Fundamentals & The Hypothalamo-Hypophysial axis Flashcards
Functions of the Endocrine System?
- Growth and development
- Sex differentiation
- Metabolism
- Adaptation to an ever-changing environment
Hormones function how?
They move through what to distant target sites of action?
WHat if they act more locally? 2
chemical messengers
blood/lymph
paracrine or autocrine messengers
- Endocrine intracellular communication happens how?
- Neuroendocrine intracellular communication happens how?
- Paracrine intracellular communication happens how?
- Autocrine intracellular communication happens how?
- Hormone is released from cell and travels through the blood to the target cell
- neuron relased hormone travels through the blood to the target cell
- Cell releases hromone, travels through interstitial fluid to target cell
- Hormone acts on the cell/tissue that released it
Factors Affecting Response of a Target Cell to a Hormone
3
- Blood level of the hormone
- Relative number of receptors
- Affinity of these receptors for hormones
How can the number of receptors be regulated?
2
Up-regulation
Down-regulation
Control of hormone levels can be affected in which type of way?
4
- Affected by fluctuations that vary with the sleep–wake cycle
- Secreted in a complicated cyclic manner
- Regulated by feedback mechanisms that monitor substances such as glucose (insulin) and water (ADH) in the body
- Regulated by feedback mechanisms that involve the hypothalamic-pituitary-target cell system
Examples of hormones that are Affected by fluctuations that vary with the sleep–wake cycle? 2
Example of a hormone that is Secreted in a complicated cyclic manner?
Growth hormone (GH) and adrenocorticotropic hormone (ACTH)
Female sex hormones
IF a hormones is water soluable what is needed for transport of the hormone to the target cell?
What about lipid/fat soluable hormones?
First messenger
Can diffuse through the lipid bilayer and into the nucleus of the cell for use in transcription
Beta blocker up or down regulate a cell?
down regulation (less binded, higher symtpathetic response, higher cardiac output)
What type of neurons act in the hypothalamus and what are their effects seen in?
4
- Autonomic neurons to preganglioinc to postganglioic to
Pancreatic islet releasing insulin - Autonomic neuron to preganglioic to adrenal gland to release adrenaline
- Magnocellular neurosecretory neuron to posterior lobe releases oxytocin and ADH
- Parvocellular neurosectretory neuron release releasing hormones to control a number of hormones in the anterior pituitary
What acts as the first messenger often in hormone effect on a target cell?
What about the second messenger?
What connects them? 2
Hormone itself
cAMP
transducer and effector (G-protein and adenyl cyclase)
What plays an important role in the affinity of insulin receptors?
pH of the body fluids
Where do fat soluable hormones usually bind in the cell?
Where do water soluable hormones usually bind in the cell?
receptor sites outside the cell and also inside the target cell (steroids)
usually only outside the cell (AA derivatives- epi and norepi)
- If capillary blood contains low concentration of Ca2 this will stimulate what?
- What type of stimuli is this an example of?
- Pregnanglionic SNS fiber stimulates adrenal medulla cells to secrete what?
- What kind of stimuli is this an example of?
- The hypothalamus secretes hormones that stimulate the anterior pituitary. What are three examples of organs that this works on?
- What kind of stimuli is this an example of?
- Parathyroid gland to secrete PTH
- Humoral
- catecholamines
(epi and norepi) - Neural
5. Thyroid gland Adrenal cortex Gonad (testes) 6. Hormonal
Diurnal variation in glucocorticoid secretion. Peak glucocorticoid levels are present sometime between?
8 and 9 AM (cardiac events happen when you first get up)
Lowest around midnight
What is the first 14 days of the ovarian cycle called and what are the four (3.5 phases) in it?
What are the last 14 days or so of the ovarian cycle and what are the 2.5 phases in it?
Follicular phase
- primary follicle
- Secondary follicle
- Vesicular follicle
- Ovulaiton
Luteal phase
- Ovulation
- Corpus luteum
- Degenerating corpus luteum