Homeostasis. What is homeostasis? The ability of the organism to maintain a constant internal state. This process by which conditions are returned to.

Homeostasis

What is homeostasis?

The ability of the organism to maintain a constant internal state . This process by which conditions are returned to a set value is achieved by a Negative Feedback Loop.

It requires; sensory receptors to detect changes in the environment. (stimuli- change to the system)

Monitors (eg. brain, pancreas) that receive and analyze the measures and commands the effector how to respond.

And effectors, (muscles, glands) to perform the appropriate response and restore the ‘change’ to its homeostatic value

Equilibriums of you body…

• Temperature : 37 C• Blood pressure :

120/80 mmHg• Blood pH : 7.4• Blood Osmolarity :

300m osmoles

• Heart Rate: 60-70 per minute

• Breathing Rate : 15/16 per minute

• Blood Glucose : 0.1%

Homeostasis…

• There are two main systems that control homeostasis…

Endocrine System…

• Eg. The Pancreas

• Produces hormones Insulin & Glucagon

• Regulates blood sugar through negative feedback

• High blood sugar = release of Insulin

• Low blood sugar = release of glucagon

Nervous System…

• Consists of the Medulla Oblongata & Hypothalamus

• Nerve stimulation and sometimes hormones to regulate: blood pressure, temperature, fluid and electrolyte balance etc.

Major monitors in homeostasis…

• Medulla Oblongata Hypothalamus

Negative Feedback…

Turns off stimuli

Low/high blood pressure, decrease/increase of body temperature, decrease/increase of breathing rate, regulation of blood sugar ssugarglucose…etc.

Types of receptors…

• External: Thermoreceptors, pressure receptor, mechano receptor, olfactory receptor, light rods/cones receptor

• Internal: chemoreceptors, pressure receptor, osmoreceptor, baroreceptors, C02 receptor, Islets of Langerhans

Thermoreceptors…

•Negative feedback Loop•Hypothalmus sends motor nerves to muscle effectors (erector pili) and glands (sweat)

Negative Feedback…

• Stimulus Receptor Monitor Effector Response

(-)Head rush Pressure in Medulla Smooth muscle Vaso constriction Cartoid Oblongata Cardiac muscle Increased heart

rate Artery

Positive Feedback…

• Increases Stimuli

• Giving birth, blood clotting

Positive Feedback…

Stimulus Receptor Monitor Effector Response

(+) Baby’s head pressure hypothalamus posterior contract uterine

On cervix receptors pituitary releases muscle

oxytocin

References

• http://images.google.ca/imgres?imgurl=http://

• http://en.wikipedia.org/wiki/Human_homeostasis

• http://pespmc1.vub.ac.be/HOMEOSTA.html

• http://www.gonzaga.k12.nf.ca/academics/science/sci_page/biology/homeostasis_notes.htm

The End…