Endocrine System 2

Endocrine System 2

1. Adrenal/ Superadrenal gland

   • Cortex
     • Corticosteroid production: aldosterone, cortisol, sexhormone
     • Mesodermal
     • Zona glomerulosa
       • Secretes mineralcorticoids
         • Involved in regulation of electrocytes in ECF
         • Aldosterone most important
           • Albumin transports in blood
           • Angiotensin II principle stimuli
           • Increases Na+/H2O absorption
           • Increase H+/K+ secretion
           • increases blood volume and pressure
           • defficency of aldosterone
             • Loss of Na+ and H20 in urine - dehydration, plasma depletion and hypotension
             • Renal retention of K+ and elevated plasma [K+] - increased cardiac excitability through depolarising plasma membrane and can cause ventricular fibrilation and cause fatal cardiac arrhythmia
             • Renal retention of H+ --> metabolic acidosis
           • Too much aldosterone production
             • Conn's syndrome
               • Tumour constantly secreting
               • High BP
               • Hypertension
               • Decreased Renin
       • Round clusters of cells surrounded by capillaries
       • Spherical nuclei, distinct nucleolus
       • Acidophilic cytoplasm with few lipid droplets
       • Extensive SER, mitochondria with lamellar cristae
     • Zona fassiculata
       • Middle zone
       • Secrete glucocorticoids
         • Increasing blood glucose levels also additional effects in proteins and fats
         • Cortisol most important
           • Role in adaptation to stress, promotes rapid supply of glucose to tissues, permissive hormone, effects counter-regulatory hormones, required for expression of adrenegenic and angiotensin II receptors in CVS
         • Corticosteroid transports in blood
         • Muscle: net loss of AA, Liver: gluconeogenesis and glyconeogenesis, Fat cells: Free fatty acid mobilisation lipolysis, Suppresses immune system and inflammation
       • Straight cords of cells radially orientated
       • Many lipid droplets
       • Many capillaries
       • Mitochondria with tubular cristae
       • Glucocorticoids and some androgens
     • Zona reticularis
       • Innermost zone
       • Androgens - aprox. same effects as testosterone
         • Albumin transports in blood
       • Smaller cells; mitochondria with tubular cristae
       • Lipofucsin granules = common and large
       • Fewer lipid droplets
       • Acidophilic cytoplasm
       • Degenerating cells
       • Macrophages present
       • Produce androgens and some gluccocorticoids
     • Addison's disease
       • Lack of glucocorticoids
         • Hypoglycaemia
         • reduction in fat + protein metabolism
         • Loss of weight
         • Poor exercise tolerance
         • Poor stress tolerance --> death
       • Lack of minralcorticoids
         • lower Na+, K+, H+
         • Lower blood volume
         • Lower cardiac output --> death
       • Aldosterones
         • loss of libido in women
   • Medulla
     • Modified sympathetic ganglion
     • Ectodermal
     • Adrenaline
     • Noradrenaline
     • 80% of catecholamines released are adrenaline
     • Hormones secreted and stored in adrenal medula nd releaased in response to appropriate stimuli
     • Chromaffin cells secrete catecholamines
       • Adrenergic receptors, response depend in type and ratio of receptors in target cell
         • Noradrenaline more effective in alpha receptros, adrenaline much more effective in beta receptors
         • Adrenaline >> Noradrenaline in cardiac stimulation
         • Adrenaline < Noradrenaline in constriction of BVs
         • Adrenaline >> Noradrenaline in increasing metabolism
     • Pheochromocytome: catecholamine secreting tumour
       • Hypertension
       • Headache
       • Sweating
       • Palpitations
       • Chest pain
       • anxiety
       • glucose intolerance
       • Increased metabolic rate
   • Flattened on 1 side
   • Superior pole of kidney in peri-renal adipose tissue
   • Capsule of dense irregular CT, may have septa/trabeculae
   • Highly vascular
   • Endothelium fenestrated
   • Cushing's syndrome
     • moon face
     • Striae
     • Redistribution of fat from lower parts of body to the thoracic and upper abdominal areas
     • Glucocorticoid excess
     • Hyperglycaemia - adrenal diabetes
     • Protein shortage - muscle weakness suppression of immune system
     • Protein and CT breakdown, skin very thin
   • Cells in cords with reticular fibre network
   • Cells have large spherical nuclei and many cytoplasmic granules containing adrenaline or noradrenaline

2. Pancreas

   • Elongated organ located across the back of abdomen, behind stomach, between duodenum and spleen
   • Part of endocrine and digestive system, 98-99% exocrine
     • Acinar cells: Digestive enzymes and alkaline solutions
   • Islets of langerhans, 1-2% endocrine
     • endocrine controls blood glucose
       • Insulin increases
       • Glucagon, catecholamines, GH and gluccocorticoids
   • β-Cells ~ 60-80% cells
     • Insulin = glucose uptake in cells
       • Inhibits
         • Gluconeogenesis
         • Glycogenlysis
         • Lipolysis
         • Ketogenesis
         • Proteolysis
       • Facilitates
         • Glucose uptake in muscle and adipose tissue
         • Glycolysis
         • Glycogen synthesis
         • Protein synthesis
         • Uptake of ions especially potassium and phosphate
       • Metabolic actions
         • Carbohydrates
           • Glucose uptake,stimulate glycogenesis and inhibits glycolysis and gluconeogenesis
         • Fats
           • Facilitates glucose and fatty acid entry to adipose tissue, activates enzymes that produce fatty acids from glucose, inhibits lipolysis
         • Proteins
           • Facilitates transport of AAs into tissues, increases rate of AA to protein, inhibits protein degradation
   • α-cells ~20% cells
     • Glucagon, increase blood glucose via gluconeogenesis during fasting
   • δ-cells
     • Somatostatin
   • F-cells
     • Pancriatic polypeptide -decrease pancreatic exocrine secretion and bile secretion
   • [Glucose] lowering reactions
     • Uptake by cells
     • Glucose breakdown for energy
     • Stored as glycogen
     • Conversion to non-carb
   • [Glucose] raising reactions
     • Use of fatty acid for energy
     • Release glucose from glycogen
     • Formation of glucose from non-carb sources (gluconeogenesis) + lactate
     • Transport glucose to blood from liver
   • ε-Cells
     • Ghrelin