Chapter 11 Endocrine Glands

Chapter 11 Endocrine Glands

Are ______and secrete hormones into bloodstream

Hormones go to target cells with receptor proteins for it

Neurohormones are secreted into blood by specialized neurons

Hormones affect metabolism of targets

Chemical Classification of Hormones

______hormones are derived from tyrosine or tryptophan

Include NE, Epi, thyroxine, melatonin

Polypeptide/protein hormones are chains of amino acids

Include ADH, GH, insulin, oxytocin, glucagon, ACTH, PTH

Glycoproteins include LH, FSH, TSH

______are lipids derived from cholesterol

Include testosterone, estrogen, progesterone and cortisol

Steroid and thyroid hormones are lipids. Can ______into target cells

Prohormones and Prehormones

Prohormones are precursors of hormones. E.g. proinsulin

Prehormones are precursors of prohormones. E.g. preproinsulin

Some hormones are inactive until activated by target ______

E.g. thyroxine (T4) is inactive until converted to T3 in target cells

Common Aspects of Neural and Endocrine Regulation

Both NS and endocrine system use chemicals to communicate

Hormones are transported in blood and has more ______of effects in targets

Some chemicals are used as hormones and NTs

Targets for both must have specific receptor proteins. Must be rapidly inactivated

Hormone Interactions

A tissue usually responds to number of hormones

2 hormones are ______if work together to produce an effect

A hormone has permissiveeffect if it enhances responsiveness of a target organ to 2nd hormone. If action of 1 hormone inhibits effect of another, it is antagonistic

Hormone Levels and Tissue Responses

______is time required for blood level to be reduced by half

Ranges from mins to hrs for most (days for thyroid hormones)

Normal tissue responses are produced only within physiological range

High (pharmacological) doses can cause number of side effects

Probably by binding to ______of other hormones

Priming effect (upregulation) occurs when a hormone induces more of its own receptors in target cells. Results in greater response in target cell

Desensitization (downregulation) occurs after long exposure to high levels of polypeptide hormone. Subsequent exposure produces a lesser response

Most peptide hormones have ______which prevents downregulation

Mechanisms of Hormone Action

Target cell receptors show specificity, high affinity, and low capacity for hormone

Lipophilic hormones have receptors in target's cytoplasm and/or nucleus;

Called ______action and takes at least 30 mins

Receptors for water-solubles are on surface of target cell

These act through 2nd messengers; effects are ______

Some steroids act on cell surface receptors - nongenomic action

Hormones That Bind to Nuclear Receptor Proteins

Lipid hormones dissociate from carriers to pass thru plasma membrane of target

Receptors are called ______hormone receptors

Serve as transcription factors when bound to hormone ligands

Activate transcription

Have ligand (hormone)-binding and DNA-binding domains

Binds hormone and translocates to nucleus

Binds to ______element (HRE) on DNA,next to target gene

Mechanisms of Steroid Hormones

HRE consists of 2 half-sites

2 ligand-bound receptors have to bind to each HRE (______)

This stimulates transcription of target gene

Hormones That Use 2nd Messengers

Water soluble hormones use cell surface receptors, can’t pass through membrane

Actions are mediated by 2nd messengers

2nd messenger carries ______from receptor to inside of cell

Adenylate Cyclase-cAMP and Phospholipase-C-Ca2+

Mediate effects of many polypeptide and glycoprotein hormones

Epi can act via two 2nd Messengers cAMP and Ca2+

Tyrosine Kinase 2nd Messenger System

Is used by ______and many growth factors to cause cellular effects

Pituitary Gland

Is structurally and functionally divided into anterior and posterior lobes

Hangs below hypothalamus by infundibulum

Anterior produces own hormones. Controlled by ______

Post. pituitary stores and releases vasopressin and oxytocin made in hypothalamus

Anterior Pituitary

Secretes 6 trophic hormones that maintain size of targets

High blood levels cause target to hypertrophy. Low levels cause atrophy

Growth hormone (GH) promotes growth, protein synthesis, movement of ______into cells

Thyroid stimulating hormone (TSH) stimulates thyroid to produce T4 and T3

Adrenocorticotrophic hormone (ACTH) stimulates adrenal cortex to secrete cortisol, aldosterone

Follicle stimulating hormone (FSH) stimulates growth of ______follicles and sperm production

Luteinizinghormone (LH) causes ovulation and secretion of testosterone in testes

Prolactin (PRL) stimulates milk production by mammary glands

Release of A. Pit. hormones is controlled by hypothalamic ______and ______factors and by feedback from levels of target gland hormones

Higher Brain Function and Anterior Pituitary Secretion

Emotional states and psychological stress can affect circadian rhythms, menstrual cycle, and adrenal hormones

Adrenal Glands

Sit on top of kidneys. Each consists of outer cortex and inner medulla

Medulla synthesizes and secretes 80% Epi and 20% NE

Controlled by sympathetic

Cortex is controlled by ______and secretes:

Cortisol: inhibits glucose utilization and stimulate gluconeogenesis

Aldosterone which stimulate kidneys to reabsorb Na+ secrete K+

And some supplementary sex steroids

Adrenal Medulla

Hormonal effects of Epi/NE last 10X ______than sympathetic NS

Activated during "fight or flight" response. Causes effects like:

Increased respiratory rate. Increased HR and cardiac output

Stress and the Adrenal Glands

Stress induces a non-specific response called ______(GAS)

Causes ACTH and cortisol release

Chronic stress can induce high levels of cortisol that causes effects like:

atrophy of hippocampus (involved in memory)

reduced sensitivity of tissues to insulin (insulin resistance)

Thyroid Gland

Is located just below the larynx

Secretes T4 and T3 which set ______and are needed for growth and development

Consists of microscopic thyroid follicles

Outer layer is follicle cells that synthesize T4

Interior filled with ______, a protein-rich fluid

Production of Thyroid Hormones

Iodide (I-) is oxidized to iodine (I2) and attached to thyroglobulin

TSH hydrolysis T4 and T3s from thyroglobulin and then it’s secreted

Diseases of the Thyroid – Goiter

______T4 and T3 don’t provide negative feedback and TSH levels go up

Thyroid gland grows, resulting in a goiter

Hypothyroidism: People with inadequate T4 and T3 levels are hypothyroid

Have low BMR, weight gain, lethargy, cold intolerance

And ______= puffy face, hands, feet

Hyperthyroid: Goiters are also produced by Grave's disease (autoimmune)

Antibodies stimulate thyroid gland to over secrete. Characterized by

Exopthalmos, weight loss, heat intolerance, irritability, high BMR

Parathyroid Glands

Are ______glands embedded in lateral lobes of thyroid gland

Secrete Parathyroid hormone (PTH)

Most important hormone for control of blood Ca2+ levels

Release stimulated by ______blood Ca2+

Acts on bones, kidney, and intestines to increase blood Ca2+ levels

Islets of Langerhans

Are scattered clusters of endocrine cells in pancreas. Contain alpha and beta cells

Alphas secrete glucagon in response to low blood glucose

Stimulates glycogenolysis and lipolysis. ______blood glucose

Betas secrete insulin in response to high blood glucose

Promotes entry of glucose into cells

Converts glucose into glycogen and fat. Decreases blood glucose

Pineal Gland

Is located in basal forebrain near thalamus

Secretes ______in response to activity of suprachiasmatic nucleus (SCN) of hypothalamus

SCN is 10 timing center for circadian rhythms. Reset by daily light/dark changes

Melatonin is involved in aligning physiology with sleep/wake cycle and ______

Secreted at night and is inhibited by light

Thymus

Is located around trachea below thyroid

Produces ______of immune system and hormones that stimulate them

Sex and Reproductive Hormones

Gonads (testes and ovaries) secrete steroid hormones testosterone, estrogen, and progesterone

______secretes estrogen, progesterone, hCG, and somatomammotropin

Autocrine and Paracrine Regulation

Autocrine regulators are produced and act within same tissue of an organ

All autocrines control gene expression in target cells

______regulators are autocrines that are produced within one tissue and act on different tissue in same organ.

Autocrines and paracrines include:

Cytokines (lymphokines, interleukins)

Growth factors (promote growth and cell division)

Neutrophins (provides trophic support for normal and regenerating neurons)

Prostagladins

Have wide variety of functions

Different PGs may exert ______effects in tissues

Some promote smooth muscle contraction and some relaxation

Some promote clotting; some inhibit

Promotes inflammatory process of immune system

Plays role in ovulation

Inhibits gastric secretion in digestive system

Chapter 19: Regulation of Metabolism

Nutritional Requirements

Living tissue is maintained by constant expenditure of energy (ATP)

ATP derived from glucose, fatty acids, ketones, amino acids, and others

______of food is commonly measured in kilocalories (1 kcal = 1000 calories)

Carbohydrates and proteins yield 4kcal/gm; fats-9kcal/gm

Metabolic Rate and Caloric Requirements

Metabolic rate (MR) is total rate of body metabolism

= amount of ______consumed by body/min

Basal metabolic rate (BMR) is MR of awake relaxed person 12–14 hrs after eating and at a comfortable temperature

BMR depends on age, sex, body surface area, ______level, and thyroid hormone levels

Hyperthyroids have high BMR; hypothyroids have low BMR

Metabolism

Is all chemical reactions in body

Includes synthesis and energy storage reactions (______); and energy liberating reactions (______)

Anabolic Requirements

Anabolic reactions synthesize DNA and RNA, proteins, fats, and carbohydrates

Must occur constantly to replace molecules that are hydrolyzed in catabolic reactions

Turnover Rate

Is rate at which a molecule is broken down and ______

Average turnover for Carbs is 250 g/day

Some glucose is reused so net need ~150 g/day

Average turnover for protein is 150 g/day

Some is reused for protein synthesis so net need ~35 g/day

9 ______amino acids must be supplied in diet because can't be synthesized

Average turnover for fats is 100 g/day

Little is required in diet because can be synthesized from ______

2 essential fatty acids must be supplied in diet

Vitamins

Are small organic molecules that serve as coenzymes in metabolism or have highly specific functions

Must be obtained in diet because body does not produce them, or does so in insufficient amounts

Can be placed in 2 classes

______-solubles include A, D, E, and K

______-solubles include B1, B2, B3, B6, B12, pantothenic acid, biotin, folic acid, and vitamin C

Serve as coenzymes in metabolism

Minerals (Elements)

Are needed as ______for specific enzymes and other critical functions

Sodium, potassium, magnesium, calcium, phosphate, and chloride are needed daily in large amounts

Iron, zinc, manganese, fluorine, copper, molybdenum, chromium, and selenium are ______elements required in small amounts/day

Free Radicals

Are highly reactive and oxidize or reduce other atoms

Because they have an ______electron in their outer orbital

The major free radicals are reactive oxygen or reactive nitrogen species

NO radical, superoxide radical, and hydroxyl radical

Serve important physiological functions

Help to destroy bacteria

Can produce vasodilation

Can stimulate cell proliferation

In excess can exert ______contributing to disease states

Can damage lipids, proteins, and DNA

Promote apoptosis, aging, inflammatory disease, degenerative, and malignant growth

Body uses enzymatic and nonezymatic means to protect itself against oxidative stress

Enzymes like ______neutralize free radicals

Nonenzymes like vitamin C and E react with free radicals

Regulation of Energy Metabolism

Blood contains glucose, fatty acids, amino acids, and others that can be used for energy

______energy substrates

Control of Adipose Tissue Levels

Body appears to have negative feedback loops (an adipostat) to maintain a certain amount of adipose tissue

Adipose cells (adipocytes) store and release fat under ______control

And may release their own hormone(s) to influence metabolism

Development of Adipose Tissue

Number of adipocytes increases greatly after birth

Differentiation promoted by high levels of ______

Endocrine Functions of Adipocytes

Adipocytes secrete regulatory hormones called adipokines

Regulate hunger, metabolism, and insulin sensitivity

The adipocyte hormones TNFa, resistin, retinol BP4, and leptin are increased in ______and Type II diabetes

Leptin signals the hypothalamus on how much fat is stored, thereby regulating hunger and food intake

Low Adiposity: Starvation

Starvation and malnutrition diminish immune function

Low adipose levels cause low leptin levels

______cells have leptin receptors

Low leptin thus diminishes immune function

Leptin may play role in timing of puberty and in the amenorrhea of underweight women

Obesity

Childhood obesity involves increases in both size and number of adipocytes

Weight gain in adulthood is due mainly to ______in adipocyte size

Obesity is often diagnosed by using using a body mass index (BMI)

 BMI = w/h2

w = weight in kilograms, h = height in meters

Healthy weight is BMI between 19 – 25

Obesity defined as BMI > 30

60% of pop in US is either ______(BMI>25) or obese (BMI>30)

Regulation of Hunger

Is at least partially controlled by hypothalamus

Involves a number of NTs: endorphins (promote overeating), Norepi (promotes overeating), serotonin (______overeating)

Calorie Expenditure of body

Has 3 components:

Number of calories used at the BMR make up 60% of total

Number used in response to temperature changes and during digestion/absorption (adaptive ______) make-up 10% of total

Starvation can lower MR 40%; eating raises MR 25-40% (thermic effect of food)

Number used during physical activity depends on type and intensity

Absorptive and Post absorptive States

Absorptive state is ______hr period after eating

Energy substrates from digestion are used and deposited in storage forms (anabolism)

Postabsorptive or fasting state follows absorptive state

Energy is ______from storage (catabolism)

Hormonal Regulation of Metabolism

Balance between anabolism and catabolism depends on levels of insulin, glucagon, GH, thyroxine, and others

Pancreatic Islets of Langerhans

Contain 2 cell types involved in energy homeostasis:

α cells secrete ______when glucose levels are low

Increases glucose by stimulating glycogenolysis in liver

β cells secrete insulin when glucose levels are high

Reduces blood glucose by promoting its uptake by tissues

Insulin and Glucagon Secretion

Normal ______glucose level is 65–105 mg/dl

Insulin and glucagon normally prevent levels from rising above 170mg/dl after meals or falling below 50mg/dl between meals

Insulin

Overall effect is to promote anabolism

Promotes storage of digestion products

______breakdown of fat and protein

Inhibits secretion of glucagon

Stimulates insertion of GLUT4 transporters in cell membrane of skeletal muscle, liver, and fat

Transports by ______diffusion

Oral Glucose Tolerance Test

Measures response to drinking a glucose solution

Assesses ability of β cells to secrete insulin and insulin's ability to ______blood glucose

In non-diabetics, glucose levels return to normal within 2 hrs

Glucagon

Maintains blood glucose concentration above 50mg/dl

Stimulates glycogenolysis in liver

Stimulates ______, lipolysis, and ketogenesis

Skeletal muscle, heart, liver, and kidneys use fatty acids for energy

Chapter 20: Reproduction Sexual Development and Disorders

Sexual Differentiation

Y chromosome induces formation of testes

Testosterone (T) from testes induces formation of male sex organs

In absence of T, female sex organs develop

Sexual Reproduction

Gametes (sperm or eggs) are formed in gonads by meiosis

Each has haploid number of chromosomes (23)

Fertilization results in diploidzygote with 46 chromosomes

Each zygote inherits 23 pairs of homologous chromosomes

22 of these are autosomal chromosomes

23rd pair are sex chromosomes: XX in females; XY in males

All ova contain an X chromosome; half the sperm, X and half contain Y

Chromosomal gender of zygote determined by the fertilizing sperm

Only 1 of 2 Xs in females becomes active

Other forms clump of inactive heterochromatin called a Barr body

Formation of Testes and Ovaries

Gonads have potential to become testes or ovaries until testis-determining factor (TDF) causes conversion to testes.

TDF is produced by SRY (sex-determining region of Y) gene

Seminiferous tubules (STs), contain germinal cells and nongerminal Sertoli cells

At ~day 65, Leydig cells (produce T) appear in clusters around STs

In absence of TDF, ovaries develop. Ovarian follicles don't appear until day 105

Development of Testes

Leydig cells secretions masculinizes embryonic structures

Testes descend into scrotum shortly before birth

Spermatogenesis doesn't occur in cryptorchidism (undescended testes)

Development of Accessory Sex Organs

Male accessory sex organs are derived from wolffian ducts

Include epididymis, vas deferens, seminal vesicles, and ejaculatory duct

Female acc.sex organs are from Müllerian ducts, includesuterusfallopian tubes

Development of External Genitalia

External genitalia are same during 1st 6 wks

Testis secretions masculinize these to form penis, male urethra, prostate, scrotum

In absence of T, clitoris forms instead of penis and labia instead of scrotum

Disorders of Embryonic Sexual Development

Hermaphroditism occurs when individuals have both ovary and testis tissue

Pseudohermaphrodites have either testes or ovaries but have accessory organs and external genitalia that are incompletely developed or inappropriate

Onset of Puberty

At beginning of female puberty, high E stimulates growth

High pubertal T in boys causes growth spurt that lags that of girls

Girls with low body fat and high activity levels enter puberty at older age

4 Phases of Human Sexual Response

Excitation phase (arousal) is characterized by increased muscle tone and engorgement of sexual organs with blood

Includes nipples, clitoris, penis, and labia minor. Vagina lubricates

During plateau phase clitoris is partially hidden by swelling labia

Areolae continue swelling. Outer third of vagina engorges

During orgasm, men ejaculate, and women have contractions of uterus and vagina

In the resolution phase, body returns to preexcitation conditions

Men enter refractory period

Male Reproductive System

Testes contain seminiferous tubules (STs) where spermatogenesis occurs; and interstitial tissue housingT-secreting Leydig cells

Sertoli cells of STs contain receptors for FSH. FSH stimulates spermatogenesis

Leydig cells contain LH receptors. LH stimulates secretion of T

Testosterone and Age

Secretion of T declines gradually and varyingly in men> 50. Causes are unknown

Not due to low GnRH, LH, or FSH because their levels are elevated

Spermatogenesis

Germ cells become spermatogonia (stem cells) and replicate thru life by mitosis.

Give rise to haploid sperm by meiosis. Spermatogenesis occurs in wall of STs

Spermatogonia and 1o spermatocytes are located in outer part of ST

Spermatids and mature spermatozoa are located toward lumen. Tails are in lumen

Spermiogenesis

Is maturation and separation of spermatids into mature spermatozoa

Requires participation of Sertoli cells

At end of 2nd meiotic division, 4 spermatids are still interconnected