endocrine system chapter 40 Flashcards
Endocrine glands
secrete products directly into the bloodstream, which delivers them throughout the body
Exocrine glands
secrete products into ducts, which subsequently take them to lumens of other organs or outside the body
endocrine system
is largely composed of glands that coordinate body activities through the secretion of hormones such as insulin.
How do hormones influence homeostatic functions of an organism?
Metabolism, growth, reproduction, osmoregulation, and digestion
How do some Some hormones control processes unique to invertebrates
metamorphosis
Dramatic transformation that some insects undergo while hatching from an egg, going through several molts, and maturing into adults
Several hormones control this process.
Hormones
Chemical signals that influence the behavior of other individuals
A target cell for a particular hormone carries a receptor protein for that hormone.
How do hormones work?
The hormone binds to the receptor protein and the target cell responds.
Example: Androgen insensitivity: An individual with XY chromosomes (chromosomally male) without receptors in body cells for testosterone appears to be a normal female
Peptide hormones
Peptides, proteins, glycoproteins, and modified amino acids
Most bind to receptors on the plasma membrane.
First messenger – hormone that never enters a cell
What is epinephrine?
Causes quickening of the heart beat
Strengthens the force of the heart’s contraction
Opens up the airways (bronchioles) in the lungs
how does epinephrine work?
The secretion of epinephrine by the adrenal gland is part of the fight-or-flight reaction.
what is another word for epinephrine?
adrenaline
Steroid hormones
All derive from cholesterol, a lipid.
How do steroid hormones work?
They enter the cell by moving through the plasma membrane rather than binding to receptor proteins.
In nucleus, a steroid hormone binds to a nuclear or cytoplasmic receptor.
The hormone-receptor complex binds with DNA and activates genes.
How fast do steroid hormones work?
Steroids act more slowly than peptides but action lasts longer.
Pheromones
(released by same species that is effected)
Women living in the same household tend to have synchronized menstrual cycles due to pheromones released by a menstruating woman affecting other women’s menstrual cycles.
hypothalamus
regulates internal environment in two ways.
Acts through autonomic system (part of the nervous system that supplies the internal organs)
Also controls the glandular secretions of pituitary gland
Posterior Pituitary
*Produces antidiuretic hormone (ADH)
-Controlled by negative feedback
–Effect of the hormone acts to shut down the release of the hormone
*Produces oxytocin
-Controlled by positive feedback
–Stimulus continues to bring about an effect that ever increases in intensity.
(Pushing things out of whack to eventually lead to homeostasis—examples?)
HGH
Use of the drug for performance enhancement is not currently approved by the FDA
Thyroid Gland
Attached to the trachea just below the larynx
Composed of a large number of follicles filled with: Triiodothyronine (T3) and thyroxine (T4)
Triiodothyronine (T3) and thyroxine (T4)
These hormones function to increase the metabolic rate by stimulating most of the body cells to metabolize at a faster rate.
Thyroid actively acquires iodine to produce T3 and T4.
Simple goiter
Thyroid Abnormality
Simple goiter – poor T3 and T4 production
Congenital hypothyroidism (cretinism)
Thyroid Abnormality
Can be iodine deficiencies in pregnant mother, genetic defects affecting production of TSH, T3 and T4 or their receptors
Hypothyroidism
Immune system produces antibodies that destroy the thyroid gland
Untreated hypothyroidism results in myxedema.
Lethargy, weight loss, loss of hair, slow heart rate, lowered body temperature, thickness and puffiness of skin
Hyperthyroidism
over secretion of T3 or T4
Graves disease – antibodies stimulate overproduction of T3 and T4
Exophthalmos – excessive protrusion of eyes
Effects of Calcitonin
Regulates blood calcium level (in part)
Calcium plays a role in both nervous conduction and muscle contraction.
A hormone secreted by the thyroid gland when blood calcium level rises.
Brings about deposit of calcium in the bones
Temporarily reduces activity and number of osteoclasts
When normal levels return, thyroid’s calcitonin release is inhibited.
Adrenal Glands
Paired
One sits atop each kidney
Each consists of an outer cortex and inner medulla.
Two functionally distinct glands (adrenal medulla & adrenal cortex).
Adrenal medulla!
Secretes epinephrine (adrenaline) and norepinephrine (noradrenaline) into the bloodstream
Adrenal cortex
Produces mineralocorticoids and glucocorticoids
Corticoid hormones
balance stress response, energy flow, body temperature, water balance, and other essential processes.
2 groups
Two groups, the glucocorticoids and the mineralocorticoids
chemically control some of the most basic actions necessary to protect, nourish, and maintain the body
Glucocorticoids-sugar levels
Cortisol
Raises blood glucose level
Promotes breakdown of muscle proteins to amino acids, which are converted by the liver into glucose
Promotes metabolism of fatty acids
Counteracts inflammatory response
Example: Cortisone, a glucocorticoid, reduces inflammation
Mineralocorticoids
regulate minerals - inorganic molecules such as sodium, potassium, and hydrogen.
Examples of Mineralocorticoids
Aldosterone, Atrial natriuretic hormone (ANH), Renin-angiotensin-aldosterone system
Renin-angiotensin-aldosterone system
Raises blood pressure
Angiotensin II constricts arterioles
Aldosterone causes kidneys to reabsorb sodium (causing water reabsorption).
Atrial natriuretic hormone (ANH)
Inhibits secretion of aldosterone from adrenal cortex
Causes excretion of sodium ions (natriuresis)
Aldosterone
Promotes two renal functions:
Absorption of sodium
Excretion of potassium
Malfunctions of the Adrenal Cortex
Addison disease, Cushing syndrome
what is the pancreas made of?
Made up of exocrine and endocrine tissue
Endocrine portion of the pancreas:
Consists of pancreatic islets
Produce and secrete
Insulin in the pancreas
Secreted during high blood glucose level
Stimulates uptake of glucose by cells
Glucagon in the pancreas
Secreted during low blood glucose level
Stimulates liver to break down glycogen
Exocrine portion of the pancreas
Secretes enzymes and buffers into the small intestine
Diabetes Mellitus
Inability of the body’s cells to take up glucose as they should
Causes blood glucose levels to be higher than normal
Cells must rely on other sources of energy, such as fatty acids.
As blood glucose levels rise, glucose, along with water, is excreted in the urine
Results in frequent urination and a feeling of extreme thirst
Type 1 Diabetes
Pancreas does not produce enough insulin.
Body turns to the metabolism of fat, which leads to the buildup of ketones in the blood (ketoacidosis).
Patients must have daily insulin injections.
Type 2 Diabetes
Patients are typically overweight and adipose tissue produces a substance that impairs insulin receptor function.
It is prevented/controlled by adhering to a low-fat diet, low-sugar diet, and exercising regularly.
Testes
-Located in the scrotum
Produce testosterone
Secondary sex characteristics
Under the influence of the gonadotropic hormones, testes release increased testosterone at puberty, stimulating growth of penis and testes.
Ovaries
-Located in the pelvic cavity
Produce estrogen and progesterone
Secondary sex characteristics
Estrogen secreted at puberty stimulates growth of uterus and vagina
Anabolic steroids
mimic the effect of testosterone and can lead to very dangerous side effects
Pineal Gland
Produces melatonin
Involved in daily sleep-wake cycle (circadian rhythms)
Controlled by an internal biological clock
Thymus Gland
Most active during childhood
Aids in differentiation of lymphocytes
Leptin
Secreted by adipose tissue
Involved in feedback control of appetite
Erythropoietin
Produced by the kidneys
Stimulates production of red blood cells
Athletes may practice blood doping by using EPO to increase oxygen-carrying capacity of blood.
Prostaglandins
Local hormones
Not distributed in blood
Implicated in pain and discomfort of menstruation
Aspirin reduces body temperature and controls pain because it prevents prostaglandin synthesis.
