Structure and Function in

Living Systems

Chapter 8: Systems in Organisms

8.1: Systems help organisms meet their needs8.2: Plants have several levels of organization

8.3 Animals have several levels of organization8.4 Human health depends on a balance among systems

Human health depends ona balance among systems

Fill in the sequential cluster diagramLevels of

Organization

respiratory, circulatory, nervous, skeletal

heart, skin, eyes; epithelial, muscle,nerve, connective

How is the human body like a city?

The body’s systems work all the time

Human body depends on processes that don’t stop needs to:

Breathe circulate blood take in food, to digest it, and to eliminate waste

materials organ systems remain active during sleep

**working constantly to maintain the balance needed to survive

Body systems maintain homeostasis

Homeostasis: the ability of the body to maintain internal conditions within normal ranges Conditions are in equilibrium =

balanced Small changes always occur

internally and externally Body must work to regulate:

Body temperature amount of sugar in blood oxygen and carbon dioxide levels,

and water and salt balance in body fluids

Homeostasis: Negative Feedback

Homeostasis is often maintained by a negative feedback loop

Homeostasis: Body Temperature

Normal internal temperature is ~ 37°C (98–99°F). homeostatic systems for temperature:

Integumentary, circulatory, muscular, respiratory, and nervous

If much above or below 37°C: The homeostatic systems are having trouble

maintaining your usual temperature

Active, or hot day body temperature may rise Body sweats Evaporation of sweat from skin cools body

brings temperature back down

Homeostasis: Ion Concentrations

Kidneys help keep body water volume constant drink a lot of water kidneys release more water in urine do not drink enough water kidneys make less urine

Why? To maintain the proper concentrations of ions and other

substances in the blood Concentration: amount of one substance that is dissolved

in another substance The less water, the higher the concentration of dissolved

substances The more water, the lower the concentration

Homeostasis: Ion Concentrations

Ion: an atom of an element that has gained or lost one or more electrons – “charged” particles (+ or -) important to many body processes:

movement of substances across cell membranes sending of nerve impulses

Electrolytes: sodium, potassium, chloride, and calcium

skin tastes salty after sweating: Sweat contains salts, ex: Sodium and chloride together sports drinks contain salts (electrolytes!)

Electrolytes and salts, in ion form, aresubstances that conduct electric current.

Electrolytes in human body fluids operate similarly to the currents caused by electrolytes in batteries.

The positive and negative charges of the ions cause them to move toward concentrations of the opposite charge.

Electrolytes such as sodium, potassium, calcium, magnesium,and chloride ions in the human bodyhelp fluids flow across cell membranesand help nerve impulses travel.

Homeostasis: Oxygen and Carbon Dioxide Concentrations

respiratory system and circulatory system maintain a balance of oxygen and carbon dioxide concentrations in the blood These dissolved gases are carried by the

blood and delivered to and from the tissues in plasma

Exercise: muscle cells use more oxygen and give off more carbon dioxide than at rest increased oxygen need increased

breathing rate and volume heart pumps faster circulatory system

increases blood supply to the limbs

Resting: breathing is shallower, heart pumps more slowly

Homeostasis: Other Nutrients

Liver breaks down large food molecules—carbohydrates,

fats, and proteins—into nutrients stores glucose, vitamins, and iron produces bile (a fluid used in digestion) breaks down alcohol, drugs, and other toxic chemicals Filters, stores, and releases materials

Pancreas Part of digestive and endocrine systems helps maintain blood glucose levels

Some people with diabetes are unable to make enough insulin to regulate their blood sugar.

They often need to take injections of insulin to keep their blood sugar in a normal homeostatic range.

The endocrine system helps regulate body conditions Controls the conditions in the body by

making and releasing hormones Hormones: chemicals that are made in one

organ, travel through the blood, and produce an effect in target cells Ex: insulin and glucagon produced in the

pancreas Ex: adrenaline makes your heart beat faster

in exciting situations “rush of adrenaline”

Are often called chemical messengers Target cells have special structures, called

receptors, that allow them to respond to the chemical messenger

Hormones and Glands Glands: specialized - tissues main structures of the

endocrine system Many glands in the body produce hormones circulatory

system

Pineal Gland: Tiny organ sizes of a pea near the center of the brain sensitive to light produces a hormone essential to body rhythms

Ex: sleep Plays a role in maintaining body temperatures, in

reproducing, and in aging

Hormones and Glands

Hypothalamus connects the nervous and endocrine systems Produces hormones that control the release of

hormones produced by the…

Pituitary Gland base of the brain director of the endocrine system produces hormones that control growth, sexual

development, and the absorption of water into the blood by the kidneys

Hormones and Glands Thyroid Gland

releases hormones necessary for Growth Metabolism regulation of calcium

Thymus Gland helps the body fight disease by controlling the

production of white blood cells called T cells

Adrenal Glands secrete about 30 different hormones

regulate carbohydrate, protein, and fat metabolism and water and salt levels in the body

adrenaline –in response to stress makes your heart beat faster allows you to react quickly in dangerous or exciting situations

Hormones and Glands Pancreas

part of both the digestive system and endocrine system

secretes insulin and glucagon Regulate levels of glucose in the blood

Ovaries (female) and Testes (male) secrete hormones that control sexual

development ovaries make more estrogen testes make more testosterone the different amounts of give males and

females different characteristics

What general area of the body are all the glands of the endocrine system in?

the center What areas do the hormones produced in the glands generally affect? all parts How do the illustrations show the role of hormones as “chemical

messengers”? The glands are located throughout the body and are able to “deliver”

hormones wherever the body needs them What are the glands of the endocrine system? pineal gland,

hypothalamus, pituitary gland, thyroid, thymus, adrenal glands, pancreas, ovaries, testes

Negative Feedback

Regulation of hormone levels Adjust volume on a sound system Friend says just right? stop changing the volume You = control center Friend = sensor Feedback = information coming back to a control

center from a sensor that tells the control center what it needs to do to maintain a level within an ideal range

signals to a gland that hormone levels are correct and no more of the hormone is needed

Homeostasis may be disrupted

Signs of imbalance range from a mild cold, to dangerous overheating of the body, to serious and even fatal diseases

Sneezing help defends the body from foreign substances Pathogens (bacteria or virus) in the body signal the immune

system Symptoms begin to go away when homeostasis is restored

Exercising usually sweat lose too much water dehydration Signs of heat exhaustion: dehydration, dizziness, nausea, fainting,

and a dangerous drop in blood pressure Heat stroke – possible if a person stops sweating temperature rise

Hypothermia - body temperature too low

Homeostasis may be

disrupted hormone imbalances can cause serious diseases

Pancreas normally maintains glucose balance in your blood by releasing insulin and glucagon as needed Imbalance diabetes

failure of other organs, heart disease, blindness, and kidney damage Kidneys continually filter the blood, taking out waste

products Malfunction?

Dialysis: blood is circulated through an artificial kidney machine that filters out the wastes (3 sessions/week!)