Unit XIII (68-74) - Metabolism and Temperature Regulation Flashcards by Emma Wright

ATP is present in all cells.

True or False

True

Guyton Pg 853

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Which of the following constitutes 80% of the products of carbohydrate digestion in the GIT?

A. Glucose
B. Fructose
C. Galactose
D. Xylose

A. Glucose

Guyton Pg 854

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Which of the following enzymes breaks up glucose-6-phosphate into glucose and phosphate?

A. Phosphorylase
B. Glucose phosphatase
C. Glucokinase
D. Hexokinase

B. Glucose phosphatase

Guyton Pg 854

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By what mechanism does glucose get transported into the cytoplasm of the cell?

A. Pores
B. Endocytosis
C. Facilitated diffusion
D. Pinocytosis

C. Facilitated diffusion by binding properties of membrane glucose carrier protein

Guyton Pg 854

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Which of the following hormones has the greatest effect on promoting facilitated diffusion of glucose?

A. Glucagon
B. Insulin
C. Estrogen
D. Thyroxine (T4)

B. Insulin

Guyton Pg 855

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In the liver, which of the following enzymes catalyzes the phosphorylation of glucose to glucose-6-phosphate?

A. Glucose phosphatase
B. Hexokinase
C. Glucokinase
D. Phosphorylase

C. Glucokinase; Hexokinase catalyzes the same reaction but in most OTHER cells vs the liver.

Guyton Pg 855

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Where is glycogen stored in the largest quantities?

A. Liver and kidneys
B. Liver and lung
C. Muscle and kidneys
D. Liver and muscle

D. Liver and muscle

Guyton Pg 855

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The phosphorylation of glucose is reversible in which of the following cells (SELECT ALL THAT APPLY)?

A. Hepatocytes
B. Renal tubular epithelial cells
C. Intestinal epithelial cells
D. Cardiac myocytes

A, B, and C. Hepatocytes, renal tubular epithelial cells, and intestinal epithelial cells. Glucose phosphatase is available and when activated can reverse the reaction.

Guyton Pg 855

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Which of the following is the correct pathway of glycogenesis?

A. Glucose-6-phosphate –> Glucose-1-phosphate –> Uridine diphosphate glucose –> Glycogen
B. Glucose-6-phosphate –> Uridine diphosphate glucose –> Glucose-1-phosphate –> Glycogen
C. Glucose-1-phosphate –> Glucose-6-phosphate –> Uridine diphosphate glucose –> Glycogen
D. Glucose-1-phosphate –> Uridine diphosphate glucose –> Glucose-6-phosphate –> Glycogen

A. Glucose-6-phosphate –> Glucose-1-phosphate –> Uridine diphosphate glucose –> Glycogen

Guyton Pg 855

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During rest, the enzyme phosphorylase is

A. Active
B. Inactive

B. Inactive because phosphorylase phosphorylates glycogen to break it down into glucose for energy (energy is not needed during rest, this promotes storage of glycogen).

Guyton Pg 856

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Which of the following pyrogens acts directly on the hypothalamus?
A.	LPS from bacterial wall
B.	IL – 1
C.	Bacterial endotoxins
D.	Prostaglandin E2

Answer: B
Ref: Guyton P. 920

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Which of the following can cause a decrease in basal metabolic rate? 
A.	Fever
B.	Malnutrition
C.	Growth hormone
D.	Testosterone

Answer: B
Ref: Guyton P. 908

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Which one of the following tissues primarily has GLUT 4?

a. Erythrocytes
b. Skeletal muscle
c. Endothelial cells of the blood-brian-barrer
d. Beta-cells of the pancreas

Correct: B Skeletal muscle

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Which one of the following is insulin dependent?

a. GLUT 1
b. GLUT 2
c. GLUT 3
d. GLUT 4

Correct: D GLUT 4

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Which of the lipoproteins transports triglycerides mainly to adipose tissue?

a. VLDL
b. HDL
c. LDL
d. VHDL

Correct: A VLDL

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Which of the following lipoproteins is protective against atherosclerosis?

a. VLDL
b. HDL
c. LDL
d. VHDL

Correct: B HDL

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Which of the following lipoproteins transports triglycerides from the liver to various tissues in the body?

a. VLDL
b. HDL
c. LDL
d. VHDL

Correct: C LDL

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Are fatty acids generally found bound to albumin or free in the blood?

a. bound
b. free

Correct: A Bound

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What is the alternative pathway (to the glycolytic pathway) in the formation of fatty acids?

a. B-oxidation
b. Kreb’s cycle
c. Glycolysis
d. Pentose phosphate pathway

Correct: D Pentose phosphate pathway

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How many moles of ATP are formed from a triglyceride molecule?

a. 8
b. 18
c. 28
d. 38

Correct: B 18 from fat

Reminder: 38 from carbs

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Ketoacidosis is a result of a deficiency in which one of the following? (The deficiency limits entry of acetyl-CoA into the citric acid cycle.)

a. Oxaloacetate
b. Citrate
c. Succinate
d. Fumarate

Correct: A Oxaloacetate

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Name the triglycertide-rich lipoprotein that is synthesized by the liver?

a. VLDL
b. HDL
c. LDL
d. VHDL

Correct: A VLDL

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Name the rate-limiting enzyme in cholesterol synthesis.

a. HMG-CoA reductase
b. HMG-CoA synthase
c. Famesyl diphosphate synthase
d. Lanosterol synthase

Correct: A HMG-CoA reductase

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HDL returns cholesterol to the liver in a pathway known as ________?

a. Receptor-mediated endocytosis
b. Exogenous pathway
c. Reverse cholesterol transport
d. Endogenous pathway

Correct: C Reverse cholesterol transport

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What is the mechanism used by cell to take up LDL cholesterol from the circulation? a. Receptor-mediated endocytosis b. Exogenous pathway c. Reverse cholesterol transport d. Endogenous pathway

Correct: A Receptor-mediated endocytosis

What protein is required for receptor-mediated endocytosis that allows LDL uptake from the circulation? a. VLDL receptor b. HDL receptor c. LDL receptor d. VHDL receptor

Correct: C LDL receptor

Which one of the following proteins is integral to buffering the blood? a. albumin b. IgG c. hepsidin d. IgM

Correct: A albumin

Which of the following organs primarily stores proteins? a. Kidneys b. Liver c. Heart d. Brain

Correct: B Liver

Which of the following enzymes initiates deaminiation of proteins? a. Glutamate dehydrogenase b. Aminotransferase c. Dehydrogenase d. Isomerase

Correct: B Aminotransferase

Which of the following hormones promotes fat synthesis by stimulating lipoprotein lipase? a. Glucocorticoids b. Insulin c. Glucagon d. Thyroid hormone

Correct: B Insulin

Which of the following hormones decreases liver glycogenolysis? a. Glucagon b. Epinepherine c. Glucocorticoids d. Growth hormone

Correct: C Glucocorticoids

Which one of the following hormones decreases liver gluconeogenesis? a. Insulin b. Glucagon c. Epinephrine d. Glucocorticoids

Correct: A Insulin

Which one of the following hormones decreases protein synthesis? a. Insulin b. Glucocorticoids c. Thyroid hormone d. Growth hormone

Correct: B Glucocorticoids

What is the most abundant store of high-energy phosphate bonds in the cells a. ATP b. Phosphocreatine c. Glucose-6-Phosphate d. Phosphofructokinase

Answer: B (Guyton Ch 73)

Which mechanism of heat loss is the most important at high temperatures? a. Conduction b. Convection c. Evaporation d. Radiation

Answer: C (Guyton Ch 74)

Which tissue is especially susceptible to damage by hyperpyrexia ? a) liver b) brain c) kidneys d) red blood cells

Answer : b; Guyton (12th edition), p. 876-877

Which of the following best describes nonshivering thermogenesis in response to cold stress ? a) Sympathetic stimulation of muscle → production of a large amounts of heat and ATP b) Sympathetic stimulation of brown fat → production of a large amounts of heat and ATP c) Sympathetic stimulation of white fat → production of a large amount of heat but almost no ATP d) Sympathetic stimulation of brown fat → production of a large amount of heat but almost no ATP

Answer : d; Guyton (12th edition), p. 865

What is the rate limiting factor of energy release in resting conditions? a. ADP b. ATP c. GDP d. GTP

Answer: A

Which of the following does not increase metabolic rate? a. Fever b. Thyroid hormone c. Sleep d. Growth hormone e. Appropriate nutrition

Answer: C

When ambient temperature becomes greater than the temperature of skin, what type of cooling is utilized and effective? a. Convection b. Conduction c. Radiation d. Evaporation

Answer: D

Where is the panting center in dogs that becomes activated when they overheat? a. Temperature regulating centers in the hypothalamus b. Pneumotaxic center in the pons c. Somatosensory neurons d. Primary motor center in the posterior hypothalamus

Answer: B

When a mammal is cold, the hypothalamus causes all of the following except which mechanism for maintaining body temperature? a. Non-shivering thermoregulation b. Shivering c. Vasoconstriction d. All of these are methods of maintaining core body temperature

Answer: D

What factors contribute to heat stroke in dogs? a. As body heat rises, the metabolic rate decreases b. Evaporation does not remain an effective method of heat loss c. Since cell function continues appropriately, there is continued heat production from metabolism d. Humidity levels remain static despite panting

Answer: B

Which of the following correctly describes the biologic function of phosphocreatinine? a. A backup energy source that can be used instead of ATP to power cellular metabolism b. A transfer molecule carrying high energy electrons to the electron transport chain c. An energy buffer allowing quick restoration of intracellular ATP pools d. An alternative energy source used for energetically demanding reactions only due to the presence of a phosphate bond that can release more energy than ATP

Answer c (Guyton 904)

Which of the following are pyrogenic? a. IL-1 b. IL-2 c. IL-10 d. TGFB

Answer a (Guyton 920)

By which method is heat transferred from deep tissues to the skin? a. Convection b. Radiation c. Conduction d. evaporation

Answer: Convection

An increase in this endogenous product results in an increase in the hypothalamic temperature set point in the face of a fever a. Prostaglandin E2 b. IL-6 c. IL-1 d. TNFa

Answer: PGE2

Which of the following species does not have a carotid rete for thermoregulation? a. Dogs b. Cats c. Horses d. Cattle

Answer: C Horses; Cunningham pg 562

In most species sweating is under the control of A] Sympathetic adrenergic nerve fibers B] Sympathetic cholinergic nerve fibers C] Parasympathetic adrenergic nerve fibers D] Adrenal medulla

Answer: B Cunningham Chapter 53, pg 563

When substrate concentrations become low, the rate of metabolic reactions depend upon A] Substrate concentration B] Enzyme concentration C] Both of the above D] None of the above

Answer: C Guyton and Hall Chapter 73

Which of the following correctly describes the carotid rete found in sheep and other ungulates? A. The carotid artery takes a tortuous path to the brain and thus heat dissipates as it travels. By the time the blood reaches the brain, it has cooled sufficiently. B. The carotid rete is a countercurrent mechanism between the jugular vein and carotid artery. The artery loses heat to the vein as blood flows in opposite directions. C. The carotid artery forms a complex network of vessels that is bathed in a sinus of arterial blood that supplies the nasal cavity. The arterial blood is therefore colder due to exposure to the environment of the nasal cavities, thus the arterial blood transfers and loses heat to the cooler sinuses and the blood delivered to the brain is cooled prior to entering the brain. D. The carotid artery forms a complex network of vessels that is bathed in a sinus of venous blood that has drained the nasal cavity. The venous blood is therefore colder than the arterial blood, thus the arterial blood transfers and loses heat to the cooler veins and the blood delivered to the brain is cooled prior to entering the brain.

Correct Answer: D | Ref: Cunningham, pg. 561-562

Which molecule is considered a reserve of energy and forms when excess ATP is present in the body? a. Creatine Kinase b. Phosphocreatine c. Guanine Triphosphate d. Adenosine Monophosphate

Correct Answer: B | Ref: Guyton pg. #904

Which of the following cytokines is considered most important in the development of fever? a. IL-1 b. IL-2 c. IL-6 d. IL-13

Answer: A

In most species (except horses), sweating is controlled by which type of nerve fibers? a. sympathetic adrenergic b. sympathetic cholinergic c. parasympathetic adrenergic d. parasympathetic cholinergic

Answer: B

The most abundant store of high-energy phosphate bonds in the body is normally: A. Adenosine triphosphate (ATP) B. Phosphocreatine C. Phosphofructokinase D. Glycogen

ANSWER: B (Guyton Ch 73)

``` The following hormone plays a crucial role in acclimization to heat: A. Thyroid hormone B. Antidiuretic hormone C. Angiotensin II D. Aldosterone ```

ANSWER: D (Guyton Ch 74)

Which of the following will decrease the body’s metabolic rate? a. Increased temperature b. Increased thyroid hormone c. Prolonged malnutrition d. Increased growth hormone

Answer: C. Reference: Guyton Ch. 73 Pg. 908

What is the only means by which the body can rid itself of heat when the temperature of the surroundings is greater than the skin temperature itself? a. Radiation b. Convection c. Conduction d. Evaporation

Answer: D. Reference: Guyton Ch. 74 Pg. 913

Which of the following is mainly a PHYSIOLOGIC mechanism to increase body temperature? a) Decreased thyroid releasing hormone secretion from the hypothalamus b) Increased neural release of norepinephrine c) Release of IL-1 from macrophages d) Increased ATP production from oxidative phosphorylation

Answer: B (Chu). C) this is a pathologic cause that is usually induced by bacteria. Source: Guyton Ch. 73 p. 909 and Ch. 74 p. 911

Which of the following is the most important mechanism to decrease core body temperature when the ambient temperature is higher than body temperature? a) Radiation b) Convection c) Conduction d) Evaporation

Answer: D (Chu); Source: Guyton Ch. 74 p. 913

``` Which of the following decreases metabolic rate? A. Male sex hormone B. Thyroid hormone C. Growth hormone D. Fever E. Sleep ```

Correct answer: E. | Ref: Guyton, Ch.73 pg. 908

``` Which of the following constitutes the primary mechanism of heat loss from the body? A. Conduction to air B. Conduction to objects C. Convection D. Evaporation E. Radiation of heat waves ```

Correct answer: E. | Ref: Guyton, Ch. 74 pg. 913 (Figure 74-4)

``` Which of the following do not increase the metabolic rate? A. Growth Hormone B. Testosterone C. Thyroid Hormone D. Malnutrition ```

Answer: D

``` Which of the following neurotransmitters is not stimulatory to sweat glands? A. Epinephrine B. Norepinephrine C. Dopamine D. Acetylcholine ```

Answer: C

``` Which anatomical area has more heat-sensitive neurons than cold-sensitive neurons? A. Anterior hypothalamic-preoptic area B. The skin C. Abdominal viscera D. The spinal cord ```

Answer: A

What is the structure of ATP?

Adenine Ribose 3 x phosphate radicals

What are the final products of CHO metabolism? Which is present in the largest quantity?

Glucose - 80% Fructose Galactose

What happens to fructose and galactose following absorption from the GIT?

Mostly converted to glucose in the liver

How is the liver able to convert other monosaccharides into glucose?

Large quantity glucose-6-phosphatase

How is glucose transported into cells in the a) GIT, b) kidneys, c) peripheral tissues

A and B - sodium glucose co-transport C - facilitated diffusion

What happens to glucose following entry into a cell? What enzyme is involved? How does the process differ in the liver/kidneys?

Phosphorylated by hexokinase (glucokinase in liver) Reversible in liver (not in other cells) - liver cells have glucose phosphatase

Describe glycogenesis

Glucose ==> glucose-6-phosphate ==> glucose-1-phosphate ==>uridine diphosphate glucose ==> glycogen

Describe glycogenolysis

Glycogen ==> glucose-1-phosphate ==> glucose-6-phosphate ==> glucose

In glycolysis, which enzyme is responsible for converting glycogen into glucose-1-phosphate?

Phosphorylase

How is phosphorylase activated?

Epinepherine Glucagon Both promote cAMP production

Where is glucagon released?

Alpha cells of pancreas

Describe glycolysis

Glucose ==> 2x pyretic acid

What are the net ingredients and products of glycolysis?

Glucose + 2 ADP + 2 P ==> 2 pyruvic acid + 2 ATP + 4H

What happens to the pyruvic acid formed in glycolysis? What else is formed in this reaction?

Concerted to acetyl-CoA 2 pyruvic acid + 2 CoA ==> 2 acetyl-CoA + 2CO2 + 4H

What happens following acetyl-CoA formation? Where does this reaction take place?

Acetyl degraded to CO2 and H in the CAC Matrix of mitochondria

What is the net result of the CAC?

2 Acetyl CoA + 6 H20 + 2 ADP ==> 4CO2 + 16H + 2CoA + 2ATP

How many hydrogen ions are produced per glucose molecule?

What happens to the H ions produced during CHO metabolism?

20 pair with NAD+ 4 pass directly into oxidative process

What happens to H+ produced during CHO metabolism?

Oxidative phosphorylation

Briefly describe oxidative phosphorylation

H split into H+ and e- e- + H2O => OH- H+ + OH- => H2O + ATP

Where is ATP produced in the oxidative phosphorylation process?

ATP synthetase - H+ passes down concentration/electrical gradient in mitochondria through ATPase molecule

How much ATP is formed per glucose molecule metabolised?

How is the rate of glycolysis controlled?

ATP and citrate inhibit phosphofructokinase - presently glycolytic pathway ADP enhance phosphofructokinase Once all ADP used, further ATP cannot be formed

Describe anaerobic glycolysis

If quantities of pyruvic acid and NADH become excessive, combine with one another to form lactic acid

What happens to lactic acid formed during anaerobic glycolysis?

Converted back to pyruvic acid and NADH once oxygen is available again

What is the alternative pathway of glucose metabolism? Where does it occur? Why is it important?

Pentose phosphate pathway Liver and adipose Releases NADP - can be used for fat synthesis

Briefly describe gluconeogenesis

Amino acids and glycerol portion of fat combined to form glucose

What stimulates gluconeogenesis?

Reduced cellular CHO and low BG ACTH secreted = ^cortisol Mobilises proteins

What promotes hydrolysis of stored fat?

1 - alpha-glycerophosphate - glucose breakdown product - maintains glycerol portion of triglycerides. When reduced glucose availability - insufficient quantity 2 - hormone sensitive lipase activated

What is the function of a) chylomicrons and b) lipoproteins?

a) Transport lipids from GIT to tissues b) Transport lipids between tissues

What are the 4 types of lipoproteins? How do they differ in composition?

VLDLs - high concentration triglycerides, moderate cholesterol and phospholipids IDLs - some triglycerides removed LDLs - almost all triglycerides removed HDLs - high concentration protein, smaller concentration cholesterol/phospholipids

Where are lipoproteins formed?

The liver

Which tissues cannot use fatty acids for energy?

Brain and RBCs

Briefly, how are triglycerides used to produce energy?

Triglyceride hydrolysed Glycerol - converted to glycerol-3-phosphate - enters glycolytic pathway Fatty acids - degraded and oxidised in mitochondria - converted into acetyl CoA - beta oxidation

What limit the rate of utilisation of ketone bodies?

Oxaloacetate - product of CHO metabolism needed to bind to acetyl-CoA before it can be processed in the CAC

Why are fats poorly synthesised in diabetes?

Little cellular glucose: - little acetyl-CoA and NADPH available for fat synthesis - reduced availability of alpha glycerophosphate

What prevents fat metabolism when excess CHO is available?

- Excess CHO = excess alpha-glycerophosphate - binds FFA in form of stored triglycerides - Excess CHO = excess acetyl-CoA and low quantities FFA - favours FFA formation - Acetyl-CoA-carboxylase - controls rate of acetyl CoA => malonyl CoA for FA synthesis. Activity accelerated in presence of CAC intermediates

What hormones are most important in promoting fat utilisation?

Ep/NEp => activate hormone sensitive lipase Cortisol and glucocorticoids => activate HSL GH => => activate HSL Thyroid hormone - overall increase in metabolism

What process allows amino acids to be used for energy?

Deamination

Draw a liver lobule

pg 872

What substances encourage hepatic growth?

Hepatocyte growth factor TNF IL-6

What substances terminate hepatic growth?

Transforming growth factor beta

How does the liver contribute towards CHO metabolism?

Glycogen storage Conversion of galactose/fructose to glucose Gluconeogenesis Formation of chemical compounds from intermediate products of CHO metabolism

What is the respiratory quotient for the metabolism of CHO?

1.0

What is the respiratory quotient for the metabolism of protein?

0.8

What is the respiratory quotient for the metabolism of fat?

0.7

What is the respiratory quotient?

Ratio or CO2 output to O2 usage

Where are the hunger and satiety centres located?

Hypothalamus

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Unit XIII (68-74) - Metabolism and Temperature Regulation Flashcards

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