Coordenation

NERVOUS SYSTEM
Coordinates our response in a variety of situations, but particularly where we need to react very quickly.

LIVING IN THE ENVIRONMENT

Are affected by:
(Both of these are constantly changing)

External environment: Everything about the bodies.

Internal environment: The body

STUMULUS

Is a change in the environment of an organism that causes the organism to respond.

Internal stimulus: Comes from inside the organism.

External stimulus: Comes from outside the organism.

HOW DO WE RESPOND TO A STIMULUS?

Five sense organs that detect external stimuli:

Parts:

The eyes, ears, nose, tongue and skin. These sense organs contain receptors, which are a special kind of cells that are sensitive to stimuli.

Works in combination with:

*EFFECTORS:* They are the parts of the body that carry out the response.

RECEPTORS: Detect stimuli and convert them into electrical signals; these can be sent around the body as messages.

NEURODEGENERATIVE DISEASES Are caused when neurons in the brain become damaged or die.

Alzheimer's disease: Causes memory problems and difficulty in
finding the right words.

*The nervous system consists of:*

Glands: Produce hormones.

Muscles: Produce movement.

The central nervous system (CNS)

which coordinates
our actions; it decides what we need to do and gives instructions to the rest of the body; it consists of the brain and the spinal cord the peripheral nervous system, which carries messages around the body very quickly

How it woks:

The peripheral nervous system

  1. Coordination
  1. Instructions
  1. Message
  1. Stimulus

which carries messages around the body very quickly

SENSORY NERVES

  1. Responde

carry messages from the receptors to the CNS

MOTOR NERVES

NERVES: Are made of groups of neurons.

end instructions from the CNS to the effectors
Nerves carry messages to and from all parts of the body

Neurones:

Cell body: Contains all the usual parts of a cell.

Dendrites: Connect to other neurons so that impulses can pass from cell to cell.

Myelin sheath: Surrounds and protects the axon.

Axon: This part is long and thin, like a cable.

CENTRAL NERVOUS SYSTEM: Consists of the brain and the spinal cord.


Reflexes:
Our brain can decide very quickly how to respond to a stimulus.

  1. Relay: Another impulse is sent along a relay neuron in the spinal cord o brain stem.
  1. Response: The signal is passed on to a motor neuron.
  1. Stimulus: You touch something hot.

MENTAL ILLNESS
Are medical conditions that affect a person's thinking, feelings, moods and/or ability to relate to others.

Parkinson's disease: Causes muscle problems, which make it difficult to move, and it also results in involuntary movements (shaking) of parts of the body.

Multiple Sclerosis: Occurs when the myelin sheath becomes damaged.

SCHIZOPHRENIA: Is a long-term condition that can affect people of all ages.

ATTENTION DEFICIT/HYPERACTIVITY: Often affect children, but they can also affect teenagers and adults.

DEPRESSION: The symptoms of depression may include feeling sad or hopeless, and not enjoying things that you used to enjoy.

ENDOCRINE SYSTEM
The endocrine system consists of glands that produce hormones and release them into the blood. They are therefore sometimes called "chemical messengers". .

WHAT ARE HORMONES USED FOR?

controlling gradual changes

like growth and sexual development

regulating the level of substances in the body

the diagram below shows the main glands in the human body, together with the hormones they produce and what these hormones do.

Hypothalamus: is a part of the brain. It receives messages from receptors and monitors conditions such as temperature, hunger and thirst. It controls the production of hormones in the other glands, including the pituitary gland.

Adrenal glands: are on top of the kidneys. They produce adrenaline when we are angry or scared. This hormone prepares our body for action.

Pituitary gland produces many hormones, including:

  • growth hormone
  • hormones that control when eggs
    are released from the ovaries
  • anti-diuretic hormone (controls the amount of water in the blood)

Thyroid gland: produces thyroxine, which controls the rate of metabolism thymus.

The ovaries: (in females) produce oestrogen. This hormone causes changes in girls during puberty (it also helps to control the menstrual cycle).

The pancreas: produces the hormones insulin and glucagon, which control the level of sugar in the blood.

The testes: (in males) produce testosterone, which causes changes in boys during puberty (it also controls sperm production).

COORDINATION AND HOMEOSTASIS
Homeostasis means maintaining a constant internal environment.

it incluide:

• keeping the body temperature close to 37°C

• maintaining the correct levels of various substances in the blood, including water, sugar and sodium ion

This is done through the body's coordination systems (the nervous and endocrine systems using a process called negative feedback. There are two examples below

MAINTAINING A CONSTANT TEMPERATURE
Negative feedback works like the thermostat on a central heating system:

If the body temperature starts to increse, the body acts to reduce the temperature

If the body temperature starts to decrese, the body acts to increse the temperature

REGULATING BLOOD SUGAR
Glucose in our blood provides us with energy. However, too much glucose can be harmful, so our body stores excess glucose as glycogen. Our blood sugar level (the amount of glucose in the blood)

is regulated by two hormones:

Insulin

Glucagon.

PROBLEMS WITH THE ENDOCRINE SYSTEM
Is too much or too little of a hormone in the body, it can cause various problems (see the avamples below). There are various reasons why this can happen.

For example:

• not enough hormone is produced

  • the body's feedback system is not working properly • he hormone is not removed from the blood quickly enough

THYROID PROBLEMS

Overactive thyroid produces too much thyroxine. This speeds up the body's metabolism, leading to symptoms such as nervousness, hyperactivity and weight loss. The opposite problem is an underactive thyroid.

DIABETES

type 1

Usually starts in childhood. The body stops producing insulin, so the blood sugar level can rise dangerously. Type 1 diabetes can be controlled by injecting insulin before meals.

type 2

Affects older people. Either too little insulin is produced, or the insulin doesn't work properly. Overweight or obese people are most at risk of type 2 diabetes.

COORDINATION - SUMMARY
you have learned about our two coordination systems: the nervous and endocrine

this incluide:

n

• how we respond to stimuli, including voluntary actions and reflexes

• the parts of the nervous system, including the brain, spinal cord and nerves

• neurodegenerative diseases and mental illnesses

• how the endocrine system controls gradual processes and performs homeostasis

• what happens if hormone levels are too high or too low

POST TRAUMATIC STRESS DISORDER
Post-traumatic stress disorder (PTSD) is a long-term feeling
of anxiety caused by very stressful or frightening events.

PTSD can be caused by many things, including:

• being attacked or abused by someone.

• seeing people being deliberately killed, for example in a

• witnessing a serious road accident or a natural disaster