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chapter 18
martini and roth essentials of anatomy
108
Anatomy
Undergraduate 1
04/24/2012

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Term
Nervous and Endocrine Systems
Definition

Act together to coordinate functions of all body systems

 
Term

Nervous system

 
Definition

Acts through nerve impulses and “messenger molecules”: neurotransmitters

Faster responses, briefer effects, acts on specific targets in body

 
Term

Endocrine system

 
Definition

Acts through “messenger” molecule: hormones

Released in one part of the body but regulates activity of cells in other parts of body

Slower responses, effects last longer, broader influence in body

 
Term

Exocrine Glands

 
Definition

Secrete their products into ducts that carry secretions into body cavities, into the lumen of an organ, or to the outer surface of a body

Exs.: sweat, sebaceous, mucous and digestive glands

 
Term
Endocrine glands
Definition

Secrete products (hormones) into interstitial fluid which eventually diffuse into blood

Hormones are quite potent – so circulating levels are low in blood

 
Term

Pituitary

Thyroid

Parathyroid

Adrenal 

Pineal 

Definition
Endocrine Glands
Term

Hypothalamus, pancreas, thymus, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, and placenta

 
Definition

Several organs and glands are not exclusively classified as endocrine glands but contain cells that secrete hormones:

 
Term
Endocrine system
Definition
all endocrine glands and hormone-secreting cells 
Term
Hormone Activity
Definition

Hormones bind and thus affect target tissues with specific receptors

Ex.  Thyroid-stimulating hormone only binds to receptors on cells of thyroid gland and not the ovaries (because it does not have TSH receptors)

Receptors for hormones are constantly synthesized and broken down

Down-regulation: Number of target cell receptors decreases if hormone is present in excess

Up-regulation: Number of target cell receptors increases if hormone is deficient

Blocking hormone receptors

RU486: “morning-after” drug; blocks receptor for the hormone, progesterone, which is necessary for implantation of the embryo to take place

 
Term
Down-regulation
Definition
Number of target cell receptors decreases if hormone is present in excess
Term
Up-regulation
Definition
Number of target cell receptors increases if hormone is deficient
Term

Blocking hormone receptors

 
Definition

RU486: “morning-after” drug; blocks receptor for the hormone, progesterone, which is necessary for implantation of the embryo to take place

 
Term
Responses to Hormones
Definition

Response depends on both hormone and target cell

Various target cells may respond differently to same hormone

Insulin stimulates synthesis of glycogen in liver cells and synthesis of triglycerides in adipose cells

Hormone may cause change in permeability  of plasma membrane to a substance in target cell

Hormone may alter the rate of specific metabolic reactions in target cells

Hormone may cause contraction of smooth or cardiac muscle

Term

Hormone’s concentration

Abundance of target cell receptors

Target cells will respond more vigorously the higher the concentration of hormone and the more receptors it has for that particular hormone

Influence exerted by other hormones

Other hormones may enhance or antagonize the effect of a hormone

 
Definition

Responsiveness of target cell depends on: 

 
Term

Lipid-soluble hormones

 
Definition

Steroid hormones: derived from cholesterol

Aldosterone, testosterone, calcitriol, estrogen, progesterone

Thyroid hormones: T3 and T4

Can generally be taken orally

 
Term

Water-soluble hormones

 
Definition

Amine: modified amino acids

Epinephrine (E), norepinephrine (NE), melatonin

Peptide (3 - 49 AA)/ protein (50 – 200 AA)

Insulin, human growth hormone, oxytocin, etc. 

Usually given by injection or iv to avoid being broken down by digestive enzymes in GI tract 

 
Term

Hormones secreted in short bursts

 
Definition

When stimulated, an endocrine gland will release hormone in more frequent bursts, increasing the concentration of the hormone in the blood

Without stimulation, blood level of hormone decreases

 
Term
negative feedback 
Definition
Most hormonal regulation by 
Term
Control of Hormone Secretion
Definition

Hormones secreted in short bursts

When stimulated, an endocrine gland will release hormone in more frequent bursts, increasing the concentration of the hormone in the blood

Without stimulation, blood level of hormone decreases

Regulated by:

Signals from nervous system

Chemical changes in the blood

Ex.: Blood calcium levels regulates secretion of PTH hormone

Other hormones

Most hormonal regulation by negative feedback 

Few examples of positive feedback such as oxytocin in childbirth

 
Term
Hypothalamus and Pituitary Gland
Definition

Both secrete hormones involved in growth, reproduction, metabolism and homeostasis

 
Term
Hypothalamus
Definition

“Grand-master” of the endocrine system

Pituitary gland’s boss

A major link between nervous and endocrine system

 
Term

Pituitary gland

 
Definition

Pea-shaped structure about 0.5 inches in diameter that lies in sella turcica of sphenoid bone

Attached to hypothalamus by infundibulum (stalk)

 
Term

Two anatomically and functionally different portions of Pituitary gland

  

Definition

Anterior pituitary 

Posterior pituitary 

Term
blood portal system
Definition
Hypothalamic hormones reach the anterior pituitary by a 
Term
portal system 
Definition
blood flows from one capillary (microscopic blood vessel in tissue) network into a portal vein, and then into a second capillary network bypassing the heart!
Term
In the hypophyseal portal system
Definition

blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries of the anterior pituitary

This direct route allows hypothalamic hormones to act immediately on anterior pituitary, without them getting diluted or destroyed in the general circulation

 
Term
neurosecretory cells
Definition
Within the hypothalamus are clusters of specialized neurons, called
Term
neurosecretory cells
Definition

They synthesize hypothalamic releasing and inhibiting hormones in their cell bodies and package the hormones inside vesicles

Nerve impulses stimulate the vesicles to undergo exocytosis which then diffuse into the hypophyseal portal system and reach the anterior pituitary gland

Hormones secreted by anterior pituitary gland pass into the hypophyseal portal system and out into the general circulation to travel to target tissues throughout the body

 
Term

hGH, TSH, FSH, LH, PRL, ACTH, (MSH)

 
Definition
nSeven hormones are secreted by anterior pituitary
Term

1)  Releasing hormones which stimulate secretion of anterior pituitary hormones and inhibiting hormones which suppress secretion of anterior pituitary hormones from the hypothalamus

2)  Negative feedback loops by hormones produced by target glands of pituitary hormon

Definition

Secretion of anterior pituitary hormones is controlled by:

 
Term

Human growth hormone (hGH) 
 
Definition

Stimulates secretion of small protein hormones, insulin-like growth factors (IGFs), by tissues such as liver, skeletal muscles, cartilage, and bones. 

 
Term

Functions of IGF’s:

 
Definition

Cause cells to grow and multiply 

Increase protein synthesis in cells

In children and teenagers, increases growth rate of skeleton and skeletal muscles 

In adults, promotes healing of injuries and tissue repair in muscles and bones

Increase lipolysis (breakdown of fatty acids for ATP production) 

 
Term

Pituitary Dwarfism

 
Definition

Hyposecretion of hGH during childhood slows bone growth

Epiphyseal plates close before normal height is reached

Other organs of body also fail to grow

Body proportions are childlike (person is abnormally short but the body parts are in proportion)

Treatment: administer hGH during childhood before epiphyseal plates close

 
Term
Giantism
Definition

Caused by hypersecretion of hGH during childhood

Often due to a pituitary tumor 

Condition causes an abnormal increase in length of long bones

Person grows very tall, but body proportions are about normal

 
Term
Acromegaly
Definition

Caused by hypersecretion of hGH during adulthood

Epiphyseal plates are closed - so bones can no longer lengthen

Bones of hands, feet, cheeks, jaws thicken and other tissues enlarge

Eyelids, lips, tongue, and nose enlarge, skin thickens

 
Term

Thyroid-stimulating hormone (TSH)

 
Definition

Stimulates synthesis and secretion of thyroid hormones (T3 and T4) by thyroid gland

Controlled by TRH (thyrotropin releasing hormone) from hypothalamus

 
Term

Follicle-stimulating hormone (FSH)

 
Definition

In females, stimulates development of oocytes in ovaries

In males, stimulates testes to produce sperm

 
Term

Luteinizing hormone (LH)

 
Definition

In females, stimulates secretion of estrogen and progesterone, and ovulation (release of ovum)

In males, stimulates testes to produce testosterone 

 
Term

Prolactin (PRL)

 
Definition

In females, stimulates secretion of estrogen and progesterone, and ovulation (release of ovum)

In males, stimulates testes to produce testosterone 

 
Term

Adrenocorticotropic hormone (ACTH)

 
Definition

Stimulates secretion of cortisol and other glucocorticoids by adrenal cortex

Regulated by hypothalamus (CRH) and blood levels of glucocorticoids via negative feedback

 
Term
Posterior Pituitary
Definition

Does NOT synthesize hormones

Stores and releases two hormones made by the hypothalamus: oxytocin (OT) and antidiuretic hormone (ADH) 

Consists of axons and axon terminals of more than 10,000 hypothalamic neurosecretory cells

Cell bodies of the neuroscretory cells are in hypothalamus 

OT and ADH are produced in hypothalamus, packaged into vesicles and are stored in axon terminals in posterior pituitary until nerve impulses trigger exocytosis and release of the hormone

 
Term
Oxytocin (OT)
Definition

During and after delivery of baby OT affects mother’s uterus and breasts

During delivery, enhances smooth muscle contraction in wall of uterus (late pregnancy ↑ OT secretion)

After delivery, stimulates milk ejection (‘letdown”) from mammary glands in response to suckling by infant (suckling ↑ OT secretion)

Promotes expulsion of the placenta (afterbirth) and helps uterus to regain smaller size

Synthetic OT (Pitocin): used to induce labor or increase uterine tone and decrease hemorrhage 

In males and non-pregnant females, function of OT is not known – may promote feelings of pleasure during intercourse

 
Term
Antidiuretic
Definition
decreases urine production
Term
Diuretic
Definition
increases urine production
Exs.: caffeine, alcohol (inhibits secretion of ADH)
 
Term
Antidiuretic Hormone (ADH)
Definition

conserves body water by causing the kidneys to return more water to the blood, thus decreasing urine volume

also decreases water lost through sweating and constriction of arterioles which increases BP 

Term
Antidiuretic Hormone (ADH)
Definition

is secreted in response to low BP, dehydration, loss of blood volume

is inhibited in response to high BP and high blood volume

Term
osmoreceptors
Definition
Low blood volume due to hemorrhage, diarrhea, or excessive sweating or dehydration stimulates 
Term
osmoreceptors
Definition
neurons in the hypothalamus that monitor blood pressure and activate the hypothalamic neurosecretory cells that synthesize and release ADH
Term
Diabetes insipidus (DI)
Definition

Disorder due to defects in ADH receptors on kidneys or an inability to secrete ADH (due to brain tumor or head trauma that damages posterior pituitary or hypothalamus)

Symptom is large excretion of large volumes of urine, with resulting dehydration and thirst

Bed-wetting is common in children

A person with DI may die of dehydration if deprived of water for only a day or so

Treatment: subcutaneous injection or nasal spray of replacement ADH (if its due to inability to secrete ADH)

 
Term

Thyroid Gland

 
Definition

Located inferior to larynx (voice box) in neck region

Composed of right and left lobes, one on either side of trachea; connected by an isthmus (anterior to trachea)

Highly vascularized

 
Term
Thyroid follicles 
Definition
are microscopic spherical sacs that make up most of thyroid gland
Term
Wall of each follicle 
Definition

consists of follicular cells which produce thyroid hormones

Thyroxine or tetraiodothyronine (T4)

Triiodothyronine (T3) 

Parafollicular cells produce calcitonin

 
Term
Thyroid hormones (T4 and T3)
Definition

T4 contains 4 atoms of iodine

T3 contains 3 atoms of iodine

Thyroid gland normally contains most of the iodine in the body

Thyroid gland is only endocrine gland to store its hormones in large quantities (100 day supply)

T4 is normally secreted in greater quantity, but T3 is several times more potent

After T4 enters a body cell, most of it is converted to T3 by removing one iodine molecule

Most cells in body have receptors for T3 &T4 so they exert their effects throughout most of body!

 
Term
Actions of Thyroid Hormones
Definition

Increase basal metabolic rate (BMR): rate of oxygen consumption under standard or basal conditions (awake, at rest, or fasting) 

↑BMR = ↑ cellular metabolism of carbohydrates, lipids and proteins

Increase calorigenic effect: the more cells produce and use ATP, the more heat is given off and body temperature rises

Thyroid hormones are important in maintaining body temperature

 
Term
Increase basal metabolic rate (BMR): 
Definition
rate of oxygen consumption under standard or basal conditions (awake, at rest, or fasting) 
Term
Increase calorigenic effect
Definition

the more cells produce and use ATP, the more heat is given off and body temperature rises

Thyroid hormones are important in maintaining body temperature

 
Term
Actions of Thyroid Hormones 
Definition
nRegulate metabolism
qStimulate protein synthesis
qIncrease use of glucose and fatty acids for ATP production
qIncrease lipolysis (breakdown of fat)
qEnhance cholesterol excretion (reduces blood cholesterol level)

Term
Thyroid hormones 
Definition
accelerate body growth especially nervous and skeletal systems during fetal development, infancy and childhood
Term

Congenital hypothyroidism (cretinism): hyposecretion of thyroid hormones (T3 & T4) that is present at birth

 
Definition

Causes severe mental retardation and stunted bone growth if not treated promptly

At birth, baby typically is normal because mother’s thyroid hormones can cross placenta during pregnancy and allows normal development

Most states require testing of newborn thyroid function 

Treatment: oral thyroid hormones at birth and continued for life

 
Term
Adult hypothyroidism
Definition

low blood levels of T3 and/or T4

Occurs 5X more in females than males; ↑ as one ages

Underdiagnosed!!!!!!

Symptoms:

Edema: facial tissues swell and look puffy

Slow heart rate and metabolism

Gains weight easily

Low body temperature

Sensitivity to cold temperatures

Constipation

Lethargy and depression

Treatment: oral thyroid hormones

 
Term
Grave’s disease
Definition

Occurs 7 – 10X more in females than men 

Autoimmune disease

Person produces antibodies that mimic action of TSH

Treatment:

Surgical removal of all or part of thyroid gland

Radioactive iodine to destroy thyroid gland

 
Term
Goiter
Definition
: enlarged thyroid
Term
Exophthalmos
Definition

edema behind eyes which causes eyes to protrude

*Weight loss, overeating

*Elevated BMR

*Restlessness

 
Term
Goiter
Definition

Caused by:

Hypothyroidism

Hyperthyroidism

Low dietary intake of iodine

Iodine salts (iodides) to produce T3 and T4 come from foods e.g. iodized salt and absorbed by intestines

Low iodine→low levels of T3 and T4 →high levels of TSH →enlarged thyroid 

 
Term
Two adrenal glands
Definition

lie superior to each kidney 

Flattened, pyramidal shape

Covered with connective tissue capsule and highly vascularized

 
Term
Adrenal Cortex
Definition

Located in periphery

80-90% of gland

Secretes steroid hormones essential for life: mineralcorticoids, glucocorticoids, and  androgens 

 
Term
Adrenal Medulla
Definition

Located in center of gland

Secretes E and NE

 
Term
Mineralcorticoids
Definition
affect mineral homeostasis 
Term

Aldosterone

 
Definition

Helps regulate levels of Na+, K+, and H+ in blood

Helps regulate blood volume and blood pressure

Secretion of aldosterone is regulated by renin-angiotension-aldosterone pathway (RAA) and K+ levels in blood

RAA is a complex pathway involving kidneys, lungs, and liver

 
Term
Glucocorticoids
Definition
affect glucose homeostasis
Term
cortisol 
Definition

Controlled by negative feedback loop

ACTH from anterior pituitary stimulates its release

CRH from hypothalamus promotes release of ACTH due to stress and/or low level of glucocorticoids 

 
Term
Increase protein breakdown
Definition
: (mainly in muscle fibers); release free AA’s into bloodstream
Term

Increase gluconeogenesis

 
Definition

Liver cells produce and secrete glucose from AA or lactic acid to bloodstream for rest of body

 
Term

Increase resistance to stress 

 
Definition

Additional glucose made by liver cells provides tissue with ready source of ATP to combat a wide range of stresses on the body

 
Term

Decrease inflammation

 
Definition

Inhibit WBC’s that participate in inflammatory responses

 
Term

Decrease immune response

 
Definition

High doses of glucocorticoids (prednisone) are used in organ transplant recipients to depress immune system

 
Term
Effects of Glucocorticoids (Cortisol) 
Definition

Increase protein breakdown: (mainly in muscle fibers); release free AA’s into bloodstream

Increase gluconeogenesis

Liver cells produce and secrete glucose from AA or lactic acid to bloodstream for rest of body

Increase resistance to stress 

Additional glucose made by liver cells provides tissue with ready source of ATP to combat a wide range of stresses on the body

Decrease inflammation

Inhibit WBC’s that participate in inflammatory responses

Decrease immune response

High doses of glucocorticoids (prednisone) are used in organ transplant recipients to depress immune system

 
Term

Androgens (weak ones)

 
Definition

DHEA (dehydroepiandrosterone) is main one

ACTH stimulates secretion

Produced in both males and females

DHEA promotes axillary and pubic hair growth and growth spurt in pre-pubescent boys and girls

After puberty in males, the androgen, testosterone, is released in greater quantities so DHEA becomes insignificant

In women, DHEA promotes libido (sex drive) and can be converted to estrogens in other body tissues

After menopause, when ovarian secretion of estrogen stops, all estrogen comes from conversion of DHEA

 
Term
DHEA (dehydroepiandrosterone) 
Definition

ACTH stimulates secretion

 
Term
Chromaffin cells 
Definition

are the hormone-producing cells of adrenal medulla

Directly innervated by sympathetic neurons of the ANS

 
Term
ANS 
Definition
has direct control over chromaffin cells and their hormone release
Term

Adrenal medulla secretes epinephrine (E) and norepinephrine (NE)

 
Definition

Not essential for life

Enhance fight-or-flight response during sympathetic response of ANS during exercise or stress

Effects of these hormones resemble those of the sympathetic division neurotransmitters of same name, except they last up to 10X l

Term

Pancreas

 
Definition

Flattened, organ about 4-6 inches in length

Located behind stomach and in the curve of duodenum (first part of small intestine)

consists of head, body, and a tail portion.
Term
Pancreas
Definition
is both an exocrine & an endocrine gland
Term
Exocrine
Definition
: 99% of cells arranged in clusters (acini) produce digestive enzymes
Term
Endocrine
Definition
pancreatic islet or islets of Langerhans contain hormone-secreting cells:
Term
Alpha cells
Definition
: secrete glucagon
Term
Beta cells
Definition
secrete insulin
Term

Regulation of Insulin and Glucagon Secretion

 
Definition

Blood glucose levels primarily control secretion of glucagon and insulin via negative feedback

 
Term

Glucagon: increase blood glucose level

 
Definition

Acts on hepatocytes (liver cells)

 
Term

Insulin: decrease blood glucose level

 
Definition

Helps glucose into adipose, cardiac and resting skeletal muscle cells

 
Term

Low blood glucose

Increased sympathetic activity of ANS, as occurs during exercise

 
Definition
Glucagon secretion is stimulated by
Term

High blood glucose

Parasympathetic activity of ANS (“Rest and digest”)

With increasing age, insulin is released more slowly 

 
Definition
Insulin secretion is stimulated by
Term
Diabetes Mellitus
Definition

Most common endocrine disorder

Two types: Type I and Type II diabetes mellitus

4th leading cause of death in U.S. 

If present trends continue, one in three Americans, and 1 in 2 minorities, born in 2000 will develop diabetes in their lifetime

Caused by inability to produce or use insulin

Because insulin is either unavailable or not able to aid transport of glucose into cells, blood glucose levels become high (hyperglycemia) and “spills” into the urine (glucosuria)

Three “polys” of diabetes mellitus:

Polyuria: excessive urine production

Polydipsia: excessive thirst

Polyphagia: excessive eating

 
Term
Polyuria
Definition
: excessive urine production
Term
Polydipsia
Definition
excessive thirst
Term
Polyphagia
Definition
excessive eating
Term

Warning Signs of Diabetes Mellitus

Type I Diabetes

 
Definition

Polyuria: frequent urination 

Polydipsia: unusual thirst 

Polyphagia: extreme hunger 

Unusual weight loss 

Extreme fatigue 

Irritability

 
Term

Warning Signs of Diabetes Mellitus

Type II Diabetes

 
Definition

Any of the type 1 symptoms 

Frequent infections 

Blurred vision 

Cuts/bruises that are slow to heal 

Tingling/numbness in the hands/feet 

Recurring skin, gum, or bladder infections

 

Term
Complications of Diabetes Mellitus
Definition

Heart Disease and Stroke

High Blood Pressure 

Blindness 

Cataracts: excessive glucose attaches to lens causing cloudiness

Damage to blood vessels of retina (diabetic retinopathy)

Kidney Disease 

Damage to renal blood vessels (diabetic nephropathy)

Nervous System Damage (diabetic neuropathy)

Gangrene/Amputations 

Dental Disease 

Pregnancy Complications 

Sexual Dysfunction 

 
Term
Type I Diabetes 
Definition

Insulin-dependent diabetes mellitus

Usually appears before age 20, persists throughout life

Autoimmune disease

Immune system destroys beta cells of pancreas; so patients can’t make insulin

Trigger for autoimmune disease is unknown; combination of genetic factors and environmental exposure

Most common in northern Europe

In U.S., higher prevalence in whites than African or Asian populations

 
Term
Treatment of Type I Diabetes
Definition

Self-monitoring of blood glucose levels (up to 7X daily)

Regular meals 

Low fat, plant-based diet (vegetables, fruits) can decrease amount of insulin needed

Exercise

Decreases resistance of cells to insulin

Insulin injections

Typically everyday and may be up to 3X a day

Implantable pumps

Replaces repeated injections of insulin

Pancreas transplant

Need to be on immunosuppressive drugs for life 

 
Term
Type II Diabetes Mellitus
Definition

Non-insulin-dependent diabetes mellitus

Represents more than 90% of cases of diabetes mellitus

Most often occurs in overweight/obese people over age 35

Number of overweight/obese children and teenagers with type II diabetes is increasing

High number of type II diabetes in minority populations (African- and Latino-Americans) in U.S.

Most type II diabetics still produce insulin, but target cells no longer respond to it!

Due to down-regulation of insulin receptors

 
Term
Type II Diabetes Mellitus
Definition

Type II diabetes is a preventable disease!!!!!!!!!!!!!!

Disease develops primarily from LIFESTYLE FACTORS:

Being overweight/obese 

Poor diet: Too high in refined carbohydrates (white rice, bread, pasta, sugar, etc.) and fat (impedes absorption of glucose into cells)

Lack or not enough exercise 

 
Term
Prevention/Treatment of Type II Diabetes
Definition

Diet: Eating more fibrous foods (vegetables, fruits, beans, whole grains) increases satiety and decreases risk of developing diabetes.

High in fresh (cooked and raw) vegetables (especially green leafy vegetables (lettuces, kale, collards, chard, spinach)

Beans/Lentils 

Fruit 

LOWER FAT (fats should come from raw nuts/seeds, avocado) (Max. 15-20% of total calories)

*Some whole grains (brown rice, quinoa, amaranth, slow-cook oatmeal)/starchy vegetables (sweet potatoes, yams, potatoes, winter squash)

Low to no animal products (too high in fat) 

No processed/refined food, soda pop, sugary drinks (fruit juice), oils, sugar, salt

 
Term
Prevention/Treatment of Type II Diabetes
Definition

Exercise Everyday (aerobic and weight resistance) 

Increases insulin sensitivity of cells

Helps build lean muscle mass (more insulin-responsive than fat tissue)

Weight loss or maintaining healthy weight

Increases insulin sensitivity of cells

Decrease body fat (adipose tissue) 

Stored body fat has metabolic life of its own (increases appetite, causes inflammation and interferes with insulin action)

Most people are over-fat and under-muscled!

 
Term
Prevention/Treatment of Type II Diabetes
Definition

Sleep

People with chronic insomnia or who sleep five hours or less per night have highest rates of diabetes compared with normal sleepers

Sleep deprivation decreases hormone levels of leptin (makes you feel full) and increases ghrelin (makes you feel hungry)

Keep your teeth and gums clean

Moderate gum disease increases risk (2X) of developing diabetes

Bacterial infection can increase inflammation and impair insulin action

Drugs: (Metformin, Avandia, etc.)

They have side effects!!!!!!!

 
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