Endocrine system 5 Flashcards
What are the hormones involved in glucose homeostasis?
- GLUCAGON
- Adrenaline
- Growth hormone
- Cortisol
What is the role of adrenaline?
Provision of energy for emergencies & exercise
(Severe hypoglycaemia)
What is the role of cortisol?
Mobilisation of fuels during adaption to stress
What is the role of growth hormone?
Promotion of growth (normally smaller role in metabolism)
(Prolonged hypoglycaemia)
What is stress?
A state of threatened homeostasis or dysharmony;
the body responds by a complex repertoire of physiological and behavioural mechanisms to re-establish homeostasis
What is a stressor?
(stimulus that induces state of stress)
- Psychological / emotional – anxiety, fear
- Physiological - pain, fever, hypoglycaemia, fluid deprivation, injury, heavy exercise, etc.
What happens to the body during the integrated stress response?
Includes inc arousal, alertness & vigilance
Where is energy redirected during the integrated stress response?
- ↑ CV tone, ventilation
- ↑ glucose availability
- ↓ energy-consuming activities
(digestion, reproduction)
What in involved in the stress response system?
- RAAs, AVP (ADH), GH (thyroid hormones dec)
Integrated response:
- SNS & adrenaline
- CRH-ACTH-cortisol
What is CRH-ACTH-cortisol (cortisol) role in the stress response system?
Permissive action of cortisol:
- ↑ cardiac output and ventilation
- Diversion of blood flow to muscles and heart
- Mobilisation of glycogen and fat stores
“fight or flight”
What are the actions of cortisol?
- Metabolic effects
- Anti-inflammatory / immuno responsive effects (at high physiological levels)
- Role in adaption to stress
(Permissive role in action of other endocrine hormones, action on other tissues)
What are the metabolic actions of cortisol?
Build up glycogen stores
(readily-accesible source of glucose)
- Inc glycogen synthesis
- Adipose & amino acids act on liver more = more glucose
How does cortisol raise blood glucose?
- Can free up amino acids (from protein) & Adipose tissue (these are intermediates), they increase blood glucose
- Cortisol can raise blood glucose but can store it as glycogen - just in case stress situation lasts longer than expected, rather than the longer process of breaking down proteins or fats, breaking down glycogen is a much faster process
- Amino acids that are broken down can also be used to repair any damage done to tissues due to fight or flight
What can prolonged elevated cortisol lead to?
- Muscle wasting (breaks down stores in muscle & fat)
- Hyperglycaemia
- GI ulcers (increased susceptibility)
- Impaired immune response (feel run down)
What casues chronic stress?
Prolonged elevated cortisol levels
Name 2 adrenal disorders?
- Cushing’s sydrome
- Addison’s disease
What causes Cushing’s syndrome?
- Excess glucocorticoid –> effects target cell
- High-dose, long-term use of glucocorticoids
Lots of cortisol (secreted from the adrenal cortex) cortisol can activate -ive feedback loop to keep cortisol levels the same
What is a pramy defect cuasing Cushing’s syndrome?
Autonomously - secreted adrenal tumour
Primary defect = excess cortisol being released
What is a secondary defect causing Cushing’s syndrome?
Excessive production of ACTH
- Pituitary tumour
- Eptopic tumour (ACTH producing tumour, acts on the adrenal cortex, inc production of cortisol)
What are the symptoms of Cushing’s sydrome?
- Depression
- Dorsal fat pad “buffalo hump”
- Thin skin = easy bruising
- Muscle weakness = osteoperosis
- Poor wound healing
- “Moon face”
- Truncal obesity
- Purple striae (stretch marks)
- Skinny arms & legs
- Hypertension diabetes
What is the cause of Addison’s diease?
Lack of adrenal steroids
What are the signs & symptoms of Addison’s disease?
Mainly related to deficiency of mineralocorticoid
- Hyponatraemia (low blood Na+)
- Hyperkalaemia (high plasma K+)
- Muscle weakness
- Postural hypotension
What is the primary adrenal insufficiency in Addison’s diease?
Often autimmune
Loss of all 3 adrenal steroids
What is the treatment of Addison’s disease?
Treatment is to replace the hormones (hormone replacement)
What are the main thyroid hromones in the thyrooid glands?
- Thyroxine (T4)
- Tri-iodothyronine Calcitonin (T3) (less important)
The T3 and T4 are based on the amt of iron molecules attached
What does thyroud stimulating hormone (thyritropin) do?
- Maintains integrity of thyroid gland
- Regulates Th production/release
What regulates the secretion of throid hormones?
Endocrine axis
What does TRH stand for?
Thyrotropin-releasing hormone
WHat does TSH stand for?
Thyroid-stimulating hormone
(thyrotropin)
What are the main acitons of thyroid hormones?
- Inc metabolism in the body
- Stimulate growth & development
How do thyroid hormones inc metabolism in the body?
- Increase basal metabolic rate (BMR)
- Increase metabolism of CHOs, proteins, fats
Generalised inc in functional activity of almost all tissues
Why do thyroid hormones stimulate growth & development?
Particularly important for normal development and maturation of CNS
Can you please insert the signs & symptoms of hypo- and hyperthyroidism table
Thanks x
What is hypothyroidism?
Reduction in metabolic activity
Every newborn is tested for TSH & T4
What is cretinism?
(Neonate) - hypothyroidism in a newborn
Dwarfism & mental retardation
Treatment = hormone replacement - synthetic thryroxine
What si the most common cause of hypothyroidism?
Hashimoto’s thryroiditis - accoutns for abt 90% of hypothyroidism
What is Hashimoto’s thryroiditis?
Autoimmune disease:
- Arise from an overactive immune response against substances / tissues normally present in the body
- Autoantibodies to components of the thyroid cells involved in thyroid hormone synthesis
What is the most commone cause globally of Hashimoto’s thryroiditis?
Lack of dietary iodine
What is hyperthyroidism?
- Increased tissue metabolism due to excessive
thyroid hormone action - Also, enhancement of β-adrenoceptor responses
What is the most commone cause of hyperthyroidism?
Grave’s disease
What is the cause of Grave’s disease?
Autoimmune:
Thyroid-Stimulating Immunoglobulins (TSI) activate the thyroid gland to produce and release thyroid hormones
What are the classic symptoms of Graves diease?
Classic symptoms: nervousness, palpitations, weight loss, tremor, sweating, heat intolerance & goitre. Also, exophthalmos
What is Goitre?
Enlarged thyroid gland
Describe what Goitre is?
- A non-specific term for any enlargement of the thyroid gland
- Occur when there is over-stimulation by either TSH or TSI (Graves’ Disease)
What is an obvious symptom of Grave’s disease?
The protrusion of the eyeball
Deposition of abnormal amts of lipoproteins
What are the 3 ways to manage thyroid diseases?
- Anti-thyroid drugs
- Radioactive iodine (131I)
- Thyroidectomy
What do anti-thyroid drugs do?
Decrease production of thyroid hormones, by inhibiting iodination and coupling processes (via TPO).
What does Radioactive iodine (131I) do?
Destroy thyroid follicular cells (active iodide uptake process)
What does a Thyroidectomy do?
Surgical removal of part of thyroid gland
