Download - Coordination and Regulation
Coordination and RegulationThe endocrine system
homeo = same; stasis = standing Homeostasis is the term we use to describe the
constant state of the internal environment. Homeostasis is a state of
balance in the body. The processes and activities
that help to maintain homeostasis are referred to as homeostatic mechanisms.
Definition of Homeostasis
Set point
You are exposed to ever changing environmental conditions. For example, you may walk out of an air conditioned room into the hot summer sun.
However the cells in your body work best when their surroundings are kept constant. Your body has many mechanisms that keep the cells surroundings constant even though your external environment is changing. This is homeostasis.
Homeostasis is very important because when it fails you become ill and may die.
Homeostasis
Biochemical processes are vital to life and occur efficiently only within a limited temperature range and at a specific pH.
The body must have good internal communication, using the endocrine and nervous systems, to maintain homeostasis.
Maintaining Homeostasis
Linkage system
Effector
Reponse
Sensor
Stimulus
Negative feedbackOccurs when feedback (from sensory organ to CNS) results in a reversal of the direction of change.
Negative feedback tends to stabilise a system, correcting deviations from the set point.
Negative Feedback
The endocrine system
Made up of endocrine glands that release chemical messengers called HORMONES right into the bloodstream.
Allow for the maintenance of the internal environment in the body, or internal homeostasis.
The endocrine system
The endocrine glands include the hypothalamus, pituitary, thyroid, parathyroid, adrenal, thymus, and pancreas.
Functions of Endocrine Glands
The pituitary gland communicates with the hypothalamus to control many body activities.
Functions of Endocrine Glands
What Are Hormones?
Hormones are chemical substances created by the body that control numerous body functions. They actually act as "messengers" to coordinate functions of various body parts. Most hormones are proteins consisting of amino acid chains. Functions controlled by hormones include:
• activities of entire organs• growth and development• Reproduction• sexual characteristics• usage and storage of energy• levels of fluid, salt and sugar in the blood
Endocrine Glands are found throughout the body
Hypothalamus and Pituitary are in the brain
Parathyroids are in the neck and sit on the Thyroid
Adrenals sit on the kidneys
Pancreas is in the abdomen
Testes are in the scrotum and Ovaries are in the hip area
Through negative feedback, when the amount of a particular hormone in the blood reaches a certain level, the endocrine system sends signals that stop the release of that hormone.
Negative Feedback
An example...
Your cells also need an exact level of glucose in the blood.
Excess glucose gets turned into glycogen in the liver
This is regulated by 2 hormones (chemicals) from the pancreas called:
InsulinGlucagon
Controlling Glucose levels
If there is too much glucose in the blood, Insulin converts some of it to glycogen
Glycogen
Insulin
Glucose in the blood
If there is not enough glucose in the blood, Glucagon converts some glycogen into glucose.
Glycogen
Glucagon
Glucose in the blood
Some people do not produce enough insulin.
When they eat food, the glucose levels in their blood cannot be reduced.
This condition is known as DIABETES. Diabetics sometimes have to inject insulin
into their blood. They have to be careful of their diet.
Diabetes
Time
Glucose Concentration
Meal eaten
Insulin is produced and glucose levels fall to normal again.
Glucose levels rise after a meal.
Normal
Time
Glucose Concentration
Meal eaten
Insulin is not produced so glucose levels stay high
Glucose levels rise after a meal. Diabetic
The glucose in the blood increases.Glycogen
Insulin
Glucose in the blood
But there is no insulin to convert it into glycogen.
Glucose concentration rises to dangerous levels.