Chapter 5 Maintaining Balance in Organisms

Part 3

The body has mechanisms to detect change andinitiate responses to bring conditions back tonormal range Ex: how does the body make sure that just theright amount of vasopressin is released? Not toomuch or too little?Feedback Systems maintain internal balance andregulate responses

Shuts off theresponse Ex:◦ body sensesdehydration◦ Produces and releasesvasopressin◦ Body senses watervolume in the body isback to normal◦ This stimulates thehypothalamus to stopproducing andreleasinghypothalamus

Ex:◦ Low blood pressure is detected by walls of the arteries◦ Sends signal through nervous system and to the brain◦ Brains send signal to the heart to pump faster and to theblood vessels to constrict◦ Increase in heart rate and artery diameter will increaseblood pressureWhen blood pressure becomes too high, signal is sent tothe brain and the body responds by relaxing bloodvessels and pumping blood more slowly

Adjusts internalconditions toward theinitial condition Ex:◦ bleeding causes a clottingresponse◦ Clotting fibers attractmore clotting fibers(platelets) until bleedingstopsChange detectedResponseMechanismsContinue untilInitial conditionsreturnCorrectiveMechanismsActivated

1. Nervous System – rapid, short term, very specificresponsesRegulates involuntary physiological activities as wellas enabling the body to respond voluntarily tosensations2. Endocrine System – slow, long term responsesCombination of fast and slow responses,automatic and voluntary, physiological andbehavioral are all important to maintaininghomeostasis

What is a feedback system and what is itsfunction? A negative feedback system turns on or off aresponse? What is a positive feedback system? Give anexample of a positive feedback system in thebody. What are the differences between types ofresponses in the endocrine system vs the nervoussystem?

All cells in the body needoxygen to function Carbon dioxide is a byproductof energymetabolism The respiratory system isthe main organ systeminvolved in gas exchangebut there are a number ofother systems thatcooperate with therespiratory system forproper functioning

Main organs◦ LungsFollow the air –1. Mouth or nose – air iswarmed, moistened, cleaned2. Larynx – mucous and cilia3. Trachea – mucous and cilia4. Bronchi (plural) Bronchus(singular) – mucous and cilia5. Bronchioles – mucous andcilia6. Alveolar Sac (singular),Alveoli (plural)

When oxygen reaches thesmallest compartment (alveoli),it can diffuse across the thin cellwalls (alveolar membranes) These small compartments havea surface area that is 40 timesgreater than the outer surface ofthe body◦ Allows for greater amount of oxygenthat can move into the body, and agreater amount of carbon dioxidethat can move out of the body

The concentration of carbondioxide in the blood and inthe air inside the alveolidetermines the direction ofdiffusion If the concentration ofcarbon dioxide is higher inthe blood than in the air onthe inside of the alveoli, thenthe carbon dioxide willdiffuse down theconcentration gradient

Maintaining levels of carbon dioxide and oxygeninvolves a precise feedback system andcoordination between◦ Respiratory system◦ Circulatory system◦ Nervous system

When your body is working harder, it produces more carbondioxideCarbon dioxide causes the blood to be more acidicNerve cells detect this acidity and send a signal to the brainThe brain sends a signal to the respiratory system to contractthe diaphragm more frequently causing a faster breathing rateFaster BR increases oxygen levels in the blood

When exercise stops, carbon dioxide is produced at aslower rate Blood becomes less acidic Less acidity is detected by sensory receptors in theblood vessels Signal is sent to the brain Brain sends signal to diaphragm to contract moreslowly

What is carbon dioxide a product of in the body? What are the main structures (starting at the mouthand ending at the alveoli) that air we inhale passes by? What is the structural feature of the alveoli that allowsfor greater gas exchange in the lungs? Explain the process of diffusion in the alveoli. Whatareas are greater concentrations for O2 and CO2? What is the relationship between feedback systemsand regulating levels of CO2 and O2 in the body? Explain what happens in the body during rapidexercise.

Draw a diagram of the respiratory system labelingkey features. Enlarge an area around an alveoli tohighlight gas exchange processes