28.1 Levels of Organization

Keystone Anchor•BIO.A.4.2 Explain mechanisms that permit organisms to maintain biological balance between their internal and external environments.

In other words - _______________________________________________ ____________________________________________________________________________________________________________________________

•BIO.A.4.2.1 Explain how organisms maintain homeostasis (e.g., thermoregulation, water regulation, oxygen regulation).

In other words - _______________________________________________ ____________________________________________________________________________________________________________________________

28.1 Levels of Organization

KEY CONCEPT Homeostasis - regulation and maintenance of a CONSTANT environment in the body

The term ‘homeostasis’ is derived from two Greek words; Homeo which means ‘unchanging’ and Stasis which means ‘standing’

It is an organism’s internal environment which ‘stays the same’

28.1 Levels of Organization

Type 1Think about this person’s body, describe the factors that need to remain in homeostasis.

28.1 Levels of Organization

• Control systems in the body.

– Sensors -gather data and detect changes

– Control center - receives data, sends messages, usually the brain

-Communication system - delivers messages in form of nerve impulses and hormones to target organs, tissues

– Targets – organ, tissue or cell that responds to change

28.1 Levels of Organization

Negative feedback loops are necessary for homeostasis.

• Feedback compares current conditions to set ranges.• Negative feedback- counteracts change. • Reverses any change and returns body to set point

Negative Feedback Loop

Holding breath, CO2

levels rise,

Control system forces exhale, inhale

O2 / CO2 level returns to normal

Keep athlete running

*

28.1 Levels of Organization

KEY CONCEPT Systems interact to maintain homeostasis.

28.1 Levels of OrganizationEach organ system affects other organ systems.

There is no specific organ which controls homeostasis.

The skin, kidneys, liver, endocrine system, nervous system and sensory system all play a part in maintaining the internal environment within narrow limits.

The hypothalamus is involvedto a degree in each of these regulations

• Organ systems must also work together to keep the organism healthy.

28.1 Levels of Organization

Type IDescribe how this picture of an automotive race team is similar to the systems of a body.

28.1 Levels of Organization

• Body cells work best if they have the correct• Temperature• Glucose concentration, (sugar)• Water levels

• Homeostasis involves keeping the internal environment within set ranges

28.1 Levels of Organization

• Water - kidneys : • regulate water & mineral salts

concentration

• Thermoregulation –skin and muscles : • regulate body temperature

• Glucose - liver & pancreas :• regulate blood glucose level

Organs and involved:Organs and involved:

kidney

liver

pancreas

+

skin

tissue cells

blood

28.1 Levels of OrganizationThermoregulation – process of maintaining a steady body temperatureSweating•When your body is hot, sweat glands are stimulated to release sweat.•The liquid sweat turns into a gas (it evaporates)•To do this, it needs heat.•It gets that heat from your skin.•As your skin loses heat, it cools down.

28.1 Levels of Organization

Thermoregulation – process of maintaining a steady body temperature

Shivering• Hypothalamus signals skin and muscular, respiratory, and

circulatory systems• Blood vessels constrict to reduce blood flow to prevent loss

of heat• Muscles contract around pores• Muscles contract causing shivering• Thyroid releases hormones that increase metabolism

28.1 Levels of Organization

Controlling Glucose levels• 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

Insulin and Glucagon• In this way, the concentration of glucose in the blood is kept within narrow limits

28.1 Levels of Organization

The glucose concentration in the blood is controlled by the pancreas

The pancreas contains cells which produce digestive enzymes but it also produces the hormones insulin and glucagon

If the glucose concentration rises, the pancreas releases insulin

If the glucose concentration falls, the pancreas releases glucagon

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28.1 Levels of Organization

Insulin stimulates the liver and muscles to remove excess glucose from the blood and store it as glycogen

Glucagon stimulates the liver to convert its stored glycogen into glucose which is then released into the bloodstream

In this way, the concentration of glucose in the blood is kept within narrow limits

28.1 Levels of Organization

Water RegulationWater Regulation• After having a very salty meal

produce concentrated urine to remove excess salts in solution form

extra water is needed to be excreted along with the excess salts

sensation of thirst (drink more water to compensate for the water loss)

28.1 Levels of Organization

Water Regulation

• The amount of water in the blood must be kept more or less the same all the time to avoid cell damage as a result of osmosis.

• There has to be a balance between the amount of water gained (from your diet though drinks and food and the water produced by cellular respiration) and the amount of water lost by the body (in sweating, evaporation, feces and urine).

• This is achieved by the action of the hormone ADH (anti-diuretic hormone).

28.1 Levels of Organization

Water Regulation• Part of the brain, the hypothalamus, detects that there is

not enough water in the blood. The hypothalamus sends a message to the pituitary gland which releases ADH.

• This travels in the blood to your kidneys and as a result you make a smaller volume of more concentrated urine. The level of water in your blood increases until it is back to normal.

• If the level of water in your blood goes up the hypothalamus detects the change and sends a message to the pituitary. The release of ADH into the blood is slowed down or even stopped. Without ADH the kidneys will not save as much water and you produce large volumes of dilute urine.

• This is an example of negative feedback.

28.1 Levels of Organization

• There are 11 major organ systems in the human body.

28.1 Levels of Organization

TYPE I

• Name 3 systems that help maintain homeostasis and describe how they work to maintain homeostasis.

• 1.

• 2.

• 3.