Hormone Regulation Flashcards
What are endocrine glands?
Endocrine glands are ductless glands that secrete hormones into the blood.
What regulates the secretion of hormones?
Secretion of hormones occurs in response to:
- hormonal (activated by other hormones)
- humoral (by changing blood levels of ions/nutrients (PTH activated by changing Ca levels)
- neural (fight/flight where the sympathetic nervous system activates the release of norepinephrine epinephrine (adrenaline).
What are hormones?
Hormones are chemical substances secreted by endocrine cells, into the blood to regulate the activity of cells.
What are the classifications of hormones? What is the difference?
Amino acids (peptides, proteins, amines) or steroids.
Steroid hormones cross the cell membrane where they enter cell nucleus, exerting their action inside the cell. Non steroid hormones bind with receptors on the cell membrane. Resulting in the activation of enzymes which act as a second messenger type of communication inside the cell.
The hypothalamus is linked with the pituitary gland true or false?
True. The relationship between the pituitary and the hypothalamus is important because the release of each of the pituitary’s hormones is controlled by the hypothalamus.
What are the two parts of the pituitary gland?
Anterior and posterior.
Does the posterior pituitary gland produce the hormones it releases?
No, they are made in the hypothalamus. The posterior pituitary gland works as a “storage area” until they are released.
What are the two hormones released by the posterior pituitary gland? When are they released and why?
Oxytocin and ADH.
Oxytocin is responsible for childbirth and the “let down” reflex in breast feeding. This is a positive feedback mechanism.
ADH reduces and inhibits the production of urine to reduce urine output.
What 6 hormones are produced by the anterior pituitary gland?
All classified as ‘tropic’ hormones because they target other endocrine glands. Not including GH and PRL which act on non endocrine targets.
- Adrenocorticotrophic hormone (ACTH) - regulate the cortex of the adrenal glands.
- Thyroid-stimulating hormone (TSH) - regulates the thyroid.
- Luteinising hormone (LH) and 4. Follicle-stimulating hormone (FSH) - These two are gonadotrophins. They regulate the production of sperm and/or ova, testosterone, oestrogen, progesterone.
- Prolactin (PRL) - regulates the mammary glands to produce milk.
- Growth hormone (GH)
Where is the adrenals glands located? What are the two parts called?
Located over the kidneys.
Outer gland is the adrenal cortex. Inner gland is the adrenal medulla.
What hormones does the adrenal cortex secrete?
Adrenal cortex secrete a group of hormones collectively called adrenocortical hormones. These hormones include mineralocorticoids, glucocorticoids and androgens.
Where are epinephrine and norepinephrine secreted from?
The adrenal medulla. Adrenal medulla is an array of nerves extending from the autonomic nervous system / sympathetic nervous system.
What role does epinephrine and norepinephrine have on the body?
Epinephrine and norepinephrine are effective in the fight/flight response, they aid the body to cope with stressful situations by increasing
- heart rate
- blood pressure
- blood glucose level
- respirations.
They are usually the short term response to stress.
What do mineralocorticoids do?
Their target cells are in the kidney tubules, This group of hormones are important for the regulation of particular electrolytes (Na / K) in the blood..
Aldosterone is a mineralocorticoids.
What do androgens do?
Group of hormones that affect sexual drive, sexual characteristics Secreted in response to ACTH and produced throughout life.
What do glucocorticoids do?
- Maintain normal metabolism
- Regulate glucose levels therefore influence BGL
- Metabolise proteins for glucose
- Have a role in anti inflammatory & immune responses
- Ensure skeletal muscles receive adequate glucose during times of stress /during the fight/flight response therefore impacting on BP / vasoconstriction of vessels
- Cortisol is an example of this.
When is cortisol secreted?
Sometimes called the stress hormone, cortisol is secreted during times of starvation, injury, or trauma
In response to stress the hypothalamus secretes corticotrophin releasing hormone (CRH) which stimulates the pituitary glands to produce ACTH which causes cortisol release from the adrenal glands.
What can happens if cortisol levels do not return to normal after a stressful situation?
Health concerns can occur from too much or too little cortisol.
What can happen when there are excessive amounts of cortisol?
- Compromises the immune response and inflammatory pathways making the body susceptible to disease
- Prolonged healing times
- Reduction in the ability to deal with vaccinations
- Vulnerability to viruses
- Chronic stress impairs cognition, decreases thyroid functioning, causing an accumulation of abdominal fat
What is stress? What are the types of stress?
“Nonspecific response of the body to any demand or change”
- Occurs in response to a stressor / something that causes stress
- Can be physical as when lifting something heavy or running over a long distance
- Deprivation – nutrient deprivation during times of fasting or O2 deprivation during changes in atmospheric conditions
- Emotion as when watching a scary movie or reading a scary book or sitting an exam
What are the phases of stress?
Alarm phase, adaption phase and exhaustion phase.
What does the alarm phase of stress consist of?
When a threat is perceived; the sympathetic nervous system reacts and epinephrine (with smaller amounts of norepinephrine) are released from the adrenal medulla.
This is the fight/flight response (dilated pupils, increase in BP, HR, respirations etc.) This is an immediate response.
The endocrine system’s response is slower, the hypothalamus secretes CRH which stimulates ACTH production. ACTH goes to target the release of cortisol from the adrenal cortex which increases the BGL as it sends necessary glucose to the muscles to meet the need of the body in the perceived threat. This is a longer sustained response.
What does the adaption phase of stress consist of?
Adaption is more likened to the ability of people to ‘adapt’ to the stressor, to find the stressor is not as threatening as first thought
What does the exhaustion phase of stress consist of?
Exhaustion is more likened to the stressor being ongoing whereby cortisol secretion continues and levels remain raised in the body for a length of time.
