B5- Homeostatis

What’s homeostatis

The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.

Why is homeostasis important

• it is important to regulate our body’s internal conditions to ensure that our enzymes and cells function well

• If conditions are not optimal, then our enzymes can denature, reducing their ability to catalyse metabolic reactions

What does homeostatis regulate?

• Glucose levels

• Water levles

• Temperature

• Homeostasis is maintained by two main organ systems:

  • The nervous system

  • The endocrine system

• They maintain homeostasis by constantly monitoring and adjusting the composition of blood and tissues

What’s a stimulus/ stimuli

change in the environment

What do neurones do?

Neurones carry information as electrical impulses

Impulses travel from one end to the other end

What is the Nervous System?

A network of neurones (nerve cells) inside the body

What’s the function of the nervous system?

• To detect what happens around us (detecting stimuli) and coordinate our responses

• Includes responses to danger, for example moving away when we see a bee

What do receptors do

detect stimuli (changes in the environment)

What’s the function of coordination centres (brain, spinal cord, pancreas)

Receive and process information from receptors.

What’s the function of Effectors (muscles or glands)

These bring about responses which restore optimum levels.

What is the Nervous System?

A network of neurones (nerve cells) inside the body

What’s the function of the nervous system?

Detects stimuli (what happens around us)

Includes responses to danger e.g moving away when we see a bee

What’s the CNS (Central nervous system)

Is part of the overall nervous system thus also made of neurones

Consists of the brain and spinal chord

What’s the function of the CNS

Decides and coordinates responses to stimuli

What are the steps of a Nervous Response?

1. Stimulus- a moving ball

2. Receptor- Cells in eyes act as receptors, receive light which shows the ball is coming

3. Coordinator- Brian acts as a coordinator because it decides on a response, Coordinator communicates response with an effector, CNS is always the coordinator

4. Effector- E.g Muscle , performs the response

5. Response- catching the ball

What are receptors?

Cells the detect stimuli (changes in environment)

What are examples of receptors?

Light

Temperature

Touch

Chemical (through nose or mouth)

Sound

Named after the type of stimulus

What are Effectors

Parts of the body that produce a response to a stimulus

What are the types of effectors?

Muscles- contracting biceps to lift a bag

Glands- Adrenal gland produces Adrenalin

What are synapses?

A gap that connects two neurones

Info travels from neurone to neurone

How do synapses work?

Within neurones, info travels as an electrical impulse

Across synapses, information travels as a chemical signal

How does blood glucose concentration work within the normal range?

• When blood glucose concentration is high after eating a meal, insulin is secreted by pancreas causing glucose to enter cells

• Glucose converts to glycogen in the liver

• causing blood concentration return back to normal so insulin decreases

• when blood concentration is low, glucagon is secreted by pancreas

• causing the breakdown of glycogen in liver into glucose

• causing blood glucose concentration to return ti normal so glucagon decreases