The Endocrine System Chapter 13

Endocrinology The study of hormones Like nervous system- helps control the body and aid in communication Hormone- chemical messenger, travels through the bloodstream to target cells, effective at very low concentration

Hormones 1) Secreted Glands- pituitary, thyroid, etc. Into the bloodstream

Hormones 2) Travel through the blood stream to a distant target 3) Exert their effect at very low concentrations

General characteristics Some hormones are produced by small groups of specialized cells Other hormones are produced by larger endocrine glands Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Hypothalamus Pituitary gland Pineal gland Parathyroid gland Thyroid gland Thymus Adrenal gland Kidney Pancreas Ovary (in female) Testis (in male)

Terminating hormone action

Terminating hormone action Degraded in the bloodstream Degraded on the receptor Endocytosis of receptor-hormone complex

Everyone needs a little regulation…

Regulation of endocrine response Governed by negative feedback Feedback guided by multiple variables Change in physiological variable Hormone concentration

Chief cells

HPA axis Hypothalamic-Pituitary-Adrenal Complex regulation

Governs many key endocrine functions Deemed “Master Gland” Governs many key endocrine functions Growth Blood pressure Water regulation Others

Parts of the Pituitary gland Posterior pituitary Neural tissue Secretes neurohormones Oxytocin, vasopressin Vasopressin- regulates water balance

Parts of the Pituitary gland Anterior pituitary “True” endocrine gland Synthesizes/releases peptide hormones

Anterior Pituitary function Hypothalamus (part of the brain) releases hormones Those hormones signal to the anterior pituitary Anterior pituitary releases hormones that affect peripheral endocrine glands Peripheral endocrine glands release hormone to target cells

Peripheral endocrine gland – Hypothalamus – Releasing hormone (Hormone 1) + – Anterior pituitary Anterior pituitary hormone (Hormone 2) + Peripheral endocrine gland (Hormone 3) Stimulation + Inhibition Target cells

Trophic hormones

Trophic hormone- a hormone that controls the secretion of another hormone All end in “tropin”

http://www.youtube.com/watch?v=WVrlHH14q3o

Endocrine pathologies Hormone excess, hormone deficiency, or abnormal responsiveness of target tissue Can be primary (last endocrine gland in a reflex) or secondary (further up, in gland producing trophic hormone)

Hypersecretion Increase in hormone secretion Tumors Causes dysfunction in feedback pathway Can occur at any point in the axis Hypothalamus Pituitary gland Adrenal gland

Hypersecretion Hypersecretion of GH Acromegaly (adult) Bones ossified Prominent brow Reduced testosterone Soft tissue swelling

Hypersecretion Excess production of GH Gigantism (children) Exaggerated and prolonged growth in long bones

Hyposecretion Dysfunction of the pituitary Decreased secretion of GH Dwarfism Born normal height/weight Failure to grow by age 2 yr

Receptor failure Plenty of hormone Decrease or lack of receptors Initially thought lack of GH production, but actually lack of receptors

Diabetes When you eat, food is broken down into glucose Cells use glucose as energy The pancreas secretes insulin (hormone), which helps glucose get into the cells Diabetes is a lack of insulin (type 1) or decreased response of cells to insulin (type 2) Glucose can’t get to cells

Type 1

Type 2

Yum…

http://www. mayoclinic http://www.mayoclinic.org/condition/diabetes/multimedia/blood-sugar/vid-20084642

Signals from nervous and endocrine systems

Nervous v. Endocrine Nervous Endocrine Each neuron has a target cell Every cell

Nervous v. Endocrine Nervous Endocrine Each neuron has a target cell Electrical/chemical Every cell Chemical (hormones)

Nervous v. Endocrine Nervous Endocrine Each neuron has a target cell Electrical/chemical Fast Every cell Chemical (hormones) Slower

Nervous v. Endocrine Nervous Endocrine Each neuron has a target cell Electrical/chemical Fast Short duration Every cell Chemical (hormones) Slower Longer lasting

Nervous v. Endocrine Nervous Endocrine Each neuron has a target cell Electrical/chemical Fast Short duration Intensity control via frequency Every cell Chemical (hormones) Slower Longer lasting Intensity control via quantity