L8-L9 Flashcards
What is Endocrinology?
This is the study of Hormones
What are hormones and their responsibility?
Hormones are chemical messengers within the body that are responsible for long term, on going functions of the body
What are the 5 example functions of hormones?
- Metabolism
- Reproduction
- Regulation of Internal environment
- Development
- Growth
What kind of effects can hormones produce? (Hint: enzyme)
Hormones can speed up chemical reactions (act as enzymes). You can have short or long term effects with hormones that will impact tissues in the long term.
What do hormones have to be in order to not cause issues within the body?
Specific
( for example, a target tissue yields—> rate of enzyme reaction, transportation of ions across membrane, and gene expressions/proteins synthesis.
What are the classic steps to identifying endocrine glands and hormones they produce?
- Remove suspected gland
- Replace hormone
- Create hormone excess
What are ectohormones? Give an example.
Ectohormones are hormones that we put into the environment. An example is pheromones.
Five steps that make a chemical a hormone
- hormone is a chemical signal that is secreted by a cell or cell groups.
- hormones are secreted into the bloodstream either by cell—>ECF or cell—>environment (exocytosis vs endocytosis)
- hormones are transported at a distance through the bloodstream
- hormones are transported short distances through growth factors
- Hormones exert their effect at [low]
How do hormones bind to receptors?
- depends on binding to target cell receptor
- initiates biochemical responses
How are hormones terminated?
- by limiting hormone secretion (smaller amounts= smaller effect)
- removing or inactivating the hormone (half life determines length of activity)
- terminating the hormone activity in target cell
Explain ‘Active Hormones’
These are able to be released when a signal is given. Hormones are stored in a vesicle unit signal is transmitted. From here, hormone is released.
Explain ‘preprohormones’
These are large inactive precursors that need to be processed to be hormones
Explain ‘prohormones’
These ARE hormones but not ready to be used. They must be specialized in order to be functional.
Explain how peptide hormones undergo signal transduction
- peptide hormones must combine with membrane receptors that initiate signal transduction process
- these bind to surface of membrane receptors
- cellular response occurs through signal transduction system
What are steroids? Explain their lipid-solubility.
Steroids are derived from cholesterol and are another type of hormone which are lipophilic—only a select tissue is capable of making them. Lipophilic means dissolved or combines with lipids.
What happens if steroids are lipophobic?
They bind to a carrier protein that can carry them through the water.
Characteristics of steroids
- steroids are derived from cholesterol
- made only in a few organs: adrenal cortex of adrenal gland and gonads
- steroids were made when needed, never stored due to lipophilic nature
Binds to carrier proteins in blood and have longer half lives
Explain the relationship between steroids and genetics
- steroids increase or decrease expressions of genes
- majority of steroids have a response to a genome
- cytoplasm or nucleus receptors stimulate genomic effects
- cell membrane receptors stimulate non-genomics responses
Hormones are derived— wha derives from tryptophan? Tyrosine?
Tryptophan= melatonin from pineal gland Tyrosine= a single tyrosine gives rise to catechloamines. A double tyrosine gives rise to thyroid hormones that behave like steroids
For peptide hormones, list:
- Synthesis and storage location
- How its released from parent cell
- Its transportation in blood
- Half life
- Location of receptor
- Receptor response
- General target response
- Made in advance, stored in secondary vesicles
- Released via Exocytosis
- Dissolved in plasma within blood
- Short half life
- Location of receptor is within cell membrane
- Activation of a second messenger signal
- Modifying old proteins and synthesizing new ones
For steroid hormones, list:
- Synthesis and storage location
- How its released from parent cell
- Its transportation in blood
- Half life
- Location of receptor
- Receptor response
- General target response
- Synthesis on demand
- Simple diffusion
- Bound to carrier protein
- Long
- Cytoplasm or nucleus
- Activation of genes, nongenomic/genomic
- Introduction of new protein synthesis
For catechloamines, list:
- Synthesis and storage location
- How its released from parent cell
- Its transportation in blood
- Half life
- Location of receptor
- Receptor response
- General target response
- Made in advance, stored in second vesicle
- Exocytosis
- Dissolved in plasma
- Short
- cell membrane
- Activation for second messenger system
- Modification of existing hormones
For thyroid hormones, list:
- Synthesis and storage location
- How its released from parent cell
- Its transportation in blood
- Half life
- Location of receptor
- Receptor response
- General target response
- Made in advance, stored in second vesicle
- Transport protein
- Protein carrier bonded
- Long
- nucleus
- Activation for genes to transcribe/translate
- Introduction of new protein synthesis
Explain hormones and their reflexes.
- Reflex pathways have similar components
- endocrine cell is the sensor in simple endocrine reflexes (insulin or PTH)
- many endocrine reflexes involve nervous system, neurohormones are secreted to blood
What does the posterior pituitary gland do?
Releases two neurohormones:
- oxytocin (releases breast milk production in females) and vasopressin (controls kidneys and water levels within)
- stores hormones produced in hypothalamus
- when stimulated releases oxytocin and vasopressin
Explain some characteristics and functions of the anterior pituitary gland
- since it has epithelial origin it is a true endocrine gland
- secretes six hormones: PRL, ACTH, FSH, LH, TSH, GH
- trophic hormones stimulate the release of other hormones (PRL is only non-trophic hormone out of the six)
- FSH stimulates female follicles
- these are regulated by hypothalamic hormones
Explain what a portal system is
This connects hypothalamus to anterior pituitary gland. It also consists of two sets of capillaries connected in series of veins. One trophic hormone releases after the other.
Explain the pathway of the portal system
Hypothalamic neurons produce trophic hormones—> released in 1st capillary bed to anterior pituitary—> anterior pituitary produces trophic hormones—> released to second bed of capillary bed—> target tissue
Explain prolactin (PRL)
One of the six anterior pituitary hormones, controls milk production in females and has hypothalamic release inhibiting hormone.
Explain growth hormone (GH)
One of the six anterior pituitary hormones, sometimes called somatrophin . This affects metabolism and stimulates hormone production in liver. Build up and break down of proteins mainly in liver.
Explain Gonadotrophins:
Follicle stimulating hormone (FSH) Leutinzing Hormone (LH)
Two of the six anterior pituitary hormones, both control hormones in the gonads. These are sex hormones too (steroids)
Explain Thyroid Stimulating Hormone (TSH)
One of the six anterior pituitary hormones, this controls hormone synthesis and secretion in thyroid (amines)
Explain Adrenocorticotrophic hormone (ACTH)
One of the six anterior pituitary hormones, controls hormone synthesis and secretion in adrenal cortex (cortisol)
Explain long negative loop feedback systems
These are the most common type, there is an ultimate hormone at the end— this is a suppression of a positive feedback. Peripheral endocrine glands produce hormones that suppress the secretion of anterior pituitary gland.
Explain short negative loop feedback systems
Tropic hormones have an effect on the loop, suppress hypothalamus which causes less produced= decrease in stimulation. Pituitary hormone suppresses hypothalamic trophic hormone production
Explain ultra negative loop feedback system
Occurs in hypothalamus or pituitary gland, has an effect on itself. Autocrine or paracrine signals to regulate secretion.
Name and explain the three types of hormone interactions
Synergism= overall effect is greater than the sum of its parts
Permissiveness= one hormone may lead to another to exert its full effect
Antagonism= once substance opposes others— competitive inhibition= when once molecule binds to receptor but doesn’t activate it. Functional antagonists= two hormones that have opposing physiological actions
What is hypersecretion? What will happen if there is too much of this? What is it often caused by?
Hypersecretion is an exaggeration of a hormones effects. If they’re is too much secretion it can cause an inhibition. This is often caused by tumours and negative feedback loops leading to atrophy gland.
What is hyposecretion?
A diminishing or elimination of a hormones effect.
Explain what down regulation is
This occurs when hormones bind to receptors but there isn’t enough [hormone]. Thus, causes diminishing response.
What is a hyperinsulinemia an example of?
This is when a targeted cell attempts to diminish its responsiveness to excess hormones
explain the three types of diagnoses for endocrine pathology
Primary pathology- due to last endocrine gland in pathway
Secondary pathology- due to pituitary gland
Tertiary pathology- due to hypothalamus
Explain primary hypersecretion and its hormone levels
This is due to a problem with the adrenal cortex.
Hormone levels; CRH=low ACTH= low cortisol= High
Explain secondary hypersecretion and this hormone levels
Due to pituitary problems
Hormones: CRH=low ACTH=High cortisol=High
Explain tertiary hypersecretion and its hormone levels
This is due to a problem with the hypothalamus (its very rare)
Hormone levels: CRH=High ACTH=High Cortisol=High
What is the pineal gland and what does secrete?
It’s a smaller heaped pea structure within the brain.
- secretes melatonin
What is melatonin?
This is the darkness hormone, this eventually fluctuates. This hormone helps with circadian rhythm. Environmental cues can also be sued to adjust SCN.
