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05 > Endocrine Physiology & Alterations > Flashcards

Endocrine Physiology & Alterations Flashcards

1
Q

Functions of the Endocrine System

A
  • BGLs
  • sexual characteristics
  • reproduction
  • growth and development
  • stress response
  • overall maintenance of the body’s internal environment
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2
Q

What is a hormone?

A

Chemical messenger

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3
Q

Hormone regulation

A
  • regulated with negative feedback loops
  • they circulated through the bloodstream and only affect cells the posses the appropriate receptor
  • receptors are ether located on the cell membrane or in the intracellular compartment of the target cell
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4
Q

Protein based hormones

A

Examples include

  • vasopressin, insulin and growth hormone
  • water soluble
  • acts as first messengers - they bind to receptors causing intracellular signalling which activates a secondary messenger within the cell
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5
Q

Steriod based hormones

A

Examples include
- testosterone and cortisol

  • lipid soluble - can cross the cell membrane
  • act directly on the nucleus by binding to nuclear receptors
  • allow fro rapid response
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6
Q

Function of the Hypothalamus

A

exert control over production of hormones in most endocrine organs

releases hormones which bind on the target receptor on the other endocrine gland

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7
Q

Pituitary gland

A

anterior and posterior
- connected to the hypothalamus via the the hypothalamus-pituitary-axis

Posterior

  • doesn’t produce hormones it secretes them - stimulated by messengers in the nerve fibres
  • hormones are made in the hypothalamus, stored in the PPG in Herring Bodies

Anterior

  • produces and releases adrenocorticotropic hormone, and stimulates growth, reproduction (FSH, LH, PRL) hormone
  • connected by a capillary bed
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8
Q

Pineal gland

A

located in the centre of the brain

  • produces melatonin
  • melatonin regulates wake/sleep patterns and seasonal functions
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9
Q

Thyroid gland

A
  • one largest endocrine organs
  • found below the thyroid cartilage (Adam’s apple)
  • regulates the body’s metabolism, production of proteins and response to other hormones
  • Thyroid epithelia cells secrete T3 and T4
  • Parafollicular cells secrete calcitonin
  • Iodine is required for thyroxine and triidothyronine production
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10
Q

Parathyroid

A
  • located on the posterior of the thyroid gland
  • produce parathyroid hormone
  • regulate how much calcium is in the bones and blood
  • calcium homeostasis is important in muscle and nerve function
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11
Q

Thymus

A
  • needed for normal immune function
  • secretes hormones called humoral factors
  • these hormones support the development of the lymphoid system
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12
Q

Pancreas

A
  • contains both endocrine and exocrine

Hormone produced include:

  • alpha cells secrete insulin (increase BGL)
  • beta cells secrete insulin (decrease BGL)
  • delta cells secrete somatostatin (regulates alpha and beta cells)
  • gamma cells, secrete pancreatic polypeptide - regulates endo/exocrine secretion
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13
Q

Adrenal gland

A
  • located on the superior portion of the kidneys
  • several hormones: corticosteriods e.g. cortisol, catecholamines e.g. adrenalin and noradrenaline
  • Androgens
  • Aldosterone - regulates osmolarity of blood plasma
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14
Q

Testes and Ovaries

A
  • Testosterone produced in the testicles by Leydig cells
  • Testosterone is important in the development of secondary sex characteristics in men and sperm production
  • Oestrogen and Progesterone are produced by the ovaries
  • They promote the menstrual cycle and the development of secondary sexual characteristics in women
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15
Q

Hormonal Balance

A
  • may results from elevated or depressed hormones
  • may be due to a: faulty feedback loop, dysfunction of the gland, altered metabolism of hormone, non-endocrine production of hormone
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16
Q

Alterations in Pituitary function

A

Disorders include:

  • syndrome of inappropriate antidiuretic hormone
    • sodium is diluted leading to hyponatremia and hypoosmolarity
    • Results from a brain injury or from a cancer secreting ADH
  • Diabetes Inspidus (low ADH production)
    • either results from a neurogenic cause
      • insufficient ADH produced or a nephrogenic cause
      • lack of response by target cells in the kidney
17
Q

Acromegaly

A

Abnormal production of growth hormone after the skeleton and other organs finish growing

18
Q

Gigantism

A

Characterised by excessive growth and heigh significantly above average
- caused by excessive GH production in childhood

19
Q

Dwarfism

A

Mainly caused by two disorders

  • achondroplasia - autosomal dominant disorder
  • growth hormone deficiency
20
Q

Alterations in Thyroid Function

A
  • Dysfunction of the thyroid and pituitary (produces thyroid stimulating hormone) gland
  • Dysfunction of the hypothalamus (regulates the pituitary via thyrotropin-releasing hormone)
  • As we age, TSH also decreases
21
Q

Hypothyroidism

A

Major cause is iodine deficiency
- decreased production of thyroxine and triiodothyronine

Other causes include:

  • autoimmune disease
  • cold or respiratory infection
  • pregnancy
  • birth defects
  • surgical removal or radiation therapy

Symptoms include:

  • Constipation
  • Fatigue
  • Sensitivity of cold
  • Dry skin
  • Weight gain
  • Depression
  • Joint/muscle pain
22
Q

Grave’s Disease

A

Autoimmune disease
- overactive thyroid due to thyroid antibodies binding to the TSH-receptor and stimulating thyroid hormone synthesis, secretion and goiter formation

Patient may have:

  • psychiatric problems
  • rhythm irregularities
  • graves’ ophthalmopathy
  • overactive metabolism
23
Q

Thyroid Storm

A
  • life threathening
  • results from untreated thyrotoxicosis
  • may be caused by stress such as trauma or infection
  • patients may develop cardiac failure and pulmonary oedema

Symptoms includes:

  • agitation
  • change in LOC
  • confusion
  • diarrhea
  • fever
  • tachycardia
  • restlessness
  • shaking
  • sweating
24
Q

Alterations in Pancreatic Function

A

Diabetes Mellitus
- collection of disorders characterise by glucose intolerancem chronic hyperglycaemia (high BGLs) and alterations in protein, fat and carbohydrate metabolism

Type 1

  • Autoimmune (destruction of pancreatic beta cells)
  • as a result they produce insufficient amounts of insulin.
  • polyuria and polydispia are common

Gestational diabetes - glucose intolerance during pregnancy

Type 2

  • related to diet and life style
  • insulin is produced but either not in sufficient quantities or the insulin receptors on the cells surface become “blind” or resistant to insulin
25
Q

Alterations in the Adrenal Glands

A

Disorders of the adrenal cortex are mostly related to excessive production of hormones

  • Hypoaldosteronism may be caused by a primary adrenal cortex problem or a secondary production of aldosterone
  • symptoms include HTN (due to hypervolaemia), hypokalaemia leading to muscle weakness, and alkalosis
  • treatment includes surgery for a adrenal adenoma or an aldosterone antagonist such as spironolactone

Hypercortisolism is usually the result of Cushing Syndrome

  • common cause of Cushing’s syndrome is exogenous administration of glucocorticoids for asthma, immunosuppression
  • Pituitary Cushing’s, a benign pituitary adenoma secretes ACTH
  • Adrenal Cushing’s, excess cortisol is produced by adrenal gland tumours, hyperplastic adrenal glands, or adrenal glands with nodular adrenal hyperplasia
26
Q

Symptoms of Cushing’s Mnemonic

A

Symptoms include:

  • Central obesity, collagen fibre weakness
  • Urinary free cortisol and glucose increase
  • Stiae, supressed immunity
  • HTN, hyperglycaemia, hypercortisolism, hypernatremia, hypokalamia, hypercholesterolemia
  • Iatrogenic
  • Noniatrogenic
  • Glucose intolerance, growth retardation
27
Q

Treatment of Cushing’s Treatment

A
  • Stop glucorticoid administration
  • Remove tumour if present
  • Supportive therapy is required for some patients until their normal feedback loop for cortisol production is restored
28
Q

Alterations in Endocrine Function in Respons to Ageing

A

Endocrine organs undergo:

  • atrophy
  • vascular changes
  • decreased secretion and metabolism of hormones
  • decrease in receptor binding
  • decrease in intracellular signalling
29
Q

Define a feedback system and explain why endocrine feedback

mechanisms so are important for maintaining homeostasis.

A

feedback systems allow for the required levels of hormones to be maintained so as not to results in disease and imbalance

  • consist of negative and positive feedback loop
  • most are negative feedback loops
    TSH - if too much T3 and T4 in blood - feedback to hypothalamus to inhibit the production
30
Q

Describe the common hypothalamic-pituitary disorders and the

main hormones involved.

A
  • hyper/hypopituitarism
  • acromegaly - excessive growth hormone
  • prolactin secreting tumours
  • Diabetes inspidus due to ADH hypoactivity
  • syndrome of inappropriate ADH secretion
  • hypothalamic disease may cause deficiencies in any downstream hormone
    e. g. TSH, adrenocorticotrophic hormone, beta-endorphin, lutenizing hormone, FSH, MSH
31
Q

Describe two main thyroid and parathyroid disorders and discuss
the main hormones involved.

A

Graves disease - hyperthyroidism. Autoimmune disorder where thyroid stimulating immunoglobulins bind to the thyroid cells and stimulates the production of too much thyroid hormone

Hastimoto’s disease (autoimmune thyroiditis) - inflammation damages the gland leading to decreased thyroid hormone production
- has phase of both hyperthyroidism = excess thyroid hormone production in early disease onset and hypothyroidism = decreased thyroid hormone production

Hyperparathyroidism = excessive PTH and too much calcium in the blood, hypoparathyroidism in not enough PTH and low calcium in the blood

32
Q

ould a goiter occur in both grave’s disease and hashimoto’s

disease? Why/why not?

A

Yes, the excess thyroid hormone causes the T cells to mistaking attack the thyroid gland causing inflammation producing excess thyroxine

33
Q

Describe two main adrenal gland disorders including symptoms

and causes and discuss the main hormones involved.

A

Cushing’s syndrome - too much cortisol

  • symptoms include - rapid weight gain, moon face, baldness, buffalo hump, depression and anxiety
  • may be due to exogenous administration of glucocorticoids or endogenous pituitary adenoma, adrenal tumours, paraneoplastic cushing’s commonly from small cell lung cancer

Addison’s disease - too little cortisol

  • symptoms include - chronic fatigue, muscle weakness, weightloss, loss of appetite and low BP
  • adrenal insufficiency, secondary adrenal insufficiency caused by ACTH deficiency e.g. removal of the pituitary, TB which can destroy adrenal glands, cancer and chronic fungal infection
34
Q

Define diabetes mellitus, and explain how it differs from diabetes
insipidus?

A

diabetes mellitus is caused by a lack of insulin or insulin resistance whereas diabetes insipidus is caused by the lack of hormone vasopressin (ADH)

patients with both types will fell thirsty and urinate frequently

35
Q

Define metabolic syndrome

A

Conditions that increase risk of cardiovascular disease and type 2 diabetes

  • obesity
  • elevated triglycerides (greater than 1.69 mmol/L)
  • HTN (> 130/85)
  • glucose intolerance
  • decreased HDL cholesterol
36
Q

State three chronic complications of diabetes mellitus and describe the
pathophysiological cause.

A
  • Heart and blood vessel disease - excess glucose binds to the blind vessels wall causing thickening and hardening to occur
  • Nerve damage - excess glucose can damage the capillaries that nourish the nerves
  • Nephropathy - damage to the nephrons (blood vessels are damaged)
  • eye damage - blood vessels at the back or the eye balloon into pouches, this can ultimately lead to bleeding and loss of vision
  • osteoporosis - diabetes can decrease your bone mineral density and increase your risk of osteoporosis
37
Q

Outline the risk factors/causes, pathophysiology and clinical
manifestations of Syndrome of Inappropriate Anti-diuretic Hormone
Secretion.

A
  • Head injury, pituitary surgery, pulmonary disease and lung tumour

SIADH - increased ADH, causing inability to excrete dilute urine, retention of water, expansion of extracellular volume, dilutional or euvolemic hyponatremia

  • clinical manifestations; oligura, weight gain anorexia, N&V, muscle weakness, coma
38
Q

Risk factors/causes and
possible pathophysiology that may lead to the development of Type II
diabetes

A

genetic and environmental factors

  • increased appetite
  • decreased exercise
  • increased nutrient intake
  • increased metabolic efficiency
  • increased adiposity - obesity
  • low grade inflammation, reactive oxygen species, dyslipidaemia, adipokines, beta cell stress
  • insulin resistance - type 2 diabetes
  • Beta cell dysfunction - type 2 diabetes
    excess glucose production, impaired glucose uptake and utilisation

Beta cells (β cells) are a type of cell found in pancreatic islets that synthesize and secrete insulin and amylin

05 (20 decks)

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