying ions and small molecules between 2 adjacent cells

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22
Q

What does Fick’s law of diffusion relate to?

A

-Magnitude of conc gradient
-SA of the membrane diffusion is taking place across
-Lipid solubility of substance
-Molecular weight of substance
-Distance which diffusion must take place across
Q ∝ 𝝙C · A · P

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23
Q

What is an electrochemical gradient?

A

Where an electrical and a concentration (chemical) gradient may be acting on a particular ion at the same time

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24
Q

Osmosis?

A

Net diffusion of water down a concentration gradient

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25
Q

what does osmosis levels depending of ?

A

the availability of Aquaporins (water channels) in the cell membrane

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26
Q

Osmolarity?

A

Concentration of osmotically active particles in a solution

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27
Q

What is osmolarity measured in?

A

Osmoles/Litre

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28
Q

Osmolarity of body fluids?

A

~300mOsm

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29
Q

Tonicity?

A

Effect a solution has on cell volume

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30
Q

Units of tonicity?

A

NO UNITS

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31
Q

What is carrier-mediated transport?

A

Substance binds to specific carrier and undergoes transformational change to transport substance

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32
Q

What is saturation another term for?

A

Transport maximum (Tm)

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33
Q

Fact file of facilitated diffusion?
-Energy?
-Mediated?
-Gradient direction

A

No energy required
-Carrier mediated
-From high to low conc

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34
Q

Active transport fact file?
Energy?
Gradient?
Types?

A

-Energy required
-Low concentration to high concentration
-Primary= energy directly required
Secondary= Energy required but not used directly

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35
Q

Secondary active transport energy?

A

-Energy required but not used directly
-It is stored in the form of an ion concentration gradient (usually Na+)

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36
Q

Mechanisms of secondary active transport?

A

2 mechanisms
-Symport- (contransport)= the transported solute and the ion move in the same direction across the membrane. For example, the glucose-sodium symporter

-Antiport (countertransport): In this mechanism, the transported solute and the ion move in opposite directions across the membrane. For example, the sodium-calcium exchanger

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37
Q

What is K+/Na+ATPase used in? Where is it?

A

Primary active transport
Plasma membrane of all cells

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38
Q

Ratio of NA:K movement in primary AT?

A

3 Na out
2 K in

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39
Q

3 important roles of Na+/K+ATPase?

A

-Establish Na/K concentration gradients across plasma membrane
- Regulate cell volume by controlling concentration of solutes inside the cell
-Energy used to drive the pump indirectly serves as energy source for secondary AT

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40
Q

Types of vesicular transport?

A

Endocytosis
Exocytosis

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41
Q

Endocytosis?

A

Membrane pinches off to engulf substance

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42
Q

Exocytosis?

A

Vesicle fuses with membrane, releasing contents to ECF

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43
Q

What is Em? Units?

A

Membrane potential - separation of opposite charges across membrane
-mV

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44
Q

Concentration gradient direction for K+?

A

Outward

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45
Q

Concentration gradient for Na+?

A

Inward

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46
Q

Electrical gradient for K+/Na+?

A

Both positively charged so the EG for both will be towards the negatively charged side of the membrane

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47
Q

Equilibrium potential for K+?

A

When concentration and electrical gradients balance eachother

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48
Q

Membrane potential at Ek?

A

-90mV

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49
Q

Membrane potential for Na+?

A

ENa+ +61mV

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50
Q

Nernst equation?

A

Eion=
61Log10 [ion]0/[ion]i

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51
Q

Resting membrane potential for a typical nerve cell?

A

-70mV

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52
Q

What is the Nernst equation used for?

A

To find cell potential under non-standard conditions

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53
Q

Why is Em of nerve cell close but not identical to Ek?

A

Slight inward leak of Na+ into the cell, K+ gradient is most important factor here

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54
Q

Goldman-Hodgkin-Katz equation

A

Em= 61Log10 Pk+[K+]o + PNa+ [Na+]o
___________________________________
Pk+[K+]i + PNa+ [Na+]i

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55
Q

What is the Goldman Hodgkin Katz equation used for?

A

Calculating overall membrane potential

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56
Q

What does P stand for in Goldman Hodgkin Katz equation?

A

Relative permeability

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57
Q

Hyperpolarization?

A

More negative

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58
Q

Depolarisation?

A

More positive

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59
Q

Which hormones control glucose in post absorptive and absorptive states?

A

Insulin
Glucagon (pancreas)

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60
Q

Which hormone controls glucose in emergencies?

A

Adrenalin (adrenal gland)

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61
Q

Which hormones control glucose during starvation?

A

Cortisol (Adrenal)
Growth hormone (pituitary)

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62
Q

Types of pancreatic islets of langerhan?

A

Alpha
Beta
Delta

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63
Q

What do alpha pancreatic islets of langerhan produce?

A

Glucagon

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64
Q

What do beta pancreatic islets of langerhans produce?

A

Insulin

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65
Q

What do delta pancreatic islets of langerhan produce?

A

Somatostatin

66
Q

What are pancreatic islets of langerhan located in?

A

Endocrine glands

67
Q

What happens to levels of
-Glucose
-Insulin
-Glucagon
in absorptive state?

A

-Glucose rises
-Insulin rises
-Glucagon falls

68
Q

Which process does insulin favour?

A

Anabolism

69
Q

What is converted to what by insulin?

A

Glucose -> Glycogen
Fatty acids-> Triglycerides
Amino acids -> protein

70
Q

What is the hormone of the fed state?

A

Insulin

71
Q

Effects of insulin?

A

-Lowers glucose by stimulating uptake from blood and activating liver enzymes
-Promoting secretion= increased glucose= increased parasympathetic activity
-Inhibiting secretion = decreased glucose = increased sympathetic activity

72
Q

Which process does glucagon favour?

A

Catabolism

73
Q

What is converted to what by glucagons presence?

A

Glycogen -> Glucose
Triglycerides-> Fatty acids

74
Q

What is glucagon the hormone of?

A

The hungry state

75
Q

Effects of glucagon?

A

Raises glucose by increasing glycogenesis, inhibiting liver glycogen synthesis, promoting liver gluconeogenisis, lipolysis

76
Q

What happens in type 1 diabetes?

A

Little/no insulin release
-Defect in beta cells
Insulin injections required
-Early onset

77
Q

Stimulation of release of glucagon?

A

Decreased blood glucose
Amino acids
Sympathetic nerve activity

78
Q

Stimulation of inhibition of release of glucagon?

A

Raised blood glucose
Insulin

79
Q

Type 2 diabetes?

A

Insulin secretion MAY be normal
-Defect in insulin sensitivity
-Diet/exercise/oral drugs
ADULT onset

80
Q

Adrenaline raises glucose. True or false?

A

True
-Stimulates gluconeogenesis
-Stimulates glycogenolysis

81
Q

When is adrenaline released?

A

During short term emergencies

82
Q

What does cortisol do to glucose levels?

A

Raises them

83
Q

What processes does cortisol stimulate?

A

-Protein catabolism
-Gluconeogenesis
-Lipolysis
-

84
Q

Where is growth hormone secreted from?

A

Anterior lobe of pituitary

85
Q

In response to ________, growth hormone does 3 things
1.
2.
3.?

A

Starvation
1.Decreases glucose uptake by muscle
2. Mobilises glucose form liver
3. Promotes lipolysis in fat cells

86
Q

What happens to baroreceptor firing if high blood pressure is sustained?

A

Firing decreases
They only respond to acute changes

87
Q

MAP equations when you have diastolic and systolic?

A

MAP = [(2x diastolic) + systolic]/3
MAP = DBP + 1/3 difference between SBP/DBP

88
Q

MAP equations?

A

MAP = Cardiac output (CO) x Total peripheral Resistance (TPR)

89
Q

CO equation?

A

CO = stroke volume (SV) x Heart rate (HR)

90
Q

How can MAP be regulated?

A

By regulating
-HR
-SV
-TPR

91
Q

Which hormones can increase metabolic heat?

A

Adrenaline, noradrenaline, thyroxine

92
Q

What is basal metabolic rate?

A

Basic level of heat production

93
Q

Ion channels responsible for action potentials in neurones?

A

Voltage activated Na channels = depolarizing
Voltage activated K channels = Hyperpolarizing

94
Q

What are voltage activated Na/K channels activated by?

A

Membrane depolarization
-Na channels rapid, K channels slight delay allwing time for Na cahnnels to close

95
Q

What is positive feedback (upstroke of graph)?

A

Activation of Na channels is self-reinforcing, the opening of a few channels causes further depolarization

96
Q

How is the activation of K channels self-limiting?

A

The outward movement of K causes repolarisation which turns off the stimulus (negative feedback) downstroke of graph ad undershoot due to delayed closure of K channels

97
Q

What does an absolute refractory period mean?
A

A

No stimulus, however strong, can elicit a second AP

98
Q

Oligodendrocytes?

A

Produce myelinated cells in CNS (Shwann cells do it in PNS)

99
Q

Which ion is most important in determining the resting membrane potential?

A

POTASSIUM

100
Q

What is meant by autorhythmicity of the heart?
A

A

It is able to generate its own electrical impulses without external stimuli

101
Q

Where does excitation of the heart normally originate?
A

A

SA node

102
Q

What are the specialised cells within the SA node that initiate the heart beat called?
A

A

Pacemaker cells

103
Q

What is meant by sinus rhythm?
A

A

Describes the heart’s pace being controlled by the SA node

104
Q

SA node cells have a stable resting membrane potential. True/False?
A

A

False
They exhibit spontaneous pacemaker potential

105
Q

What is the function of the spontaneous pacemaker potential?
A

A

Takes the membrane potential to threshold (depolarisation) to generate an action potential

106
Q

What gives rise to pacemaker potential?
A

A

Decrease in K+ efflux
Slow Na+ influx

107
Q

What causes the rising phase of the action potential (depolarisation) in SA node cells?
A

A

Opening of Ca++ channels, resulting in Ca++ influx

108
Q

What causes the falling phase of the action potential (repolarisation) in SA node cells?
A

A

Opening of K+ channels, resulting in K+ efflux

109
Q

Summarise the phases of the SA node action potential
A

A

Pacemaker potential: decreased K+ efflux, slow Na+ influx
Rising phase: Ca++ influx
Falling phase: K+ efflux

110
Q

Which junctions allow cell-to-cell spread of excitation?
A

A

Gap junctions

111
Q

The AV node is the only point of electrical contact between atria and ventricles. True/False?
A

A

True

112
Q

AV node cells are large and slow to conduct. True/False?
A

A

False
They are small and slow to conduct

113
Q

Why is AV nodal delay present?
A

A

To allow time for atrial systole to precede ventricular systole

114
Q

Which fibres enable the excitation to spread to the ventricles?
A

A

Bundle of His and Purkinje fibres

115
Q

What gives rise to the rising phase of the action potential in ventricular contractile cells?
A

A

Fast Na+ influx

116
Q

Describe Phase 0 of the cardiac action potential
A

A

Fast Na+ influx causes reversal of the resting membrane potential from -90mV to +30mV

117
Q

Describe Phase 1 of the cardiac action potential
A

A

Closure of Na+ channels + transient K+ efflux causes some repolarisation

118
Q

What gives rise to the plateau phase (phase 2) of the cardiac action potential?
A

A

Ca++ influx

119
Q

What gives rise to the falling phase (phase 3) of the cardiac action potential?
A

A

K+ efflux

120
Q

Describe Phase 3 of the cardiac action potential
A

A

Closure of Ca++ channels and opening of K+ channels allows K+ efflux which causes repolarisation of the membrane potential back to -90mV

121
Q

Sympathetic stimulation causes increased heart rate. True/False?
A

A

True

122
Q

What is meant by vagal tone?
A

A

Parasympathetic stimulation to the heart dominating in resting conditions

123
Q

The vagus nerve supplies only the SA node. True/False?
A

A

False
Supplies both SA and AV nodes

124
Q

What does parasympathetic stimulation do to the AV node?
A

A

Increases AV nodal delay

125
Q

Which neurotransmitter acts on which receptor in parasympathetic control of the heart?
A

A

ACh on M2 receptors

126
Q

Name a competitive inhibitor of ACh that is used in bradycardia
A

A

Atropine

127
Q

Vagal stimulation causes the slope of the pacemaker potential to increase. True/False?
A

A

False
Slope decreases (increased AV node delay)

128
Q

What is meant by negative chronotropic effect?
A

A

Decreased contraction of the heart due to less frequent action potentials

129
Q

Which areas of the heart does the sympathetic system supply?
A

A

SA node
AV node
Myocardium

130
Q

Which neurotransmitter acts on which receptor in sympathetic control of the heart?
A

A

Noradrenaline on B1 receptors

131
Q

Sympathetic stimulation does what to the slope of the action potential?
A

A

Increases it (become sharper )

132
Q

What is meant by positive chronotropic effect?
A

A

Increased contraction of the heart due to more frequent action potentials

133
Q

Where does Lead I of an ECG connect?
A

A

Right arm - Left arm

134
Q

Where does Lead II of an ECG connect?
A

A

Right arm - Left leg

135
Q

Where does Lead III of an ECG connect?
A

A

Left arm - Left leg

136
Q

Cardiac muscle is striated. True/False?
A

A

True

137
Q

What creates the striated appearance of cardiac muscle?
A

A

Contractile protein elements (actin and myosin)

138
Q

Give the name of protein channels that which form electrical communication between neighbouring myocytes
A

A

Gap junctions

139
Q

What do desmosomes do in the heart?
A

A

Provide mechanical adhesion between adjacent cardiac cells
Ensure tension is developed

140
Q

What is contained within muscle fibres?
A

A

Myofibrils (contractile protein elements of muscle)

141
Q

Actin filaments are thick and appear light. True/False?
A

A

False
They appear light but are thin

142
Q

Myosin filaments are thick and appear dark. True/False?
A

A

True

143
Q

What is the arrangement of of actin and myosin within each myofibril called?
A

A

Sarcomere

144
Q

Myosin filaments slide over actin filaments to produce muscle tension. True/False?
A

A

False
Actin slides over myosin!

145
Q

What is required to generate the force by which sliding of filaments can occur?
A

A

ATP
Calcium

146
Q

What is the role of calcium in sliding of filaments?
A

A

Required to ‘switch on’ cross-bridge formation
1. binds to troponin complex on actin
2. causes conform change which exposes actin binding site
3. cross-bridge forms via site and myosin binding site

147
Q

What is the role of ATP in sliding of filaments?
A

A

Binds to myosin head to either energise it or break down the cross-bridge between myofibrils (that is created by calcium)

148
Q

Where does the calcium that activates contractile machinery come from (where is it stored)?
A

A

Sarcoplasmic reticulum

149
Q

What is meant by calcium-induced calcium release?
A

A

Ca++ influx during the plateau phase of the AP causes Ca++ to be released from the sarcoplasmic reticulum to cause contraction

150
Q

What is meant by the refractory period?
A

A

Period following action potential where it is not possible to generate another action potential

151
Q

What are the two moments where a new action potential cannot be generated?
A

A

Plateau phase (Na channels in closed state)
Falling phase (K channels open, thus membrane cannot depolarise)

152
Q

What is the clinical benefit of the refractory period?
A

A

Prevents tetanic contractions of the heart

153
Q

Define stroke volume
A

A

Volume of blood ejected by each ventricle per heart beat
EDV - ESV

154
Q

What is meant by end diastolic volume (EDV)?
A

A

Volume of blood remaining in each ventricle following diastole

155
Q

What determines EDV?
A

A

Venous return

156
Q

Describe the Frank-Starling Law of the Heart
A

A

The greater the EDV (as a result of more venous return), the greater the stroke volume will be during systole

157
Q

Optimal skeletal muscle fibre length (for contraction) is achieved by stretching the muscle. True/False?
A

A

False
Optimal length is at rest

158
Q

What is meant by preload?
A

A

Volume of blood in each ventricle before contraction

159
Q

What is meant by afterload?
A

A

The resistance against which the heart has to pump after contraction

160
Q

What determines the resting membrane potential?

A

The resting membrane potential is determined by charged ions existing on each side of the membrane in unequal distribution. due to the membrane permeability to specific ions (e.g present of potassium leak channels )

161
Q

What effect does dephosphorylation of the sodium potassium pump have on sodium transport outside of the cell?

A

The pump desphosphorylates, and changes shape to move the K+ ions inside the cell. The unphosphorylated pump has a higher affinity for Na+ ions than K+ ions, so the K+ ions are released.
therefore for every 2K+ enter the cell 3 Na+ move out the cell.

FOUNDATION MEDICINE (23 decks)

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