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Physiology (Dr H.) Flashcards

Bones, thermoregulatory systems, energy balance, energy uptake

1
Q

What are the 10 different physiological systems in humans?

A 
Circulatory
Digestive (gut bacteria)
Endocrine
Integumentary (skin)
Immune 
Musculoskeletal
Nervous
Reproductive (infections)
Respiratory (air quality/pathogens)
Urinary (infections)
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2
Q

Which physiological systems interact directly with the environment?

A

Digestive (gut bacteria), integumentary (skin), reproductive (infections), respiratory (air quality/pathogens), urinary (infections)

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3
Q

What is the classification of bones based on?

A

Origin and mode of development

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4
Q

What is the scientific name for flat bones?

A

Membranous

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5
Q

What is the scientific name for long bones?

A

Endochondral

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6
Q

What is an endochrondral bone defined as?

A

Cylindrical in shape and longer than is wide

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7
Q

What is a membranous bone defined as?

A

Typically thin and often curved e.g. calvarial bone

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8
Q

What is the calvarial bone?

A

The top part of the skull

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9
Q

What is the origin of calvarial bones?

A

Neural crest cells

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10
Q

How do calvarial bones grow?

A

By appositional growth

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11
Q

Where does a suture form?

A

At the junction of two flat bones

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12
Q

What syndrome is caused by too much FGFR2?

A

Apert syndrome

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13
Q

Why do specific areas of the skull bone remain unossified?

A

To allow for exit and entry of nerves and blood vessels into the cranium

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14
Q

What are the 3 differentiation steps in endrochondral ossification I?

A
  1. Mesenchyme tissue condenses
  2. Chondrocyte cell formation (chondrogenesis)
  3. Perichondrium tissue formation
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15
Q

What is mesenchyme tissue?

A

Directly gives rise to most of the body’s connective tissues, from bones and cartilage to the lymphatic and circulatory systems

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16
Q

What are chondrocyte cells?

A

Cells that secrete and maintain the matrix of cartilage and become embedded in it

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17
Q

What is perichondrium tissue?

A

The connective tissue that envelops cartilage where it is not at a joint

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18
Q

What are the 3 differentiation steps in endrochondral ossification II?

A
  1. Hypertrophy of chondrocytes (which is characterised by calcified cartilage matrix and expression of type X collagen)
  2. Vascular invasion of cartilage (occurs at mid-diaphyseal and epiphyseal regions)
  3. Death of chondrocytes and their replacement by bone. Bone is formed by invading osteoblasts
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19
Q

What ossification centres do bones have?

A

Primary and secondary ossification centres

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20
Q

How is it ensured that there is no further gain in height of bones after full growth is reached?

A

Growth plates disappear

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21
Q

Where do joints form?

A

Where two long bones meet

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22
Q

What are joints often invested in?

A

Cartilage

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23
Q

Is cartilage vascular or avascular?

A

Avascular

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24
Q

What happens if cartilage is destroyed or degenerated?

A

Osteoarthritis or rheumatoid arthritis

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25
Q

What are the two types of bone ultra-structure?

A

Compact and trabecular

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26
Q

Describe compact bone ultra-structure

A
  • cortical
  • makes up about 80% of all bone structure
  • has Haversian canals for blood vessels and nerves
  • has osteons: cylindrical structures containing mineral matrix and living osteocytes connected by canaliculi, which transport blood
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27
Q

Describe trabecular bone ultra-structure

A

Spongy or cancellous (mesh-like) and makes up about 20% of all bone structure

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28
Q

Can bones be composed of both cortical and trabecular structure?

A

Yes

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29
Q

What are the 6 types of long bone joints?

A
  1. Plane
  2. Saddle
  3. Hinge
  4. Pivot
  5. Ball and Socket
  6. Elipsoid
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30
Q

What does the homeostasis and remodelling of bones rely on?

A

Activity of osteoblasts, osteocytes, osteoclasts

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31
Q

What are osteoclasts?

A

Giant multinucleate cells

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32
Q

How are osteoclasts formed?

A

By fusion of macrophages and monocytes

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33
Q

Is osteoblast to osteoclast anabolic or catabolic?

A

Anabolic

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34
Q

Is osteoclast to osteoblast anabolic or catabolic?

A

Catabolic

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35
Q

Are cortical or trabecular bones more prone to the effects of osteoporosis?

A

Trabecular

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36
Q

What is osteoporosis?

A

Bone weakening which increases the risk of a broken bone

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37
Q

Is bone a dynamic or fixed structure?

A

Dynamic

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38
Q

Why is constant bone remodelling and osteoclast activity needed?

A

For bone repair

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39
Q

What are 5 important physiological functions of bones and the skeleton?

A
  • weight bearing and physical protection of organs
  • articulation at joints
  • hearing
  • calcium homeostasis and metabolism
  • (an indirect role in) hematopoiesis
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40
Q

What is weight bearing essential for?

A

Proper bone remodelling

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41
Q

What are the 5 critical roles of calcium?

A
  • muscle contraction
  • enzymatic reaction
  • mitosis and cell division
  • blood clotting
  • cell signalling pathways
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42
Q

What are the 4 key ‘players’ (e.g. organs etc.) in calcium ion homeostasis?

A
  • bone
  • kidneys
  • gut
  • parathyroid hormone (PTH)
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43
Q

Give 2 examples of metabolic bone diseases caused by delays or too little bone mineralisation

A
  • rickets

- osteomalacia

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44
Q

Give 2 examples of metabolic bone diseases caused by too much osteoclastic activity

A
  • osteoporosis

- Paget’s disease

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45
Q

Which 4 physiological systems are involved in thermoregulation?

A
  • circulatory
  • endocrine
  • integumentary (skin)
  • nervous
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46
Q

What are homeotherms?

A

Organisms that maintain their body temperature at a constant level
- mammals and birds

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47
Q

What are poikilotherms?

A

Organisms that regulate their body temperature by behavioural means
- amphibians and reptiles

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48
Q

What are the 2 disadvantage to being a poikilotherm?

A
  • when cold, body becomes less active as rate of enzymatic reactions falls which increases susceptibility to predators
  • unable to move to new territories and evolve further
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49
Q

What mechanism allows homeotherms to hibernate?

A

Generate heat but not too much energy

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50
Q

Do hibernating animals build up reserves of brown or white fat?

A

Brown

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51
Q

Why do hibernating animals build up reserves of brown fat?

A

It generates 10 times more energy than white fat

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52
Q

Which 5 organs are constantly maintained at core temperature?

A
  • brain
  • lungs
  • liver
  • heart
  • kidneys
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53
Q

Are the organs that are constantly maintained at core temperature the most or the least vascularised organs?

A

Most vascularised

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54
Q

In which 3 places can core temperature be measured accurately?

A
  • tympanic membrane (ear drum)
  • sublingual area
  • rectum
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55
Q

What are most blood vessels lined by?

A

Smooth muscle which receives nerve innervation

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56
Q

When is core body temperature the lowest during a 24 hour period?

A

Night time

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57
Q

When is core body temperature the highest during a 24 hour period?

A

Mid-afternoon

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58
Q

What is the core body temperature not optimal for?

A

Spermatogenesis

- scrotal temperature is kept 1-2 degrees below core body

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59
Q

What are the 3 contributing causes to falling sperm count?

A
  • tight clothing/underwear
  • increased laptop use and longer driving periods
  • environmental pollution
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60
Q

How is heat gained by the body?

A
  • energy from food
  • skeletal muscle activity
  • radiation
  • artificial heating
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61
Q

How is heat lost by the body?

A
  • convection
  • conduction
  • evaporation
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62
Q

What are the three roles in thermoregulation?

A
  • sensors
  • controller
  • effectors
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63
Q

What are the 2 sensors of thermoregulation?

A

Skin temperature and core temperature

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64
Q

What is the controller of thermoregulation?

A

Hypothalamus

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65
Q

What is the effectors of thermoregulation?

A
  • skin arterioles
  • sweat glands
  • involuntary skeletal muscle activity: shivery etc.
  • voluntary skeletal muscle activity: behaviour
66
Q

Where is the hypothalamus situated?

A

At the base of the brain

67
Q

What is the hypothalamus composed of?

A

Distinct neuronal nuclei

68
Q

What 5 things does the hypothalamus regulate?

A
  • water balance
  • blood pressure
  • feeding behaviour
  • mood
  • temperature control
69
Q

Where else are thermo-sensors found (4)?

A
  • spinal cord
  • abdominal viscera
  • walls of great veins
  • skin
70
Q

Are warmth- or cold-sensing fibres more abundant?

A

Cold-sensing fibres

- 10 times more

71
Q

What are the two parts of the nervous system?

A
  • central nervous system

- peripheral nervous system

72
Q

What 2 things make up the central nervous system?

A
  • brain

- spinal cord

73
Q

Which 3 systems make up the peripheral nervous system?

A
  • sensory system
  • autonomic nervous system
  • somatic nervous system
74
Q

Which 3 systems make up the autonomic nervous system?

A
  • sympathetic nervous system
  • enteric nervous system
  • parasympathetic nervous system
75
Q

What does the parasympathetic nervous system control?

A

Relaxation

76
Q

What does the parasympathetic nervous system promote?

A
  • metabolism
  • tissue regeneration
  • build up of body reserves
77
Q

What does the sympathetic nervous system control?

A
  • anxiety
  • stress
  • fight
78
Q

What does the sympathetic nervous system increase?

A
  • heart rate
  • blood pressure
  • sweating
  • respiration
  • dilation of pupils
79
Q

What does the sympathetic nervous system suppress?

A
  • gastric motility

- intestinal secretion

80
Q

What is the long term thermogenic response to cold?

A

Browning of white fat and brown fat activation

81
Q

Why is shivering an ineffective mode of heat generation?

A
  • generates only 3 times more heat than rest position

- stimulates blood circulation to the skin increasing heat loss through convection

82
Q

What happens at or below a core body temperature of 35 C?

A

Thermoregulatory responses are inactivated and rapid temperature loss begins as positive feedback

83
Q

What happens at a core body temperature of 33 C?

A

Brain electrical activity becomes abnormal

84
Q

What happens at a core body temperature of 26-28 C?

A

Myocardial fibrillation (fine twitching of heart muscles without muscle movement as a whole

85
Q

What happens at a core body temperature of 19-20 C?

A

Brain dies

86
Q

What is frostbite and what is it caused by?

A

Injury to peripheral extremities resulting from a combination of the effects of vasoconstriction and freezing ambient temperature

87
Q

How is frostbite accelerated?

A

Wind chill

88
Q

Why is frostbite dangerous?

A

Inappropriate rate of thawing can induce cellular shrinkage, platelet activation, and thrombosis

89
Q

What is non-exercise related abnormal and excessive sweating called?

A

Hyperhidrosis

90
Q

What is lost through sweat?

A

Water and electrolytes (Na+ and Cl- ions)

91
Q

What happens to cause heat exhaustion and heat stroke?

A
  1. Heaving exercise leads to vasodilation and reduced plasma volume
  2. This leads to a lower blood pressure
  3. This causes heat exhaustion with symptoms such as nausea and dizziness
  4. Core body temperature over 41-42 C is heat stroke with symptoms such as cessation of sweating and signs of brain damage
92
Q

Define a fever

A

A natural elevation of core body temperature during immune response

93
Q

Which group of hormones have an effect on the sympathetic nervous system?

A

Catecholamines

94
Q

What effect do catecholamines have on the sympathetic nervous system?

A
  1. Activate the sympathetic NS
  2. This can increase enzyme activity, energy expenditure, and heat produced
  3. This leads to a raised body temperature
95
Q

What is hyperthyroidism?

A

The production of too much thyroid due to an overactive thyroid; has a longer lasting effect than catecholamines

96
Q

What happens to body temperature due to hyperthyroidism?

A

There is increased enzyme activity, energy expenditure, and heat produced, leading to a raised body temperature

97
Q

What condition leads to raised body temperature in patients taking anti-psychotic drugs?

A

Malignant hyperthermia

98
Q

How do hot flushes during menopause happen?

A
  1. Reduced oestrogen levels
  2. Narrowing of the hypothalamic thermo-neutral zone from 0.4 C to 0.1 C
  3. Hypothalamus produces more norepinephrine (a catecholamine)
  4. Hot ‘flushes’ and sweating followed by immediately by shivering and cold sweat
99
Q

Where is energy in food stored?

A

In chemical bonds

100
Q

What is the basic currency of energy?

A

ATP

101
Q

What is body energy equal to?

A

energy intake - energy output

102
Q

What is energy output equal to?

A

work + heat

103
Q

What are the 3 main sources of work?

A
  • transport: transporting ions across cell membranes etc.
  • mechanical work: muscle contraction etc.
  • chemical work: energy needed to break bonds etc.
104
Q

Where are metabolites generally absorbed?

A

Through gut epithelial cells

105
Q

Where are metabolites first processed?

A

Liver

106
Q

What is metabolite I?

A

Carbohydrates

107
Q

What is the most important metabolite?

A

Glucose

108
Q

Why is glucose the most important metabolite?

A

The brain can only use glucose

109
Q

How are carbohydrates absorbed?

A

Through both active and passive transport

110
Q

What happens to excess glucose?

A

Converted to triglycerides (fat) and stored adipocytes

111
Q

What is metabolite II?

A

Digestion of proteins into amino acids

112
Q

What are 3 sources of protein?

A
  • diet
  • turnover of gut mucosal membrane cells
  • enzymes within the gut
113
Q

What are 2 modes of protein absorption?

A
  • symportation with Na+ or H+ ions

- exported out of the gut epithelial cells via passive carriers

114
Q

What are amino acids used for in the liver?

A

To make lipoproteins

115
Q

What is metabolite III?

A

Digestion and absorption of fats

116
Q

What type of fat is dietary fat mostly?

A

Triglycerides

117
Q

Are triglycerides water soluble?

A

No

118
Q

What produces biles salts?

A

The liver

119
Q

What is the role of bile salts in digesting fats?

A

They help to disperse triglyceride molecules, providing greater surface area for their digestion by lipase

120
Q

What are triglycerides broken down into?

A

Monoglycerides and FFA

121
Q

What happens to monoglycerides and FFA once they are produced from the breakdown of triglycerides?

A

They are packaged into micelles and inside epithelial cells, they are packed into chylomicrons and absorbed into lymphatic vessels

122
Q

Where does the lymphatic system transport chylomicrons to?

A

The liver

123
Q

What breaks down fats in the liver?

A

Lipoprotein lipase

124
Q

What is fat broken down into by lipoprotein lipase?

A

Cholesterol and free fatty acids

125
Q

What do liver cells convert cholesterol into?

A

HDLs and LDLs

126
Q

How are HDLs and LDLs taken up by cells?

A

Through an active process and specific proteins

127
Q

What are the two types of adipocytes?

A

White adipose tissue (WAT) and brown adipose tissue (BAT)

128
Q

Which type of adipocyte is used for thermogenesis?

A

BAT

129
Q

Name 7 factors that influence metabolic rate

A
  • age and gender
  • amount of lean muscle mass
  • activity level
  • diet
  • hormones
  • genetics
  • energy intake
130
Q

How does age and gender influence metabolic rate?

A

Young males have the fastest metabolic rate and older females have the slowest metabolic rate

131
Q

How does the amount of lean muscle mass influence metabolic rate?

A

Muscles use more oxygen than other tissues so more lean muscle means a faster metabolic rate

132
Q

How does activity level influence metabolic rate?

A

The more energy spent the faster the metabolic rate

133
Q

How does type of diet influence metabolic rate?

A

Higher protein intake means faster metabolic rate as high amounts of heat are produced by their digestion

134
Q

How do hormones influence metabolic rate?

A

High levels of thyroid hormone and catecholamines increases metabolic rate

135
Q

How can genetics influence metabolic rate?

A

Some inherited genes increase efficiency in storing fat in adipose tissue or predispose obesity, both of which slow metabolic rate

136
Q

Which two hormones help regulate plasma glucose level?

A

Glucagon and insulin

137
Q

What happens in the fed state (glucose levels > 100 mg/dL) where insulin dominates over glucagon?

A

Increase in:

  • glucose oxidation
  • glycogen synthesis
  • fat synthesis
  • protein synthesis
138
Q

What happens in the fasted state (glucose levels < 90 mg/dL) where glucagon dominates over insulin?

A

Increase in:

  • glycogenesis
  • gluconeogenesis
  • ketogenesis
139
Q

Give 5 factors that control insulin release

A
  • increased plasma glucose concentration
  • increased amino acids concentration
  • feed-forward effects of GI hormones
  • Digestion (parasympathetic activity)
  • Stress and anxiety (sympathetic activity)
140
Q

What type of molecule is insulin?

A

Signalling

141
Q

How does insulin work at a molecular level?

A
  1. Insulin binds to tyrosine kinase receptor
  2. Receptor phosphorylates insulin-receptor substrates (IRS)
  3. Second messenger pathways alter protein synthesis and existing proteins
  4. Membrane transport is modified
  5. Cell metabolism is changed
142
Q

Give 5 of the metabolic and molecular effects of insulin

A
  • induce the expression of glucose transporters (GLUTs)
  • increase the activity or sensitivity of GLUTs for glucose transport
  • enhance anabolic pathways within cells
  • enhance utilisation of amino acids and therefore protein synthesis
  • enhance fat synthesis
143
Q

Define Diabetes Mellitus

A

A pathological dysregulation of energy usage and uptake

144
Q

What is Type 1 diabetes?

A

Insulin deficiency

145
Q

What is Type 1 diabetes caused by?

A

Genetic/autoimmune destruction of pancreatic beta-cells

146
Q

How is Type 1 diabetes managed?

A

Regular injections of insulin

147
Q

What is Type 2 diabetes?

A

Insulin resistance where insulin is produced but responding cells become insensitive or less sensitive to insulin

148
Q

Give 7 knock on effects of diabetes

A
  • muscle breaks down to release glucose
  • concentration of plasma proteins increases
  • excess urination
  • fats are broken down into excess fatty acids and ketones
  • satiety centres in the brain do not sense glucose so act to increase appetite
  • problem wound healing and nerve repair
  • glaucoma
149
Q

What are 4 of the adverse consequences of obesity for the individual?

A
  • type 2 diabetes
  • cardiovascular disease
  • arthritis
  • certain cancers (e.g. ovarian)
150
Q

What are 3 of the adverse consequences of obesity for society?

A
  • cost of treating obesity-related diseases
  • economic and ecological costs of greater need for calories
  • adjustments to ambulances, plane seats, toilet seats etc.
151
Q

What is energy uptake controlled by?

A

Hypothalamus

152
Q

What are the 5 peripheral signals that are sent to the hypothalamus to make the decision to eat?

A
  • the gut, liver, skeletal muscle, pancreas, adipocytes
  • plasma glucose concentration
  • hormones
  • sensory in put
  • neurotransmitters
153
Q

What is feeding behaviour regulated by?

A

A set of hypothalamic neurons

154
Q

What contains first order neurons?

A

Arcuate (AVN) nucleus

155
Q

What are first order neurons?

A

Orexigenic or anorexigenic

- work in response to hormones received within and outside the brain

156
Q

What do orexigenic and anorexigenic neurons stimulate?

A

Second order neurons

157
Q

Where are second order neurons found?

A

In the paraventricular (PVN) and lateral hypothalamic area (LHA) nucleus

158
Q

What is satiety?

A

State of ‘fullness’

159
Q

What is satiety controlled by?

A

The nucleus tractus solitarius (NTS) in the brain stem

160
Q

What happens if the feeding centre is destroyed?

A

Eating stops altogether

161
Q

What happens if the NTS which controls satiety is destroyed?

A

Continuous eating

162
Q

What are the 2 theories about how hypothalamic feeding circuits are destroyed?

A
  • glucostatic theory (short term)

- lipostatic theory (lipostatic)

Physiology and Chemistry for Life Sciences (2 decks)

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