Metabolism

Metabolism Overview

• Definition of metabolism (from transcript): the processes of biochemical reactions occurring in the body’s cells that are necessary to produce energy, repair and facilitate the growth of cells, and maintain life.

• Context: Metabolism is controlled by the endocrine system and is part of the body’s integration with the environment through hormones.

Endocrine System & Metabolism

• The endocrine system is involved in all integrative aspects of life, including metabolism and adaptation to an ever-changing environment by using chemical substances called hormones (as noted from Porth).

• Hormones act as chemical messengers influencing target tissues to regulate physiological processes.

Role of Endocrine System

• Metabolism of energy

• Fluid and electrolyte balance

• Inflammation and immune responses

• Muscle and adipose tissue distribution

• Sexual development

• Growth and development

Types of Glands in the Body

• Endocrine glands: secrete directly into the bloodstream.

• Exocrine glands: secrete into a ductal system, then into body cavities, an organ, or outer surface of the body.

Major Glands and Organs in the Endocrine System

• Hypothalamus

• Parathyroids (posterior view)

• Pituitary

• Thyroid

• Glands of the Endocrine System

• Adrenals

• Testes (male)

• Pancreas (islets of Langerhans)

• Ovaries (female)

Key Definitions

• Hormone: chemical substance that stimulates action in target tissues.

• Target tissue: a specific tissue that the hormones can influence.

• Receptor site: location on cell surface where hormone attaches and enters the cell.

Hormones: Basic Characteristics

• Produced by endocrine glands; some produced by other tissues.

• Alter function of the target tissue (on or in the cell).

• Site of action: transported in circulation to the target tissue.

• Acts on cells in the area where released; can produce action on the releasing cell.

• Scope of Concept on Continuum

• Hormonal levels can be hypo-, normal, or hyper- (Hypo, Normal, Hyper) along a continuum of hormonal level regulation.

Hypothalamus

• Function: Sends hormones to the pituitary gland for regulation of many body functions.

Pituitary Gland

• Central (master) endocrine gland influenced by the hypothalamus; releases multiple hormones that regulate other glands and body functions.

Pituitary Hormones (Overview)

• Growth: acts on bones, muscles, and organs.

• Prolactin: acts on breasts and reproductive system.

• Anterior pituitary hormones are regulated by hypothalamic hormones.

• Posterior pituitary hormones: Vasopressin (ADH) and Oxytocin.

• Hormones associated with specific targets include LH, FSH, ACTH, TSH, and downstream hormones from target glands.

Anterior Pituitary Hormones

• Adrenocorticotropic hormone (ACTH)

• Thyroid-stimulating hormone (TSH)

• Also produced (by the pituitary or under hypothalamic control):

  • Follicle-stimulating hormone (FSH)

  • Luteinizing hormone (LH)

  • Prolactin

  • Growth hormone (GH, somatotropin)

Posterior Pituitary Hormones

• Vasopressin (antidiuretic hormone, ADH)

• Oxytocin

Hormone Level Regulation

• Feedback Mechanisms:

  • Positive feedback

  • Negative feedback

• Biological rhythm

• Central nervous system stimulation

Hormonal Dysfunctions - Deficiency (Hypofunction)

• Understimulation from hypothalamus/pituitary

• Causes include:

  • Genetic disorder

  • Autoimmune conditions

  • Tumors

  • Infections/toxins

  • Vascular disorders

  • Aging

  • Receptor malfunction

  • Disease or medications

Hormonal Dysfunctions - Excess (Hyperfunction)

• Over stimulation from hypothalamus/pituitary

• Causes include:

  • Hyperplasia or neoplasia

  • Tissue hypersensitivity

  • Exogenous hormone administration

  • Enzyme defects

  • Disease

Risk Factors for Hormonal Imbalances

• Modifiable vs Non-modifiable:

  • Modifiable: Obesity, Sedentary lifestyle, Diet, Lifestyle choices

  • Non-modifiable: Age, Gender, Genetics

• Additional factors:

  • Chromosomal deficiencies

  • Family history

  • Immunity disorders

  • Cancer treatment

  • Hormonal supplement therapy

  • Chronic medical conditions

Life Span Considerations

• Lifelong changes in hormones and metabolism

• Self-perception and body changes

• Children and adults

Cultural & Spiritual Considerations

• Ethnicity

• Diet

• Social pressures

• Health care follow-up

• Religious beliefs

Nursing Process: Assessment – Health History

• Assess for changes in:

  • Energy level

  • Activity

  • Heat and cold tolerance

  • Weight

  • Nutrition

  • Elimination

  • Fat and fluid distribution

  • Memory, concentration

  • Sleep patterns, mood

Physical Assessment

• Vital signs

• Height and weight

• Inspection:

  • Head/Neck and facial puffiness

  • Eye protrusion

  • Changes in hair: distribution, texture, hair loss, hirsutism

  • Neck thickening/Goiter

• Integument assessment (Texture, Pigmentation, Striae, Dryness, Wounds, Lesions, Fingernails, Edema)

Laboratory and Diagnostic Tests

• Blood tests:

  • Hormone levels

  • Autoantibodies

  • Effects of hormones on other substances

  • Electrolytes

  • Stimulation testing

  • Suppression testing

• Urine tests:

  • Amount of hormones or end products of hormones

• Other diagnostics:

  • Imaging: Ultrasound, MRI, CT

  • Biopsy

  • Genetic screening

Health Promotion Strategies

• Primary prevention:

  • Education

  • Diet

  • Exercise

  • Weight control

  • Injury/environmental hazard avoidance

• Secondary prevention (screening):

  • Thyroid screening

  • Diabetes screening

Nursing Interventions

• Pharmacology

• Nutrition

• Symptom management

• Fluid & electrolyte management

• Surgery (pre/during/after care)

• Radiation (pre/during/after care)

• Psychosocial support

• Education

Discharge Plan

• Lifelong changes

• Medication administration

• Knowledge of acute complications

• Knowledge of long-term issues

Evaluation: Effectiveness of Care

• Ability to maintain normal organ function

• Improvement in signs and symptoms

• Following prescribed treatment

• Follow-up as appropriate

Priorities in Care

• Hormone levels close to normal

• Avoid complications (coma & crisis)

• Hypo/hyperglycemia

• Hypo/hyperthyroidism

• Hypo/hyperadrenalism

Relationship to Other Concepts

• Comfort

• Elimination

• Mobility

• Nutrition

• Perfusion

• Sensory perception, etc.

Exemplars (Clinical Focus Areas)

• Pituitary – excessive or lack of function

• Thyroid – hypo- and hyperthyroidism

• Parathyroid – calcium deregulation

• Adrenal dysfunction – hypo- and hyperadrenalism

• Pancreas – Type I & Type II diabetes