Biology - Chemical Coordination - Quick Guides | Biology

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Study GuideBiology–Chemical Coordination1. Hormones and GlandsThe animal body usestwo main systems to coordinate activitiesand keep everything workingtogether smoothly:1.Nervous coordination–fast, direct control using nerve impulses2.Chemical coordination–slower, long-lasting control using hormonesThis section focuses onchemical coordination, which is carried out by a group of glands called theendocrine system.1.1 The Endocrine System: Chemical CoordinationTheendocrine systemis made up of special glands located throughout the body. Some importantendocrine glands include thepancreas,thyroid gland, andadrenal glands.These glands release chemical messengers calledhormones.•Hormones are made ofproteins or sterol lipids•They travel through thebloodstream•They affect specific organs or tissues calledtarget organsRather than causing quick, short actions, hormones usually bring aboutslow but widespread andlong-lasting changesin the body.1.2 What Do Hormones Do?Hormones help coordinate body systems and regulate important processes such as growth,metabolism, and energy use.Here are two key examples:•Insulin○Secreted by thepancreas○Helpsglucose move into body cells

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Study Guide○Allows cells to use glucose forenergy metabolism•Thyroxine○Secreted by thethyroid gland○Regulates the body’soverall metabolic rate○Influences how fast cells carry out chemical reactionsThese hormones don’t act instantly, but their effects are essential for normal body function.1.3 Hormones vs. Nerve SignalsBoth the endocrine system and the nervous system coordinate bodyactivities, but they work indifferent ways.1.3.1 Endocrine Coordination•Useshormones•Hormones travel through theblood•Effects areslowerbutlong-lasting•Influences the body in ageneral and widespread way1.3.2 NervousCoordination•Usesnerve impulses•Signals move alongspecific nerve pathways•Effects arefast and localized•Controls actions likemuscle contractionandgland activityTogether, these two systems allow the body to respond both quickly and steadily to changes.1.4 Endocrine vs. Exocrine GlandsEndocrine glands have a unique feature:they have no ducts.

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Study Guide•Hormones are releaseddirectly into the bloodstream•Because of this, endocrine glands are also calledductless glandsIn contrast,exocrine glands:•Release substances throughducts•Examples includesalivary glands, which secrete digestive enzymes into the mouthThis difference explains how hormones can reach many parts of the body at once.1.5 A Shared System Across AnimalsThe basicstructure and function of endocrine glands and hormonesare very similar in mostanimals. While this chapter focuses on humans, the same principles of hormonal control applybroadly across the animal kingdom.2. Human Endocrine SystemThehuman endocrine systemhelps control and coordinate many body activities by releasinghormones. Hormones act as chemical messengers that travel through the bloodstream and tellorgans and tissueswhat to do and when to do it. In this way, the endocrine system carefullyregulates growth, metabolism, stress responses, reproduction, and many other vital processes .2.1 Pituitary Gland: The Master GlandThepituitary glandis located at the base of the brain. It is often called themaster glandbecausemany of its hormones control other endocrine glands.The pituitary has two parts:2.1.1 Anterior Pituitary (Adenohypophysis)This lobe produces several important hormones:•Human Growth Hormone (HGH)○Also calledsomatotropin○Stimulates body growth by increasing protein synthesis

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Study Guide○Too little HGH causesdwarfism○Too much HGH causesgigantism•Prolactin (Lactogenic Hormone)○Promotes breast development andmilk productionin females•Thyroid-Stimulating Hormone (TSH)○Controls hormone release from thethyroid gland•Adrenocorticotropic Hormone (ACTH)○Stimulates hormone secretion from theadrenal glands•Follicle-Stimulating Hormone (FSH)○In females: stimulates development of egg-containing follicles○In males: stimulatessperm production•Luteinizing Hormone (LH)○In females: completes follicle maturation and forms thecorpus luteum○In males: calledinterstitial cell-stimulating hormone (ICSH)and promotes malehormone production•Melanocyte-Stimulating Hormone (MSH)○Stimulates production of the pigmentmelanin2.1.2 Posterior Pituitary (Neurohypophysis)The posterior pituitarystores and releaseshormones made in the hypothalamus:•Antidiuretic Hormone (ADH or Vasopressin)○Increaseswater reabsorptionin the kidneys•Oxytocin○Stimulatesuterine contractionsduring childbirth

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Study Guide2.2 Thyroid GlandThethyroid glandis located at the base of the neck, just below the pharynx. It has two lobesconnected by a narrow bridge called theisthmus.•Producesthyroxine, which controls the body’smetabolic rate•Producescalcitonin, which helps regulatecalcium levelsin the bloodThyroid Disorders•Iodine deficiencycauses thyroid enlargement calledgoiter•Low thyroxine in childhood causescretinism•Low thyroxine in adults causesmyxedema•Excess thyroxine causesGraves’ disease, marked by a high metabolic rate2.3Parathyroid GlandsTheparathyroid glandsare tiny glands located on the back of the thyroid gland.•They produceparathyroid hormone (parathormone)•This hormone:○Increases calcium reabsorption in the kidneys○Increases calcium absorption from the digestive tract•Together, these actions regulatecalcium balancein the body2.4 Adrenal GlandsTheadrenal glandssit on top of the kidneys and have two regions:2.4.1 Adrenal Cortex (Outer Layer)Producescorticosteroids, including:•Mineralocorticoids(such as aldosterone)

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