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Homeostasis- Heart Rate

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Jodie Shudell

on 17 October 2013

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Transcript of Homeostasis- Heart Rate

Homeostasis- Heart Rate
By Jodie Shudell, Terilee Nunn, Danielle Marsland, Emma May, Keziah Powell, Eanna Genocky, and Chelsea Willis

What is it?
Homeostasis control heart rate by sending and receiving messages through the nervous system, and interpreting and responding appropriately to the demands of the body.
Body Temperature
Your body temperature is controlled to maintain the temperature at which enzymes work best, of which is 37 (degrees celcius).
Your body temperature is controlled by the blood flow to the skin, sweating and shivering.
Adrenaline
When you get adrenaline you heart rate increases, this increases the strengh of each heart contraction. When you do get adrenaline you need more oxygen going into your lungs as your body is using up more energy to pump more blood round.
As the adrenaline increases the brain senses this. It then sends signals to the adrenal glands (the kidney) where it secretes adrenaline into the bloodstream.
The role of the internal receptors
There is a part in the brain called the medulla, this is where the cardiac centre is. It receives signals from the chemoreceptors, these detect chemicals. It detects the amount carbon dioxide that is in the bloodstream.
The role of autonomic nervous system
The autonomic nervous system is part of the central nervous system where it controls involuntary activities such as; digestion, respiration and and cardiac function. It controls the cardiovascular system which orginates in the medulla section of the brain. Two neural pathways; the parasympathetic and the sympathetic nervous systems have a direct influence on the heart.
What does it do?
The brain consists of five parts. The medulla controls the heart rate. Two chemicals called epinephrine and norepinephrine go along the nervous system where it will reach the electrical system of the heart, this is called the sinus node. This triggers the heart contractions. Homeostasis always monitors messages that come from the nervous system corresponding between the muscles and joints. When you stop doing any active things your muscles send a message along to the medulla where it releases a hormone called acetylcholine, this slows the heart rate, which slows the contracting of the heart's muscles down.
Why it is important?
Homeostasis for heart rate is important because if your heart rate was not controlled, you can have serious defects such as a heart murmur. This is where your heart beat is irregular, and you can have a heart attack. This is where your heart beats too quickly.
Your body's temperature is controlled by the brain. If too hot or too cold then your brain sends nerve impulses to the skin. The body has three ways to increase or decrease temperature.
- The first way is the hairs on your skin. They trap more air if they are standing up and less air if they are lying flat. (Tiny muscles in the skin quickly pull the hairs upright to reduce heat loss).
- The second way is if the body is too hot, glands under the skin secrete sweat onto the surface of the skin, this is to increase heat loss by evaporation. (Sweat secretion stops when the body temperature returns to normal).
- The third way is your blood vessels supply blood to the skin where it can swell or dilate. (This is vasodilation). This causes more heat to be carried by the blood to the skin, where it can be lost to the air. The blood vessels can shrink down again. (This is called vasodillation). This reduces heat loss through the skin once the body's temperature has returned to normal.
Muscles recieve messages from the brain when the body is too cold. they respond by shivering which then warms you up.
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