Homeostasis, The Endocrine System Flashcards
What is homeostasis?
The maintenance of a stable internal environment.
Conditions regulated include body temperature, water content, CO₂ levels, blood sugar, and blood pressure.
What are the key elements of a homeostatic control system?
Receptor: Detects changes in the environment.
Control Centre: Processes the information and decides on a response.
Effector: Executes the response to restore balance.
What are negative feedback systems?
Primary mechanism for homeostasis.
Restores a normal range, not a fixed value.
Examples: Temperature regulation, pH balance, blood sugar control.
What are positive feedback systems?
Less common in homeostasis.
Amplifies changes to complete critical processes.
Examples: Blood clotting (haemostasis), labour, and delivery.
What are the two types of homeostatic regulation?
Autoregulation (Intrinsic): Cells and tissues adjust locally to changes.
Extrinsic Regulation: Involves the nervous and endocrine systems.
How do the nervous and endocrine systems regulate homeostasis?
Nervous System: Fast response, short duration (crisis management).
Endocrine System: Slower response, longer-lasting effects.
What happens when homeostasis fails?
Severe disruptions (e.g., infection, injury, genetic abnormalities) lead to illness or disease.
Why are new-borns vulnerable to homeostatic disruption?
Immature systems:
Immune system.
Renal function.
Endocrine system.
Thermoregulation.
How does aging affect homeostasis?
Degeneration exceeds regeneration.
Hormonal responsiveness decreases.
Reduced efficiency of the heart and circulatory system.
Loss of neurons and neurotransmitter production.
Why is understanding homeostasis important in physiotherapy?
Enables physiotherapists to assess, diagnose, and treat imbalances effectively.
Helps restore normal function and address patient needs.
What is the endocrine system?
A system of glands that secrete hormones into the bloodstream.
Hormones act as chemical messengers, regulating functions like growth, metabolism, and reproduction.
What are the functions of the endocrine system?
Regulate sodium and water balance (blood volume).
Control calcium and phosphate balance.
Manage energy balance and nutrient storage/utilization.
Respond to stress.
Support reproduction, growth, and development.
What are the two categories of hormones?
Non-Steroidal Hormones: Bind to membrane receptors and use second messengers (e.g., insulin, adrenaline).
Steroidal Hormones: Lipid-soluble, derived from cholesterol, and enter cells directly (e.g., testosterone, oestrogen).
What are the five pathways through which hormones exert effects?
Paracrine Pathway: Hormones act on nearby cells.
Autocrine Pathway: Hormones act on the same cell that produces them.
Endocrine Pathway: Hormones travel through the bloodstream to distant cells.
Synaptic Pathway: Hormones act across a synapse on adjacent neurons.
Neuroendocrine Pathway: Hormones released by neurons enter the bloodstream and act on distant cells.
What is the role of the hypothalamus and pituitary gland in the endocrine system?
Hypothalamus: Produces releasing/inhibiting hormones (e.g., TRH, CRH, GHRH).
Pituitary Gland: Acts on signals from the hypothalamus to secrete tropic hormones.
What are the differences between negative and positive feedback loops in hormone regulation?
Negative Feedback: Maintains stability by reducing changes (e.g., insulin and blood sugar regulation).
Positive Feedback: Amplifies changes until a process is complete (e.g., oxytocin during childbirth).
What are common causes of altered hormone function?
Hypothalamus or pituitary impairment.
Overproduction or underproduction of hormones.
Receptor binding issues.
Impaired feedback mechanisms.
Ectopic hormone production.
Inadequate hormone metabolism.
What are common endocrine system disorders?
Hyperthyroidism (Graves’ disease).
Hypothyroidism (e.g., myxoedema).
Cushing’s syndrome.
Diabetes mellitus and insipidus.
Acromegaly/Gigantism.
Pheochromocytoma.
What is the function of the thyroid gland?
Stimulates metabolism, regulates energy production, and supports growth.
Produces T3 (triiodothyronine) and T4 (thyroxine).
What are the symptoms of hyperthyroidism?
Excessive thyroid hormone secretion leads to:
Increased metabolic rate.
Weight loss.
Heat intolerance.
Nervousness.
Palpitations.
What is Graves’ disease?
An autoimmune disorder causing excessive thyroid stimulation.
Symptoms include thyroid gland enlargement and increased metabolic rate.
What is hypothyroidism, and what are its types?
Congenital Hypothyroidism: Occurs during fetal development due to lack of thyroid hormone.
Acquired Hypothyroidism: Caused by autoimmune disorders, iodine deficiency, or thyroid removal.
