Endocrine Organs Flashcards
Serve as effectors to regulate activities of various cells, tissues, and organs in the body
Hormones
Cell Signaling:
Act on adjacent cells or diffuse to nearby target cells that express specific receptors for that particular hormone
hormones released into connective tissue spaces
Paracrine Control
Cell Signaling:
Cells that express receptors for hormones they secrete
Autocrine Control
Two major integration and control system of the body
1) endocrine system
2) nervous system
Communicate through transmission of neural impulses along nerve cell processes and the discharge of neurotransmitter
Nervous System
Communicate through hormones
Endocrine System
Nervous vs. Endocrine
- resspond rapidly and precisely to stimuli
- rsponses are consciously generated
Nervous System
Nervous vs. Endocrine
- responds more slowly and more diffusely
- long lasting effect of responses
- responses are unconsciously generated
Endocrine System
Master organ of the endocrine system - Plays a central role in number of regulatory feedback mechanism
Pituitary gland
Pitutary gland characteristics:
1) size
2) shape
3) location
4) weight
1) small pea sized
2) ovoid
3) centrally at base of brain; sits on the sella turcica of the sphenoid bone
4) Male - 0.5g; Female - 1.5g
Connected to the hypothalamus by a short stalk aka infundibulum
The pituitary gland consists of 2 functional compartments namely:
1) Anterior lobe/ Adenohypophysis (glandular epithelial tissue)
2) Posterior lobe/ Neurohypophysis (neural secretory tissue)
Pituitary Gland
Pituitary compartment that is more cellular and produces hormone
adenohypophysis
the neurohypophysis does not produce hormone but instead stores hormone produced by the hypothalamus
Pituitary Gland
3 Subparts of the adenohypophysis:
1) Pars distalis
2) Pars tuberalis - pars infundibularis
3) Pars intermedia
What are tropic hormones?
Hormones that regulate the hormone secretion of other cells in different endocrine glands throughout the body
Pituitary Gland
Enumerate the hormones of the anterior lobe of the pituitary gland
Tropic Hormones
- adrenocorticotropic hormone (ACTH)
- Thyroid stimulating (thyrotropic) hormone (TSH or thyrotropin)
- follicle stimulating hormone (FSH)
- lutenizing hormone (LH)
Hormones that act directly on the target organ - not endocrine organ
- growth hormone (GH) or somatotropin
- Prolactin (PRL)
Pituitary Gland
Enumerate the 5 functional cells or the anterior lobe - pars distalis
1) somatotrophs (GH cells)
2) Lactotropes/ Mammotropes (PRL cells)
3) corticotropes (ACTH cells)
4) gonadotropes (FSH and LH cells)
5) Thyrotropes (TSH cells)
Types of secretory epithelial cells based on staining
(1) Chromophils
(2) Chromophobes
Chromophils are further classified into: acidophils and basophils
Pituitary Gland
Somatotropin (GH) affects practically all cells
What disease is due to the hypersecretion of somatotropin
- Gigantism
- Acromegaly
Pituitary Gland
Summary of the staining characteristics of adenohypophysis cells
1. Somatotrope
2. Lactotrope
3. Corticotrope
3. Gonadotrope
4. Thyrotrope
Pituitary Gland
Hormones of the Anterior lobe of the Pituitary gland
Somatotropin is stimulated by (1) and inhibited by (2)
(1) growth hormone releasing hormone (GHRH) & Ghrelin
(2) Somatostain - secreted by the hypothalamus and the pancreas
Lactotrope secretion and its function
Prolactin
stimulate the growth and activity of the mammary glands during lactation and pregnancy
Stimulated by: Thyrotropin releasing hormone (TRH) and vasoactive inhibitory peptide
Inhibited by: Dopamine
Lactotrope secretion and its function
Prolactin
stimulate the growth and activity of the mammary glands during lactation and pregnancy
Stimulated by: Thyrotropin releasing hormone (TRH) and vasoactive inhibitory peptide
Inhibited by: Dopamine
Corticotrope secretion
Adrenocorticotropic hormone (ACTH)
& pro-opiomelanocortin (POMC)
Regulated by: corticotropin releasing hormone (CRH) by the hypothalamus
Hormones secreted by the gonadotropes
- lutenizing hormone (LH)
- follicle stimulating hormone (FSH)
Regulated by: gonadotropin releasing hormone (GnRH) by the hypothalamus
Lutenizing hormone function in male & females
MALE
* stimulate the production of testosterone by the Leydig cells of the testes
FEMALE
* triggers ovulation
* responsible for the formation and maintenance of the corpus luteum in the ovary
* produce estrogen and progesterone
Follicle stimulating hormone function in males & females
MALE
* stimulate the activity of the sertoli cells in the seminiferous tubules of the testes
FEMALE
* responsible for the growth and development of the ovarian follicle - maturation of the ovum
* secretion of estrogen
Thyrotrope secretion
Thyroid stimulating hormone (TSH) or Thyrotropin
Regulated by: thyrotropin releasing hormone (TRH)
Boundary between the anterior lobe and the posterior lobe
represent the original lumen of the Rathke’s pouch
Rudimentary in adults
Par intermedia
Has parenchymal cells that surround colloid filled follicles
Hormone secretion of the pars intermedia
Melanocyte stimulating hormone (MSH)
by basophilic corticotropes
Extension of the anterior lobe along the stalk-like infundibulum
Pars tuberalis
Highly vascularized region by the vessels of the hypothalamo hypophyseal system
Pars tuberalis
Subdivisions of the Posterior lobe
- infundibulum
- pars nervosa
Is a downward continuation of the hypothalamus; formed by the axons of the secretory neurons (supraventricular and paraventricular nuclei)
Posterior lobe of the pituitary gland
Not an endocrine gland but a storage site for neurosecretions of the neurons
Neuroglial cells of the posterior lobe of the pituitary gland
pituicytes
- only cellular element in the neurohypophysis
- non-secretory cells
Hormones stored by the posterior pituitary gland
Blood Supply to the pituitary gland
Serves as one of the conrtolling centers of the autonomic nervous system
Hypothalamus
Hypothalamic Regulating Hormones
Endocrine or neuroendocrine gland that regulates the daily body rythm - develops from neuroectoderm of the posterior portion of the root of the diencephalon
important time keeper and regulator of day/night cycle
Pineal gland, pineal body, or epiphysis
located at the posterior wall of the 3rd ventricle near the center of the brain
Chief cells of the pineal gland
pinealocytes
The pineal body is characterized by the prescence of calcified concretions derived from percipitation of calcium phosphate and carbonates
corpora arenacea or brain sand
Hormone of the pineal gland
Hormones produces by the thyroid gland
Is a bilobed endocrine gland developed from the endodermal lining of the floor of the primitive pharynx
Thyroid
Connects the 2 lobes of the thyroid
Isthmus
Characteristics of a Hypoactive thyroid
- squamous or low cuboidal follicular cells
- large lumen
Thyroid hormone storage and secretion
Disease caused by the enlargement of the thyroid
Goiter
Disease caused by the excess production of thyroid hormone
Hyperthyroidism
Disease caused by the deficiency/decrease in TSH production
Hypothyroidism
* Adult: Myxedema
* Children: Cretinism
Small ovoid bodies at the posterior surface of the lateral lobes of the thyroid (#4)
Derived from the branchial pouch
* superior - 4th pouch
* inferior - 3rd pouch
Parathyroid gland
Maxmum size attained at 20 y.o.
Parathyroid Hormone Function
Parathyroid Cells
- Chief cells/Principal cells
- oxyphil cells
Adrenal Gland
