Hormone Overview and Types

Hormone Overview

• Hormones are signaling molecules in multicellular organisms
• They regulate physiology and behavior via complex biological processes
• Hormone secretion responds to specific biochemical signals
• Hormone secretion is often regulated by negative feedback

Hormone Secretion

• Hormones are secreted by different types of glands
  • Endocrine glands secrete hormones directly into the bloodstream
  • Exocrine glands secrete hormones indirectly via ducts
  • Paracrine glands secrete hormones to nearby target tissues

Hormone Types

• Hormones can be classified by their structure and origin
  • Protein/peptide hormones: Made up of amino acids. Examples include insulin and oxytocin
  • Amino Acid Derivatives: Derived from amino acids. Examples include thyroxine and melatonin
  • Steroid hormones: Derived from cholesterol. Examples include estradiol, testosterone, and cortisol
  • Eicosanoids: Derived from lipids, such as arachidonic acid. Examples include prostaglandins and thromboxane
  • Gasses: Examples include nitric oxide

Insulin

• Insulin is a polypeptide hormone
• It has an A-chain (21 amino acids), a B-chain (30 amino acids), and a C-chain
• Secreted from beta cells in the pancreas
• Its release is triggered by glucose levels in the blood

Insulin Production

• Human insulin is produced using rDNA technology
• This involves modifying the amino acid sequence to produce insulins with varying pharmacokinetic properties

Insulin Administration

• Administration routes include:
  • Subcutaneous (SC)
  • Intravenous (IV)
  • Inhalation
  • Continuous subcutaneous infusion (insulin pump)

Insulin Preparations

• Rapid-acting insulins (e.g., lispro, aspart, glulisine) are designed for rapid absorption and shorter duration of action
  • They mimic the mealtime release of insulin
  • This control postprandial glucose -Regular insulin is often used when IV route is needed
  • Regular insulin should be injected 30 minutes before meal
• Intermediate-acting insulin: Neutral protamine Hagedorn (NPH)
  • Formed by adding zinc and protamine to regular insulin
  • Results in delayed absorption and longer duration of action
  • Used for basal (fasting) control
  • Usually given along with rapid- or short-acting insulin for mealtime control,
• Long-acting insulins (e.g., glargine, detemir):
  • Glargine's isoelectric point causes a precipitate at injection site, releasing insulin over an extended period.
  • Detemir has a fatty acid side chain, promoting albumin association, leading to a slow dissociation and extended action

Insulin Combinations

• Premixed combinations (e.g., 70% NPH + 30% regular) are available
• These reduce daily injections

Insulin Pharmacokinetics

• A table provides pharmacokinetic details (onset, peak, duration, maximum duration, and appearance) for various insulin types.

Standard vs. Intensive Treatment

• Standard insulin therapy uses twice-daily injections
• Intensive treatment involves more frequent injections and monitoring
• Intensive treatment aims for lower mean blood glucose (154 mg/dL or less)

Adverse Effects

• Hypoglycemia is the most common adverse effect
• Other adverse effects include weight gain, local injection site reactions, and lipodystrophy
• Diabetics with renal insufficiency may require decreased insulin dose.
• Inhaled insulin should not be used by patients with asthma, COPD and smokers due to bronchospasm risk.

This quiz covers the essential aspects of hormones, including their secretion, types, and regulation. Explore how hormones function as signaling molecules in multicellular organisms, their classification by structure and origin, and the roles of various glands in hormone secretion.