Endocrine Flashcards
Pituitary Gland
A. Anterior Pituitary Gland
B. Posterior Pituitary Gland
Uses chemical messages (hormones) that are
released into the blood
Endocrine System
Amino acid-based hormones
Proteins
Peptides
Amines
made from cholesterol
Steroids
made from highly active lipids
Prostaglandins
- Diffuse through the plasma membrane of target cells
- Enter the nucleus
- Bind to a specific protein within the nucleus
- Bind to specific sites on the cell’s DNA
- Activate genes that result in synthesis of new proteins
Steroid Hormone Action
Non-steroid Hormone Action
1. Hormone binds to a membrane receptor
2. Hormone does not enter the cell
3. Sets off a series of reactions that activates an enzyme
4. Catalyzes a reaction that produces a second messenger molecule
5. Oversees additional intracellular changes to promote a specific response
Non-steroid Hormone Action
Hormone levels in the blood are
maintained by
negative feedback
low hormone levels in the blood triggers the release of
more hormone
A stimulus
release stops once an appropriate level in the blood is
reached
Hormone
- Endocrine glands are activated by other
hormones
Hormonal Stimuli of Endocrine Glands
- Nerve impulses stimulate hormone release
- Most are under control of the sympathetic
nervous system
Neural Stimuli of Endocrine Glands
- Changing blood levels of certain ions
stimulate hormone release
Humoral Stimuli of Endocrine Glands
- Pea-sized
- Hangs by a stalk from the hypothalamus
- Surrounded by the sella turcica (“Turk’s saddle”) of the sphenoid bone
Pituitary Gland
– glandular tissue
Anterior pituitary
nervous tissue
Posterior pituitary
- General metabolic hormone
- Major effects are directed to growth of skeletal muscles and long bones
Growth Hormone (GH)
- Stimulates and maintains milk production following childbirth
- Function in males is unknown
Prolactin (PRL)
➢ Regulate hormonal activity of the gonads
Gonadotropic Hormones
Stimulates follicle development (ovaries)and sperm development (testes)
Follicle-stimulating hormone (FSH)
Triggers ovulation (females) and testosterone production (males)
Luteinizing hormone (LH)
- Regulates endocrine activity of the adrenal cortex
Adrenocorticotropic hormone (ACTH)
Influences growth and activity of the thyroid
Thyroid-stimulating hormone (TSH)
- Release of hormones is controlled by
releasing and inhibiting hormones produced
by the hypothalamus
Pituitary - Hypothalamus Relationship
produces two hormones that
are transported to neurosecretory cells of
the posterior pituitary
Hypothalamus
- Stimulates contractions of the uterus during
labor - Causes milk ejection
Oxytocin
- Can inhibit urine production
- In large amounts, causes vasoconstriction
leading to increased blood pressure
(vasopressin)
Antidiuretic hormone (ADH)
- Found at the base of the throat
- Consists of two lobes and a connecting isthmus
- Composed of hollow structures called follicles
Thyroid Gland
Produces two hormones
▪Thyroid hormone
▪Calcitonin
- Major metabolic hormone
- Composed of two active iodine-containing hormones
Thyroid Hormone
secreted by thyroid follicles
Thyroxine (T4)
conversion of T4 at target tissues
Triiodothyronine (T3)
- Decreases blood calcium levels by causing its deposition on bone
- Antagonistic to parathyroid hormone
Calcitonin
- Tiny masses on the posterior of the thyroid
Parathyroid Gland
- Stimulate osteoclasts to remove calcium from
bone - Stimulate the kidneys and intestine to absorb more calcium
- Hypercalcemic
Parathyroid Hormone (PTH)
outer glandular region in three layers
Cortex
Inner neural tissue region
Medulla
Adrenal Cortex
Contains three concentric zones
-> Zona Glomerulosa (superficial)
-> Zona Fasiculata (middle)
-> Zona Reticularis (innermost)
Regulate mineral content in blood, water, and
electrolyte balance
Stimulated by renin and aldosterone
Inhibited by atrial natriuretic peptide
Zona Glomerulosa
Help resist long-term stressors
Released in response to increased blood levels of
ACTH
Zona Fasiculata
Responsible for formation of secondary sexual
characteristics
Zona Reticularis
These hormones prepare the body to deal with short-term stress
* Epinephrine (Adrenaline)
* Norepinephrine (Noradrenaline)
Catecholamines
has both endocrine and exocrine functions
Mixed gland
α-cells
Hyperglycemic
Β-cells
Hypoglycemic
Delta cells
Inhibits pancreatic, and pituitary secretions
- Found on the third ventricle of the brain* AKA Epiphysis Cerebri
Pineal Gland
▪Helps establish the body’s wake and sleep cycles
Melatonin
Located posterior to the sternum
Largest in infants and children
Thymus
▪Matures some types of white blood cells
▪Important in developing the immune system
Thymosin
▪Produced by Graafian follicles or the placenta
▪Stimulates the development of secondary female characteristics
▪Helps prepare the uterus to receive a fertilized egg
Estrogens
▪Produced by the corpus luteum
▪Acts with estrogen to bring about the menstrual cycle
▪Helps in the implantation of an embryo in the uterus
Progesterone
Interstitial cells of testes are hormone-producing
Produce several androgens
Hormones of the Testes
▪Responsible for adult male secondary sex characteristics
▪Promotes growth and maturation of male reproductive system
▪Required for sperm cell production
Testosterone
preparing the breasts for lactation
Human placental lactogen (hPL)
causes pelvic ligaments and the pubic symphysis
to relax
Relaxin
is brought about by lack of efficiency of the ovaries
Menopause
production declines with age
Growth hormone
Diabetes Insipidus
– Hyposecretion of ADH
- Increased volume of urine
- Frequent urination
Hyposceretion of GH during childhood
Pituitary Dwarfism
Hypersecretion of GH during childhood
Pituitary Gigantism
- Hypersecretion of GH after long bone growth has ended
- Facial bones (ridges of eyebrows and lower jaw) are enlarged
- Hands also become enlarged
Acromegaly
Hyposecretion of FSH and LH for both males and females
Sterility
- Hyposecretion of Thyroxine in early childhood
- Short, stocky body type.
- Causes mental retardation of severe hypothyroidism
Cretinism
- Hypothyroidism in adulthood
- Adults-lethargy, weight gain, loss of hair
Myxedema
- Hyperthyroidism
- Causes exophthalmic goiter.
- Edema behind eyes causes bulging
Grave’s disease
- Enlargement of the thyroid gland
- Diet is deficient in iodine
Goiters
- ACTH accumulates causing stimulation of melanocytes (bronze skin color).
Addison’s Disease
- Hypersecretion of the adrenal cortex hormone, cortisol is primary problem.
- Results in Diabetes mellitus from increased blood glucose;
- Subcutaneous fat deposited in midsection;
- High blood pressure
Cushing’s Syndrome
