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DENT 262 > Physiology > Flashcards

Physiology Flashcards

1
Q

Define Homeostasis

A

Maintenance of a relatively stable internal environment through self-regulating processes

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2
Q

List examples of controlled variables managed through homeostatic control

A
  • Body water volume and ionic composition
  • Blood pressure and flow
  • Core body temperature
  • Membrane potential
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3
Q

What are the 3 components in a homeostatic control mechanism?

A
  • Receptor/Sensor
  • Control Centre
  • Effector
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4
Q

What do Receptors/Sensors do in a homeostatic control mechanism?

A

Detects changes in a specific variable (stimulus) and sends signals to the control centre
- Receptors are often specialised cells or sensory organs

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5
Q

What does the Control Centre do in a homeostatic control mechanism?

A

Processes the information received from the receptor and determines the appropriate response
- It compares the detected value to a set point (the optimal range) and sends commands to effectors to restore balance
- The brain and endocrine glands often serve as control centres

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6
Q

What does the Effector do in a homeostatic control mechanism?

A

Carries out the response to bring the variable back to its normal range
- Effectors are typically muscles or glands

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7
Q

What is a Negative Feedback Loop?

A

Where the response reduces the original stimulus
- E.G: regulating body temperature, blood glucose, and blood pressure

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8
Q

What are the 4 components of Gastric Secretion?

A

1) Gastric acid
2) Pepsin
3) Intrinsic Factor
4) Mucus

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9
Q

What is the function of Gastric acid?

A
  • Protective role
  • To further mechanically breakdown food
  • Denature and digest proteins
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10
Q

What is the function of Pepsin?

A

Protein digestion

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11
Q

What is the function of Intrinsic Factor?

A

Vitamin B12 absorption

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12
Q

What is the function of Mucus?

A

Protects against acid and mechanical forces

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13
Q

What does the Esophagus and Antrum secrete?

A

HCO3- and Mucus

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14
Q

What does the Fundus secrete?

A
  • H+
  • Intrinsic factor
  • Mucus
  • HCO3-
  • Pepsinogens (Precursor for Pepsin)
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15
Q

What do Surface Epithelium cells secrete?

A

HCO3- and mucus to try and protect the epithelium

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16
Q

What do Parietal cells secrete?

A

Intrinsic Factor

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17
Q

What do Chief cells secrete?

A

Pepsinogen (which is a precursor for Pepsin)

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18
Q

What do ECL cells secrete?

A

Histamine

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19
Q

How many litres of Gastric acid do we secrete in a day?

A

2-3 litres

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20
Q

How many times higher do we secrete Gastric acid while we are eating?

A

5-10x higher at 150 mL h-1 (same as saliva)

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21
Q

How much Gastric acid do we secrete in between meals?

A

15-30 mL per hour

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22
Q

What are the switch ON systems for Gastric acid secretion?

A
  • Acetylcholine
  • Gastrin
  • Histamine
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23
Q

Which system facilitates the switch ON system?

A

Parasympathetic system

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24
Q

What are the switch OFF systems for Gastric acid secretion based on ?

A

Somatostatin

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25
Where is the ONLY place that absorption takes place?
Small Intestine
26
Which organ controls blood pressure regulation?
Kidneys
27
What is the function of the Liver?
- Processing of absorbed nutrients and control of metabolism - Secretion and excretion
28
What is the Resting Membrane Potential value?
-70mV
29
Which ions leave the cell?
Na+
30
Which ions enter the cell?
K+
31
What is the charge of Na+ in the Intracellular fluid?
15 mM
32
What is the charge of K+ in the Intracellular fluid?
150 mM
33
What is the charge of Na+ in the Extracellular fluid?
145 mM
34
What is the charge of K+ in the Extracellular fluid?
5 mM
35
What do G-alpha s proteins do?
Increases intracellular cAMP
36
What do G-alpha i proteins do?
- Works to oppose G-alpha s - Inhibits AC, decreases intracellular cAMP and inhibits PKA
37
What do G-alpha q proteins do?
Increases intracellular Ca2+ concentration
38
What is the main driver of Saliva Secretion?
Chloride
39
What is the main driver for Water Absorption?
Sodium
40
What is the pH of Plasma?
7.4
41
What is the pH of Saliva
7.5
42
What is the Osmolarity of Plasma?
300
43
What is the Osmolarity of Saliva?
100
44
What is the Volume of Plasma?
3
45
What is the Volume of Saliva?
1.5
46
By how much can the stimulation of Saliva be increased by?
10-fold starting from 0.5 mL/min (basal), to 5 mL/min when it is activated
47
What is the composition of Saliva?
- Mucus - Digestive enzymes - Serous Secretion
48
What are the different functions of Saliva?
- Oral hygiene - Talking - Chewing and Swallowing - Assists in rendering food isosmotic - Amylase
49
What are the pairs of glands that secrete Saliva?
- Parotid glands - Sublingual glands - Submandibular glands - Buccal glands
50
What do Parotid glands produce?
Serous or watery saliva
51
What do Submandibular glands produce?
Mixed mucous and serous saliva
52
What do Sublingual glands produce?
Mucous
53
Is the epithelium tight or leaky in Acini cells?
Leaky
54
Is the epithelium tight or leaky in Duct cells?
Tight
55
What type of Saliva is produced in Acini cells?
Isotonic/Isosmotic
56
What type of Saliva is produced in Duct cells?
Hypotonic/Hyposmotic
57
What types of ducts are in the Duct cells?
Intercalated and Striated
58
Which system is Saliva primarily controlled under during eating?
Parasympathetic control
59
What are the functions of Chewing?
- Mechanical and Chemical digestion - Saliva stimulation - Voluntary and involuntary - Stimulus for the Cephalic phase
60
What are the 2 types of control of Chewing?
- Voluntary (Skeletal muscle) - Involuntary (Brainstem)
61
What are the 5 different types of taste?
1) Sweet 2) Salty 3) Sour 4) Bitter 5) Unami
62
Where is taste detected?
In the taste buds on the tongue
63
What do Type I cells detect?
Salty tastes (Most abundant types of cells on your tongue)
64
What do Type II cells detect?
* Sweet * Bitter * Umami
65
What do Type III cells detect?
Sour tastes
66
What do Type II cells do?
- Express taste receptors and use GPCR signalling pathways - Release ATP as a neurotransmitter to communicate with sensory nerves
67
What do Type III cells do?
- Contain synapses and directly release neurotransmitters to transmit signals to nerve fibres - Function as presynaptic neurons in taste signal processing
68
How many tastebuds do we have?
Up to 10,000
69
Where does the main flavour experience come from?
Olfactory Bulb
70
What is the Sweet, Bitter and Unami tastes detected via?
- A receptor coupled to G-protein alpha q - PLC - IP3 - Ca2+ - TRPM5 - The release of ATP as a transmitter
71
What are the Sour and Salty tastes detected via?
- Channels - Depolarising the cell and transmitting the signal via Ca2+
72
What are the 2 events of swallowing?
1) Oral events 2) Oesophageal events
73
What are the steps within the Oral events?
- Initiation by stretch receptors - Soft palate - Epiglottis
74
What happens in the Initiation by Stretch Receptors?
1) Food forced into pharynx by tongue (Only voluntary part!!!) 2) Stretch receptors are activated 3) Brainstem initiates swallowing
75
What happens in the Soft Palate?
1) Soft palate pushes upwards - Prevents food from entering nasal passage
76
What happens in the Epiglottis?
1) Moves down to cover the entrance to the trachea - Prevents aspiration of food
77
What are the steps within the Oesophageal events?
- Upper Oesophageal sphincter (UOS) - Lower Oesophageal sphincter (LOS) - Oesophageal
78
What happens in the Oesophageal?
1) Smooth muscle contracts (Non voluntary) 2) Peristaltic wave pushes food to stomach 3) Lasts about 9 seconds
79
What happens in the Upper Oesophageal sphincter?
1) Relaxes (opens) 2) Allows food to enter the oesophagus
80
What happens in the Lower Oesophageal sphincter?
1) Once the food has been pressed down, the LOS opens (relaxes) at the start to swallowing 2) Food enters stomach 3) Closes after peristalsis wave
81
Describe the Voluntary Control for swallowing
- Activate stretch receptors - Activate the swallowing centre in brainstem
82
Which 2 muscles are controlled Voluntarily?
1) Striated muscles - Controlled directly by swallowing centre 2) Smooth muscle - Controlled indirectly
83
Which 2 muscles are controlled Involuntarily?
1) Pharyngeal muscles - striated 2) Oesophageal muscle – upper striated
84
What is GERD?
Reflux of acidic chyme into oesophagus - Irritation to oesophageal mucosa (‘heartburn’)
85
What are some causes of GERD?
- Abnormal relaxation of LOS - Lack of receptive relaxation in the stomach - Excessive gastric secretion (due to stress) - Infection with H. pylori
86
What are the digestion and absorption of Minerals via?
Calcium and Magnesium - Paracellular pathway in leaky epithelium
87
What is Chronotropic?
Changes in heart rate
88
What is Dromotropic?
Conduction velocity
89
What is the ideal requirements for gas exchange?
High cross sectional (surface) area, low constant flow of blood velocity
90
What does Cardiac Output improve via?
1) Sympathetic venous constriction 2) Skeletal muscle pump 3) Respiratory pump 4) Increase in blood volume
91
Define Postural Hypotension
Sudden drop in blood pressure when standing up, due to venous pooling, less venous return, should quickly be restored by baroreflex via autonomic system
92
Define Vasovagal Syncope
Sudden drop in blood pressure due to anxiety (emotions), drops sympathetic and ups parasympathetic system
93
What to do for Postural Hypotension and Vasovagal Syncope?
- Increase preload, by increasing venous return - Contract (leg) muscles (muscle pump) - Take a good deep breath, to initiate the respiratory pump, before standing up
94
Define Arteriosclerosis
Stiffer arteries - Due to ageing and genetic predispositions
95
Define Atherosclerosis
Blockage of arteries - Due to lifestyle and genetic predispositions
96
Where in the heart has the fastest conduction?
Bundle of His
97
Where in the heart has the slowest conduction?
Atrioventricular (AV) Nodes (0.05 ms-1)
98
What are the 2 Intrinsic Controls of Vessels?
1) Active Hyperaemia 2) Flow Autoregulation
99
What are the important vasodilators for Intrinsic Control?
- Oxygen being used up - Carbon dioxide being produced
100
What is the delivery rate via large arteries?
Fast - With slow exchange in capillaries
101
What is the structure of the Pancreas
- Endocrine pancreas - Exocrine pancreas
102
What are the components within the Endocrine Pancreas?
- Alpha cells (glucagon) - Beta cells (insulin)
103
What is the function of the Endocrine Pancreas?
Makes the hormone insulin, which helps to control blood sugar levels
104
What are the components within the Exocrine Pancreas?
- HCO3- - Enzymes for digestion
105
What is the function of the Exocrine Pancreas?
Produces enzymes that help to digest food, particularly protein
106
What is the tonicity of Pancreatic solution?
Isotonic
107
What is the pH of the Pancreas?
7.8
108
How much grams and Litres does the Pancreas secrete?
1-1.5 L of alkaline solution 5-15 g of proteins
109
What is the composition of the Pancreas?
Acinar cells - Leaky epithelium Duct cells - Leaky epithelium
110
What is responsible for the stimulation for Pancreatic secretion?
- CCK - Secretion
111
What is the stimulus and function of CCK?
- Fat and products of protein digestion in the duodenal lumen - Responsible to release the enzymes
112
What is the stimulus and function of Secretin?
- Acidic chyme/bolus in the duodenal lumen - Responsible for the secretion of HCO3-
113
What is CFTR?
The key chloride channel for HCO3- secretion
114
What are some dental complication associated with CFTR?
- Higher risk of enamel defects - Tooth discolouration - More plaque
115
What is involved in Nutrient Dependent Absorption of Na and Cl?
Na+ coupled solute absorption - SGLT1
116
What is involved in Nutrient Independent Absorption of Na and Cl?
- Na+/H+ exchanger (NHE3) - Cl-/HCO3 exchanger
117
What are sugar consumed as?
Polymers
118
What types of sugars are absorbed?
Monosaccharides - Via SGLT1 and GLUT5
119
What are the 2 types of digestion of Sugars and Proteins?
1) Luminal digestion 2) Contact/Brush border digestion
120
What are the important structures that helps the heart to generate its own beat?
1) SA Node 2) AV Node 3) His Bundles 4) Purkinje Fibres
121
What is the function of the SA Node?
Generates action potentials and determines heart rate
122
What is the RMP of the SA Node?
-60 mV
123
What is the Unstable Pacemaker Potential of the SA Node via?
- Funny Na+ Channels - T-Type Ca2+ Channel
124
What is the Fast Depolarisation of the SA Node via?
L-Type Ca2+ Channel (LTCC)
125
What is the Repolarisation of the SA Node via?
K+ channels (Slow K+ efflux)
126
What is the function of the AV node?
Allows atria to complete contraction before the ventricles excite/contract
127
What is the RMP of the AV Node?
-90 mV (Stable)
128
What is the Fast Depolarisation of the AV Node via?
Na+ channels
129
What is the Depolarisation Plateau of the AV Node via?
L-Type Ca2+ channels (LTCC)
130
What is the Repolarisation of the AV Node via?
K+ channels (Fast K+ efflux)
131
What is the function of the Bundle of His?
A branch of specialised heart cells that are supplying the electrical signal to the LV and RV
132
What does the P-wave in an ECG represent?
Electrical activity in the atria
133
What does the QRS Complex in an ECG represent?
Electrical activity in the ventricles
134
What does the T-wave in an ECG represent?
Repolarisation of the ventricles
135
What is the Excitation-Contraction Coupling induced by?
Ca2+ - Depolarisation causes Ca2+ induced Ca2+ release
136
What does the Cardiac Cycle show?
1) Periods 2) Pressures 3) Volumes 4) Electrical Events (ECG) 5) Heart sounds
137
What are the periods of Diastole?
- Relaxation - Filling - 0.5s - 63%
138
What are the periods of Systole?
- Contraction - Ejection - 0.3s - 37%
139
What is the total stoke volume in the heart?
70 ml
140
What is the EDV volume?
135 ml
141
What is the ESV volume?
65 ml
142
What does the 1st Lub sound represent and when does it occur?
AV Valves closing - Systole
143
What does the 2nd Dub sound represent?
Semilunar Valves closing - Diastole
144
What is Endocarditis?
Inflammation of the inner lining of the heart, particularly the heart valves
145
What is Endocarditis caused by?
Infection with bacteria, virus, fungi or parasites
146
What are the risk factors for Endocarditis?
- Artificially implanted heart valves - Damaged heart valves - Implanted heart devices (pacemakers) - IV drug use (dirty needles) - Long-term catheter use
147
What does the PNS release?
ACh - Activates muscarinic receptors in the heart
148
What is the purpose of ACh release?
ACh release REDUCES the heart rate
149
What are the 2 responses in the SNS?
1) Release of Norepinephrine 2) Release of Epinephrine via the Adrenal Medulla
150
What is Norepinephrine?
Neurotransmitter
151
What is Epinephrine?
Hormone
152
What is the Osmolarity of Pure Water?
Hyposmotic
153
What is the Tonicty of Pure Water?
Hypotonic
154
What is the Osmolarity of 100 mmol.L NaCl?
Hyposmotic
155
What is the Tonicity of 100 mmol.L NaCl?
Hypotonic
156
What is the Osmolarity of 150 mmol.L NaCl?
Isosmotic
157
What is the Tonicity of 150 mmol.L NaCl?
Isotonic
158
What is the Osmolarity of 300 mmol.L NaCl?
Hyperosmotic
159
What is the Tonicity of 300 mmol.L NaCl?
Hypertonic
160
What is the Osmolarity of 5% glucose?
Isosmotic
161
What is the Tonicity of 5% glucose?
Isotonic
162
What is the Osmolarity of 300 mmol.L Urea?
Isosmotic - Does NOT disassociate
163
What is the Tonicity of 300 mmol.L Urea?
Hypotonic
164
Which solution Tonicity would be ideal for injections used in dental procedures?
Isotonic
165
What does Ca2+ bind to in Vesicle Fusion
Synaptotagmin
166
What is the Total Body Water for Females?
55%
167
What is the Total Body Water for Males?
60%
168
What is the TBW for ICF?
2/3
169
What is the TBW for ECF?
1/3
170
What is the TBW for ISF
4/5 of ECF

DENT 262 (5 decks)

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