Endocrine System Anatomy

Question 1

Endocrine System

Answer 1

Influences metabolic activity by means of hormones.

Chemical messengers released into the blood to be transported throughout the body through feedback loops.

Question 2

Function of the Endocrine System

Answer 2

Respiration
Metabolism (responsible for chemical responses of metabolic activity)
Reproduction
Sensory perception
Movement
Sexual development
Growth

Question 3

Pineal Gland (Epithalamus) - Function and Location

Answer 3

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.

Question 4

Blood Supply of Pineal Gland (Epithalamus)

Answer 4

Posterior choroidal arteries (branches from the posterior cerebral artery).
Veinous drainage: internal cerebral veins.

Question 5

Pituitary Gland (Hypophysis)

Answer 5

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.

Question 6

Lobes of the Pituitary Gland (Hypophysis)

Answer 6

Adenohypophysis: Anterior lobe (majority of pituitary hormones)
Neurohypophysis: Posterior lobe (nuclei, neuro responses)

Question 7

Role of the Pituitary Gland

Answer 7

Production of hormones for regulation of vital processes.

Question 8

Anatomical Relations of Pituitary Gland (Hypophysis)

Answer 8

Anterior: Sphenoid sinus
Posterior: Posterior intercavernous sinus, dorsum sellae, basilar artery and the pons. 
Inferior: Sphenoid sinus
Lateral: Cavernous sinus
Superior: Diaphragm sellae

Question 9

What is the connection between the Hypothalamus and Pituitary Gland (Hypophysis) called?

Answer 9

Infundibulum through the hypothalamohypophyseal tract.

Question 10

Adenohypophysis (Anterior) - Division

Answer 10

Divided in 3:

• Pars anterior (distalis)
• Pars intermedia
• Pars tuberalis

Question 11

Pars Anterior (Distalis) - Adenohypophysis

Answer 11

Strongest secretory activity, composed of numerous follicles.
Somatotrophs (growth hormone) and lactotrophs (prolactin)
gonatrophs (FSH, LH), corticotrophs (ACTH), thyrotrophs (TSH)
progenitor cells

Question 12

Pars Intermedia - Adenohypophysis

Answer 12

Between pars anterior and neurohypophysis.

Corticotropic cells: produce melanocytes (skin), stimulate hormones and endorphins (pleasure)

Question 13

Pars Tuberalis - Adenohypophysis

Answer 13

Extension of pars anterior.

Gonadotrophs - reproductive system.

Question 14

Neurohypophysis (Posterior)

Answer 14

Neuroendocrine structure - has neurological pathways

• Infundibulum
• Pars nervosa

Question 15

Infundibulum - Neurohypophysis

Answer 15

Connects pituitary gland and hypothalamus.

Serves for transport of the neurohormones.

Question 16

Pars Nervosa - Neurohypophysis

Answer 16

Neural lobe.

Contains either antidiuretic hormone (ADH, controls water balance) or oxytocin (pleasure, uterus contraction).

Question 17

Blood Supply: Hypophyseal Portal System

Answer 17

Blood vessels that connect adenohypophysis to hypothalamus.

Originates from superior and inferior hypophyseal arteries.

Question 18

Hypothalamus - Location, Function and Composition

Answer 18

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

Question 19

Preoptic Region - Hypothalamus

Answer 19

Preoptic Nucleus - connected to optic nerve.

Question 20

Supraoptic Region

Answer 20

Suprachiasmatic, supraoptic, paraventricular and anterior nuclei.

Question 21

Tuberal Region

Answer 21

Dorsomedial, ventromedial, arcuate, premammillary and lateral tuberal nuclei.

Question 22

Mammillary Region

Answer 22

Mammillary and posterior nuclei.

Question 23

Blood Supply of the Hypothalamus

Answer 23

Anterior and posterior branches of the circle of Willis, superior hypophyseal artery.

Question 24

Thyroid - Location and Function

Answer 24

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.

Question 25

Anatomical Relations - Thyroid

Answer 25

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.

Question 26

Blood Supply - Thyroid

Answer 26

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.

Question 27

Parathyroid - Location and Function

Answer 27

posterior to the thyroid, responsible for the production of the parathyroid hormone (PTH).
Vary in numbers from 2-6.

Question 28

Superior Parathyroid Glands

Answer 28

Normally 2.

Located at the middle of each posterior border of thyroid.

Question 29

Inferior Parathyroid Glands

Answer 29

Normally 2.

Usually found near the inferior poles of the thyroid gland.

Question 30

Blood Supply - Parathyroid Gland

Answer 30

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.

Question 31

Adrenal (Suprarenal) - Location and Function

Answer 31

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

Question 32

Cortex of Adrenal Glands

Answer 32

Secretes two cholesterol derived hormones - corticosteroids and androgens.

Question 33

Medulla of Adrenal Glands

Answer 33

Secrete catecholamines such as adrenaline into blood stream in response to stress.

Question 34

Anatomic Relations - Right Adrenal (Suprarenal)

Answer 34

Anterior: Inferior vena cava, Right lobe of liver.
Posterior: Right crus of diaphragm.

Question 35

Anatomic Relations - Left Adrenal (Suprarenal)

Answer 35

Anterior: Stomach, tail of pancreas, spleen.
Posterior: Left crus of diaphragm

Question 36

Blood Supply - Adrenal (Suprarenal)

Answer 36

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.

Question 37

Innervation - Adrenal (Suprarenal)

Answer 37

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.