Unit 3 Internal Systems and Regulation

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Unit 3 Internal Systems and Regulation

    Unit 3: Internal Systems and Regulation

    Chapter 8 The Breath of Life

    8.1 The Task of Respiration ; Aerobic organisms need oxygen to survive

    ; Every respiratory system requires a surface for gas exchange (respiratory surface) and a moist

    environment for respiration to take place

    ; Single-celled aerobic organisms (protists, algae) live in aquatic or other moist environments where oxygen in water diffuses into the cell and CO 2

    diffuses out

    The Specialized Respiratory System

    ; Gills: feather tissue structures that enables

    aquatic organisms like fish, tadpoles, molluscs

    and crayfish to ventilate (move a oxygen-

    containing medium over a respiratory surface)

    ; As water passes through the mouth and over

    the gills, oxygen diffuses in, CO diffuses out 2

    Respiration on Land

    ; Terrestrial animals carry a moist respiratory environment wherever they go

    ; Act of ventilation with air is breathing

    ; Air always moves from a region of higher pressure to one of lower pressure

    ; Volume decreases in a container = air pressure


    ; Volume increases in a container = air pressure


    ; Breathing makes use of this principle

    The Tracheal Respiratory System

    ; Spiracles pores in the skin of an

    insect that can be opened to admit air

    into the trachea for respiration

    ; Tracheae internal network of tubes

    ; Respiratory and circulatory systems are

    separate in insects

    The Lung

    ; An internal respiratory surface connected to air through internal passageways

    ; Always consists of three elements:

    ; One or two lungs with have moist surface

    ; A mean of forcibly bringing air in contact with the

    lung surface

    ; A circulatory system to move gases between the

    lungs and other body cells

    ; Efficiency and structure vary by species

    Chapter 8: The Breath of Life

    8.2 The Mammalian Respiratory System

    Mammalian Respiration ; In humans, breathing involves 2 movements:

    ; 1) Inhalation (inspiration): air moves in

    ; 2) Exhalation (expiration): air moves out

    ; External respiration exchange of O and CObetween air and blood 22

    ; Internal Respiration exchange of O and CO between blood and cells of 22

    the surrounding tissue

    ; Cellular respiration chemical reactions mainly in the mitochondria

    The Upper Respiratory


    ; Air enters through the nostrils or the

    mouth where is it cleaned and moistened

    and then passes through:

    ; Pharynx the throat; connects the

    mouth and the nasal cavity to the


    ; Larynx “voice box”; contains vocal


    ; Glottis opening of the trachea,

    protected by the epiglottis, which

    prevents food from entering the


    ; The trachea (“windpipe”) is protected by

    semicircular cartilage rings to prevent it from collapsing and lined with mucous and cilia to remove dust

    The Lower Respiratory Tract ; Trachea branches off into two passageways (bronchi) around which each lung is formed

    ; Bronchioles smaller tubes that branch off the bronchi; pass air into the alveoli

; Alveoli air sacs where gas exchange takes place

    ; Left lung has two lobes and right lung has three ; Lungs are protected by layers of tissue (pleura)

    Chapter 8: The Breath of Life

    8.3 The Mechanics of Breathing

; Breathing relies on air flow from a region of higher pressure to lower


    ; Air pressure inside lungs is controlled by:

    ; Intercostal muscles muscles that expand and contract the rib cage

    ; Diaphragm a muscle layer at the floor of the thoracic cavity (region

    of the lungs)

    Inhalation and Exhalation

     Rib Air Rib Air Intercostal Diaphragm Pressure Intercostal Diaphragm Pressure cage Movement cage Movement muscles muscles

    Contracts Contracts Up and Up and Inhalation Contract and pulls Decreases In Inhalation Contract and pulls Decreases In out out downward downward

    Relaxes Relaxes Normal Normal Exhalation Relax and moves Increases out Exhalation Relax and moves Increases out position position upward upward

    Exchange of Gases

    ; Exchange of oxygen and carbon dioxide takes place across cell membranes

    ; Oxygen diffuses into bloodstream and carbon dioxide moves out since:

    ; Concentration of oxygen in inhaled air > concentration of oxygen in the

    blood of capillaries

    ; Concentration of carbon dioxide in blood > carbon dioxide

    concentration in inhaled air

    Lung Capacity

    ; Tidal volume the volume or air inhaled and exhaled in a normal breathing movement

    ; Inspiratory reserve volume additional volume of air that can be taken in

    ; Expiratory reserve volume additional volume that can be forced out of the lung

    ; Vital capacity total volume that can be moved in or out (tidal volume + inspiratory reserve volume + expiratory volume)

    ; Residual volume amount of gas that remains even after a full exhalation

    ; Is not exchanged with air from external environment ; Respiratory efficiency rate of oxygen transfer into the blood stream for transport to the body

    Counter-current Flow

    ; An arrangement in which two fluids exchange substances or heat with one another as they flow in opposite directions

    ; Maximizes the concentration or heat gradient between vessels containing the fluids

    The Respiratory System in Birds

    ; Respiratory system has evolved to allow birds to fly for long periods without rest

    ; Arrangement of air sacs around the lungs allow fresh air to flow constantly over its surface

    ; No gas exchange occurs in the air sacs

    ; Anterior air sacs located between the lungs and trachea ; Posterior air sacs located on the posterior side of the lungs

    Chapter 8: The Breath of Life

    8.4 Control and Regulation

    High Altitude Breathing

    ; At high elevations, air pressure is lower and air is “thinner”, which may

    cause altitude sickness (hypoxia)

    ; Increased breathing rate is the body’s first response

    ; In about two weeks, the body produces more red blood cells to take up

    from oxygen

    ; Athletes often train at high altitudes to increase their physical


    The Control of Breathing

     Physical exertion causes an increased level of ;

    cellular respiration and the production of

    more CO2

    ; An increase in CO in the body leads to a 2

    faster breathing rate

    ; If the concentration of CO exceeds a certain 2

    level, the medulla oblongata (portion of the

    brain controlling many automatic functions)

    sends out nerve impulses to increase the

    movement of rib cage muscles

    Respiratory Impairment

    ; Drowning

    ; largyngospasm is the reflex closing of the

    larynx; death occurs by asphyxiation

    instead of water entering the lungs

    ; In fresh water water washes away the lipoprotein that coats the

    alveoli, causing it to collapse

    ; In salt water fluid is drawn out of the capillaries into the lungs due to

    the concentration gradient

    ; Carbon Monoxide (CO) Poisoning

    ; CO is a clear, odourless, tasteless gas

    ; Toxic because it binds to hemoglobin and prevents blood from

    transporting oxygen to the cells of the body

    ; A concentration of 0.002% of CO can be harmful in exposure for more

    than a few hours

; Smoking

    ; Smoke paralyzes the cilia, preventing it from removing foreign


    ; A steady smoker suffers mild CO poisoning since CO is present in


    ; May lead to a breathing disorder called emphysema, where the lungs

    lose elasticity and breathing becomes difficult ; Air pollution

    ; Airborne pollutants include nitrogen oxides, chlorine, methane and CO

    ; May contribute to respiratory problems like asthma

    Chapter 8: The Breath of Life

    8.5 Gas Exchange in Plants

    Gas Exchange in Roots

    ; Surface of root is covered with root hairs that increase surface

    area for gas exchange

    ; Oxygen diffuses from the soil to the root as long as it is aerated

    and contains water

    ; CO diffuses from the root hairs into the soil 2

    Gas Exchange in Leaves

    ; Photosynthesis and respiration both require

    leaves to exchange gases

    ; Cuticle (waterproof coating) of the leaf is

    perforated with structures called stomata

    where they can be opened or closed

    ; Stomata open into the intracellular air spaces

    within the leaf

    ; Oxygen produced from photosynthesis can

    be reused for respiration

    ; CO released by respiring cells can also be 2

    reused in photosynthesis

    Gas Exchange in Stems

    ; Lenticels loose arrangement of cells

    in the outer bark of a woody plant

    ; Arrangement provide openings from the environment into the tissue of the stem

    ; Diffusion is enough for the woody stem of a large tree because only a relatively thin layer is made of living cells

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