Week 5 Flashcards
What is the endocrine system?
A collection of glands and organs that release hormones into the circulatory system to regulate physiological functions such as:
- Digestion
- Metabolism
- Sleep–wake cycles
- Development
- Growth
The endocrine system plays a critical role in maintaining various bodily functions.
How do endocrine glands produce hormones?
In response to different stimuli:
- Hormone signals
- Environmental signals
- Nervous system signals
These stimuli trigger the production and release of hormones into the bloodstream.
What are the three major components of the endocrine system?
They are:
- Glands
- Hormones
- Receptors
Each component plays a crucial role in hormone regulation and function.
What is the function of the hypothalamus?
Controls homeostasis and regulates the release of hormones.
The hypothalamus exerts direct influence over the autonomic nervous system.
Why is the pituitary gland called the master gland?
Because it secretes many important hormones and regulates the activity of other hormone-secreting glands.
The pituitary gland plays a significant role in various biological processes.
What hormones are secreted by the posterior pituitary?
Secretes:
- Oxytocin
- Antidiuretic hormone (ADH)
These hormones are produced in the hypothalamus and released from the posterior pituitary.
What hormones does the anterior pituitary synthesize and secrete?
Synthesizes and secretes:
- Growth hormone
- Prolactin
- Follicle stimulating hormone (FSH)
- Luteinising hormone (LH)
- Thyroid stimulating hormone
- Adrenocorticotropic hormone
Each hormone has specific roles in regulating growth, reproduction, and metabolism.
What is the role of the thyroid gland?
Key role in:
- Growth
- Development
- Energy metabolism
The thyroid secretes hormones that affect virtually every tissue in the body.
What hormones are secreted by the thyroid gland?
Secretes:
- Thyroxine (T4)
- Triiodothyronine (T3)
T4 is converted into its active form, T3, in the body.
What is the function of the parathyroid glands?
Secrete parathyroid hormone, which regulates calcium, magnesium, and phosphate levels in the blood.
This regulation is crucial for maintaining bone health and metabolic functions.
What hormones are produced by the adrenal glands?
Produce:
- Cortisol
- Aldosterone
- Adrenaline
- Noradrenaline
These hormones are involved in stress response, metabolism, and electrolyte balance.
What is the role of the pancreas in the endocrine system?
Secretes:
- Insulin
- Glucagon
These hormones regulate blood glucose levels.
What are gonads and their function?
The ovaries in females and testis in males that secrete sex hormones such as:
- Oestrogen
- Testosterone
These hormones control the growth and function of reproductive organs.
How does the endocrine system differ from the nervous system?
Endocrine system:
- Acts via hormones released into the blood
- Slow response time (seconds to days)
- Long-lasting effects
Nervous system:
- Acts via electrochemical impulses
- Rapid response time (milliseconds)
- Short duration responses
These differences highlight the distinct roles each system plays in body regulation.
What defines a target cell in the endocrine system?
A cell that has a specific receptor for a particular hormone.
Only target cells respond to their specific hormones, leading to characteristic physiological changes.
What are the three major types of stimuli that control hormone release?
They are:
- Humoral stimuli
- Neural stimuli
- Hormonal stimuli
Each type of stimulus triggers hormone synthesis and release in different ways.
What is humoral stimuli?
Stimulated by factors in the blood, such as ion and nutrient concentrations.
For example, low calcium levels stimulate parathyroid hormone release.
What is neural stimuli?
Hormone secretion regulated by the central nervous system.
The hypothalamus plays a key role in controlling pituitary hormones through neural stimuli.
What is hormonal stimuli?
Release of hormones in response to hormones produced by other endocrine organs.
This creates a cascade effect where one hormone stimulates the release of another.
What role do transport proteins play in the endocrine system?
Transport proteins carry lipid-soluble hormones in the bloodstream and help regulate their circulation.
They protect hormones from degradation and ensure even distribution within the body.
What is the biological half-life of a hormone?
The time it takes for half of a hormone’s concentration to be degraded or removed from the bloodstream.
Hormones with shorter half-lives require more frequent secretion to maintain activity.
What factors influence hormone activity?
Factors include:
- Concentration of the hormone
- Biological half-life
- Receptor numbers and affinity
- Influence from other hormones
These factors determine how effectively a hormone can exert its effects on target cells.
What is the permissive effect of hormones?
When one hormone enhances the responsiveness of a target organ to another hormone.
For example, estrogen increases the uterus’s responsiveness to progesterone.
What are antagonistic hormones?
Hormones that act to return body conditions to acceptable limits from opposite extremes.
An example is insulin and glucagon in regulating blood glucose levels.
