Endocrine System Anatomy Flashcards
Endocrine System
Influences metabolic activity by means of hormones.
Chemical messengers released into the blood to be transported throughout the body through feedback loops.
Function of the Endocrine System
Respiration Metabolism (responsible for chemical responses of metabolic activity) Reproduction Sensory perception Movement Sexual development Growth
Pineal Gland (Epithalamus) - Function and Location
Synthesizes and secretes melatonin (sleep hormone).
Located on the midline, between 2 cerebral hemisphere, attached to third ventricle of brain.
6 mm - 1 cm in length.
Blood Supply of Pineal Gland (Epithalamus)
Posterior choroidal arteries (branches from the posterior cerebral artery).
Veinous drainage: internal cerebral veins.
Pituitary Gland (Hypophysis)
Master gland of the endocrine system which controls the rest of the body glands.
Ovoid-shaped, located in sella turcica of sphenoid bone.
Closely related to hypothalamus.
Lobes of the Pituitary Gland (Hypophysis)
Adenohypophysis: Anterior lobe (majority of pituitary hormones)
Neurohypophysis: Posterior lobe (nuclei, neuro responses)
Role of the Pituitary Gland
Production of hormones for regulation of vital processes.
Anatomical Relations of Pituitary Gland (Hypophysis)
Anterior: Sphenoid sinus Posterior: Posterior intercavernous sinus, dorsum sellae, basilar artery and the pons. Inferior: Sphenoid sinus Lateral: Cavernous sinus Superior: Diaphragm sellae
What is the connection between the Hypothalamus and Pituitary Gland (Hypophysis) called?
Infundibulum through the hypothalamohypophyseal tract.
Adenohypophysis (Anterior) - Division
Divided in 3:
- Pars anterior (distalis)
- Pars intermedia
- Pars tuberalis
Pars Anterior (Distalis) - Adenohypophysis
Strongest secretory activity, composed of numerous follicles.
Somatotrophs (growth hormone) and lactotrophs (prolactin)
gonatrophs (FSH, LH), corticotrophs (ACTH), thyrotrophs (TSH)
progenitor cells
Pars Intermedia - Adenohypophysis
Between pars anterior and neurohypophysis.
Corticotropic cells: produce melanocytes (skin), stimulate hormones and endorphins (pleasure)
Pars Tuberalis - Adenohypophysis
Extension of pars anterior.
Gonadotrophs - reproductive system.
Neurohypophysis (Posterior)
Neuroendocrine structure - has neurological pathways
- Infundibulum
- Pars nervosa
Infundibulum - Neurohypophysis
Connects pituitary gland and hypothalamus.
Serves for transport of the neurohormones.
Pars Nervosa - Neurohypophysis
Neural lobe.
Contains either antidiuretic hormone (ADH, controls water balance) or oxytocin (pleasure, uterus contraction).
Blood Supply: Hypophyseal Portal System
Blood vessels that connect adenohypophysis to hypothalamus.
Originates from superior and inferior hypophyseal arteries.
Hypothalamus - Location, Function and Composition
Central location in the brain.
Thermoregulation, osmoregulation, hormonal regulation (works closely with pituitary gland).
Composed mainly of different nuclei that synthesize different hormones in response to physiological changes.
- Preoptic region
- Supraoptic region
- Tuberal region
- Mammillary region
Preoptic Region - Hypothalamus
Preoptic Nucleus - connected to optic nerve.
Supraoptic Region
Suprachiasmatic, supraoptic, paraventricular and anterior nuclei.
Tuberal Region
Dorsomedial, ventromedial, arcuate, premammillary and lateral tuberal nuclei.
Mammillary Region
Mammillary and posterior nuclei.
Blood Supply of the Hypothalamus
Anterior and posterior branches of the circle of Willis, superior hypophyseal artery.
Thyroid - Location and Function
Vascular, red-brown endocrine gland situated in the midline of the anterior neck.
Secretes thyroid hormones that regulate body metabolism (T3, T4 hormones) and calcium homeostasis (calcitonine).
Extends from C5 - T1, 15-25 g.
Anatomical Relations - Thyroid
Anterior: Infrahyoid muscles.
Lateral: Carotid sheath: common carotid artery, internal jugular vein and vagus nerve.
Medial: Larynx, pharynx, trachea and esophagus. External laryngeal nerve, recurrent laryngeal nerve.
Blood Supply - Thyroid
Superior and inferior thyroid artery
Inconsistently: arteria thyroidea that arises directly from brachiocephalic trunk (increased risk of thyroid cancer metastasizing).
Venous drainage: superior, middle and inferior thyroid vein.
Parathyroid - Location and Function
posterior to the thyroid, responsible for the production of the parathyroid hormone (PTH).
Vary in numbers from 2-6.
Superior Parathyroid Glands
Normally 2.
Located at the middle of each posterior border of thyroid.
Inferior Parathyroid Glands
Normally 2.
Usually found near the inferior poles of the thyroid gland.
Blood Supply - Parathyroid Gland
Similar to thyroid →
Superior thyroid artery
Inferior thyroid artery
Inconsistently: arteria thyroidea that arises directly from brachiocephalic trunk (increased risk of thyroid cancer metastasizing).
Venous drainage: superior, middle and inferior thyroid vein.
Adrenal (Suprarenal) - Location and Function
Paired endocrine glands situated over the kidney, in posterior abdomen between superomedial kidney and diaphragm.
Secretion of steroid and majorly catecholamine directly into blood.
Right: pyramidal shape
Left: semi-lunar shape (spleen pushes on it)
Consist of: Cortex and medulla
Cortex of Adrenal Glands
Secretes two cholesterol derived hormones - corticosteroids and androgens.
Medulla of Adrenal Glands
Secrete catecholamines such as adrenaline into blood stream in response to stress.
Anatomic Relations - Right Adrenal (Suprarenal)
Anterior: Inferior vena cava, Right lobe of liver.
Posterior: Right crus of diaphragm.
Anatomic Relations - Left Adrenal (Suprarenal)
Anterior: Stomach, tail of pancreas, spleen.
Posterior: Left crus of diaphragm
Blood Supply - Adrenal (Suprarenal)
Superior adrenal artery Middle adrenal artery Inferior adrenal artery Venous drainage: - Right and left adrenal veins drain into inferior vena cava and left renal vein.
Innervation - Adrenal (Suprarenal)
Coeliac plexus and greater splanchnic nerves.
Sympathetic innervation to the adrenal medulla is via myelinated pre-synaptic fibers, mainly from T10 - L1 spinal chord segments.
