Excretory System (formation of urine; anatomy and physiology) Link:

Nervous System LInk

Endocrine System Link (or any other body parts/ illness/ nosebleeds/ cysts)

Unit 5: Homeostasis
Homeostasis: To maintain a constant internal environment despite changes in the external environment (reffered to as dynamic equilibrium)

- Body maintains these constant conditions via a series of monitored adjustments
- therefore there must be CONSTANT monitoring/adjustments happening
3 functional components:
1.Monitor (sensor): Senses something is outside the normal limits and sends a message to the coordinating center
2.Coordinating Center: Relays info from monitor to the appropriate regulator
3.Regulator: Restores the normal balance
In order to maintain internal conditions your body uses mainly 2 feedback loops: negative/positive feedback:

Negative Feedback:
- Means the opposite
- These systems (many) make adjustments to bring the body to a normal range
- Prevent small changes from becoming a large change

Positive Feedback:
- These systems (few) reinforce a change from the normal range
- less common
- Ex: Childbirth (oxytocin -----> small contraction innitiate larger contraction until stronger :) baby is born)



Steroid vs. Protein

Causes kidneys to increase water reabsorption in response to high blood osmotic pressure.
Acts on nephrons to increase Na+ and H2O reabsorption in response to low blood pressure and volume.
Islets of Langerhans (beta cells)

Blood Sugar
Regulates blood sugar levels by increasing the permeability of cells to glucose. Promotes conversion of glucose to glycogen by liver.
Islets of Langerhans (alpha cells)

Blood Sugar
When blood sugar levels are low glucagon promotes conversion of glycogen to glucose by liver.
anterior pituitary gland
Growth Hormone
Most cells
Stimulates growth of body. Mostly affects cartilage and bone cells.
anterior pituitary gland

mammary glands
only released after childbirth; stimulates the mammary glands to make breast milk.
posterior pituitary gland

uterus & mammary glands
causes the uterus to contract during childbirth.
thyroid gland

Reduces calcium in the blood; calcium moves into bones.
thyroid gland

most body cells
increases rate of metabolism of body cells
adrenal gland
liver and other body cells
Increases the level of amino acids in the blood (which get converted to glucose) to help the body recover from stress.
Adrenal Medulla

Released with norepinephrine in times of stress/crisis.
Increases blood sugar, heart rate, breathing rate, cell metabolism.
Dilates blood vessels and the irises of the eyes.
adrenal medulla

Initiates the same physiological responses as epinephrine to stress/crisis.
Initiates fight-or-flight response.
anterior pituitary gland

promotes testosterone production in males and ovulation in females.
anterior pituitary gland

promotes development of follicles in ovary and increases sperm production

male sex hormone stimulating maturation of sperm cells and development of secondary sexual characteristics.

female sex hormone causing thickening of endometrium and development of secondary sexual characteristics

female sex hormone; maintains uterine lining during pregnancy
anterior pituitary gland

thyroid gland
stimulates thyroid gland to secrete thyroxine which regulates cell metabolism
anterior pituitary gland

adrenal cortex
stimulates the outer layer of the adrenal gland to secrete hormones involved in stress responses
parathyroid glands
Parathyroid Hormone (PTH)

special cells in bone
raises calcium levels in blood; calcium released from bones.


Maintains the body's circadian rhythm; our internal 24 hour clock that helps us wake up and fall asleep


Plays a role in our immune system function; stimulates the production of immune cells (ex. killer T cells)

responsible for the release of FSH and LH from the anterior pituitary gland
Cow's Eye Dissection

Sheep's Brain Dissection

Nerve Impulse/Action Potential Animations

Urinary System
January 11th, 2011
Fiona D'Arcy
  • We get rid of wastes as they are toxic.
  • Specifically urea and ammonia
  • Urea is produced from the deamination of ammonia (ammonia is more toxic to the body so it is mainly converted to urea, which is less toxic)
  • Complex organisms must store and later dispose of wastes
  • To lower the concentrations of these wastes as they stay in our bodies, we must keeps fluids up by drinking beverages with lots of water.
  • Dieretics such as coffee, tea, and cola only serve to make you have to urinate, and thus aren't good fluids
  • The average human bladder can store up to 600ml of urine until voluntary control is lost (you wet your pants!)
Kidney structure
  • The kidneys are the main organ involved in the formation of urine
  • Note that the word renal refers to anything kidney related
  • The path wastes travel into our kidneys(carried in the blood) is as follows:
  • Renal arteries -> renal pelvis -> renal medulla -> nephron
external image slide0008_image027.jpg external image image1.png
  • There are about one million nephrons in your kidney's
  • They begin as the renal artery branches into arterio;es within the kidney
  • The structure of the nephron is as follows:
  • Glomerulus -> Bowman's capsule -> proximal tubule -> Loop of Henle -> distal tubule -> collecting duct
external image 08nephron1.jpg
  • The glomerulus filters small molecules and substances from blood into Bowman's capsule(selects based on size so that large molecules like blood cells and proteins do not go though). It is sort of like a capillary-bed in a fist shape that squeezes the blood to let the liquid and tiny things out but keeps the big solids in.
  • The Bowman's capsule surrounds the glomerulus, like a cup that catches and funnels the resulting substances let in by the glomerulus.
  • The proximal tubule is where reabsorbtion occurs, that is, nutrients that are needed get put back into the blood.
  • The Loop of Henle has a descending arm (where water leaves) and an ascending arm (where salt leaves).
  • The distal tubule is where secretion occurs, that is, any other wastes leave the blood to enter the nephron.
  • The collecting duct is where the resulting urine joins the collecting ducts of other nephrons to lead it out of the kidney (like a little drains collecting it together)
  • Reabsorbtion and secretion, as well as the diffusion of water and salt, are to keep the threshold level needed in the body
For more information, see chapters 7.4 to 7.7 of the textbook.
Refer to the worksheet, Comparing Solutes in the Plasma, Nephron, and Urine
Also see the chapter 7 review handout of key terms and concepts.

Here is a narrated animation that gives a nice visual of the kidney and nephron fuction, though it goes more into depth and has added info and details for extra knowledge. Still good to skim over for the basics though.

Here is a really cool website with an interactive animation that has info and shows the path of each kind of molecule as it enters the nephron. Check it out.
And don't forget there are links at the top of this page too!

Endocrine System - January 2011
Marshell Kurniawan

Hormones: Chemicals that are released by cells in order to affect other cells. These chemicals are considered to be regulators.
Glands of the endocrine system secrete chemicals into the blood to be carried to other organs of the body. These chemicals are called endocrine hormones.
2 types of hormones which are classified by their activation site:
1) Non-target Hormones: hormones that affect MANY cells THROUGHOUT the body
ex. ex. Growth hormone (GH) or Somatotropin (STH): used to stimulate growth of the body
Insulin: regulate blood sugar, increase permeability of cells to glucose
Adrenaline: accelerates heart rate and body reaction during crisis

2) Target Hormones: hormones that affect SPECIFIC cells or TARGET tissues
Ex. Parathyroid hormone: regulate calcium level in body
Gastrin: stimulate cells of stomach to produce digestive enzymes

-The endocrine system, like the nervous system, provides control of the organ tissue.

What’s their difference then?
Nervous system: enables the body to adjust QUICKLY to changes in the environment
Endocrine System: designed to maintain control over a LONGER DURATION.
The hypothalamus makes their differences more apparent.
The Hypothalamus regulates the pituitary gland through nerve stimulation. The pituitary gland then stimulates the endocrine gland to secrete chemicals that affect the nerve activity of the hypothalamus. Their relationship is not linear, it’s circular.
Hormones acts as regulators to either speed up or slow down certain bodily processes.

Chemical Signals
Hormones do not affect all cells… why? Cells have a variety of receptors and some cells have receptors for one hormone, but not another. Less active cells contain fewer receptor sites, such as cartilage and bone cells.

There are 2 types of hormones (different in structure and functions):
1) Steroid hormones
a. Made from cholesterol, a lipid compound, which is made up of rings of C, H, O and not soluble in water
b. Action of steroid hormone:
i. The Steroid Hormones is removed from the cell that created them, through diffusion.
ii. The Steroid Hormone then enters another cell called the target cell, through diffusion, and attaches to a molecule called the receptor molecule, located in the cytoplasm of the target cell.
iii. When the hormone attaches to the receptor, a hormone-receptor complex is created, and this hormone-receptor complex moves into the nucleus and attaches to a DNA, specifically a segment of chromatin with a shape complementary to the complex.
iv. The hormone activates a gene that sends a message to the ribosome in the cytoplasm to produce a specific protein.
2) Protein Hormones
a. Contain chains of amino acids of different lengths and are soluble in water. Examples of such hormones are insulin and growth hormones
b. Function
i. Protein hormones are released from the cell.
ii. The hormone then attaches to a receptor site which is located on the outside of cell membrane, the cell membrane that it came out from.
iii. The combination of the protein hormone and the receptor site creates a hormone-receptor complex, which activates the production of an enzyme called Adenylyl cyclase (This only happens to some of the protein hormones… why?)
1. Specific hormones combine at specific receptor site
iv. The enzyme, adenylyl cyclase, will cause the cell to convert Adenosine triphosphate (ATP) into cyclic adenosine monophosphate (cAMP).
1. The cyclic AMP acts as a messenger which activates enzymes in the cytoplasm to carry out their normal function

What controls the endocrine gland? The pituitary gland!
-Small sac-like structure connected to the hypothalamus (the hypothalamus is the area of the brain in association with homeostasis)
-The hypothalamus-pituitary complex shows the interaction between the Nervous system and the Endocrine system
The pituitary gland: produce and store hormones
The hypothalamus: stimulate the release of hormones by the pituitary gland by nerves


-The pituitary gland is composed of:
a) Posterior Lobe: stores and release hormones such as antidiuretic hormone (ADH) and oxytocin, which have been produced by the hypothalamus.
-ADH acts on the kidneys and regulate water flow
-Oxytocin: strong uterine contraction during labour
-Hormones travel by way of specialized nerve cells from the hypothalamus to the pituitary
b) Anterior Lobe: produces its own hormones.
-The anterior lobe: richly supplied with nerves from the hypothalamus
The hypothalamus regulates the release of hormones from the anterior pituitary… How? Hormones are secreted from the nerve ends of the cells of the hypothalamus and transported in the blood to the pituitary gland. Specific cells in the pituitary are activated by the hormones secreted from the hypothalamus, causing the release of pituitary hormones which are carried by the blood to target issues.
-Hypothalamus-releasing factors: inhibit the secretion of hormones from the anterior lobes
- Dopamine: inhibit secretion of prolactin (PRL) a pituitary hormone that stimulates the production of milk in women after giving birth
-Stomatostatin: inhibit secretion of somatotropin, hormone responsible for the growth of long bones

Awesome Website to reinforce the importance of the endocrine system

Nervous System - January 17, 2011
Aleena Dipede

Check out this link if you are having some troubles or want a quick review, it's pretty basic but gives you a great general idea.

Action Potential - January 17, 2011
Aleena Dipede

This is a really good website, goes through everything there is to know about Action Potential with words and animated diagrams.

Good luck everyone! :)