Physiology Lecture 23
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Questions and Answers

What are the three forms of energy storage in the body?

  • Triglycerides, protein, glucose
  • Glycogen, triglycerides, protein (correct)
  • Glycogen, starch, protein
  • Glycogen, triglycerides, minerals

    • Triglycerides are primarily stored in the liver.

    False

    Where is glycogen stored in the body?

    Liver and muscle

    During the fasting phase, glucose is derived from the ______.

    <p>liver</p> Signup and view all the answers

    Match the hormones with their functions:

    <p>Insulin = Promotes nutrient storage Glucagon = Releases glucose from storage Epinephrine = Stimulates glycogenolysis and lipolysis Cortisol = Promotes catabolism</p> Signup and view all the answers

    How long can triglycerides provide energy?

    <p>Several weeks</p> Signup and view all the answers

    The use of protein for energy is efficient and cost-effective.

    <p>False</p> Signup and view all the answers

    What hormone primarily controls anabolic processes for nutrient metabolism?

    <p>Insulin</p> Signup and view all the answers

    Glucose is stored as ______ and/or triglycerides during the digestive phase.

    <p>glycogen</p> Signup and view all the answers

    Match the hormones with their classification;

    <p>Insulin = Anabolic hormone Glucagon = Counter-regulatory hormone Epinephrine = Catabolic hormone Growth hormone (GH) = Counter-regulatory hormone</p> Signup and view all the answers

    What effect does insulin have on skeletal muscle?

    <p>Stimulates insulin independent glucose transport with muscle activity via GLUT4</p> Signup and view all the answers

    Insulin decreases ketogenesis in the liver.

    <p>True</p> Signup and view all the answers

    What is the main target of glucagon?

    <p>Liver</p> Signup and view all the answers

    Insulin increases the activity of ________ in adipose tissue.

    <p>Lipoprotein Lipase (LPL)</p> Signup and view all the answers

    Match the hormone with its action:

    <p>Insulin = Increases FFA storage Glucagon = Promotes glucose synthesis FFA = Act as a glucose sparing effect LPL = Facilitates lipid storage</p> Signup and view all the answers

    Which GLUT transporter is involved in glucose transport in the liver?

    <p>GLUT2</p> Signup and view all the answers

    FFA can be directly converted to glucose.

    <p>False</p> Signup and view all the answers

    What happens during a marathon in terms of metabolic hormone activity?

    <p>Nearly all metabolic hormones are active.</p> Signup and view all the answers

    During a sprint, hormonal activity is too ________ for the body to respond effectively.

    <p>quick</p> Signup and view all the answers

    Match the activity with its phase:

    <p>During sprint = Too quick for hormonal activity After sprint = Repletion from liver to muscle During marathon = Nearly all metabolic hormones active After marathon = Repletion by eating</p> Signup and view all the answers

    What role do alpha cells in the pancreas play?

    <p>Secretion of glucagon</p> Signup and view all the answers

    Carbo-loading guarantees improved performance.

    <p>False</p> Signup and view all the answers

    What causes the closure of ATP-dependent K+-channels in pancreatic beta cells?

    <p>Increase in ATP levels</p> Signup and view all the answers

    The initial burst of insulin secretion represents the release of ________ insulin.

    <p>pre-formed</p> Signup and view all the answers

    Match the pancreatic mechanisms with their functions:

    <p>Alpha cells = Secrete glucagon Beta cells = Secrete insulin Somatostatin = Inhibit glucagon and insulin C peptide = Diagnostic purposes for insulin production</p> Signup and view all the answers

    Which of the following hormones inhibits insulin secretion?

    <p>Somatostatin</p> Signup and view all the answers

    Insulin secretion is controlled solely by hormones.

    <p>False</p> Signup and view all the answers

    What is the main function of glucose entering pancreatic beta cells?

    <p>To trigger insulin secretion</p> Signup and view all the answers

    The ________ phase of insulin secretion involves the synthesis of new insulin.

    <p>secondary</p> Signup and view all the answers

    What is more efficient for insulin response, oral administration or intravenous?

    <p>Oral administration</p> Signup and view all the answers

    What is one function of epinephrine during physical activity?

    <p>Enhances oxygen transport to muscles</p> Signup and view all the answers

    Growth hormone decreases blood glucose levels by increasing insulin sensitivity.

    <p>False</p> Signup and view all the answers

    What role does cortisol play during stress or fasting?

    <p>It stimulates hepatic gluconeogenesis, promotes protein catabolism, and supports lipid metabolism.</p> Signup and view all the answers

    During exercise, plasma glucose remains steady because the liver releases __________ to match increased skeletal muscle uptake.

    <p>glucose</p> Signup and view all the answers

    Match the hormone to its primary effect:

    <p>Epinephrine = Increases cardiac output and oxygen transport Growth Hormone = Promotes protein anabolism and mobilizes energy Cortisol = Stimulates gluconeogenesis and supports metabolism Thyroid Hormone = Has permissive effects for other hormones</p> Signup and view all the answers

    What happens to insulin levels during exercise?

    <p>Insulin levels fall</p> Signup and view all the answers

    Fat oxidation can sustain high-intensity activities effectively.

    <p>False</p> Signup and view all the answers

    What does prolonged exposure to growth hormone stimulate in the kidneys?

    <p>Glucose production</p> Signup and view all the answers

    Cortisol has permissive effects with hormones like __________ and glucagon.

    <p>epinephrine</p> Signup and view all the answers

    Which hormone is primarily responsible for regulating metabolism during stress?

    <p>Cortisol</p> Signup and view all the answers

    Study Notes

    Energy Storage Forms

    • The three energy storage forms in the body are glycogen, triglycerides, and protein.

    Glycogen Storage

    • Glycogen is stored in the liver and muscle.
    • The liver's glycogen stores can supply energy for less than a day, while the muscles' stores are smaller.
    • Only the liver can supply glycogen to other tissues.

    Triglyceride Storage

    • Triglycerides are stored in adipose tissue.
    • Adipose tissue is the largest energy reservoir, lasting several weeks.

    Protein Storage

    • Protein is stored in muscle tissue.
    • Protein use for energy is costly as it involves breaking down functional muscle tissue.

    Glucose during Digestive Phase

    • During digestion, glucose is absorbed and enters skeletal muscle, liver, and adipose tissue.
    • Glucose is stored as glycogen or triglycerides (TG).

    Glucose, Amino Acids, and FFA during Fasting Phase

    • Glucose is derived from the liver.
    • Amino acids are obtained from skeletal muscle.
    • Free fatty acids are released from adipose tissue.

    Anabolic Hormone

    • Insulin primarily controls anabolic processes.
    • Increased insulin levels promote nutrient storage.

    Counter-Regulatory Hormones

    • Glucagon, epinephrine, growth hormone, and cortisol are counter-regulatory hormones which promote catabolism.

    Epinephrine

    • Epinephrine is a hormone crucial in exercise and stress situations.
    • It encourages glycogenolysis in muscle and adipose tissue, and lipolysis to release fatty acids.
    • It also increases blood flow and oxygen to muscles and vital organs.

    Growth Hormone (GH)

    • GH increases lean body mass promoting protein anabolism in muscles.
    • It mobilizes energy from carbohydrates and lipids.
    • GH reduces peripheral tissues' insulin sensitivity, leading to higher blood glucose levels.
    • GH also plays a role in regulating acidosis and ammonia production during metabolic stress.

    Cortisol

    • Cortisol is essential for life and energy regulation.
    • It has permissive effects on glucagon and epinephrine, enabling them to function efficiently.
    • Cortisol stimulates hepatic gluconeogenesis to maintain blood glucose.
    • Cortisol promotes protein catabolism to supply amino acids for energy.
    • Cortisol supports lipid metabolism.

    Thyroid Hormone

    • Thyroid hormone primarily has a permissive effect in metabolic processes.

    Blood glucose during Exercise

    • During exercise, plasma glucose remains stable because the liver releases glucose to match the increased muscle uptake.
    • Insulin levels decrease during exercise, reducing storage processes and promoting the release of glucose and fats for energy.

    Metabolism during Exercise

    • The body adapts to energy demands during exercise by regulating energy expenditure; mobilizing different fuel sources, such as glycogen.
    • Fat oxidation cannot sustain high-intensity activities relying on glycogen.
    • Glucose intake must be controlled during exercise to prevent disruptions in free fatty acid availibility or redirection of glucose to non-working tissues.
    • Muscle fatigue is linked to glycogen depletion, though other factors like carbohydrate intake may contribute.

    Insulin Secretion

    • Insulin secretion is controlled by nutrients, hormones, and nerves.
    • Glucose metabolism within beta cells triggers insulin release through a sequence of steps involving ATP-sensitive K+ channels.

    Additional Control of Insulin Secretion

    • GLP-1 is an important stimulator of insulin secretion.
    • Amino acids and oral administration trigger a more potent insulin response compared to intravenous administration.
    • Insulin secretion is biphasic—consisting of an initial burst and a secondary phase—with pre-formed insulin released initially and new insulin synthesized and released afterward.

    Insulin's Acute Effects

    • Insulin's actions on skeletal muscle, liver, and adipose tissue involve glucose transport differently—independent of insulin.
    • Insulin's action on tissues includes decreased ketogenesis in the liver and increased FFA storage in adipose tissue.
    • Insulin's role includes increased activity of lipoprotein lipase and decreased activity of hormone-sensitive lipase.

    Prolonged Insulin Deficiency

    • Prolonged insulin deficiency leads to various metabolic disturbances.
    • Elevated free fatty acids, hyperglycemia, oxidative stress, and potentially further damage may occur.
    • Insulin resistance can be a result of elevated oxidative stress, contributing to diabetic complications.

    Glucagon's Role

    • Fatty acids indirectly increase glucose synthesis, but cannot be directly converted to glucose.
    • Glucagon acts as a glucose-sparing factor, increasing plasma ketones.
    • Glucagon plays a role in lipid and protein actions.
    • Regulation of glucagon and GLP-1 involves a multitude of factors and metabolic processes during exercise and recovery.

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