endocrine system
DESCRIPTION
Endocrine System. Glands . Organs which secrete substances Made of epithelial cells 2 types Exocrine glands : secrete materials into ducts Endocrine glands (ductless): secrete materials called hormones into bloodstream. Hormones. Released in bloodstream Usually in low concentrations - PowerPoint PPT PresentationTRANSCRIPT
Endocrine System
Glands Organs which secrete
substances Made of epithelial cells
2 types Exocrine glands: secrete
materials into ducts Endocrine glands (ductless):
secrete materials called hormones into bloodstream
Hormones Released in bloodstream Usually in low concentrations Each type of hormone recognizes only a
certain type of tissue to regulate Target Tissue: hormone increases or decreases
activity
Hormones Regulate
Metabolism Homeostasis Growth Reproduction
The process that controls the level of hormones in the blood is called negative feedback
Organisms must maintain homeostasis to survive in diverse environments.
Homeostasis is the maintenance of constant internal conditions.
Homeostasis is usually maintained through negative feedback.
Negative feedback systems return a condition to its normal (set) point.
• Homeostasis is the maintenance of constant internal conditions.
Human Endocrine System Hypersecretion: excess Hyposecretion: not enough Can cause a disorder
Glands Pituitary (master gland)
Controlled by hypothalamus Location= base of brain Secretes
Follicle stimulating hormone (FSH) ACTH Thyroid simulating hormone (TSH) Growth Hormone (GH)
FSH Stimulates development of eggs in ovaries
ACTH Adrenocorticotropic hormone Stimulates adrenal gland
TSH Stimulates production of thyroxin in thyroid
gland Controls metabolic processes
GH Affects growth of bones and metabolism of
glucose Disorders
Hypersecretion: giantism (enlarged bones) Hyposecretion: dwarfism (reduced bones)
7 feet 8 inches (2.36 meters)
29.2 inches (73 centimeters)
Thyroid Location= neck Secretes thyroxin
Regulates rate of metabolism Needed for mental and physical development
Hypersecretion: nervousness, weight lossHyposecretion: cretinism (mental retardation), small size
Lack of iodine enlarges thyroid (goiter)
Parathyroid Location: Embedded in back of thyroid Secretes parathormone
Controls metabolism of calcium Nerve and muscle functions
Hyposecretion: brittle bones, clotting probelms
Adrenal Gland location: top of kidneys Has outer cortex and inner medulla Secretes
Adrenaline (epinephrine) which raises blood sugar levels, increases heartbeat, increases breathing rate “Fight or flight” hormone Hyposecretion: inability to deal with stress
Adrenal Gland Secretes
Norepinephrine Same effects as adrenaline
Islets of Langerhans Location: pancreas Secretion
Insulin: lets glucose enter cells and liver to be stored as glycogen (lowers blood glucose level in blood) Hypersecretion: low blood
sugar Hyposecretion: diabetes
(sugar in blood and urine)
Islets of Langerhans Secrete
Glucagon: enables conversion from glycogen to glucose (increases blood sugar) Hypersecretion:
high blood sugar
Gonads (sex glands) Male= testes
Produce testosterone Responsible for development of secondary sex
characteristics (deep voice, facial hair) Female= ovaries
Produce estrogen Responsible for secondary sex characteristics (broad
hips, breast development) Hyposecretion: reduction of secondary sex
characteristics
Nervous vs. Endocrine Both forms of cellular communication
Nervous System Endocrine System
Nervous regulation Chemical regulation
Involves neurotransmitters Involves hormones
Fast response Slow response
Short duration Long duration
Only in multicellular organisms
Common to call organisms