Module 4 Flashcards
- Hypophysis cerebra
- Master of Endocrine Glands
- 13x8mm in size; 0.5gm in weight
- covered by the dura mater
- Protected by the Sphenoid bone
Pituitary gland
Boundaries of Pituitary Gland
● Anterior: Sphenoid sinus
● Posterior: Dorsum sella, Basilar artery and Pons
● Superior: Diaphragma sellae, Optic chiasma
● Lateral: Cavernous sinus and its contents
(ICA, Abducens nerve)
Two functional lobes of the Pituitary Gland
Anterior pituitary – glandular tissue
Posterior pituitary – nervous tissue
- Anterior Pituitary gland
- Buccal/ glandular portion
- Derived from an upgrowth (Rathke’s pouch) from the roof of the primitive pharynx (Stomodeum)
- Stalk connecting to the lobe and roof of mouth disappears
- may persist as Craniopharyngeal Canal
Adenohypophysis
- Nervous in origin
- Derived from the brain
- From the floor of the 3rd ventricle and forms the infundibulum
Neurohypophysis
(Lobes of the Pituitary Gland)
- constitute 80% of the gland
- pars anterior (pars distalis) – largest subdivision
- pars intermedia
- pars tuberalis
Adenohypophysis (Anterior lobe)
Pars Distalis
- Acidophils (alpha cells)
- Somatotropes - Somatotropin
- Lactotropes/Mammotropes – Prolactin/ luteotropic H/ lactogenic H - Basophils (beta cells)
- Thyrotropes – TSH
- Corticotropes – Adrenocorticotropic H (ACTH), POMC, lipotropins, endorphins - Delta Basophils
- Gonadotropes – FSH, LH, ICSH - Chromophobes
- contains small masses of colloid material, and some finely granulated cells
- produces melanocyte stimulating hormone
- relatively avascular zone
pars intermedia
- projection from pars anterior
- most vascular part of the gland
- no hormone
pars tuberalis
(Lobes of the Pituitary Gland)
- No nerve cells
- Has numerous neuroglial cells and fibers and small collection of colloid materials
- Cell bodies are located in the hypothalamus
- supraoptic nuclei – vasopressin (pitresin, ADH)
- paraventricular nuclei – oxytocin (pitocin)
- Pars nervosa
Neurohypophysis (Posterior lobe)
Artery (branches from the Internal Carotid Artery) of the Pituitary Gland
- Superior hypophyseal artery
- Supplies the infundibulum
- Forms the capillary that forms the hypothalamic-hypophyseal portal system - Inferior hypophyseal artery
- Supplies the posterior lobe
Venous Blood supply of the Pituitary Gland
- cavernous sinus
- intercavernous sinus
Dwarfism vs Gigantism vs Acromegaly
Dwarfism: hyposecretion of the growth hormone in children
Gigantism: hypersecretion of growth hormone in children
Acromegaly: hypersecretion of growth hormone in adult. Results in exaggerated features esp in facial bone.
produced by anti insulin effects of excessive growth hormone
pituitary diabetes
(Anterior Pituitary Hormone)
- Stimulates breast development and maintains milk production following childbirth
- Secreted in response to high Estrogen and Progesterone levels in pregnancy
- Control is from PRH and PIH from the Hypothalamus
- Function in males is unknown
Prolactin (PRL)
(Anterior Pituitary Hormone)
- Stimulates the release of Corticosteroids from the Adrenal Cortex. Released in response to CRH
- Binds to melanocytes in the skin and increase skin pigmentation
Adrenocorticotropic hormone (ACTH)
(Anterior Pituitary Hormone)
- Influences growth and activity of the thyroid
- Secreted in response to TRH from the Hypothalamus
- Causes the Thyroid to secrete T4 and T3
Thyroid-stimulating hormone (TSH)
Regulate hormonal activity of the gonads
Gonadotropic hormones
(Gonadotropic hormones)
- stimulates follicle development in ovaries and sperm development in testes
Follicle-stimulating hormone (FSH)
(Gonadotropic hormones)
- triggers ovulation
- causes ruptured follicle to become the corpus luteum
- Stimulates testosterone production in males > Referred to as interstitial cell-stimulating hormone (ICSH)
Luteinizing hormone (LH)
(Hormones of the Posterior Pituitary)
- Stimulates contractions of the uterus during labor
- Causes milk ejection
- Can be stimulated by infant suckling and physical and chemical stimuli at the end of pregnancy
Oxytocin
(Hormones of the Posterior Pituitary)
- Inhibits urine production in response to increasing blood osmolarity
- In large amounts, causes vasoconstriction leading to increased blood pressure (vasopressin)
- Destruction of cells resulting in decrease __ secretion causes Diabetes Insipidus a medical condition with production of large volume of diluted urine
Antidiuretic hormone (ADH)
- is a surgical procedure performed through the nose and sphenoid sinus to remove pituitary tumors.
- can be performed with a microscope, endoscope, or both
Endoscopic Transsphenoidal Approach
Hormones released from the Hypothalamus
- Thyroid-stimulating hormone releasing hormone (TRH)
- Corticotropin-releasing hormone (CRH)
- Growth hormone releasing hormone (GHRH)
- Growth hormone inhibitory hormone (GHIH) - somatostatin
- Gonadotropin-releasing hormone (GnRH)
- Prolactin inhibitory factor (PIH)
- Also called Epiphysis, derived from the roof of Diencephalon
- Pinecone-shaped organ
- 100-180 grams
- Located between the superior colliculi
- Composed of pinealocyte/ chief cells (produce melatonin-Antigonadropic effect)
- Calcify during adult age
Pineal gland
Exocrine and Endocrine Function of Pancreas
exocrine portion - enzymes hydrolyzing proteins, fats, and carbohydrates.
Endocrine portion - pancreatic islets (islets of Langerhans)
- produces insulin and glucagon
- elongated structure that lies in epigastrium and left upper quadrant.
- soft and lobulated and situated on the posterior abdominal wall
- crosses the transpyloric plane
Pancreas
Pancreas divided into a
head, neck, body, and tail
Head and Uncinate process of the pancreas
Head - disc shaped and lies within concavity of duodenum
Uncinate process - part of head extends to the left behind the superior mesenteric vessels
- is the constricted portion of the pancreas
- in front of the beginning of the portal vein
- in front of origin of the superior mesenteric artery
neck of the pancreas
Body and Tail of the Pancreas
body runs upward and to the left across the
- somewhat triangular in cross section.
The tail passes forward in the splenicorenal ligament
- comes in contact with the hilum of the spleen
Relation of the Pancreas Anteriorly
From right to left: transverse colon, attachment of transverse mesocolon, lesser sac, and stomach
Relation of the Pancreas Posteriorly
:From right to left: bile duct, portal and splenic veins, inferior vena cava, aorta, origin of the superior mesenteric artery, left psoas muscle, left suprarenal gland, left kidney, and hilum of the spleen
(pancreatic duct)
- begins in the tail and runs the length of the gland
- opens into the second part of the duodenum with the bile duct on the major duodenal papilla
- Sometimes drains separately into the duodenum.
The main duct (Wirsung)
- drains the upper part of head
- opens into the duodenum above the main duct on minor duodenal papilla
- communicates frequently with the main duct.
accessory duct (Santorini)
Arteries that supply the pancreas
- splenic artery
- superior and inferior pancreaticoduodenal arteries
Veins of the Pancreas
- corresponding veins drain into the portal system.
Lymph Drainage and Nerve Supply of the Pancreas
Lymph Drainage
- along the arteries
- drain into celiac and superior mesenteric lymph nodes.
Nerve Supply
- Sympathetic and parasympathetic (vagal) nerve fibers
Arterial Suppy of the Pancreas: Celiac
gastroduodenal artery»_space; superior pancreaticoduodenal artery»_space; anterior and posterior»_space; superior pancreaticoduodenal arteries.
- passes behind the neck, it gives off the inferior pancreaticoduodenal artery
- divides into the anterior and posterior inferior pancreaticoduodenal arteries.
Superior Mesenteric Artery
Arterial supply from the Splenic Artery
- Dorsal Pancreatic artery,
- Great Pancreatic artery
- Caudal pancreatic artery,
Development of Pancreas
- from dorsal and ventral bud from the foregut.
Dorsal bud - originates above the ventral bud
- grows into the dorsal mesentery.
Ventral bud - arises in common with the hepatic bud
Rotation of stomach and duodenum + rapid growth of left side of the duodenum -> ventral bud’s coming into contact with the dorsal bud, and fusion occurs
Development of Pancreas: Ducts
Fusion occurs between the ducts
Main pancreatic duct - derived from entire ventral pancreatic duct and distal part of dorsal pancreatic duct.
Accessory duct - proximal part of the dorsal pancreatic duct
- arise as small buds from the developing ducts.
- form isolated groups of cells that secrete insulin and glucagon at about the fifth month.
pancreatic islets
- form a common dilatation, the hepatopancreatic ampulla (ampulla of Vater)
- pass obliquely through the wall of the second part of the duodenum
- open on the summit of the major duodenal papilla, which is surrounded by the sphincter of Oddi
- sometimes open separately on the summit of the duodenal papilla.
bile duct and the main pancreatic duct
- ventral pancreatic bud becomes fixed
- when the stomach and duodenum rotate -> ventral bud is pulled around the right side of the duodenum to fuse with the dorsal bud of the pancreas ->encircling the duodenum
- may cause obstruction of the duodenum
Anular Pancreas
- may be found in the submucosa of the stomach, duodenum, small intestine (including Meckel’s diverticulum), and gallbladder, and in the spleen.
- may protrude into the lumen of the gut and be responsible for causing intussusception.
Ectopic Pancreas
- caused by an abnormality in the secretion of mucus
- mucus produced is excessively viscid and obstructs the pancreatic duct which leads to pancreatitis with subsequent fibrosis
- also involves the lungs, kidneys, and liver.
Congenital Fibrocystic Disease
- consists of 2 lobes connected by isthmus.
- surrounded by sheath derived from pretracheal layer of deep fascia.
thyroid gland
- attaches thyroid gland to larynx and trachea.
Ligament of Berry
(thyroid gland)
- muscular band connects the pyramidal lobe to the hyoid bone
levator glandulae thyroideae
(thyroid gland)
- projects upward from isthmus, to the left
pyramidal lobe
Relations to the Lobe: Anterolateral and Posterolateral (Thyroid)
Anterolaterally: sternothyroid, superior belly of the omohyoid, the sternohyoid, anterior border of sternocleidomastoid
Posterolaterally: carotid sheath (common carotid artery, internal jugular vein, vagus nerve
Relations to the Lobe: Medially and Posteriorly (Thyroid)
Medially: larynx, trachea, pharynx, esophagus. Cricothyroid and external laryngeal nerve. recurrent laryngeal nerve
Posteriorly: superior and inferior parathyroid glands
Relation to the Isthmus: Anteriorly and Posteriorly
Anteriorly: sternothyroids, sternohyoids, anterior jugular veins, fascia, and skin
Posteriorly: second, third, and fourth rings of the trachea
Blood Supply of the Thyroid gland
arteries anastomose profusely with one another over surface of the gland.
- superior thyroid artery
- inferior thyroid artery
- thyroidea ima - arise from brachiocephalic artery or arch of the aorta
- a branch of the external carotid artery
- accompanied by the external laryngeal nerve
superior thyroid artery
- a branch of the thyrocervical trunk
- recurrent laryngeal nerve crosses either in front of or behind the artery
inferior thyroid artery
- arise from brachiocephalic artery or arch of the aorta
thyroidea ima