Endocrine ii

Question 1

Thyroid gland
summarise the hormones released, including target tissues, effects and how they are regulated

Answer 1

• *thyroid hormones (T3/T4)**
• target tissues- most body cells
• effects - increase basal metabolic rate and heat production, also maintains BP, regulates tissue grwoth, develops nervous system, reproductive capabilities

-regulation: hormonal stimuli (TSH from APG), negative feedback + follows circadian rhythm of TSH

Calcitonin

- target tissues- bones - osteoclasts

effects- reduce breakdown of bones, thus allowing retained / uptake of calcium in bones, reducing excess calcium in blood

regulation- humoral stimuli, excess Ca stimulates more Calcitonin/ reduced Ca inhibits Calcitonin. most important during childhood growth

Question 2

Gonads
summarise the gland, hormones released, including target tissues, effects and how they are regulated

Answer 2

Gland- ovaries and testes

Hormones released - Oestrogen, progesterone, testosterone

Oestrogen / Progesterone
target tissues-mainly reproductive organs (incl. breasts) but also a variety of other tissues

Effects-

• Oestrogen only- maturation of female reproductive organs and appearance of secondary sex charateristics
• oestrogen + progesterone together - breast dev (+ breast maturation in pregnancy), cyclical changes in endometrium of uterus
• during pregnancy - Oestrogen + Progesterone have various effects throughout body (water retention, relaxing smooth muscle)

Testosterone

• • target tissue- mainly reproductive organs, but also variety of other tissues
• effect- appearance of male secondary sex characteristcs and normal sperm production
• Regulation
  
  • Hormonal stimuli (GnRH released by Hypothalamus stimulates APG to release LH FSH )
  • Negative Feedback- increasing Testosterone inhibits GnRH + LH/ FSH

Question 3

Parathyroid Gland
summarise the gland, hormones released, including target tissues, effects and how they are regulated

Answer 3

• 4 bumps posterior to thyroid gland
• Hormone- Parathyroid Hormone
• Targets- Bones
• effects- increases blood calcium levels
  
  • stimulates osteoclasts to break down bone and release Ca into blood
  • increase reabsorption of Ca from filtrate back into blood
  • increase absorption of Ca from intestines, through activating Vit D to calcitriol
• Regulation
  
  • humoral stimuli- declining Ca in blood stimulates increased parathyroid hormone
  • negative feedback- when Ca blood levels return to normal, parathyroid hormone inhibit
    *

Question 4

Describe components of adrenal glands, and the hormones relelased

Answer 4

• Adrenal glands - 2 sitting above the kidney, divided into medulla (middle) and cortex
  
  • adenal medulla releases steroid hormones ( corticosteroids)
    
    • Aldosterone
    • Cortisol
    • Gonadocorticoids
  • adrenal cortex innervated by SNS
    
    • epinephrine + norepinephrine

Question 5

Adrenal Gland- adrenal cortex
summarise the gland, hormones released, including target tissues, effects and how they are regulated

Answer 5

Peripheral to adrenal medulla

Hormones- Steroid hormones - Corticosteroids

• Mineralcorticoids- -Aldosterone
  
  • target tissue- kidneys
  • Effects-
    
    • increase reabsorption of Na into blood / excrete K
    • Na causes more water reabsorption, increasing extracellular fluid
  • Regulation
    
    • humoral stimuli (K levels too high, blood volume + pressure too high)
    • Neg feedback- as K levels decrease, Aldosterone release decreases
    • • Glucocorticoids- Cortisol
  • target tissue- most body cells
  • effects
    
    • gluconeogenesis (create glucose from glycerol + AA)
    • mobilise fat for energy use
    • stimulate protein breakdown
    • depress inflammatory / immune response
  • regulation
    
    • hormonal stimuli - Adrenocorticotrophic hormone (ACTH)
    • negative feedback (increasing cortisol inhibits ACTH
• Gonadocorticoids- Androgens ( converted to testosterone / oestrogen)
  
  • target tissue- most tissue
  • effects- contribute to onset of puberty / after menopause

Question 6

Adrenal Gland- adrenal medulla
summarise the gland, hormones released, including target tissues, effects and how they are regulated

Answer 6

• middle section of adrenal gland / innervated by SNS
• Hormones-
  
  • enhance effects of SNS
  • Epinephrine - ​increase metabolic activity, dilates bronchioles (increase oxygen), increased blood flow to heart + skeletal muscles
  • Norepinephrine - increase BP through vasoconstriction of peripheral blood vessels
• Regulation
  
  • SNS stimulates Adrenal medulla
  • Neg feedback- when stress is removed, the medulla stops releasing adrenaline /noradrenaline

Question 7

Pancreas
summarise the gland, hormones released, including target tissues, effects and how they are regulated

Answer 7

• Pancreaas- combined endocrine + exocrine (pancreastic juices) gland
• Hormones
  
  • Insulin
    
    • targeted tissues- all body cells (esp liver, fat and skeletal muscles)
    • effect
      
      • increase take up of glucose from blood into cells (Esp fat + skeletal muscle)
      • increase glycogenesis (conversion of glucose into glycogen and stored in muscle cells + liver)
      • stimulate conversion of glucose into fat
      • inhibit gluconeogenesiss, and glycogenolysis)
    • regulation
      
      • humoral stimuli- increased blood glucose levels + increasing AA and lipid levels stimulates pancreas to release insulin
      • negative feedback
• • Glucagon
    * targeted tissues- liver
    * effect- increase BGL
    * stimulate glycogenolysis- convert glycogen to glucose
    * Stimuliate gluconeogenesis- create glucose from glycerol + lactic acid
    * stimulate release of glucose from liver into blood
    * regulation-
    * humoral (BGL) + Neural (SNS )stimuli
    * Negative feedback - Increasing BGL + Insulin inhibit

Question 8

Describe the stress response (short term and long term) including benefits and detrimental effects

Answer 8

Stress stimuli is physical, psychological, emotional

stress response involves Cortisol (Adrenal Cortex), SNS, HPA axis (Hypothalamus - Pituitary - Adrenal )

Short term

• Activates SNS, which activates Adrenal medulla
  
  • epinephrine + norepinephrine
  • cortisol released from adrenal cortex

Long term

• SNS activity may initially decrease and then increase
• HPA axis activated
  
  • Cortisol levels may remain high, if stress is prolonged (failure of neg feedback cycle)
• Negative effects
  
  • depressed immune / inflammatory response (Get sick)
  • depressed cartilage + bone formation (too much protein synthesis)
  • altered CDV , nervous + Gastrointestinal functions (increased BGL, raised BP, IBS)