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Physiology Flashcards

1
Q

What is the maintenance of steady state within our bodies by coordinated physiological mechanisms?

A

Homeostasis

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2
Q

Where does a lot of physiological control occur?

A

Cell membrane

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3
Q

What is central to the functionality of nerve and muscle cells?

A

Changes in membrane potential

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4
Q

What must a control system be able to do to maintain homeostasis?

A

Sense deviations from normal, integrate this information, make appropriate adjustments

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5
Q

What is intrinsic control?

A

Local controls within an organ

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6
Q

What is extrinsic control?

A

Regulatory mechanisms from outside an organ, accomplished by the nervous and endocrine systems

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7
Q

What is feedforward?

A

Responses made in anticipation of a change

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8
Q

What is responses made after a change has been detected?

A

Feedback

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9
Q

What is a deviation in a controlled variable detected by?

A

Sensors

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10
Q

What does a sensor inform?

A

Appropriate control centre

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11
Q

What do control centres instruct?

A

Effectors

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12
Q

What is an example of positive feedback?

A

Contractions during labour

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13
Q

Where are membranes found?

A

The outer boundary of every cell

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14
Q

How permeable are membranes?

A

Selectively permeable

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15
Q

What do membranes control entry and exit of?

A

Entry of nutrients and exit of waste/secretory products

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16
Q

What are the amphipathic parts of lipids?

A

Hydrophilic head, hydrophobic tail

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17
Q

What do lipids form in aqueous solution?

A

Fluid, lipid bilayer

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18
Q

What is movement of membrane phospholipids dependent on?

A

Temperature

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19
Q

What does cholesterol do in the membrane?

A

Aids stiffening and can flip easily

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20
Q

What is the lipid membrane permeable/impermeable to?

A

Impermeable- charged molecules and water soluble substances

Permeable- small polar molecules

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21
Q

Where are peripheral membrane proteins?

A

Not embedded within the membrane and adhere tightly to the cytoplasmic/extracellular surface

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22
Q

What are transmembrane proteins?

A

Integral proteins which span the membrane

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23
Q

What can integral proteins be linked to?

A

Membrane lipids or fatty acids

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24
Q

What can integral proteins act as?

A

Ligand binding receptors, adhesion molecules, transporters, enzymes, intracellular signals

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25
Q

What do pores and channels allow?

A

Passive transport

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26
Q

What do carrier transporters do?

A

Facilitate or couple the transport of a molecule

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27
Q

What do transport pumps do?

A

Use energy from ATP to transport substances against a gradient

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28
Q

What are docking marker acceptors and where are they found?

A

Inner membrane surface, interact with secretory vesicles leading to exocytosis

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29
Q

What are short chain carbohydrates bound to membrane proteins or lipids known as?

A

Glycoproteins or glycolipids

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30
Q

What do glycoproteins/lipids form a layer called?

A

Glycocalyx

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31
Q

What do membrane carbohydrates have a role in?

A

Self identity markers and tissue growth

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32
Q

What are tight junctions?

A

Join the lateral edges of epithelial cells near the apical membranes

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33
Q

What are adhering junctions which anchor together cells, especially in tissues subject to stretching?

A

Desmosomes

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34
Q

What are gap junctions?

A

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

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35
Q

What two properties determine whether a particle can pass through the membrane or not?

A

Lipid solubility and size

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36
Q

What is required for any transport through membranes?

A

A driving force- active or passive

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37
Q

What two mechanisms drive unassisted transport?

A

Diffusion down a concentration gradient or movement along an electrochemical gradient

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38
Q

Increasing what factors increases the rate of diffusion?

A

Concentration gradient, membrane surface area, lipid solubility

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39
Q

Decreasing what factors increases the rate of diffusion?

A

Molecular weight and distance

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40
Q

What type of channels are always open, or ligand gated?

A

Leak channels

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41
Q

What is it known as when electrical and chemical gradients act on an ion at the same time?

A

Electrochemical gradient

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42
Q

What is the electrochemical gradient involved in setting up?

A

Resting membrane potential

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43
Q

What is the relative speed of osmosis?

A

Slow

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44
Q

What is used to help water transport?

A

Aquaporin channels- passive

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45
Q

What makes different cells have different permeabilities to water?

A

Different numbers of aquaporins

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46
Q

What is osmolarity?

A

The concentration of osmotically active particles in a substance

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47
Q

What are two methods for carrying molecules against concentration gradients?

A

Carrier mediated transport or vesicular transport

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48
Q

What happens when a substance binds to a carrier transporter?

A

The carrier changes conformation

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49
Q

What 3 characteristics determine the kind and amount of material transferred through carrier mediated transport?

A

Specificity, saturation, competition

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50
Q

What are the two forms of carrier transport?

A

Facilitated diffusion or active transport

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51
Q

What is primary active transport?

A

Energy directly required

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52
Q

What is secondary active transport?

A

Energy not used directly, uses second hand energy stored in ion concentration gradients

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53
Q

What does Na+/K+ ATPase transport?

A

3Na+ out for every 2K+ in

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54
Q

What does the Na+/K+ ATPase pump have a role in?

A

Establishing Na+/K+ gradients, regulates cell volume, energy source for secondary active transport

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55
Q

What ion is usually coupled in secondary active transport?

A

Sodium

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56
Q

What is symport transport?

A

Secondary active transport where the solute and sodium move in the same direction

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57
Q

What is antiport transport?

A

Secondary active transport where the solute and sodium move in different directions (Na+ into)

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58
Q

Does vesicular transport require energy?

A

Yes

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59
Q

What are examples of vesicular transport?

A

Exo and endocytosis

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60
Q

What is a membrane potential?

A

Uneven distribution of charge across a membrane

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61
Q

What does membrane potential refer to?

A

Differences in charge between layers of ECF and ICF

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62
Q

What type of cells have the ability to produce rapid changes in membrane potential?

A

Excitable cells e.g. nerve and muscle

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63
Q

What is the resting membrane potential?

A

-70mV

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64
Q

What will the electrical gradient be towards for Na+ and K+?

A

Negative side

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65
Q

What is the resting membrane potential more permeable to, K+ or Na+?

A

K+

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66
Q

What is the concentration gradient for K+?

A

Outwards

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67
Q

What is the electrical gradient for K+?

A

Inwards

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68
Q

What is the equilibrium potential for K+?

A

-90mV

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69
Q

What does the +/- sign on a polarity represent?

A

The excess charge on the inside of the membrane

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70
Q

What is the concentration gradient for Na+?

A

Inwards

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71
Q

What happens when more Na+ moves into the cell following its chemical gradient?

A

Outside becomes more negative and is full of Cl- ions

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72
Q

After an influx of Na+, what is the electrical gradient for Na+?

A

Outwards

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73
Q

What is the equilibrium potential for Na+?

A

+60mV

74
Q

What happens with increasing permeability of the membrane to an ion?

A

This ion drives the membrane potential towards its own equilibrium potential more strongly

75
Q

Which of K+ and Na+ has a bigger effect on membrane potential?

A

K+

76
Q

What helps maintain K+ and Na+ gradient across the membrane?

A

Na/K ATPase

77
Q

What type of current does Na/K ATPase create?

A

Hyperpolarising

78
Q

What are examples of what membrane potential changes can cause?

A

Contraction of muscle or secretion of insulin

79
Q

What is depolarisation?

A

Membrane potential becomes less negative

80
Q

What is hyperpolarisation?

A

Membrane potential becomes more negative

81
Q

What are ion channels?

A

Transmembrane proteins which allow rapid flow of selected ions

82
Q

What are the three types of gated ion channels?

A

Membrane voltage (voltage gated), chemical substances (ligand gated), physical stimuli

83
Q

What ion channels are responsible for the depolarisation (upstroke) of APs?

A

Voltage gated Na+

84
Q

What ion channels are responsible for the hyperpolarisation (downstroke) of APs?

A

Voltage gated K+

85
Q

When do Na+ ion channels become activated during and AP and what does this cause?

A

Threshold potential- rapid depolarisation

86
Q

What do neuron APs allow signalling over?

A

Long distances

87
Q

Does the size of the stimulus have an effect on the size of the AP?

A

No- it happens or it doesn’t

88
Q

What activates both Na+ and K+ channels?

A

Membrane depolarisation

89
Q

Which ion channel responds to membrane depolarisation quicker?

A

Na+

90
Q

The activation of which ion channel is self reinforcing and what does this mean?

A

Na+: the opening of a few channels causes more to open which causes more depolarisation (positive feedback)

91
Q

The activation of which ion channel is self limiting and what does this mean?

A

K+: outward movement of K+ causes repolarisation which then turns off the stimulus for opening (negative feedback)

92
Q

What is the refractory period?

A

During maintained depolarisation, Na+ channels enter a non-conducting, inactivated state

93
Q

What is required after the refractory period?

A

Repolarisation for the channels to enter the closed state

94
Q

On an AP graph, the area from the start of hyperpolarisation to the lowest point on the graph is known as what?

A

Absolute refractory period

95
Q

What does the absolute refractory period mean?

A

No stimulus, however large can elicit a second AP

96
Q

What is the state of the Na+ channels in the absolute refractory period?

A

All inactivated

97
Q

On an AP graph, what is the area from the end of the absolute refractory period to the area where the next AP begins known as?

A

Relative refractory period

98
Q

What does the relative refractory period mean?

A

A stronger than normal stimuli may elicit a second AP

99
Q

What is the state of Na+ channels in the refractory period?

A

Mixed inactivated and closed channels as the membrane is hyperpolarised

100
Q

What is the maximum number of APs in a second?

A

1000

101
Q

Why do passive signals in nerve cells not spread far?

A

Current loss

102
Q

What is the potential change of an axon relative to?

A

The given current

103
Q

What does membrane potential decrease exponentially with?

A

Distance

104
Q

What does the distance over which the current spreads depend on?

A

Membrane and axial resistance

105
Q

What is the effect of diameter of the axon on current flow resistance?

A

Bigger the diameter, lower the resistance

106
Q

What does greater current spread increase?

A

AP conduction velocity

107
Q

Is conduction faster in myelinated or non-myelinated axons?

A

Myelinated

108
Q

What are Nodes of Ranvier?

A

Points between myelin sheaths of axons

109
Q

What id Saltatory conduction?

A

APs jumping between Nodes of Ranvier

110
Q

What are examples of demyelinating conditions?

A

MS and Guillian-Barre syndrome

111
Q

What do demyelinating conditions cause?

A

Slowing or cessation of nerve conduction

112
Q

What is fuel metabolism regulated by?

A

Hormones- glucagon, insulin, growth hormone, adrenaline and cortisol

113
Q

What does thyroid hormone regulate?

A

Metabolic rate

114
Q

What can be used instead of glucose in prolonged starvation?

A

Ketones

115
Q

What does hypoglycaemia lead to?

A

Confusion and coma

116
Q

What does hyperglycaemia lead to?

A

Damaged blood vessels

117
Q

What are the two types of glands which the pancreas contains?

A

Exocrine and endocrine (islets of Langerhans)

118
Q

What do exocrine pancreatic cells produce?

A

Secrete digestive enzymes and HCO3- to intestinal lumen

119
Q

What do alpha cells in the islets of Langerhans produce?

A

Glucagon

120
Q

What do beta cells in the islets of Langerhans produce?

A

Insulin

121
Q

What do delta cells in the islets of Langerhans produce?

A

Somatostatin

122
Q

What do F cells in the islets of Langerhans produce?

A

Pancreatic polypeptide

123
Q

What does insulin stimulate?

A

Anabolism: glucose to glycogen, amino acids to proteins and fatty acids to triglycerides

124
Q

What is insulin the hormone of?

A

The fed state

125
Q

What does glucagon stimulate?

A

Catabolism: glucagon to glucose, triglycerides to fatty acids

126
Q

What is glucagon the hormone of?

A

Hunger state

127
Q

What does glucagon have no effect on?

A

Protein metabolism

128
Q

What are the most abundant cells in the islets of Langerhans and whereabouts are they found?

A

Beta cells in the centre

129
Q

Which cells are found around the outsides of islets of Langerhans?

A

Alpha and delta

130
Q

What are all the different types of cells of the islets of Langerhans linked by?

A

Gap and tight junctions

131
Q

What happens to insulin when glucose in the blood is high?

A

More is secreted into the blood

132
Q

During fasting, less insulin is secreted and lipids and amino acids are mobilised. What do these lipids and amino acids do?

A

Provide fuel for oxidation and act as precursors for hepatic ketogenesis and gluconeogenesis

133
Q

What effect does sympathetic/parasympathetic stimulation have on insulin secretion?

A

Sympathetic- inhibits, parasympathetic- stimulates

134
Q

What effect does exercise have on insulin secretion?

A

Suppresses it

135
Q

What 3 incretins (peptides) increase insulin secretion?

A

CCK, GLP-1 and GIP

136
Q

Where are incretins released and what do they do?

A

GI tract cells- feedforward mechanism to prime Beta cells for insulin secretion

137
Q

What are the three prime targets for insulin?

A

Liver, skeletal muscle and adipose tissue

138
Q

Where else can insulin affect but isn’t a prime target?

A

Cardiac muscle

139
Q

Where are insulin insensitive cells?

A

Brain, kidneys and RBCs

140
Q

What is the glucose storage molecule in liver and skeletal muscle?

A

Glycogen

141
Q

What is the glucose storage molecule in adipose tissue?

A

Triglycerides

142
Q

How does insulin lower plasma glucose in the liver?

A

Activating enzymes which convert glucose to glycogen

143
Q

How does insulin lower plasma glucose in skeletal muscle?

A

Stimulating uptake of glucose from blood into muscle via GLUT4

144
Q

Where is the defect in type 1 and 2 diabetes?

A

Type 1- beta cell function

Type 2- insulin receptor sensitivity

145
Q

Which type of diabetes is more prone to ketogenesis?

A

1

146
Q

How is diabetes diagnosed?

A

Glucose after a meal higher then 11mmol/l

147
Q

What are some effects of severe diabetes?

A

Increased plasma glucose after a meal, glucose in urine, formation of ketone bodies, decreased pH and hyperventilation

148
Q

What is glucagon secreted in response to?

A

Ingested proteins

149
Q

What is the principle target of glucagon?

A

Liver

150
Q

Where are adrenaline and cortisol released?

A

Adrenal gland in response to stress

151
Q

What do adrenaline and cortisol do to plasma glucose?

A

Increase it

152
Q

What do adrenaline and cortisol do to gluconeogenesis?

A

Stimulate it

153
Q

What does adrenaline stimulate which cortisol doesn’t?

A

Glycogenolysis

154
Q

What does cortisol stimulate which adrenaline doesn’t?

A

Protein catabolism and lipolysis

155
Q

When are adrenaline and cortisol released?

A

Adrenaline- short term emergencies

Cortisol- long term

156
Q

Where is growth hormone secreted?

A

Anterior lobe of pituitary gland

157
Q

What does growth hormone cause in response to starvation?

A

Decreased glucose uptake by muscles, ,obilises glucose from liver, promotes lipolysis in fat cells

158
Q

What is core optimum body temperature?

A

Around 37.8 degrees C

159
Q

How can body heat be gained?

A

Metabolic heat (internal), radiation, convection, conduction (external)

160
Q

How can body heat be lost?

A

Radiation, convection, conduction, evaporation

161
Q

What hormones increase heat production through metabolic heat?

A

Adrenaline, noradrenaline, thyroxine

162
Q

What external action does increased metabolic heat cause?

A

Muscle activity and hence shivering

163
Q

What is conduction?

A

Transfer of heat from objects in contact- heat moves from warmer to cooler

164
Q

What is convection?

A

Transfer of heat by air or water currents which carry heat away from the body

165
Q

What is an active evaporative heat loss process?

A

Sweating

166
Q

What controls sweating?

A

Sympathetic nervous system

167
Q

What is body temperature controlled by?

A

A negative feedback system

168
Q

Where are central thermoreceptors?

A

Hypothalamus and abdominal organs

169
Q

Where are peripheral thermoreceptors?

A

Skin

170
Q

Where are the effectors for maintaining body temperature?

A

Skeletal muscle, skin arterioles, sweat glands, behavioural adaptations

171
Q

Where is the temperature control centre?

A

Hypothalamus

172
Q

What part of the hypothalamus is activated by cold?

A

Posterior

173
Q

What part of the hypothalamus is activated by warmth?

A

Anterior

174
Q

What adaptations does cold result in?

A

Vasoconstriction and increased skeletal muscle tone (shivering)

175
Q

What adaptations does warmth result in?

A

Vasodilation, evaporation of sweat and decreased skeletal muscle tone

176
Q

What happens to the temperature setpoint in fever?

A

Increases

177
Q

Where are chemicals released from in response to infection/inflammation?

A

Macrophages

178
Q

What do macrophages stimulate release of which act on the hypothalamus to change the set point?

A

Prostaglandins

179
Q

What response does the hypothalamus have to an increased temperature setpoint?

A

Elicits the cold response to increase temperature

180
Q

What classes as hyperthermia?

A

> 40 degrees

181
Q

What classes as hypothermia?

A

< 35 degrees

Principles (11 decks)

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