INTRODUCTION TO ENDOCRINOLOGY FOR THE PRIMARY CARE PA Flashcards
Main funciton of the endocrine system?
maintains homeostasis
Definition of hormones?
2
- Any substance normally produced by specialized cells in some part of the body, carried by the blood stream to another part, where it effects the body as a whole
- Vehicles for intracellular and extracellular communication
Functions of Hormones?
6
- Maintain homeostasis
- Regulate growth and development
- Promote sexual maturation, sexual rhythms and facilitate reproduction
- Regulate energy production
- Adapt/adjust body to stressful/emergency situations
- Promote/inhibit production or release or other hormones
Characteristics of Hormones
5
1. Specificity Only target cells respond 2. Multiple actions 3. Variable half-life --Often depends on solubility properties 4. Variable forms --Depends on weight 5. Excretion rates
What are the two funtional types of hormones?
Tropic
Non-tropic or Direct effector
WHat is the difference between Tropic (2) and
Non-tropic or Direct effectors (3)?
- Originate from anterior pituitary gland
- Specific for another endocrine gland
- Secreted by non-pituitary endocrine glands
- Act directly on peripheral tissue
- Exert a feedback effect on the hypothalamus or anterior pituitary gland
Chemical Types of Hormones
3
Peptides/proteins
Amines
Steriods
Examples of Peptides/proteins?
They are soluable in what?
They interact with target cells to trigger what?
What kind of effects?
Polypeptides or glycoproteins
Soluble in plasma
Interact with target cell membrane receptors to trigger a second messenger to complete the specific action of the hormone.
Short term effects
Amines are what kind of derivitives?
poorly soluble in?
WHat do they interact with?
What kind of effects? 2
Amino acid derivatives
Poorly soluble in plasma
Interact with membrane receptors of target cells
Provide long and short term effects
Steriods are composed of what?
What does this allow them to do?
Prodced by what? 4
Insoluble in?
Effects?
Composed of lipids (cholesterol)
Can transverse through the cell membrane
Produced by
- ovaries
- testis
- placenta, and
- adrenal cortex
Insoluble in water
Long-lasting
Where are hormone receptors located? 2
What does the binding of hormones to target cells result in?
Located on cell membrane or within cell cytoplasm
Binding of hormone to receptor initiates a signal
Results in changes in gene expression
Ultimately causes a biological response
Regulation and Control of Hormones
is accomplished how?
Occurs by controlling the rate of synthesis rather than the rate of degradation
Primary hormome control is controlled by what?
Hypothalamus
Small gland next to pituitary gland
Connected to the pituitary by the “pituitary stalk”
What does the pituitary gland release? 2
Releases both tropic and effector hormones
How is signaling in the nervous system different from endocrine?
The nervous system exerts point-to-point control through nerves, similar to sending messages by conventional landline telephone. Nervous control is electrical in nature and immediate.
The endocrine system broadcasts its hormonal messages to essentially all cells by secretion into blood and extracellular fluid. Like a radio broadcast, it requires a receiver to get the message - in the case of endocrine messages, cells must bear a receptor for the hormone being broadcast in order to respond.
- nervous- point ot point
- needs a receptor to receive
Are the two main systems (endocrine and nervous system) that coordinate and regulate function mutually exclusive?
NOO
So, one more time….what does the endocrine system do?
4
What systems does it work with?
2
growth and development
metabolism
reproduction
homeostasis
Involves numerous organs and tissues located throughout the body
Works in conjunction with the nervous system (and to a lesser extent with the immune system)
What are EXOCRINE GLANDS?
Examples? 4
Produce secretions which are released to the outside;
- sweat
- salivary
- mammary
- digestive gland systems
are examples.
What are ENDOCRINE GLANDS?
Hormones are secreted directly into the blood and are carried throughout the body where they influence the appropriate receptor sites for that hormone.
What are MIXED GLANDS?
Example?
(Exocrine and Endocrine) Some glands have non-endocrine regions that have functions other than hormone secretion.
For example, the pancreas has a major exocrine portion that secretes digestive enzymes and an endocrine portion that secretes hormones.
Organs of the endocrine system
9
HYPOTHALAMUS PINEAL GLAND PITUITARY GLAND THYROID GLAND THYMUS PARATHYROID GLANDS ADRENAL GLANDS GONADS PANCREAS
What is the Primary link between endocrine and nervous systems?
Hypothalamus
The hypothalamus regulates activities of nervous and endocrine systems in three ways?
- Acts as an endocrine organ…releases hormones ADH (antidiuretic hormone) and OXYTOCIN
- Secretes REGULATORY HORMONES (releasing hormones or inhibiting hormones)
- Control endocrine cells in the adrenal medulla
Pituitary is also known as what?
Where is it found?
Consists of how many lobes and what are their funtions?
Also know as HYPOPHYSIS
Small oval gland seated in the sella turcica of the sphenoid bone
Consists of two lobes (anterior and posterior)
Anterior – ADENOHYPOPHYSIS (made up of glandular cells)
Posterior – NEUROHYPOPHYSIS (cells are non-secretory, resemble neuroglial tissue)
Adenohypophysis is which lobe?
It can be divided into what parts? 2
WHat does it contain?
How many hormones does it secrete (the majority are produced by which part?)
(Anterior lobe of the Pituitary)
Can be divided into an anterior pars distalis and a posterior pars intermedia
Contains endocrine cells surrounded by an extensive capillary network (HYPOPHYSEAL PORTAL SYSTEM )
Secretes seven important hormones, and six are produced by the pars distalis
Hormones of adenohypophysis
7
- Thyroid-stimulating hormone (TSH)
- Adrenocorticotropic hormone (ACTH)
- Follicle-stimulating hormone (FSH)
- Luteinizing hormone (LH)
- Prolactin (PRL)
- Somatotrophin (Growth hormone)
- Melanocyte-stimulating hormone (MSH) - pars intermedia
Neurohypophysis (Posterior lobe of the pituitary gland):
Contains what?
What does it produce? 2
Contains the axons of hypothalamic neurons
Nuclei of hypothalamus produce ADH (antidiuretic hormone) and OXYTOCIN
Where is the pineal gland?
What does it contain (3) and what is its function?
Lies in the roof of the thalamus (third ventricle), under the posterior end of the corpus callosum
It contains
- neurons,
- glial cells and
- secretory cells
that synthesize the hormone MELATONIN
Thyroid gland is located where?
How many lobes does it have?
How would you describe its vascularture?
What does it produce? 3
Lies anterior to the trachea and just below the thyroid cartilage, which forms most of the anterior surface of the larynx
Has two lobes (bow tie or butterfly shape) united by the isthmus
Has an extensive blood supply
Produces the hormones
- triiodothyronine (T3),
- thyroxine(T4), and
- calcitonin
Parathyroid glands are located where?
What are the two kinds of cells in parathyroid glands?
There are two pairs of parathyroids embedded in the posterior surface of the thyroid gland
There are two different types of cells within the parathyroid glands (chief cells and oxyphil cells)
What do the chief cells produce?
What is the funtion of this hormone? 4
What does the oxyphil cell produce?
The CHIEF CELLS produces parathyroid hormone (PARATHORMONE ) PTH
Parathormone
- stimulates osteoclasts
- inhibits osteoblasts
- increases intestinal absorption, and
- reduces urinary excretion of calcium ions
The function of oxyphil cells is not known
Appear at onset of puberty.
Where is the thymus located?
How many lobes does it have and what are the parts of each lobe 2?
Embedded in the mediastinum, usually posterior to the sternum
Organized in two lobes separated by a septae. Each lobe consists of a dense outer CORTEX and a central MEDULLA
What does the cortex of the thymus consist of?
What does it produce and what is the funtion of that hormone?
The CORTEX consists of epithelial cells that
secrete the thymic hormones (thymosins= T Cells) which play a key role in development and maintenance of inmunological defenses
Funtion of the medulla of the thymus?
What does it consist of?
The MEDULLA has the thymic corpuscles (Hassall´s corpuscles) surrounded by lymphocytes
Function: unknown
What is another name for the adrenal glands?
Where are they located?
What are the different parts of the adrenal glands?
What does it produce?
Also know as SUPRARENAL glands
Lie along the superior borders of the kidneys
Can be subdivided on histological grounds into an outer cortex and an inner medulla
ADRENAL CORTEX
Produces steroid hormones called adrenocortical steroids, or CORTICOSTEROIDS
Contains three distinct zones
Has a yellowish color due to the presence of stored lipids
What are the zones of the adrenal cortex and what are the functions of each?
3
ZONA GLOMERULOSA – outermost and relatively narrow layer. Secretes MINERALOCORTICOIDS (aldosterone)
ZONA FASCICULATA – extends toward the capsule in a series of radiating cell columns. Produces GLUCOCORTICOIDS (cortisol, corticosterone and cortisone)
ZONA RETICULARIS – surrounds the adrenal medulla. Produces ANDROGENS
What is the funtion of the adrenal medulla?
Contains two populations of secretory cells, one produce EPINEPHRINE ( 75-80% ) and the other NOREPINEPHRINE ( 20-25%
Pancreas contains what kind of cells? 2
What cells are in the islets of langerhans?
What do alpha cells secrete and why?
What do beta cells secrete and why?
Contains exocrine and endocrine cells
Endocrine cells are found within the pancreatic islets (ISLETS OF LANGERHANS)
Alpha cells secrete glucagon
Released when glucose levels too low
Beta cells produce insulin
Released when glucose levels too high
What are the testes made of and what do they produce?
Between the tubules are what?
These secrete what?
Each testicle is made up seminiferous tubules which produce spermatozoa.
Between the tubules are the INTERSTITIAL CELLS that secrete steroid hormones know as ANDROGENS, notably TESTOSTERONE
Follicle cells in the ovaries produce what?
After ovulation the cells reorganize into what structure that produces what hormone?
If a pregnancy occurs the placenta will gradually develop what?
Follicle cells in the ovaries produce steroid ESTROGENS while eggs are developing.
After ovulation the cells reorganize into a corpus luteum that produces PROGESTERONE.
If a pregnancy occurs, the placenta will gradually develop endocrine functions of its own
What nonendocrine organs produce hormones?
7
brain heart lungs kidneys liver skin placenta
also produce and release hormones
Diseases and Disorders of the Endocrine System
are characterized by what?
4
Characterized by:
- Hypo or hyper hormone release
- Inappropriate response to signaling
- Absence of a gland
- Structural enlargement
Diseases and Disorders of the Endocrine System are classified as?
3
- Primary (inhibits the action of downstream glands)
- Secondary (Indicative of a problem with the pituitary gland)
- Tertiary (Dysfunction of the hypothalamus)
What are the two adrenal insufficiency disorders?
2
- Addison’s disease (primary adrenal insufficiency)
2. Mineralocorticoid deficiency
What are the adrenal hormone excess disorders?
5
- Conn’s syndrome (aldosterone producing adenoma)
- Cushing’s syndrome (high levels of cortisol in the blood by a tumor or systemic steroids)
- GRA/Glucocorticoid remediable aldosteronism (cause of primary hyperaldosteronism)
- Congenital adrenal hyperplasia
- Adrenocortical carcinoma
What are the three pancreas disorders?
Diabetes mellitus
Hypoglycemia
Glucagonoma
What are the three types of Diabetes mellitus?
Type 1
Type 2
Gestational Diabetes
What are two examples of hypoglycemia?
2
- Idiopathic hypoglycemia
2. Insulinoma (tumor of the beta cells in the pancreas)
What is glucagonoma?
(tumor of the islet cell in the pancreas)
Types of thyroid disorders?
5
Goiter (Iodine deficiency) Hyperthyroidism Hypothyroidism Thyroiditis Thyroid cancer
Examples of Hyperthyroidism? 2
Examples of thyroiditis? 1
- Graves disease
- Toxic multinodular goiter
- Hashimoto’s thyroiditis
Parathyroid disorders?
4
- Parathyroid gland disorders
- Osteoporosis
- Osteitis deformans (Paget’s disease of bone)
- Rickets and osteomalacia
Examples of Parathyroid gland disorders?
4
- Primary hyperparathyroidism
- Secondary hyperparathyroidism
- Tertiary hyperparathyroidism
- Hypoparathyroidism
- –Psuedohypoparathyroidism
Posterior pituitary disorders? 1
Anterior pituitary disorders?
2
Diabetes insipidus
Hypopituitarism
Pituitary tumors
Disorders of sex development? 3
Hypogonadism (Gonadotropin deficiency)?
3
- Hermaphroditism
- Gonadal dysgenesis
- Androgen insensitivity syndromes
Hypogonadism (Gonadotropin deficiency)
- Inherited (genetic and chromosomal disorders)
- Kallmann syndrome
- Klinefelter syndrome
- Turner syndrome - Disorders of Puberty
- Delayed puberty
- Precocious puberty - Menstrual function or fertility disorders
- Amenorrhea
- Polycystic ovary syndrome
