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Excretory System May 29, 2012
Endocrine System –regulates overall metabolism, homeostasis, growth and
reproduction through chemicals released into the bloodstream
Endocrine Glands – secrete hormones directly into the bloodstream
Exocrine Glands –Discharge hormones into ducts which carry the secretions to where
they are used
...
They
are chemical messengers which cause a specific change in behaviours by specific
target tissues
...
These hormones
are produced in the outer layer of the adrenal gland and in the gonads
...
This then enters
the nucleus and binds to the DNA and produces its effect by acting on the DNA
...
They act without entering the target cells by

binding to receptor proteins located on the surface of the target cell’s membrane
...
It causes
the victim to be tall but normally proportioned
Acromegaly – a hyper secretion of growth hormone by the anterior pituitary that
causes abnormally large hands and feet with enlarged facial structures
Dwarfism – A hypo secretion of growth hormone by the anterior pituiaty that causes
the effected individual to be small but normally proportioned
...

Crushings Disease- A hyper secretion of aldosterone cortisol by the adrenal cortex
that causes excess fat deposits in the upper body
...
Symptoms include being
sluggish, weak, weight loss and increased skin pigmentation
Hypoglycemia – A hypo secretion of glucagon by the pancreas that causes low blood
glucose levels
Hyperthyroidism – A hyper secretion of thyroxine by the thyroid that causes
nervousness, irritability, weight loss, insomnia, goiter and protruding eyes
Cretinism – a hypo secretion of thyroxine by the thyroid in early childhood causing
dwarfism with out of proportioned limbs and often mental retardation
...
It directly affects protein, carbohydrate and
fat metabolism at the cellular level
Follicle Stimulating Hormone (FSH)- Stimulates the development of egg cells in the
ovaries of females and the production of sperm cells in the testes of males produced
by the pituitary gland
Luteinizing Hormone (LH)– causes the release of egg cells from the ovaries and
controls the production of sex hormones produced by the pituitary
Prolactin – stimulates the secretion of milk by the mammary glands after birth
Posterior Pituitary
Oxytocin – stimulates the contraction of smooth muscles of the uterus during
childbirth
Antidiuretic (AdH)– controls reabsorption of water by the nephrons of the kidneys
...

Adrenal Cortex
Cortisol Hypercortisone – Targets the liver and is involved in glucose synthesis
...
It is produced synthetically and is used as a
drug for the treatment of arthritis and counteract the symptoms of allergies
Aldesterone – Targets the kidneys to maintain a normal mineral balance in the blood
...
It also controls the volume of intercellular fluid
Pancreas – an organ both an endocrine and exocrine gland that secretes digestive
juice and the hormones insulin and glucagon
Islets of Langerhans – clusters of hormone secreting cells in the pancreas
Alpha cells – secrete glycagon
Beta cells – Secrete insulin

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Diabetes Mellitus – When the islets of Langerhans fail to produce enough insulin and
the amount of glucose that can enter the body cells is decreased resulting in the
concentration of glucose in the blood increasing and the excess sugars being excreted
in the urine
...
It increases the rate at which
glucose is moved through the cell membranes in most of the body tissues
...
It lowers blood
sugar and increases absorption
Glucagon – Targets body cells, the liver and fat cells
...
It promotes the conversion of glycogen to glucose in the liver
...
It is involved in the regulation of the blood
calcium level
...
It increases the rate of protein,
carbohydrate and fat metabolism and the rate of cellular respiration
...

Parathyroid glands – 4 tiny oval glands embedded in the back of the thyroid
...
They are secreted in response to sudden
stresses (fear, anger, pain, physical exertion)
...
It burns
amino acids, stores sugar as glycogen and is involved in detoxification
...
This is usually caused by overloading the kidneys with harmful substances
like alcohol
Jaundice – when bile is improperly excreted and its metabolic wastes are reabsorbed
into the blood
...
They are the ovaries of the females and testes of the males
...
It acts with progesterone to
regulate the menstrual cycle
...

Progesterone – a hormone produced by the corpus luteum to prepare the uterus for
pregnancy and help maintain the uterine lining during pregnancy
Corpus Luteum - a progesterone secreting yellow body in the ovary formed when
luteinizing hormone causes a ruptured follicle

Follicle – the structure in the ovaries in which the mature egg develops under the
influence of FSH
Thickening of the Uterus Lining – caused by estrogen and progesterone
...
It helps in the processing of
lymphocytes and produces the hormone thymosin
...

Thymosin – produced by the thymus it is though tot stimulate the development of T
cells
Pineal Gland – a pea-sized shaped structure attached to the base of the brain
...
The major ones are cortisol and aldosterone but 30 others are known
...
It receives information from the nervous system to help determine
when it should stimulate the pituitary to release a hormone which is influenced by the
various hormones in the blood
Releasing Factors –hormones produced by the hypothalamus that control the release
of hormones from the anterior love
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Renal Cortex – the outer layer of the kidney that contains the nephrons and filters
the blood
Renal Medulla – the middle layer of the kidney that is made of collecting ducts which
carry the filtrate to the pelvis
Renal Pelvis – The inner layer of the kidney that is the cavity connected to the ureter
...

Distal Convoluted Tubules – absorbs salts and help regulate pH
Collecting Duct – collects the urine from the nephron and brings it to the renal pelvis

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Filtration – takes place in the gomeruli and the Bowman’s capsule where under
pressure blood’s filtrate is forced through the thin walls of the glomeruli into the
Bowman’s capsule
...

Filtrate – mostly blood plasma it is composed of water, urea, glucose, amino acids and
various salts
Reabsoption – Occurs in the renal tubules where the volume of filtrate is reduced and
important substances are returned to the blood
...

Kidney Threshold Level –if the concentration of a substance in the blood is greater
than a certain level, the excess substance is not reabsorbed
Urine – the fluid remaining in the tubules after reabsorption
...
If the stones are too big to be passed with the urine they must be surgically
removed or shattered
Dialysis – An artificial kidney machine used to filter the blood when both kidneys fail
Nitrogenous wastes – come from the amino acids of proteins being changed into
ammonia
...
It supports
the skin and binds it to the muscle and bone lying beneath
Sebaceous Glands – produce oily secretions that provide a protective coating to the
skin and hair and keep them soft and pliable
Sweat Glands – made of tiny coiled tubes that open to the surface of the skin through
pores where sweat containing small amounts of urea and salts is released
4 functions of skin
-keeping microorganisms and foreign materials from entering the body

-keeps the body from drying out

-excretes small amounts of urea, salt and water

-removes excess heat

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