A&P Ch. 16- Endocrine System

SPC BSC 2086 A&P 2 Chapter 16- Endocrine System

Endocrine system

acts with nervous system to coordinate and integrate activity of body cells

hormones

the Endocrine system Influences metabolic activities via _ transported in

blood

negative

is the Endocrine system mainly controlled by positive or negative feedback systems?

Endocrinology

study of hormones and endocrine organs

slower

Endorcrine system responses _ and last longer than nervous system responses

Exocrine glands

Produce nonhormonal substances (sweat, saliva) ; Have ducts to carry secretion to membrane surface

Endocrine glands

Produce hormones; Lack ducts

Reproduction, Growth and development, water balance, cellular metabolism and energy, body defenses

Endocrine system controls and integrates:

pituitary, thyroid, parathyroid, adrenal, and pineal glands

what are the endocrine glands?

neuroendocrine

Hypothalamus is _ organ

Pancreas, gonads, placenta

what glands have both exocrine and endocrine functions

adipose cells, thymus, and cells in walls of small intestine, stomach, kidneys, and heart

other tissues and organs that produce hormones:

Hormones

long-distance chemical signals; travel in blood or lymph

Autocrines

chemicals that exert effects on same cells that secrete them

Paracrines

locally acting chemicals that affect cells other than those that secrete them

local

Autocrines and paracrines are _ chemical messengers; not considered part of endocrine system

Amino acid–based hormones and steroids

two main classes of hormones:

Amino acid–based hormones

Amino acid derivatives, peptides, and proteins

Steroids

Synthesized from cholesterol, Gonadal and adrenocortical hormones

eicosanoids

A possible third class of hormone; considered a hormone by some scientists, but most classify it as a paracrine

receptors

Though hormones circulate systemically, only cells with _ for that hormone are affected

Target cells

tissues with receptors for a specific hormone

Hormones

_ alter target cell activity

alter membrane permeability, synthesis of enzymes, activate/ deactivate enzymes, stimulate mitosis, induce secretory activity

Hormone action on target cells may be to:

water and lipid soluble hormones

Hormones act in what two ways, depending on their chemical nature and receptor location

Water-soluble hormones

Hormones that act on plasma membrane receptors, Act via G protein second messengers; cannot enter the cell

Lipid-soluble hormones

Hormones that act on intracellular receptors that directly activate genes; can enter the cell

water

are all amino acid–based hormones except thyroid hormones water or lipid soluble hormones?

lipid

are steroid and thyroid hormones water or lipid soluble hormones?

Lipid-soluble, thyroid

_ steroid hormones and _ hormone can diffuse into target cells and bind with intracellular receptors

nucleus

Receptor-hormone complex enters _ and binds to specific region of DNA

Receptor-hormone complex

Helps initiate DNA transcription to produce mRNA

negative

Blood levels of hormones are controlled by positive or negative feedback systems?

Endocrine gland stimuli and Nervous system modulation

hormone release needed for blood levels is triggered by:

Humoral stimuli

Changing blood levels of ions and nutrients directly stimulate secretion of hormones

parathyroid hormone (PTH)

Declining blood Ca2+ concentration stimulates

parathyroid glands to secrete _

Ca2+

PTH causes _ concentrations to rise, and stimulus is removed

Neural stimuli

Nerve fibers stimulate hormone release

adrenal medulla

Sympathetic nervous system fibers stimulate _ to secrete catecholamines

Hormonal stimuli

Hormones stimulate other endocrine organs to release their hormones

anterior

Hypothalamic hormones stimulate release of most _ pituitary hormones

Nervous system

_ can modify stimulation or inhibition of endocrine glands

Nervous system

_ can override normal endocrine controls

specific receptors

Target cells must have _ to which hormone binds

blood levels of hormone, number of receptors, strength of binding

Target cell activation depends on three factors:

Up-regulation

target cells form more receptors in response to low hormone levels

Down-regulation

target cells lose receptors in response to high hormone levels

overreacting

down regulation desensitizes the target cells to prevent them from _ to persistently high levels of hormone

steroids, thyroid

_ and _ hormone are attached to plasma proteins; All others circulate without carriers

Rate of release, speed at which it is inactivated and removed from body

Concentration of circulating hormone reflects:

Degrading enzymes, kidneys, liver

Hormones can be removed from blood by:

Half-life

time required for level of hormone in blood level to decrease by half; Varies anywhere from fraction of a minute to a week, depending on hormone

infundibulum

Hypothalamus is connected to pituitary gland (hypophysis) via stalk called _

8

Pituitary secretes at least how many major hormones?

Posterior pituitary

composed of neural tissue that secretes neurohormones

neurohypophysis

Posterior lobe of pituitary gland, along with infundibulum make up the:

Anterior pituitary (adenohypophysis)

consists of glandular tissue

hypothalamic-hypophyseal tract

Posterior pituitary love maintains neural connection to hypothalamus via _

paraventricular, supraoptic

The hypothalamic-hypophyseal tract arises from neurons in _ and _ nuclei in hypothalamus; runs through the infundibulum

oxytocin and ADH

the posterior lobe of the pituitary secretes what two hormones?

Anterior

Which lobe of the pituitary is glandular tissue derived from an outpocketing of oral mucosa?

Primary capillary plexus, Hypophyseal portal veins, Secondary capillary plexus

The anterior pituitary is vascularly connected to hypothalamus via hypophyseal portal system consisting of:

Hypothalamus

_ secretes releasing and inhibiting hormones to anterior pituitary to regulate hormone secretion

Oxytocin

Strong stimulant of uterine contractions released during childbirth, hormonal trigger for milk ejection; Both are positive feedback mechanisms

Antidiuretic hormone (ADH)

Targets kidney tubules to reabsorb more water to inhibit or prevent urine formation

vasopressin

releases in response to dehydration or high blood salt/sugar concentrations. Causes vasoconstriction

Diabetes insipidus

ADH deficiency due to damage to hypothalamus or posterior pituitary, must stay well hydrated

Syndrome of inappropriate ADH secretion (SIADH)

Too much ADH. Retention of fluid, headache, disorientation. Fluid restriction; blood sodium level monitoring

TSH, ACTH, FSH, LH

which hormones released by the anterior pituitary are tropic hormones (tropins)?

peptide

all six hormones released by the anterior pituitary are _ hormones

all but growth hormone

which hormones released by the anterior pituitary gland activate target cells via cAMP second-messenger system?

GH, TSH, ACTH, FSH, LH, PRL

what hormones are released by the anterior pituitary gland?

Growth hormone (GH)

Has direct actions on metabolism and indirect growth-promoting actions

somatotropin

another name for growth hormone, as it is produced by somatotropic cells

Glucose-sparing actions

direct action of GH on metabolism; _ decrease rate of cellular glucose uptake and metabolism (anti-insulin effects)

liver

direct action of GH on metabolism; Triggers _ to break down glycogen into glucose

fatty acids

direct action of GH on metabolism; Increases blood levels of _ for use as fuel and encourages cellular protein synthesis

insulin-like growth factors (IGFs)

indirect action of GH on metabolism; GH triggers liver, skeletal muscle, and bone to produce _

cellular uptake of nutrients, formation of collagen and deposit bone matrix

IGFs stimulate:

GH

_ stimulates most cells to enlarge and divide, but major targets are bone and skeletal muscle

Growth hormone–releasing hormone (GHRH)

stimulates GH release; Triggered by low blood GH or glucose, or high amino acid levels

Growth hormone–inhibiting hormone (GHIH)

somatostatin, inhibits release; Triggered by increase in GH and IGF levels

Ghrelin

hunger hormone, also stimulates GH release

gigantism

Hypersecretion of GH is usually caused by anterior pituitary tumor; In children results in _

acromegaly

Hypersecretion of GH is usually caused by anterior pituitary tumor; In adults results in _

pituitary dwarfism

Hyposecretion of GH in children results in _

no problems

Hyposecretion of GH in adults results in _

Thyroid-stimulating hormone

Stimulates normal development and secretory activity of thyroid

thyrotropin, thyrotropic cells

Thyroid-stimulating hormone is a tropic hormone that is also called _ as it is produced by _

thyrotropin-releasing hormone

Thyroid-stimulating hormone release is triggered by _ from hypothalamus

thyroid hormones, GHIH

Thyroid-stimulating hormone is inhibited by rising blood levels of _ that act on both pituitary and hypothalamus; also inhibited by _

Adrenocorticotropic hormone (ACTH)

stimulates adrenal cortex to release corticosteroids

corticotropin, corticotropic cells

Adrenocorticotropic hormone (ACTH) is also called _ as it is secreted by _

pro-opiomelanocortin

Precursor to corticotropin is _

corticotropin-releasing hormone (CRH)

ACTH is triggered to release by hypothalamic _ in daily rhythm; highest levels in the morning

fever, hypoglycemia, and stressors

internal and external factors that alter release of CRH include _

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

what are the gonadotropins?

gonadotropic

FSH and LH are secreted by _ cells of anterior pituitary

FSH

_ stimulates production of gametes (egg or sperm)