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Chapter 16A

Endocrine System

The Endocrine System acts with what to coordinate and integrate the activity of body cells ? The Nervous System
The Endocrine System influences _______ _________ by means of hormones transported in the blood Metabolic activities
Responses of the Endocrine system occurs more ______ than the nervous system and tend to last _____than the nervous system Slowly,and tend to last longer
What are the five endocrine glands ? 1.Pituitary Gland 2.Thyroid Gland 3.Parathyroid Gland 4.Adrenal gland 5. Pineal Gland
What are some organs that produce both hormones and endocrine products ? Pancreas and Gonads
The hypothalamus has both what ? Neural and endocrine functions (neuroendocrine)
What are other tissues and organs that produce hormones ? 1. Adipose cells 2.Thymus cells 3.Cells in walls of small intestine 4.Stomach 5.Kidneys 6.Heart
What produces non hormonal substances such as sweat and saliva ,has ducts and secrete to membrane surfaces ? Exocrine Glands
What produces hormones and is known as ductless glands, releases their hormones into surrounding tissue fluids and has a rich vascular and lympathetic drainage ? Endocrine Glands
What are the four mixed exocrine and endocrine glands ? 1.Pancreas 2.Testes 3.Ovary 4.Hypothalumus (neuroendocrine)
What are the three chemical messengers of the endocrine system ? 1.Hormones 2..Autocrines 3.Paracrines
What are long distance chemical signals that travel in the blood or lymph is called ? Hormones
What are chemicals that exert effects on the same cells that secrete them is known as what ? Autocrines
What are locally acting chemicals that affect cells other than those that secrete them are called ? Paracrines
Autocrine and Paracrine are local chemical messengers and will not be considered part of what ? The endocrine system
The Two main classes of hormones are Amino acid-based hormones and Steroids
Amino acid-based hormones are Water based and make up the majority of hormones such as Amines, thyroxine,peptides and proteins .
Steroids are Synthesized from cholesterol and are gonadal and adrenocortical hormones
The mechanism of hormone action on target cells consist of these 5 steps 1.Altering PLASMA MEMBRANE PERMEABILITY of membrane potential by opening or closing ion channels. 2. Stimulating SYNTHESIS OF PROTEINS or regulatory molecules 3. ACTIVATING OR DEACTIVATING ENZYME SYSTEMS 4.Induce SECRETORY activity 5.Stimulate MITOSIS
What utilizes 2nd messenger systems and cyclic AMP and PIP 2 calcium systems and cannot enter target cells and act on PLASMA MEMBRANE RECEPTORS and is coupled by G-proteins to intracellular messengers ? Water-Soluble Hormones ( all amino acid-based hormones except thyroid hormone)
What acts on intracellular receptors that directly activate genes? Lipid-Soluble Hormones (steroid and thyroid hormones)
cAMP signaling mechanism of the plamsa membrane receptors and second messenger system consist of 1. Hormone( 1st messenger) binding to receptor 2. And Receptor activating G-proteins 3.The G-Proteins activating ADENYLATE CYCLASE 4. Andenylate cyclase then converts ATP to cAMP (second messenger) 5.Finally, cAMP activates protein kinases
cAMP is rapidly degraded by the enzyme Phosphodiesterase
PIP2-calcium mechanism is used by some amino acid-based hormones in some tissues and involves a ______ _______ G Protein
G Protein activates what ? Phospholipase C enzyme
Steroids and thyroid hormone utilizes what method ? Intracellular receptors and direct gene activation
steroids and thyroid hormones diffuses into their target cells and does what ? 1. Binds with intracellular receptors 2.Then, receptor-hormone complex enters the nucleus 3.Receptor-hormone complex then binds to a specific region of DNA 4.Which prompts DNA transcription to produce mRNA 5.The mRNA then directs protein synthesis
Target Cells must have a _______ ________ to which the hormonebinds to Specific receptor
ACTH receptors are only found on certain cells of the adrenal cortex
Thyroxin receptors are found on nearly all cells of the body
What three factors does target cells activation depends on 1. Blood levels of the hormone 2.relative # of receptors on or in the target cell 3.Affinity of binding between receptor and hormone
Hormones influence the number of their recptors by Up-reglation and down-regulation
when target cells form more receptors in response to the hormone is known as Up-regulation
when target cells lose receptors in response to the hormone it is known as Down-regulation
Hormones_____ in the blood either _____ or bound Circulate, free
Steroids and thyroid hormones are attached to plasma proteins, while others circulate without carriers.
The concentration of a circulating hormone reflects Rate of releases and speed of inactivation and removal from the body.
Hormones are removed from the body by Degrading enzymes such as the Kidneys and Liver
Multiple hormones may interact in several ways Interaction of hormones on targets cells
One hormone cannot exert its effects without another hormone being present is known as Permissiveness
More than one hormone produces the same effect on a target cell is know as Synergism
One or more hormones opposes the action of another hormone is known as Antagonism
Blood levels of hormones are Controlled by negative feedback systems
Hormones are synthesized and released in response to 1. Humoral stimuli 2.Neural Stimuli 3.Hormonal Stimuli
Changing of blood levels of ions and nutrients directly stimulates secretion of hormones is known as Humoral Stimuli
Nerve fibers stimulate hormone release and sympathetic nervous system fibers stimulate the adrenal medulla to secrete catecholamines is known as Neural Stimuli
Hormones stimulate other endocrine organs to release their hormones Hormonal Stimuli
The nervous system modifies the stimulation of endocrine glands and their negative feedback mechanisms
The pituitary gland (hypophysis) has two major lobes,what are they called ? Posterior pituitary lobe and Anterior pituitary lobe
Posterior pituitary (lobe) : part of the brain that stores what ? Stores ADH & Oxytocin Oxytocin-Paraventricular nuclei ADH- Supraoptic neclei Pituicytes (glial-like supporting cells) and nerve fibers
Anterior pituitary (lobe) (adenohypophysis) Glandular tissue makes what ? FSH, ACTH, LH,TSH, PRL & GH FALT = tropic hormones.
Posterior lobe A downgrowth of hypothalamic neural tissue
The posterior lobe has a Neural connection to the hypothalamus
Nuclei of the hypothalamus synthesize the neurohormones ______and ________ and Neurohormones are then transported to the posterior pituitary and stored. oxytocin and antidiuretic hormone (ADH)
Anterior Lobe Originates as an out-pocketing of the oral mucosa and Carries releasing and inhibiting hormones to the anterior pituitary to regulate hormone secretion
What is the only connection between the ant & post pit ? A vascular connection
All are proteins All except GH activate cyclic AMP second-messenger systems at their targets TSH, ACTH, FSH, and LH are all tropic hormones (regulate the secretory action of other endocrine glands) Anterior Pituitary Hormones
Produced by somatotrophs Stimulates most cells, but targets bone and skeletal muscle Promotes protein synthesis and encourages use of fats for fuel Most effects are mediated indirectly by insulin-like growth factors (IGFs) Growth Hormones
What is the action of growth hormone ? 1.Stimulates liver, skeletal muscle, bone, and cartilage to produce insulin-like growth factors 2.Mobilizes fats, elevates blood glucose by decreasing glucose uptake and encouraging glycogen breakdown (anti-insulin effect of GH
Hypersecretion imbalances of growth hormone results in what in what in children and adults ? In children results in gigantism In adults results in acromegaly
Hyposecreation imbalances of growth hormone results in what in children ? In children results in pituitary dwarfism
Thyroid-Stimulating Hormone (Thyrotropin) is produced and stimulated by what ? Produced by thyrotrophs of the anterior pituitary and Stimulates the normal development and secretory activity of the thyroid
Regulation of TSH release is stimulated and inhibitated by what ? Stimulated by thyrotropin-releasing hormone (TRH) and is Inhibited by rising blood levels of thyroid hormones that act on the pituitary and hypothalamus ( negative feedback)
Adrenocorticotropic Hormone is secreated by and stimulates what ? Secreted by corticotrophs of the anterior pituitary and Stimulates the adrenal cortex to release corticosteroids
Regulation of ACTH release is triggered by what and peaks in AM after rising ? Triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm
What factors can alter the release of CRH ? Internal and external factors such as fever, hypoglycemia, and stressors can alter the release of CRH
Gonadotropins are Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) Secreted by gonadotrophs of the anterior pituitary
FSH stimulates gamete (egg or sperm) production
LH LH promotes production of gonadal hormones Absent from the blood in prepubertal boys and girls
Prolactin (PRL) is secreted by and stimulates what ? Secreted by lactotrophs of the anterior pituitary Stimulates milk production
Regulation of PRL release Primarily controlled by prolactin-inhibiting hormone (PIH) (dopamine) Blood levels rise toward the end of pregnancy Suckling stimulates PRH release and promotes continued milk production
Created by: jennysevere24



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