Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Anatomy and Physiology 2 > Chapter 24- Metabolism > Flashcards

Chapter 24- Metabolism Flashcards

1
Q

Nutrients definition

A

Any substance the body uses for growth, repair, maintenance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Macronutrients

A

Carbohydrates, lipids, proteins- make up most of our diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Micronutrients

A

Vitamins and minerals- only required in minute amounts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sources of carbohydrates in the diet

A

Mostly plants, but also dairy (lactose) and meats (glycogen)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Uses of carbohydrates (3)

A
  1. ATP production by body- monosaccharide molecule glucose used
  2. Nucleic acid synthesis with pentose sugars
  3. Glycocalyx formation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How much carbohydrates are recommended?

A

Recommended- 45-60% of daily caloric intake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Complex carbohydrates

A

Grains and plant based sources that are unprocessed, nutrient rich

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Empty carbohydrates

A

Processed sugars (soda, candy, etc) offers little nutritional value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Types of lipids (2)

A
  1. Triglycerides

2. Cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Types of triglycerides (2)

A
  1. Saturated

2. Unsaturated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where are saturated triglycerides found?

A

meat, dairy, margarine, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where are unsaturated triglycerides found?

A

nuts, seeds, olive oil, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where is cholesterol found?

A

85% produced by the liver regardless of lipid intake. Remaining 15% comes from meat, eggs, dairy, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Uses of lipids (4)

A
  1. Used to build adipose tissue
  2. Phospholipids used for cell membranes
  3. Bile salt, steroid hormones, and other molecule construction
  4. Absorbing fat soluble vitamins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Functions of adipose tissue (2)

A
  1. Insulating, retains body heat- found around internal organs
  2. A concentrated energy source the body can rely on if you haven’t eaten.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Steroid hormones

A

Testosterone and estrogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How much lipids are recommended?

A

Recommended 20-35% total daily intake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Why should saturated fat and cholesterol intake be limited?

A

Fats stick to inside of blood vessels, builds up and causes atherosclerosis, forcing the heart to work harder. If it happens in coronary blood vessels, can cause a heart attack

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Sources of protein (2)

A
  1. Complete proteins- meet all the body’s amino acid requirements
  2. Incomplete proteins- are short 1 or more amino acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where are complete proteins found? (4)

A

egg, meat, dairy, fish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where are incomplete proteins found? (3)

A

seeds, nuts, legumes. Exception- soybeans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Uses of protein (2)

A
  1. Structural molecules

2. Functional molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Which structural molecules are made of proteins?

A

Ex- keratin, collagen, elastin, muscle protein- help to build other molecules. Keratin makes the skin tough and dry, elastin lets tissues stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Which functional molecules are made of proteins?

A

enzymes, hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How much protein is recommended?

A

.8 grams per kg body weight, this is on an individual basis. Depends on an individual’s dietary needs and their nitrogen balance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Nitrogen balance

A

When the rate of protein synthesis equals the rate of protein breakdown in the body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Positive nitrogen balance

A

When protein synthesis is greater than protein breakdown. Ex- growing children, pregnant women, tissue repair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Negative nitrogen balance

A

When protein breakdown is greater than protein synthesis. Ex- stress, low protein content or quality in diet, starvation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When are amino acids not used by the body? (3)

A
  1. Inadequate dietary intake
  2. Insufficient amino acid supply
  3. Hormonal control
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does inadequate dietary intake prevent amino acids from being used?

A

being short of carbohydrates or fats forces the body to use proteins for energy source (skeletal muscle tissue)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How does inadequate amino acid supply prevent amino acids from being used?

A

All amino acids must be present to build a particular protein. If one or more is missing, or if there is not enough of one type of amino acid, the rest are used for energy (all or none rule)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How do hormones affect amino acid use?

A

Anabolic hormones promote protein synthesis and growth, adrenal glucocorticoids promote protein breakdown

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Importance of vitamins

A

vitamins act as coenzymes- assist enzymes in accomplishing various tasks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Sources of vitamins (2)

A
  1. Made by the body- vitamin D (in skin), vitamin K and some vitamin B (some bacterial flora)
  2. Diet
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Types of vitamins (2)

A
  1. Water soluble (B and C)- have to be absorbed with water because they dissolve in it
  2. Fat soluble (A, D, E, K)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Sources of minerals

A

Primary sources- legumes, vegetables, dairy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Function of minerals

A

Primary function is structural. Others are bound to organic compounds- creates phospholipids, hormones, several different proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why is balance between uptake and excretion necessary with minerals?

A

Like fat soluble vitamins- toxic overload can occur. Can be poisoned by bringing in too many minerals. Ex- iron overdose, low iodine intake and goiters (swelling of thyroid), high sodium intake and fluid retention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Metabolism definition

A

The sum of all the chemical reactions occurring in the cells of the body used to provide energy for vital processes synthesizing new material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Anabolic metabolic reactions

A

building larger, more complex molecules/structures from their smaller subdivisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Catabolic metabolic reactions

A

Any reaction that breaks down larger molecules into smaller ones. Cellular respiration is a group of reactions that form ATP from the breakdown of food fuels (glucose).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Oxidation-reduction reactions are attributed to

A

The breakdown of glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Oxidation

A

The gain of oxygen or the loss of hydrogen (electron). An oxidized substance always loses electrons. Oxygen is electronegative and will attract electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Reduction

A

The gain of electrons. This process is coupled with oxidation- when one substance loses an electron, another must gain the electron. A reduced molecule becomes more negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Redox reactions are catalyzed by

A

Enzymes and coenzymes- they are specific to the reaction being carried out. Most enzymes derived from B complex vitamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Importance of coenzymes in redox reactions

A

Enzymes can remove hydrogen atoms, but they cannot hold it or bond it- removed hydrogens transferred to coenzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Important coenzymes in redox reactions (2)

A
  1. Nicotinamide adenine dinucleotide (NAD+)- derived from niacin
  2. Flavin adenine dinucleotide (FAD)- derived from riboflavin (B complex vitamin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What source is preferred for ATP production?

A

Glucose. All carbohydrates brought into the body will eventually be converted into glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Once inside the cell, glucose is converted to

A

glucose-6-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Normal glucose level

A

90-120 grams per deciliter of blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Substrate level phosphorylation

A

The direct transfer of a phosphate group to an ADP molecule. Glycolysis and citric acid cycle- net gain of 4 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Oxidative phosphorylation

A

The transfer of a phosphate group to an ADP molecule by the oxidation of food fuels and transfer of electrons. Electron transport chain- 28 ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

A single glucose molecule yields how many ATP?

A

32

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Glucose oxidation reaction

A

C6H12O6 + 6O2 yields 6H2O + 6CO2 + 32 ATP + heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

3 sequential pathways of glucose breakdown

A
  1. Glycolysis
  2. Citric acid cycle (aka Krebs cycle)
  3. Electron transport chain (ETC) and oxidative phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Where does glycolysis occur?

A

Cytosol of the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Glycolysis reactants

A

Glucose. This is an anaerobic process- oxygen is not necessary for this reaction to take place

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Glycolysis products (3)

A
  1. 2 pyruvic acid
  2. 2 NADH and hydrogen
  3. Net gain of 2 ATP
59
Q

Glycolysis phase 1

A

Glucose is phosphorylated to produce fructose 1,6-bisphosphate, 2 ATP are used for this conversion

60
Q

Glycolysis phase 2

A

Fructose 1,6 bisphosphate is split to form 2 carbon fragments

61
Q

Glycolysis phase 3

A

4 ATP molecules are produced by oxidizing carbon fragments. 2 NAD pick up hydrogen- forms 2 NADH. 2 pyruvic acids produced

62
Q

What happens to pyruvic acid formed during glycolysis?

A

Depends on oxygen availability. If oxygen is available- pyruvic acid pumped into the next pathway (citric acid cycle). If oxygen is not available- pyruvic acid converted to lactic acid. Some lactic acid pumped out of the cell, transported to liver for processing. Once oxygen becomes available again, lactic acid oxidized back to pyruvic acid and used in citric acid cycle

63
Q

Where does the citric acid cycle occur?

A

The mitochondrial matrix

64
Q

What occurs during the citric acid cycle?

A

One glucose molecule causes 2 turns of the citric acid cycle. Aerobic process- reaction requires oxygen to be completed. This reaction does not directly utilize oxygen, but products from citric acid cycle are used in ETC

65
Q

Citric acid cycle reactants (4)

A
  1. Acetyl CoA (derived from pyruvic acid)
  2. Pyruvic acid is oxidized to form acetyl CoA
  3. 1 CO2 produced
  4. NAD+ converted to NADH
66
Q

Citric acid cycle products (3- after one turn)

A
  1. 3 carbon dioxide molecules
  2. 5 reduced coenzymes: 4 NADH and hydrogen, 1 FADH
  3. 1 ATP
67
Q

Where does the electron transport chain and oxidative phosphorylation occur?

A

Occurs in the inner mitochondrial membrane. Aerobic process- reaction directly utilizes oxygen

68
Q

ETC/oxidative phosphorylation reactants (2)

A
  1. NADH + H and FADH from citric acid cycle

2. Oxygen

69
Q

ETC/oxidative phosphorylation products (2)

A
  1. 28 ATP molecules

2. 6 water

70
Q

What occurs during ETC/oxidative phosphorylation? (3 things)

A
  1. NADH and FADH are relieved of their hydrogen ions- NAD+ and FAD available again
  2. H+ pumped into intermembrane space to create a proton gradient
  3. H+ from proton gradient created by complex 5 (ATP synthase) to create ATP molecules
71
Q

Why can’t your body utilize endless amounts of glucose to produce large quantities of ATP?

A

Rising intracellular ATP inhibits glucose breakdown- glucose is either stored as fat or converted. Three processes allow for glucose storage and access- glycogenesis, glycogenolysis, and gluconeogenesis

72
Q

3 ways the body can store/access glucose

A
  1. Glycogenesis
  2. Glycogenolysis
  3. Gluconeogenesis
73
Q

Glycogenesis

A

Glucose is converted to glycogen and stored in animal tissue. Skeletal muscle and liver most active in glycogen production and storage

74
Q

Glycogen

A

polysaccharide stored in animal tissue (muscle tissue cells)

75
Q

Glycogenolysis

A

Glycogen is converted to glucose 6 phosphate to be used for glycolysis. In skeletal muscle, glucose 6 phosphate cannot be released. In liver tissue, hepatocytes convert glucose 6 phosphate to free glucose. Liver can quickly release glucose to blood for use by other body tissues

76
Q

Gluconeogenesis

A

Formation of glucose molecules from noncarbohydrate sources. Conversion of glycerol and amino acids to glucose

77
Q

Importance of gluconeogenesis

A

Protective measure- prevents important, glucose hogging organs from experiencing low blood sugar. ATP synthesis can occur even in the absence of carbohydrate sources

78
Q

Purpose of lipid metabolism

A

Use for energy production. Glycerol and fatty acids can be oxidized for energy- fat stores are concentrated sources of energy

79
Q

During lipid metabolism, what are fatty acids and glycerol converted to?

A

Glycerol is converted to glyceraldehyde 3 phosphate-glyceraldehyde yields about 15 ATP. Fatty acids are converted to acetyl CoA

80
Q

2 ways in which the body can store/access lipids

A
  1. Lipogenesis

2. Lipolysis

81
Q

Lipogenesis

A

Synthesis of triglycerides (glycerol and fatty acid chains). Acetyl CoA and glyceraldehyde 3 phosphate accumulate, begin triglyceride synthesis to prevent excessive build up. Acetyl CoA join to form fatty acid chains and glyceraldehyde 3 phosphate to converted to glycerol

82
Q

Lipolysis

A

Break down triglycerides to glycerol and fatty acids. Glycerol and fatty acids released to blood to be used for pathways

83
Q

Amino acids can produce energy by (2)

A
  1. Degrading them into molecules that can be used in the citric acid cycle
  2. Converted to glucose
84
Q

For the body to use amino acids for energy, what has to happen?

A

they must first have their amine group (NH2) removed

85
Q

3 processes that can convert amino acids into useable energy source

A
  1. Transamination
  2. Oxidative deamination
  3. Modification of keto acids
86
Q

Transamination

A

The transfer of an amine group to alpha ketoglutaric acid. Alpha ketoglutaric acid transformed to glutamic acid, amino acid transformed to a keto acid

87
Q

Oxidative deamination

A

Amine group of glutamic acid from 1 is removed as ammonia. Ammonia is combined with carbon dioxide to form urea- excreted by kidneys. This step can regenerate alpha-ketoglutaric acid

88
Q

Modification of keto acids

A

Keto acids formed in step 1 are altered. The products of this step can be used in the citric acid cycle- creates energy

89
Q

Anabolic-catabolic balance

A

Molecules are constantly broken down and rebuilt

90
Q

Absorptive state

A

Anabolic activity is greater than catabolic activity in the body, nutrient storage is occurring. Lasts about 4 hours after eating a meal- nutrients enter bloodstream from GI tract. Large amounts of glucose available for energy needs, amino acids used to build new protein molecules, fats used to build new triglycerides (adipose tissue) and other lipid molecules

91
Q

Hormonal control of absorptive state

A

Insulin. Need hormonal controls, don’t want blood glucose to drop very quickly.

92
Q

Effects of insulin (3)

A
  1. Diffusion of glucose into body cells increases (hypoglycemic hormone- lowers blood glucose levels).
  2. Uptake of amino acids increases- stimulates protein synthesis
  3. Prohibits gluconeogenesis and glucose export by liver. Have a lot of glucose coming in already, don’t need the liver to help. Blood glucose would increase drastically.
93
Q

When is insulin released?

A

Beta cells of pancreas release insulin in response to increasing blood glucose and amino acid levels

94
Q

Postabsorptive state

A

Catabolic activities are greater than anabolic activities in the body. Nutrients used to create energy, occurs when GI is completely empty- no absorption occurring. Importance- maintains blood glucose levels at a desirable level (about 110 g glucose/dL blood)

95
Q

Sources of glucose in postabsorptive state (4)

A
  1. Liver- glycogenolysis begins
  2. Skeletal muscle- glycogenolysis begins
  3. Adipose tissue and the liver- lipolysis begins
  4. Cellular proteins (the last resort)
96
Q

How are cellular proteins used as a source of glucose as a last resort?

A

Amino acids deaminated and converted to glucose in liver, kidneys eventually begin gluconeogenesis

97
Q

Hormonal controls of the postabsorptive state (2)

A
  1. Glucagon

2. Epinephrine

98
Q

Glucagon

A

Alpha cells of pancreas release glucagon in response to drop in blood glucose levels (hyperglycemic hormone- raises blood glucose levels). Glycogenolysis and gluconeogenesis in liver, adipose releases fatty acids and glycerol to blood

99
Q

How does epinephrine influence the postabsorptive state?

A

The adipose tissue is supplied with sympathetic fibers. Epinephrine release mobilizes adipose tissue- promotes glycogenolysis

100
Q

Metabolic functions of the liver

A

Glycogenolysis, gluconeogenesis, glycogen storage, fat storage, vitamin and mineral storage, and cholesterol metabolism

101
Q

Transport of cholesterol

A

Cholesterol is insoluble in water. Cholesterol and lipoproteins aren’t the same thing- lipoproteins act as transport molecules for cholesterol. They transport cholesterol to and from body tissues

102
Q

Lipoproteins

A

Transport cholesterol to and from body tissues, contain both fats and proteins. High lipid content= low density. High protein content= high density. There are 3 types

103
Q

Very low density lipoproteins (VLDLs)

A

Most come from liver, transport triglycerides from liver to peripheral tissues

104
Q

Low density lipoproteins (LDLs)

A

What remains after triglycerides are unloaded from VLDLs, transport cholesterol from liver to peripheral tissues. High LDL is not desirable (keep LDL low). 160+ mg/dl is not good

105
Q

High density lipoproteins (HDLs)

A

Transport cholesterol from peripheral tissues to liver. Cholesterol is broken down in liver, used for bile. Provides steroid producing organs with cholesterol for hormone production. HDL is healthy, 60+ mg/dL is desirable

106
Q

Regulation of blood cholesterol

A

Negative feedback loop between diet and liver. Intake of saturated and unsaturated fats influences cholesterol levels. Saturated fat intake stimulates cholesterol production by liver and inhibits its excretion- high saturated fat intake= higher blood cholesterol levels. Unsaturated fats stimulate catabolism to bile salts and its excretion- high unsaturated fat intake= lower blood cholesterol levels. Trans fat intake increases LDL and decreases HDLs

107
Q

Other influences on blood cholesterol (3)

A
  1. Stress and smoking will lower HDL levels
  2. Regular exercise and estrogen will lower LDL- people with XX chromosomes produce more estrogen
  3. Body shape- “apple” shape prone to higher LDL and cholesterol levels than “pears”- apple shape means more fat along waistline, unclear why this happens
108
Q

Energy balance

A

Energy released by catabolizing food molecules must be balanced by the total energy output of the body. In the body, energy intake= energy output. Each must be regulated to ensure this balance

109
Q

Energy intake

A

energy liberated during food oxidation

110
Q

Energy output

A

Energy used to do work, energy stored as fat or glycogen, or energy lost as heat. Heat cannot be used by the body for energy source, but it’s useful for warming tissues and blood and maintaining internal body temperature

111
Q

Which region of the brain regulates and influences feeding behaviors?

A

Hypothalamus

112
Q

Hunger promoting regions of hypothalamus

A

Arcuate nucleus (ARC)- NPY/AgRP neurons release neuropeptide Y and agouti-regulated peptide (AgRP)

113
Q

Satiety promoting regions of hypothalamus

A

Arcuate nucleus- POMC (pro-opiomelanocortin)/CART (cocaine and amphetamine regulated transcript) neurons release peptides. These peptides cause the ventromedial nucleus (VMN) to release corticotropin releasing hormone.

114
Q

Factors that provide short term regulation of food intake (3)

A
  1. Neural signals from digestive tract
  2. Blood levels of nutrients
  3. GI tract hormones
115
Q

How do neural signals from the digestive tract regulate food intake in the short term?

A

Vagal nerve fibers carry information between brain and gut- allow brain to tell content of ingested foods and suppression of appetite via activation of stretch receptors

116
Q

How do blood levels of nutrients regulate food intake in the short term?

A

Nutrient signals that suppress appetite include rising blood glucose, rising amino acid levels in blood, and fatty acid content of blood. Protein makes the vagus nerve send impulses to hypothalamus for longer, makes you feel food for a longer period of time

117
Q

Appetite suppressing GI tract hormones (2)

A
  1. Insulin

2. Cholecystokinin (CCK)- blocks effects of NPY

118
Q

Appetite stimulating GI tract hormones (3)

A
  1. Glucagon
  2. Epinephrine
  3. Ghrelin (Ghr)- hormone produced by stomach during fasting periods
119
Q

Leptin

A

Hormone released long term by adipose tissue in response to increasing body fat stores. Allows the brain to keep track of how much total energy is stored in fat tissue. Rising leptin levels bind ARC, NPY release is inhibited, and stimulates CART. Leptin’s role is to prevent weight loss during a time of nutrient deprivation

120
Q

Is leptin the solution to obesity?

A

No. Obese individuals have higher than normal leptin levels, but appear to be resistant to its effects. Leptin’s main role is to prevent weight loss during times of nutritional deprivation

121
Q

Metabolic rate

A

The body’s rate of energy output, including the total heat produced by all chemical reactions and mechanical work of the body

122
Q

Basal Metabolic Rate (BMR)

A

The energy the body needs to perform only its most essential activities. Includes breathing and resting level of organ function. Approximate BMR many different ways

123
Q

Factors affecting BMR (5)

A
  1. Age- younger individuals tend to have higher BMR
  2. Gender- BMR is higher in males
  3. Body temperature- high body temp= higher BMR
  4. Stress- higher stress= higher BMR
  5. Thyroxine
124
Q

How does thyroxine affect BMR?

A

Higher thyroxine release= higher BMR. Thyroxine causes increased oxygen consumption and heat production by accelerating ATP use. Thyroid hormones impact the metabolic rate

125
Q

Total metabolic rate

A

The rate of calorie consumption needed to fuel all ongoing activities (involuntary and voluntary). Most of TMR comes from BMR

126
Q

Factors influencing TMR (2)

A
  1. Skeletal muscle use can cause dramatic increases in TMR and heat production- TMR increases during physical activity, remains elevated several hours after
  2. Ingesting food increases TMR- food induced thermogenesis- heightened metabolic activity of digestive organs
127
Q

Normal body temperature range

A

Normal body temperature ranges from 96-101. Fluctuates no more than 2 degrees during the day, lowest in morning, highest in early evening

128
Q

How is most body heat generated?

A

At rest, most heat generated by liver, brain, heart, kidneys, endocrine organs. When active, skeletal muscle tissue can produce 30-40 times more heat than the rest of the body

129
Q

Importance of maintaining body temperature

A

Metabolism and enzyme activity are linked to body temperature. Increasing body temperature increases metabolic rate and enzyme activity, while decreasing body temperature decreases metabolic rate

130
Q

Core temperature

A

Temperature of organs within the skull and thoracic and abdominal cavities. This is the highest temperature of the body. Must be precisely regulated- if heat needs to be conserved, vasoconstriction occurs so that blood bypasses the skin

131
Q

Shell temperature

A

Temperature of the skin- lowest temperature of the body. When blood bypasses the skin, shell temperature falls toward environmental temperature. This temperature varies substantially and doesn’t have an impact on internal body processes.

132
Q

Heat exchange mechanisms (4)

A
  1. Radiation
  2. Conduction
  3. Convection
  4. Evaporation
133
Q

Radiation

A

Loss of heat in the form of infrared rays- 50% of heat lost by body is by radiation. Heat can also be gained by radiation (via sunlight, etc)

134
Q

Conduction

A

Transfer of heat between two objects that are in direct contact

135
Q

Convection

A

Transfer of heat that occurs due to circulating air. Warm air expands and rises, cooler air is dense and falls. Air immediately surrounding the body is warmed, which then rises- continuously replaced by cooler air

136
Q

Evaporation

A

The body is cooled as heat is absorbed by water to escape as gas. Insensible water loss- basal level of body heat due to continuous evaporation of water from the lungs, mouth, and skin. Sensible water loss- sweating

137
Q

Thermoregulatory center of the hypothalamus is composed of (2)

A
  1. Heat promoting center- promotes creation of heat to increase body temperature
  2. Heat loss center
138
Q

How does the hypothalamus receive information?

A

Peripheral thermoreceptors and central thermoreceptors send information about temperature to anterior portion of hypothalamus
Peripheral- found in the shell. Central- found in core, more important, send info about internal organ temp

139
Q

When are heat promoting mechanisms stimulated?

A

Stimulated when blood temperature falls or external temperature is low

140
Q

Heat promoting mechanisms (4)

A
  1. Vasoconstriction of cutaneous blood vessels- blood bypasses the skin
  2. Shivering- involuntary muscle contractions. Most important, provides the most heat overall
  3. Increase in metabolic rate- sympathetic stimulation increases. Epinephrine and norepinephrine enhance heat production by increase metabolic rate
  4. Thyroxine release
141
Q

How does thyroxine release increase body temperature?

A

Increases metabolic rate- increases heat produced. Effect usually seen only in infants

142
Q

When are heat loss mechanisms stimulated?

A

Stimulated when core temperatures rise

143
Q

Heat loss mechanisms (2)

A
  1. Vasodilation of cutaneous vessels- blood floods to skin. Body loses heat by radiation, conduction, and convection
  2. Noticeable sweating- evaporation. Sympathetic fibers activate sweat glands to pour out larger volumes of sweat. This only works well in a “dry heat”- sweat won’t evaporate well in a humid environment

Anatomy and Physiology 2 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions