A&PII Ch.16,25,26 FINAL EXAM

what is the thyroid gland?

-largest endocrine gland

-follicles contain T3 and T4

-Parafollicular cells produce calcitonin

What is calcitonin for?

decreasing blood calcium levels

What is more active, T3 or T4?

T3

peripheral tissues convert T4 to...

T3

what are the major T4 to T3 effects?

•Glucose oxidation

•Increase metabolic rate; Increase heart rate

•Heat production

•receptors for these hormones in mitochondria & nucleus

what is a goiter?

lack of iodine; TSH keeps being released because T3 & T4 levels too low

what is Graves disease?

•thyroid hypertrophy (elevated T3 & T4); autoimmune disorder where antibodies mimic TSH

•increased metabolic & heart rates; eyes bulge due to edema;

what is Myxedema?

-adult hypothyroidism

-low metabolic rate, weight gain

what regulates calcitonin?

humoral negative feedback mechanism (Ca2+ concentration in blood)

what is PTH for?

-increasing blood calcium levels

-stimulates osteoclasts, enhances reabsorption of Ca2+ from kidneys

what inhibits PTH?

rising Ca2+ levels

what is the adrenal medulla?

•nervous tissue; acts as part of SNS

what is the adrenal cortex?

glandular tissue

what does the adrenal cortex do?

-Synthesizes & releases steroid hormones called corticosteroids

-3 types produced: mineralocorticoids, Glucocorticoids, Gonadocorticoids

Describe mineralocorticoids

•Regulate electrolyte concentrations of extracellular fluids

•EX: Aldosterone

what is aldosterone for?

most important mineralocorticoid; stimulates reabsorption of Na+ & K+ secretion

-also stimulates consumption of salty foods

aldosterone secretion is stimulated by:

•Decreasing blood volume or pressure

•Rising levels of K+

•ACTH - causes small increases of aldosterone during stress

describe Glucocorticoid (cortisol)

•Secreted in response to ACTH

•Help body resist stress by keeping blood sugar levels constant

•Cortisol promotes gluconeogenesis and increases blood fatty acids & amino acids

what happens with excess levels of glucocorticoids?

•Inhibit inflammation

•Suppress immune system in excess

describe Gonadocorticoids

•Most are androgens (most important is testosterone); some estrogens

what do androgens do?

•contribute to the following in BOTH sexes:

-Onset of puberty

-Appearance of secondary sex characteristics

-Sex drive

•Androgens may be converted to estrogens in bloodstream & brain

what is adrenogenital syndrome

-Genetic

-hypersecretion of adrenal androgens; masculinizing effect (↑ body hair, enlarged genitals)

-40% of females identify as lesbian or bisexual

What does the adrenal medulla do?

secretes epinephrine and norepinephrine

describe epinephrine

•more potent stimulator of heart rate & causes blood glucose levels to rise (glycogenolysis)

-DILATES BRONCHIOLES

describe norepinephrine

•more influential on peripheral vasoconstriction

what does the pancreas do?

•Islets produce insulin & glucagon

•Islets contain 2 major cell types:

-Alpha (a) cells produce glucagon

-Beta (b) cells produce insulin

what does glucagon do?

•Major target: liver, where it promotes:

1) Glycogenolysis

2) Gluconeogenesis

What is glycogenolysis?

breakdown of glycogen to glucose

What is gluconeogenesis?

synthesis of glucose from noncarbohydrates such as glycerol, fatty acids, amino acids (and glucose from lactic acid)

what does insulin do?

•Lowers blood glucose levels by enhancing transport of glucose into body cells

what is the mechanism through which insulin works?

After glucose enters cell, insulin binding triggers enzymatic activity that:

•1) Catalyzes oxidation of glucose (ATP production)

•2) Polymerizes glucose to form glycogen

•3) Converts glucose to fat (in adipose tissue)

insulin also stimulates absorption of what other substance(s)?

stimulates amino acid absorption and protein synthesis by cells AND absorption of glycerol and fatty acids by adipocytes > store triglycerides

what is nervous system modulation?

Nervous system can override normal endocrine controls of blood glucose levels

what does the hypothalamus influence?

1) sympathetic nervous system (E and NE) activated to supply ample glucose

2) if stress continues, ACTH release > to adrenal cortex > glucocorticoids to also elevate glucose

Describe Diabetes mellitus

•From hyposecretion or hypoactivity of insulin

•Three signs:

Polyuria - large urine output

Polydipsia - excessive thirst

Polyphagia - excessive hunger

Describe Type I Diabetes Mellitus

•insulin-dependent

•Autoimmune disorder (beta cells attacked)

•When cells cannot use glucose for energy, turn to fatty acids > ↑ in ketone bodies from fatty acid breakdown >

describe ketosis

↓ pH > may depress brain activity (coma) and decrease "pumping efficiency" of heart.

describe type II diabetes mellitus

•Insulin receptors of target cells don't respond as they once did

•Heredity, obesity/diet

•OFTEN managed with diet & exercise

describe Gestational diabetes

during pregnancy in some women.

what are the other hormone-producing structures?

-Thymus gland

-Pineal gland

-Gastrointestinal tract...gastrin, secretin, CCK

-Adipose tissue - releases leptin, which suppresses appetite

-Gonads

metabolic alkalosis

The cause might include excess consumption of TUMS (antacid)

respiratory acidosis

MOST common type of acid/base imbalance

alkalosis

Nephrons will reabsorb H+ & secrete bicarbonate ions to REVERSE the condition (respond to the condition) of:

c) proteins

Which of the following provides the GREATEST buffering capacity in your BLOOD?

a) HCO3-

b) phosphate ions

c) proteins

d) CO2

b) phosphate ions

Which of these provides the GREATEST buffering capacity inside your CELLS?

a) HCO3-

b) phosphate ions

c) proteins

d) CO2

blood, target cells

Hormones are secreted into your _________ and bind to specific receptors on/in ____________.

different effects on specific tissues

Different combinations of receptors produce _________________________________________________________: regulate metabolic function of cells

seconds to hours

How long can hormone lag time last?

negative feedback

What are hormones regulated by most times?

humoral stimuli

secrete hormones in response to chaning blood levels of ions and nutrients

ex: declining blood Ca2+ concentration stimulates secretion of PTH

neural stimuli

neurons stimulate hormone relese

ex: sympathetic nervous system stimulates adrenal medulla to secrete E & NE

hormonal stimuli

release hormones in response to hormones produced by other endocrine organs ("tropic hormones")

ex: pituitary hormones stimulate targets to secrete more hormones

blood levels of the hormone, relative number of receptors on target cell, affinity of receptors for the hormone

What are 3 factors that target cell activation depends on?

up-regulation

target cells form more receptors in response to low hormone levels; to improve sensitivity to the hormone

down-regulation

target cells lose receptors in response to a hormone; in response to exessively high levels of a hormone

improve sensitivity to the hormone

What is the goal of up-regulation?

excessively high levels of a hormone

What is down-regulation a response to?

free, bound

What are the two forms in which hormones circulate blood?

bound

steroids & thyroid hormones attach to plasma proteins because these hormones are hydrophobic (proteins have charges to help them be carried in plasma)

free

Hormones other than steroids and thyroid hormones are not bound to plasma proteins

steroids, thyroid hormones

What hormones circulate the blood bound?

by the liver (enzymes) and kidneys

How are MOST hormones removed from the blood?

amino acid derivatives, peptide hormones, lipids

What are the 3 hormone groups based on chemical structure?

amino acid derivatives

includes thyroid hormones, epinephrine, and norepinephrine (all from tyrosine), and melatonin (from tryptophan)

tyrosine

What are the amino acid derivative hormones epinephrine, norepinephrine, and thyroid hormones derived from?

tryptophan

What is the amino acid derivative hormone melatonin derived from?

peptide hormones

MOST hormones are this kind

lipids

Include steroid hormones (cholesterol based) and eicosanoids (paracrine factors)

steroid hormones, eicosanoids

What are the two types of lipid hormones?

steroid hormones

cholesterol based, released by ovaries/testes, adrenal cortex, remain in circulation much longer since bound to plasma proteins

ovaries/testes, adrenal cortex

What are steroid hormones released by?

they are bound to plasma proteins

Why do steroid hormones remain in circulation much longer than others?

eicosanoids

paracrine factors, have local effect, hormone-like activity

ex: prostaglandins (inflammation and smooth muscle contraction)

local effect

What kind of effect to eicosanoids (paracrine factors) have?

in plasma membrane, in cytoplasm or nucleus

Where are the two possible locations of receptors on target cells?

first messenger

What do receptors in plasma membranes act as?

second messenger

after receiving signal from first messenger, this affects enzyme activity, altering cellular metabolic reactions

cAMP, Ca2+

What are some examples of second messengers?

G protein (enzyme complex coupled receptor)

Generally, first and second messengers involve this

steroids

affect transcription and protein synthesis; alter synthesis of enzyme and structural proteins affecting cell's metabolic activity and structure

cytoplasmic or nuclear

What kind of cell receptors do steroid hormones bind to?

thyroid hormones

bind to receptors on mitochondria, affecting energy production; bind to receptors in nucleus, affecting cell's metabolic activity and structure

mitochondria, nucleus

What kind of cell receptors do thyroid hormones bind to?

energy production

What does thyroid hormones binding to receptors on mitochondria affect?

cell's metabolic activity and structure

What does thyroid hormones binding to receptors in nucleus affect?

posterior pituitary

ADH & oxytocin secreted and released from which part of pituitary?

regulatory hormones that control anterior pituitary gland

What does the hypothalamus secrete?

through a small portal system

How are regulatory hormones from the hypothalamus transported to the pituitary?

releasing hormones, inhibiting hormones

What are the two regulatory hormone types secreted from the hypothalamus?

adrenal medulla

The hypothalamus has sympathetic neurons that stimulate the release of hormones from where?

epinephrine, norepinephrine

What does the adrenal medulla release?

hypophyseal portal system

blood travels from the hypothalamus to the anterior pituitary

neurophyophysis (posterior lobe), adenohypophysis (anterior lobe)

What are the two lobes of the pituitary (hypophysis) gland?

neurohypophysis, posterior lobe

stores and releases ADH and oxytocin

adenohypophysis, anterior lobe

synthesizes and secretes 7 hormones

water

ADH (vasopressin) increases retention of ? (its main role) & vasoconstriction

increased osmolarity

When do osmoreceptors monitoring solute concentration of blood signal for ADH release?

angiotensin II, ADH, aldosterone

Renin --> ? --> ? and ? release

diabetes insipidus

lack of ADH; can back up to 15 liters of urine per day! treat with nasal spray or tablets

positive

What type of feedback is involved in smooth muscle contraction in breasts during milk release and in the uterus during birth?