endocrine system Flashcards
(37 cards)
What is homeostasis?
A state of overall internal chemical and physical stability that is required for the survival of cells and the body
What do homeostatic mechanisms do?
keep the body’s internal environment stable by detecting changes and activating effectors to restore conditions to a set point, usually through negative feedback.
What does deviation from homeostasis indicate?
Disease
What is a set point?
The physiological value around which the normal range fluctuates
What is a negative feedback loop?
A negative feedback loop is a control mechanism where a change in a variable triggers responses that counteract that change, bringing the variable back to its set point.
Example: when blood glucose rises, insulin lowers it back to normal
What are the elements of a feedback loop
Stimulus, receptor, integrator, effector, response
What is positive feedback?
Where the response increases the original stimulus
Pathway of steroids hormones
Lipid-soluble steroid hormones diffuse through the cell membrane → enter the cytoplasm and/or nucleus → bind to intracellular receptors → form a hormone–receptor complex (acts as a transcription factor) → complex binds to promoter regions of DNA → stimulates or inhibits transcription of target genes → alters protein synthesis → changes cell function
Diffuse → Receptor → Complex → DNA binding → Transcription change → Protein synthesis
What are the two types of hormones?
Lipid hormones
Non lipid hormones, peptides
Pathway of peptide hormones
binds to a receptor on the cell membrane
- activates a Secondary messenger
Paracrine
Hormone stimulates a nearby cell, travels through extra cellular material
Autocrine
The hormone secretion acts on the cell itself or cell type
Which hormones does the anterior pituitary secrete?
Growth hormone (GH)
Prolactin (PRL)
Thyroid-stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Follicle-stimulating hormone (FSH)
Luteinising hormone (LH)
Which hormones does the posterior pituitary produce?
ADH, oxytocin
What does the adrenal cortex secrete
Cortisol, aldosterone, sex hormones
What does the adrenal medulla secrete?
Adrenaline and noradrenaline
What do the ovaries and testes secrete?
the ovaries secrete estrogens, progesterone, inhibin, and androgens
estes primarily secrete testosterone and inhibin.
What does the pineal gland secrete?
melatonin,
What does the thyroid secrete?
thyroxine (T4) and triiodothyronine (T3), which regulate metabolism and energy use, as well as calcitonin
What does thyroid hormone do?
are vital for regulating metabolism
growth
development
cardiovascular function
temperature regulation,
lipid metabolism
reproductive health.
What does calcitonin do?
helps lower blood calcium levels by inhibiting osteoclast activity in the bones and promoting the excretion of calcium by the kidneys
What do the parathyroid glands secrete?
secrete parathyroid hormone (PTH)
What does parathyroid hormone do
- increases blood calcium by stimulating bone resorption
- enhancing renal calcium reabsorption,
- promoting intestinal absorption via vitamin D activation.
What are normal blood glucose levels?
between 70 and 99 mg/dL
