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Endocrine system Beatrice Mwachugu (Endocrine Organs (Pancrease (Alpha…
Endocrine system Beatrice Mwachugu
Endocrine Organs
Pituitary gland
Parathyroid Gland
Secretes parathyroid hormone
Parathyroid hormone increases the concentration of Ca2+ in blood
Thyroid Gland
Secretes thyroid hormone which increase basal metabolic rate
Thyroid cells also secrete calcitonin which lowers blood levels of Ca2+by slowing the release of Ca in the blood.
Adrenal gland
Adrenal Medulla
Secretes amino acid based hormones,epinepherine, and norepinephrine into blood to enhance the fight or flight
Adrenal Cortex
Secretes lipid based steroid hormones
Has 3 layers
Zona reticularis
cells arranged in a branching network
Zona fasciculata
Cells are arranged in a parallel cord
Zona glomerulosa
Cells arranged in spherical clusters
Pineal gland
Secretes melatonin which is a sleep hormone.
Pancrease
Alpha cells
Secretes glucagon that signals liver cells to release glucose to raise sugar levels in blood
Beta cells
Secrete Insulin hormone that signals the body to take glucose from blood
Delta cells
Secretes somatostatin that inhibits secretion of insulin and glucagon
PP cells
Secrete pancreatic polypeptide that inhibits exocrine activity.
Thymus
Located in the lower neck
Thymic hormes which is a family of peptide molecules
Gonads
Ovaries
Estrogen
maintain reproductive organs a nd maintain secondary characteristics of females
Progestrone
Signals uterus to prepare for pregancy
Testies
Androgens
Give secondary characteristics of male and maintain male reproductive organs
Hormones
Classes of Hormones
Amino acid based
Made of amino acids,peptides and proteins and produced by cells that a rough endoplasmic reticulum
Steroid hormones
Lipid molecules produced by smooth ER
Control of hormone secretion
Humoral stimuli
Controlled by change in nutrient and ions in blood
Hormonal Stimuli
Controlled by certain hormones which control the secretion of other hormones
Neural stimuli
Nervous system stimulates endocrine glands to release hormones .
Types of hormones
Anterior lobe
Thyroid stimulating hormone
Adrenocorticotropic Hormone
Gonadotropins
Prolactin
Melanocyte stimulating Hormone
Growth Hormone
Posterior lobe
(ADH)
Oxytocin
Endocrine system
For the hormones to cause changes target cells must have receptor.
Hormones act as triggers or stimulators
They travelin blood or body fluids
Hormones travel slowly
Hormones are messanger molecules