Endocrine system
How does a positive feedback loop differ from a negative feedback loop?
Positive loops amplify the original change; negative loops reverse it.
Describe the overall function of the endocrine system.
It regulates body functions through the secretion of hormones into the bloodstream.
A homeostatic cycle typically involves a stimulus, a receptor, a control center, and an.
effector
Provide a specific example of a positive feedback loop in the human body.
Childbirth labor contractions or blood clotting.
The specific brain region that plays a crucial role in maintaining various homeostatic functions, such as body temperature and hunger, is the.
hypothalamus
The first step in a water-soluble cell signalling pathway often involves:
Ligand binding to an extracellular receptor
A chemical messenger that binds to a receptor to initiate a cellular response is known as a.
signalling molecule
A breakdown in cellular communication can lead to:
Disrupted tissue development
Explain one key reason why cells communicate with each other.
To coordinate activities, respond to environmental changes, or regulate growth and development.
Explain how the body maintains blood glucose levels through homeostasis.
When blood glucose is high, insulin is released to lower it; when low, glucagon is released to raise it.
The main function of the peripheral nervous system (PNS) is to:
Link the central nervous system to the body
Which statement best describes a characteristic of a negative feedback loop?
It reduces change, returning to a set point.
Following activation of a water-soluble cell surface receptor, the signal is typically transmitted into the cell's interior via a series of intracellular events known as a signal.
transduction pathway
A receptor's primary role in cell communication is to:
Detect and bind specific ligands
The inability of cells to properly communicate can lead to which physiological issue?
disease or dysfunction
Which endocrine gland synthesizes and secretes melatonin, regulating sleep cycles?
Pineal gland
The main hormone secreted by the thyroid gland, crucial for metabolism.
Thyroxine
The most common type of regulatory mechanism that controls hormone secretion rates.
Negative feedback
A medical condition characterized by insufficient thyroid hormone production.
Hypothyroidism
The gland often referred to as the "master gland" of the endocrine system.
Pituitary gland
The hormone vital for stimulating uterine contractions during the process of childbirth.
Oxytocin
Which hormone is primarily responsible for increasing blood calcium levels?
Parathyroid hormone
Explain how the hypothalamus effectively controls the secretion of hormones from the anterior pituitary gland.
The hypothalamus produces and releases specific releasing hormones (e.g., TRH, CRH, GnRH) and inhibiting hormones (e.g., somatostatin, dopamine) that travel through the hypophyseal portal system to stimulate or inhibit hormone synthesis and release from the anterior pituitary.
What is the fundamental distinction between an endocrine gland and an exocrine gland in terms of secretion?
Endocrine glands secrete hormones directly into the bloodstream without ducts, whereas exocrine glands secrete substances (like enzymes, sweat, saliva) through ducts to an internal or external body surface.
Describe the primary physiological role of antidiuretic hormone (ADH) in the body.
ADH regulates water balance by promoting the reabsorption of water in the kidney tubules, thereby decreasing urine volume.
The specific name of the endocrine glands situated atop each of the kidneys.
Adrenal glands
The hormone primarily associated with the body's "fight or flight" response.
Epinephrine hormone
The hormone that acts to lower blood glucose concentrations after a meal.
Insulin
Briefly explain the main effect of the hormone glucagon on blood glucose levels.
Glucagon increases blood glucose levels by stimulating the liver to break down stored glycogen into glucose (glycogenolysis) and to synthesize new glucose from non-carbohydrate sources (gluconeogenesis), releasing it into the bloodstream.
Which organ performs both endocrine and exocrine functions within the human body?
Pancreas gland
The specialized cell clusters within the pancreas responsible for hormone production.
Islets of Langerhans
Identify two different steroid hormones that are produced and secreted by the adrenal cortex.
Cortisol and Aldosterone (or Androgens like DHEA).