Hormones/Endocrine Flashcards
Endocrine system
Works with nervous to maintain homeostasis, relatively slow compared to nervous system
Composed of endocrine glands and their respective hormones
Hormones are secreted by endocrine glands in the surrounding interstitial fluid where they will diffuse directly into the blood (diffusion)
Functions through homeostatic feedback
Hormones
Chemical messenger molecules into our bloodstream
Hormones then travel via blood vessels to the target cells, with receptors for the hormone
2 kind of hormones: fat/steroid based (can diffuse through simple diffusion into the membrane, direct gene activation, made of cholesterol)
protein based/amino acid based (attaché to cell surface receptor outside, most common, function through a second messenger system except for thyroid hormone)
Effects:
Change plasma membrane permeability or membrane potential by opening or closing ion channels
Activate or inactivate enzymes
Stimulate or inhibit mitosis/meiosis
Promote or inhibit secretion
Turn on or off gene expression (transcription)
Tiny amount of a hormone can make huge changes (pico, 10^-12)
Maintain and are maintained by feedback systems (negative mostly)
Mechanism of hormone regulation
direct gene activation: steroid based goes to the nucleus
Steps:
Simple diffusion
Will meat a receptor inside nucleus of cytoplasm (target receptor)
Travel to gene sequence on chromosome, bind to specific site
Transcription and translate happens
new protein
2nd messenger system: protein based, attaches outside, much faster becomes no need for gene transcription/translation)
Steps:
Bind to the surface receptor
Receptor will set off a series of reactions to activate an enzyme
Enzyme will produce a second messenger molecule (ex cAMP)
Effects on cellular function (ex breakdown of glycogen)
Negative feedback
External conditions
Hypothalamus
Releasing hormones
Anterior pituitary gland
Tropic hormone (can negative feedback inhibiting the production)
Endocrine gland
Hormone (can negative feedback inhibiting the production)
Hormone releases stops when appropriate level reached
Activation of hormone gland
Hormonal stimulus:
Hormone from hypothalamus will trigger the anterior pituitary gland to secrete another hormone that will trigger other endocrine glands to secrete hormones
Humoral stimulus:
Looks at levels of ions and nutrients in blood (ex glucose, calcium) stimulates hormone release
Neural stimulus:
Nervous system detects and will send a nervous pathway to release a hormone
Pineal gland
Back of brain, along sagittal cut
Secretes melatonin
Believed to coordinate fertility hormones
Pituitary gland
Posterior lobe and anterior lobe (glandular tissue)
Behind bridge of nose, hangs of the hypothalamus
Posterior lobe:
nervous tissue
doesn’t make its own hormones
Connected to hypothalamus, which makes ADH (kidney to reabsorb water) and oxytocin (during childbirth and breastfeeding), and they will be stored in posterior lobe
Will be released when body needed through the capillary network
Anterior:
Regulated by hypothalamus
ADH
Less ruine volume increases blood pressure
More ADH less ruine less water in urine
Causes constriction of artérioles to increase blood pressure
GH
Made by anterior pituitary gland
target organs that don’t produce hormones on their own (non endocrine targets)
Bones and muscles
Target growth of skeletal muscle and long bones
Break down amino acids to be built into proteins and fat to be a source of energy
PRL
Made by anterior pituitary gland
Target organs that don’t make hormones on their own (non endocrine targets)
Mammary Glands
Stimulates milk production
FSH and LH
Anterior Pituitary gland
Tropic hormones: targets other endocrine tissues
Also known as gonadotropic hormones
Testes and ovaries
FSH: stimulates follicle development (women) and sperm (men)
LH: triggers ovulation and production of testosterone
TH/TSH
Anterior Pituitary gland
Tropic hormones: targets other endocrine tissues
Thyroid
Stimulates growth and activity of thyroid gland
Hypothalamus release TRH to tell pituitary gland to make more TSH, or inhibiting hormone
ACTH
Anterior Pituitary gland
Tropic hormones: targets other endocrine tissues
Adrenal cortex
Regulates endocrine activity of the adrenal cortex
Acromegaly
High GH in adulthood, causes bones to thicken
Pituitary dwarfism
Insufficient GH in childhood, causes dwarfism, can be treated with GH in childhood
Gigantisms
Too much GH, bones don’t stop growing, but rest of the body doesn’t follow up, causes problems with blood pressure (heart can’t pump too far)
Thyroid gland
On throat
Produces 2 hormones
Thyroid hormone: regulated by anterior pituitary gland
Nearly all cells are affected
Regulates metabolic rate of glucose to supply body heat and energy
Affects blood pressure, heart rate, muscle tone, and more
Needed for tissue growth and development
Composed of T4: secreted by thyroid follicles, inactive form
T3: conversion of T4 at target issue, active form
Calcitonin:
Decreases calcium lève,s by causing calcium deposition into bones
Antagonistic to parathyroid hormone
None or Very little in adults
Not controlled by pituitary gland, controlled by levels of calcium in the bones
Simple goiter
Deficient in iodine, needed to produce thyroid hormone, causes thyroid to swell
Treated by iodine supplement
Hypothyroidism
Under secretion of t3/t4
Weight gain, not enough energy, memory loss, cold, depression
Hyperthyroidism
Oversecretion of t3/t4
Increased metabolic, heart hart, sweating, nervousness, weight loss
Eyes bulge
Cretinism
Too little t3/t4 during fetal development
Dwarfism and delayed mental and sexual development
Parathyroid gland
On inferior side of the thyroid gland
4 small round masses at the back of the thyroid gland
Produce PTH (parathyroid hormone)
Antagonistic to calcitonin
Will take calcium from bones and puts it into blood, stimulates osteoclasts
Nervous system needs calcium, others uses than just bones
Triggered by blood levels of calcium
So these are a pair of hormones that work together to maintain homeostasis
Pancréas
Mixed glands, endocrine and exocrine functions
Pancreatic islet: produces insulin and glucagon (another antagonistic pair)
Beta cells make insulin
Alpha cells make glucagon
Diabètes mellitus (type 1 type 2)
Excessive urination (polyuria)
Excessive thirsty (polydipsia )
Excessive hunger (polyphagia)
Inability to produce or use insulin
Blood glucose rise
Kidneys not able to réabsorba the glossed so it spills into urine, and the water follows, causing dehydrations
Cells break down fats and proteins (body weight loss), causing blood acidosis/ketosis (acidic blood) from fat breakdown, leads to death
Type 1: born with it, pancreas doesn’t make insulin, destroyed beta cells
Type 2: target cells have be one less sensitive to insulin
