Endocrine System Flashcards
Hormones regulate
Growth (TH and GH)
Stress management (NE and cortisol)
Blood sugar levels (insulin and glucagon)
Reproduction cycles (testosterone)
Hypothalamus
Production of ADH, oxytocin, and regulatory hormones
Pineal gland
Melatonin
Parathyroid glands
Parathyroid hormone (PTH)
Thyroid gland
Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin (CT)
Adrenal glands
Adrenal medulla
Epinephrine (E)
Norepinephrine (NE)
Adrenal cortex
Cortisol, corticosterone, aldosterone, androgens
Pancreas
Insulin
Glucagon
Because hormones are released into the bloodstream…
The effect of hormones are typically slow to appear
But effects last a longtime.
Amino acid derivatives
Tryptophan and tyrosine
Tryptophan
An amino acid that is used to make a hormone called melatonin
Tyrosine
An amino acid that makes thyroid hormones
Classes of hormones include
Amino acid derivatives
Lipid derivatives
Small peptides
Many hormones never actually enter the cell…
They bind to receptors which then trigger responses inside the cell
Steroid based hormones
Tend to diffuse across the plasma membrane before binding to receptors in the nucleus
What sits in the sella turcica of the sphenoid bone
The pituitary gland
Hormones released by the….
Posterior pituitary
- oxytocin
- antidiuretic hormone (ADH)
Anterior pituitary Growth hormone (GH) Thyroid stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL)
Supraoptic and paraventricular nucleus secretes…
Supraoptic: secretes ADH
Paraventricular: secretes oxytocin
When ADH is released by posterior pituitary
- diuretics= increases urine production
- ADH= decreases urine production and helps avoid dehydration
- hypothalamic neurons in the SON are osmoreceptors= they monitor the solute (osmotic) concentration of blood
- when the blood is too concentrated (high osmolarity) ADH is released
Osmoreceptors…
Baroreceptors…
Detect increased osmotic pressure
Detect decreased blood pressure
Because ADH is a vasoconstrictor…
ADH is also called vasopressin
Examples of things that inhibit the release of ADH
Caffeine
Alcohol
Diabetes insipidus
Most common form occurs when a blow to the head reduces ADH by posterior pituitary
- patient is constantly thirsty
- patient exhibits polyuria (pees a lot)
Functions of oxytocin
1) stimulates smooth muscle construction in the uterus during childbirth. A spike in oxytocin levels promotes delivery
2) oxytocin is part of the milk let-down reflex in nursing mothers
Portal system
A capillary bed feeds into veins which feed into another capillary bed
The thyroid gland contains 2 lobes connected by an
Isthmus
What synthesizes T3 and T4 and what stores T3 and T4
1) cuboidal epithelium of the follicle
2) colloid of the follicle
What affects nearly every cell of the body
T3 and T4
Thyroid hormones increase the metabolic rate of nearly every cell in the body by…
1) binding to receptors in the mitochondria thus increasing rates of ATP production
2) binding to receptors in the nucleus thus increasing the production of enzymes of glycolysis, Krebs and ETC
Thyroid hormones also
1) increase the force of heart contraction which results in increased blood pressure
2) in growing children, thyroid hormone is also essential in the development of skeletal, muscular and nervous systems
Hypothyroidism symptoms (adults)
Aka myxedema
- dry skin
- feeling chilled
- constipation
- mental sluggishness
- lethargy
- weight gain
Hypothyroidism can result from..
1) Low iodine levels
2) low thyroid gland function
3) low blood levels of TSH or TRH
Some cases it may result in a goiter
Hypothyroidism (in infants)
Aka cretinism Symptoms: Thick tongue and neck Short stature Mental retardation
Causes:
1) genetic deficiency
2) lack of iodine during pregnancy
Hyperthyroidism
Aka Graves’ disease
Symptoms:
1) weight loss
2) expothalmos (bulging eyes)
3) anxiety
4) heat intolerance
Thyroid gland also contains C cells aka
Parafollicular cells
What hormone do c cells produce
Calcitonin which is released in response to high blood calcium levels
Calcitonin lowers blood calcium levels in three ways
1) promote the entry of calcium into bone
2) increasing the rate of calcium excretion by the kidneys
3) decreasing the absorption rate of calcium by intestines
Parathyroid glands
Release PTH in response to low blood calcium levels
PTH raises blood calcium levels by
1) stimulating calcium release from bone
2) increasing calcium reabsorption by kidneys (it stops calcium loss in urine)
3) increases calcium absorption by the intestines
4) stimulates the release of calcitriol by kidneys
Calcitriol main function is
To enhance calcium absorption by intestines
The thyroid gland and the 4 parathyroid glands are very…
Vascular
The parathyroid glands respond to circulating blood and release PTH when….
Blood calcium levels are too low
