Hormonal Changes After Injury and Infection

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Questions and Answers

Which hormone is considered a counter-regulatory hormone that opposes insulin's action?

Epinephrine

Growth Hormone

Cortisol (correct)

Glucagon

What metabolic condition characterized by an increase in basal metabolic rate is often observed after an injury?

Stable metabolic state

Hypometabolic state

Hypermetabolic state (correct)

Anabolic state

In response to injury, how does the presence of mild hyperglycemia benefit healing tissues?

By enhancing glucose uptake and anaerobic metabolism (correct)

By promoting aerobic metabolism exclusively

By limiting amino acid availability

By decreasing glucose uptake

Which metabolic process is significantly promoted by cortisol during the response to injury?

Gluconeogenesis Signup and view all the answers

How are triacylglycerols utilized during the metabolic response to injury?

They provide fatty acids and glycerol for metabolic needs. Signup and view all the answers

Which of the following hormones is primarily responsible for the rapid mobilization of fuels in the 'fight or flight' response?

Epinephrine Signup and view all the answers

What role do amino acids derived from skeletal muscle play following injury?

They provide substrates for protein biosynthesis and gluconeogenic needs. Signup and view all the answers

How does liver metabolism change in response to injury?

The liver increases its synthesis of proteins and glucose. Signup and view all the answers

What is the most common cause of excess cortisol in the body?

Adrenal gland tumor Signup and view all the answers

Which symptom is typically associated with Addison disease due to insufficient cortisol?

Hypoglycemia Signup and view all the answers

What physiological state does an injury induce that increases the basal metabolic rate (BMR)?

Hypermetabolic state Signup and view all the answers

Which factor does NOT typically determine an individual's basal metabolic rate (BMR)?

Injury status Signup and view all the answers

By how much can burns increase the basal metabolic rate (BMR)?

Up to 200% Signup and view all the answers

What can lead to hyperglycemia during a hypermetabolic state?

Inter-organ carbohydrate metabolism Signup and view all the answers

What is the typical response of glucose utilization in kidneys after an injury?

Increased glucose utilization Signup and view all the answers

Which of these factors does NOT cause an increase in basal metabolic rate (BMR)?

Starvation Signup and view all the answers

What happens to skeletal muscle during injury or trauma?

It is broken down releasing amino acids for restoration. Signup and view all the answers

Which of the following statements about cardiac muscle is true?

It is not broken down to ensure heart function. Signup and view all the answers

What role do counter-regulatory hormones play in fatty acid metabolism?

They induce the breakdown of triacylglycerols in adipose tissue. Signup and view all the answers

Which of the following is NOT an acute phase protein produced by the liver in response to trauma?

Transferrin Signup and view all the answers

During a response to injury, what primarily happens to the production of albumin in the liver?

Its production decreases. Signup and view all the answers

Which molecule serves as a substrate for gluconeogenesis when released during injury response?

Glycerol Signup and view all the answers

Why might the brain still require glucose during a response to injury?

Fatty acids are not primarily used as energy by the brain. Signup and view all the answers

What is the primary function of haptoglobin during the acute phase response?

To bind and neutralize hemoglobin from cell lysis. Signup and view all the answers

What is essential for the synthesis of ATP during the healing process?

Good nutrition Signup and view all the answers

What role does glucose play in preventing skeletal muscle protein catabolism?

It reduces the utilization of amino acids for gluconeogenesis. Signup and view all the answers

Which hormone's action can be inhibited by using propranolol after an injury?

Adrenaline Signup and view all the answers

What intervention cannot completely prevent muscle catabolism following an injury?

Counter-regulatory hormone regulation Signup and view all the answers

Which of the following proteins does the liver increase secretion of after an injury?

C-reactive protein Signup and view all the answers

What is the principal fuel for energy production in the initial phases of wound repair?

Glucose Signup and view all the answers

How does cortisol affect metabolism during injury?

It promotes gluconeogenesis in the liver. Signup and view all the answers

What is a consequence of skeletal muscle catabolism following injury?

Release of amino acids into circulation Signup and view all the answers

What is the primary function of counter-regulatory hormones in response to injury?

Promote a state of insulin-resistance Signup and view all the answers

Which hormone is primarily responsible for opposing the effects of insulin?

Cortisol Signup and view all the answers

What role does cortisol play in the body's response to injury?

It has immunosuppressive effects Signup and view all the answers

How does cortisol affect metabolic processes?

By promoting catabolic processes Signup and view all the answers

When is cortisol typically at its highest levels during the day?

Just before waking Signup and view all the answers

Which of the following best describes the action of cortisol?

Increases resistance to stress and inflammation Signup and view all the answers

Which substance is a synthetic derivative of cortisol used for its anti-inflammatory effects?

Prednisone Signup and view all the answers

What is the response of the body to injury regarding hormonal balance?

Increased counter-regulatory hormones and decreased insulin Signup and view all the answers

Study Notes

Introduction

Injury and infection trigger various metabolic changes in the human body.

Hormones

Counter-regulatory hormones oppose insulin's actions on metabolism:
- Glucagon: Synthesized in the pancreas, secreted when blood glucose is low, promotes glucose production.
- Epinephrine: Synthesized in the adrenal medulla, secreted in response to stress, increases blood glucose and heart rate.
- Cortisol: Synthesized in the adrenal cortex, secreted in response to stress, promotes glucose production and protein breakdown.
Following injury, counter-regulatory hormones increase while insulin decreases, promoting a temporary state of insulin resistance.

Cortisol

Cortisol is a steroid hormone synthesized in the adrenal gland.
It affects gene regulation by binding to its receptor within target cells.
Cortisol levels normally fluctuate with our circadian rhythm, peaking before waking.
Its actions oppose those of insulin, promoting catabolism and suppressing inflammation.
It's used medicinally for its anti-inflammatory and immunosuppressive effects (e.g., prednisone, dexamethasone).

Hypermetabolic State

Injury induces a hypermetabolic state, increasing basal metabolic rate (BMR).
BMR is affected by various factors:
- Body surface area: Larger surface area increases heat loss and raises BMR.
- Age: Infants and children have higher BMR for growth.
- Activity levels: Regular exercise increases BMR.
Starvation decreases BMR by up to 50%.

Metabolism During the Hypermetabolic State

Carbohydrate metabolism: Injury causes hyperglycemia due to increased counter-regulatory hormones.
- Cells involved in repair and pathogen clearance (immune cells, fibroblasts) utilize glucose for energy through anaerobic metabolism.
- Kidneys increase glucose utilization following injury.
- Skeletal muscle breakdown provides amino acids for gluconeogenesis in the liver.
Fatty acid metabolism: Counter-regulatory hormones stimulate triacylglycerol breakdown in adipose tissue, releasing fatty acids and glycerol.
- Glycerol is used for gluconeogenesis in the liver.
- Fatty acids provide energy for tissues and organs, especially skeletal muscle.
Protein metabolism: Skeletal muscle catabolism releases amino acids, essential for protein synthesis in healing tissues and the liver.

Protein Production in the Liver

The liver changes its protein production in response to injury and infection.
- It synthesizes less of certain proteins like albumin and transferrin.
- It increases production of acute phase proteins during injury and infection:
  - C-reactive protein: Multi-purpose protein involved in inflammation and immune response.
  - Serum amyloid A: Recruits immune cells to injury sites.
  - Haptoglobin: Binds to hemoglobin released from damaged cells.
  - Coagulation factors: Promote blood clotting.
  - Lipopolysaccharide binding protein: Binds to bacterial components to stimulate immune response.
  - Component C3: Involved in the complement system.

Biochemical Responses to Injury and Clinical Support

Healing tissues require good nutrition for ATP synthesis and enzyme function.
Minimizing protein catabolism:
- Nutritional support reduces muscle loss.
- Medications like propranolol can inhibit epinephrine's actions, reducing hypermetabolism and muscle breakdown.
- Supplying glucose decreases reliance on amino acids for gluconeogenesis, reducing muscle breakdown.
- Amino acid supplementation provides building blocks for tissue repair and liver protein synthesis.
Despite these interventions, skeletal muscle catabolism can't be completely prevented due to counter-regulatory hormones and insulin resistance.
Recovery depends on injury severity, care, and nutritional support.

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Description

This quiz explores the metabolic changes in the human body triggered by injury and infection, with a focus on the role of counter-regulatory hormones like glucagon, epinephrine, and cortisol. Understand how these hormones interact with insulin and their impact on metabolism during stress conditions.