Endocrine System Flashcards
Hormones
Chemical messengers
Circulate in the blood
Act upon specific target cells
Bring about specific changes in cellular function
Exocrine glands
Glandular portion - lines with secretory epithelial cells
Duct portion - lines with simple cuboidal or columnar epithelial cells
Exocrine glands function
Secrete non-hormone products via ducts to a target organ, body cavity or tissue surface
Endocrine glands
Ductless
Hollow spherical follicles lines with secretory epithelial cells
Each follicle is surrounded by an extensive capillary network
Endocrine glands function
Produce hormones that are secreted into interstitial fluid and diffused into the blood where it travels to the target organ, tissue or cell
Functions
Co-ordination
Homeostasis
Glandular secretion
Metabolism
Behaviour
Growth and development
Physical appearance
Reproduction
Digestion
Circadian rhythm
Body fluids
Immune response
Mood and emotions
Hunger
Hypothalamus
Anterior region of the brain
Below thalamus
Above brainstem
Neurosecretory cell bodies
Hypothalamus - function
Co-ordinating homeostatic mechanisms, behaviour patterns and neuroendocrine outputs
Regulates - temperature, fluid volume, growth, pain and pleasure response, hunger and thirst
Hypothalamus - releasing and inhibiting hormones
Corticotropin (CRH) - releasing hormone
Thyrotropin (TRH) - releasing hormone
Growth hormone (GH) - releasing hormone
Gonadotropin - releasing hormone
Somatostatin - inhibiting GH and thyroid stimulating hormone (TSH)
Pituitary gland
Small pea-shaped gland
Lies at the base of the brain within the pituitary fossa of the sphenoid bone
Suspended from hypothalamus by the infundibulum
Anterior and posterior lobes
Pituitary gland - function
Anterior - endocrine organ
Posterior - endocrine organ and nervous functions, intrinsically connected to the hypothalamus
Pituitary gland - anterior pituitary gland
75% of total weight
Mass of endocrine glandular epithelial cells forming continuous cords around sinusoid capillary network
Pituitary gland - hormones released by anterior pituitary gland
Thyroid-stimulating hormone (TSH) - thyroid hormone synthesis
Adreno-corticotropic hormone (ACTH) - secretion of glucocorticoid hormones
Melanocyte-stimulating hormone (MSH) - influence brain activity
Human growth hormone (HGH) - growth and repair, lipid, carbs and protein metabolism
Follicle-stimulating hormone (FSH) - oestrogen, sperm production
Luteinizing hormone (LH) - progesterone, testosterone
Prolactin (PRL) - milk production and secretion
Pituitary gland - posterior pituitary gland
Includes the infundibulum and the pard nervous
Pituitary gland - hormones released by posterior pituitary gland
Oxytocin (OT) - uterine contractions, milk release
Antidiuretic hormone (ADH) - reduces urine output
Kidneys
Outer cortex - arcuate and interlobular arteries and veins
Inner medulla - renal pyramids
Nephrons
Kidney - hormones
Erythropoietin (EPO) - increased RBC production
Calcitriol - absorption of calcium from intestines
Renin - targets angiotensinogen, vasodilation, suprarenal cortex produces aldosterone
Ovaries
Located in ovarian fossa close to lateral pelvic wall
Uterine tube covers medial surface
Fimbrae covers lateral surface
Fimbrae - finger-like projections surrounding the opening of the uterine tubes
Ovaries - hormones
Oestrogens and progesterone - menstrual cycle, pregnancy
Testes
Suspended outside the body in the scrotum
Two testes separated by fibrous tissue called median raphe
Epididymis - tube like structure from, the superior aspect and descends to the tail at the base of the testes, forms the ductus deferens
Testes - hormones
Testosterone - secondary sexual characteristics, sperm production
Thymus
Lobulated gland
Located in the anterior mediastinum posterior to the sternum and anterior to the trachea
Cortex and medulla
Divided into lobules by connective tissue septa forming enters routes
Thymus - hormones
Thymosin
Thymic humoral factor
Thymic factor
Thymopoietin
Promoter the development and maturation of T-lymphocytes
Pineal gland
Pea-sized pineal body lies inn the middle of the brain in the midline
Between the two superior colliculi
Associated with regulation of sleep-wake cycle
Pineal gland - hormones
Melatonin - during darkness the pineal gland synthesises melatonin. Promote sleep and regulate sleep-wake cycles
Thyroid gland
Sits in front of the trachea at the level of C7-T1
Right and left lob which sit either side connected by the isthmus
Thyroid gland - hormones
Triidothyronine (T4) - increases BMR, synthesis sodium potassium pump
Thyroxine (T3) - body temperature, increase heart rate, blood pressure and contractility, body growth
Calcitonin - increase calcium uptake by bones
Parathyroid glands
Four, rice-sized
Two superior and two inferior
Lie on the posterior surface of the lobe of the thyroid gland
Parathyroid glands - hormones
Chief cells secrete the hormones
Increase calcium in the blood
Calcium is removed from the bone tissue into the blood
Adrenal gland
Small, yellow, lobular glands that lie superomedial to the kidneys
Behind the peritoneum
Surrounded by fat
Inner medulla and outer cortex
Right - pyramid shaped
Left - flatter and slightly larger
Adrenal glands - function
Regulation of mineral homeostasis
Regulation of glucose homeostasis
Promote puberty
Triggering fight-or-flight response
Adrenal glands - cortex hormones
Mineralocorticoids - increase Na+ and water reabsorption into blood, increase blood volume and pressure
Glucocorticoids - cortisol, metabolism growth, blood sugar levels, anti-inflammatory
Androgens - growth spurts, growth of auxiliary and pubic hair, libido
Adrenal glands - medulla hormone
Epinephrine and norepinephrine - enhances effects of nervous system during stress response
Pancreas
12-15cm long, leaf shaped
Lies horizontally, deep to the stomach
Cover in front by peritoneum
Endocrine and exocrine
Four parts - uncinate process, head, body and tail
Central branching duct
Ducts join with common bile duct
Pancreas - hormones
Glucagon - raise blood glucose
Insulin - lowers blood glucose
Somatostatin - inhibits insulin and glucagon secretion, suppresses reabsorption of nutrients
Pancreatic polypeptide - inhibits somatostatin secretion, suppresses gallbladder contraction
