Endocrine

• What are glands primarily composed of?

  Groups of epithelial cells
• How do exocrine glands distribute their secretions?

  Through a duct or onto specific tissue
• How do endocrine glands distribute their secretions?

  Directly into the blood
• What type of secretions do endocrine glands produce?

  Hormones
• What are the main differences between endocrine and exocrine glands?

  • Endocrine:
  • Secrete into interstitial fluid
  • Ductless, highly vascular
  • Exocrine:
  • Secrete into ducts
  • Into specific cavities
• What is the role of the endocrine system?

  Controls cell growth and metabolism

  
• How are hormones released in the endocrine system?

  Due to stimuli or blood levels

  
• What feedback mechanism do hormones usually use?

  Negative feedback loop

  
• What are the two types of hormones based on their structure?

  1. Lipid-based:

  • Steroids (e.g., glucocorticoids)
  • Thyroid hormones

  1. Peptide-based:

  • Adrenaline
  • Insulin
• How do steroid hormones act within cells?

  Bind to DNA and regulate gene expression

  
• What is the role of nonsteroid hormones?

  Act as first messengers triggering second messengers

  
• What does the hypothalamus control?

  Release of hormones from the pituitary

  
• What hormones are controlled by the hypothalamus and pituitary?

  • Growth Hormone (GH)
  • Thyroid Stimulating Hormone (TSH)
  • Adrenocorticotrophic Hormone (ACTH)
  • Prolactin (PRL)
  • Follicle Stimulating Hormone (FSH)
  • Luteinising Hormone (LH)
  • Oxytocin
  • Antidiuretic Hormone (ADH)
• What is the function of Growth Hormone (GH)?

  Regulates metabolism and promotes tissue growth
• What does Thyroid Stimulating Hormone (TSH) do?

  Stimulates secretion of T3 and T4

  
• What is the role of Adrenocorticotrophic Hormone (ACTH)?

  Stimulates adrenal cortex to secrete glucocorticoids
• What does Prolactin (PRL) stimulate?

  Growth of breast tissue
• What is the function of Follicle Stimulating Hormone (FSH)?

  Stimulates sperm production and ovarian secretion
• What does Luteinising Hormone (LH) stimulate?

  Secretion of testosterone and progesterone
• What is the role of Oxytocin?

  Stimulates smooth muscle contraction in uterus
• What does Antidiuretic Hormone (ADH) do?

  Increases permeability in kidney tubules
• Where is the thyroid gland located?

  In the neck, near cervical vertebrae
• What is crucial for the formation of thyroid hormones?

  Iodine from the blood
• What do thyroid hormones T3 and T4 regulate?

  Gene expression and metabolic rate

  
• What are the effects of hypothyroidism?

  Low metabolic rate and weight gain
• What are common causes of hypothyroidism?

  Autoimmune thyroiditis and iodine deficiency
• What is hyperthyroidism characterized by?

  Excessive levels of T3 and T4
• What are the main causes of hyperthyroidism?

  Graves Disease and toxic nodular goitre
• What are the effects of hyperthyroidism?

  1. Increased metabolic rate
  2. Weight loss with good appetite
  3. Anxiety and restlessness
  4. Hair loss
  5. Tachycardia and palpitations
  6. Warm sweaty skin
  7. Diarrhoea
• What are the effects of hypothyroidism?

  1. Decreased metabolic rate
  2. Weight gain and anorexia
  3. Depression and lethargy
  4. Dry skin and brittle hair
  5. Bradycardia
  6. Dry cold skin
  7. Constipation
• What does the adrenal gland secrete?

  Hormones from cortex and medulla

  
• What is the role of the adrenal cortex?

  Produces corticosteroids from cholesterol

  
• What does the adrenal medulla release?

  Adrenaline and noradrenaline
• What is the function of adrenaline?

  Augments the sympathetic response
• What is the function of the Islets of Langerhans?

  Produce insulin and glucagon
• What do alpha cells in the pancreas secrete?

  Glucagon
• What do beta cells in the pancreas secrete?

  Insulin
• What is the role of somatostatin?

  Inhibits insulin release
• What is insulin stored as in pancreatic islets?

  Proinsulin
• When is insulin released?

  After rising levels of intracellular Ca2+