Lecture 8 Flashcards
how does exchange occur within unicellular organisms?
-directly with the environment
how does exchange occur within multicellular organisms?
-not direct with the environment
-done with specialized systems (ex: gills)
How does exchange work within small or thin animals?
-exchange materials directly with the surrounding medium (diffusion)
how does exchange work within more complex/larger animals?
-internal transport systems that connect organs with the bodies cells
-circulate with fluid (diffusion is too slow)
how does internal transport work with the gastrovascular cavities of simple animals such as cnidarians?
-the body wall enclosing the cavity is only 2 cells thick
-the cavity functions in digestion + distribution of substances
-some will have more elaborate cavities
how do internal circulatory systems work?
-gases transported between respiratory surfaces + deep tissues
-nutrients get taken up + distributed by the digestive tract
-allow for cell-cell communication through hormones
what is common to both open + closed circulatory systems?
-circulatory fluid (blood or hemolymph)
-a set of tubes (blood vessels)
-a muscular pump (heart)
how does the heart push fluid through the circuit?
-uses metabolic energy to generate a pressure that forces fluid through the circuit
what animals have an open circulatory system?
-insects
-other arthropods
-most molluscs
what are the key aspects of an open circulatory system?
-blood bathes the organs directly
-no distinction between blood + interstitial fluid
-lower pressure needed
what is fluid in an open circulatory system referred to as?
-hemolymph
what animals have a closed circulatory system?
-annelids
-cephalopods
-vertebrates
what are the key aspects of a closed circulatory system?
-blood is confined to vessels
-blood is distinct from interstitial fluid
-higher pressure
which circulatory system is more efficient at transporting circulatory fluids to tissues + cells?
-closed circulatory system
how does chemical exchange occur within a closed circulatory system?
-blood > interstitial fluid > body cells
what can help deliver oxygen + nutrients more effectively in larger and more active animals?
-higher blood pressure
what are the 3 main types of blood vessels?
-arteries (smaller arteries called arterioles)
-capillaries
-veins (smaller veins called venules)
in which direction do arteries move?
-away from the heart towards the capillaries
what is key about capillaries?
-exchange with body cells
-have thin + porous walls to do so
what direction do veins move in?
-from capillaries towards the heart
what are capillary beds?
-networks of capillaries
-sites of chemical exchange between blood + interstitial fluid
what is the purpose of the atria?
-to receive blood
what is the purpose of the ventricles?
-to pump blood out
how many chambers do vertebrae hearts contain?
-2 or more
what animals have a single circulation system?
-bony fishes
-rays
-sharks
what does a single circulation system consist of?
-2 chambered heart
-1 atrium + 1 ventricle
what is the pathway through a single circulatory system?
-ventricle > arteries
-diffusion of oxygen into the blood from gills
-carbon dioxide diffuse out of the blood
-blood travels from gills to the rest of the body before returning to the heart
what are the disadvantages of a single circulation system?
-efficiency is low due to pressure dropping as blood passes through the gill capillaries
-heart must rely on deoxygenated blood for its metabolic needs
what is an advantage of a single circulation system?
-low metabolic demands
what animals have a double circulation system?
-amphibians
-reptiles
-mammals
what does it mean to have a double circulation system?
-oxygen rich and oxygen poor blood are pumped separately from the right and left sides of the heart
what type of circuit does oxygen poor blood typically follow?
-pulmonary circuit to get oxygen from the lungs
what is the circuit for oxygen poor blood called in amphibians?
-pulmocutaneous circuit to get oxygen from the lungs and skin
what type of circuit does oxygen rich blood deliver oxygen through?
-the systemic circuit
what does a double circulation maintain?
-a higher blood pressure in the organs
what animals have a 3 chambered heart with 2 atria and 1 ventricle?
-amphibians
-reptiles
how does the ventricle of an amphibian split blood between circuits?
-pumps blood into a forked artery that splits the outputs between the two circuits
what is key about an amphibians circulatory system underwater?
-blood flow to the lungs is nearly shut off
how does the ventricle of a reptile split blood between circuits?
-ventricle is divided by a septum to partially or fully divide the ventricle
how many chambers is a mammals/birds heart?
-4 chambers with 2 atria and 2 ventricles
where does the blood from the left side of the heart go? what type of blood is this?
-to the body
-oxygen rich blood
where does the blood from the right side of the heart go? what type of blood is this?
-to the lungs
-oxygen poor blood
do endotherms or ectotherms require more oxygen?
-endotherms
what is the purpose of gas exchange?
-to supply oxygen for cellular respiration
-dispose of carbon dioxide
what is partial pressure?
-the pressure exerted by a gas in a mixture of gases
-gases (O2 + CO2) will diffuse from a region with high partial pressure to a region with low partial pressure
does air or water breathing require greater efficiency?
-water breathing
-less O2 content
-greater density
-higher viscosity
what do animals require of their respiratory surfaces?
-need to be large + thin + moist
what is the respiratory medium?
-either air or water
-where O2 is gained
how does gas exchange take place across respiratory surfaces?
-diffusion
what counts as a respiratory surface?
-lungs
-gills
-skin
-tracheae
how do gills perform gas exchange?
-often have a greater total surface area than the bodys exterior
-ventilation aids in movement (moving through water)
-countercurrent exchange system (blood + water flow oppositely)
how does the tracheal system of insects work?
-consists of tiny branching tubes that penetrate the body
-tracheal tubes supply O2 and remove CO2 directly
-respiratory + circulatory systems are separate
how must larger insects ventilate their tracheal system?
-rhythmic body movements
what correlates with the size and complexity of an animals lungs?
-their metabolic rate
what is the big difference between the tracheal system and a system involving lungs?
-lungs are localized
where are the lungs located?
-in the thoracic cavity
what is the pathway of air in a mammalian respiratory system?
-nostrils > pharynx > larynx > trachea > 2 bronchi > bronchioles > alveoli
what occurs at the pharynx?
-paths for air and food cross
what occurs at the alveoli?
-site of gas exchange
what are the alveoli?
-air sacks clustered at the tips of the smallest bronchioles
-wrapped in capillaries for gas exchange
what is positive pressure breathing? which animals use it to ventilate?
-forces air down the trachea
-amphibians
what is negative pressure breathing? which animals use it to ventilate?
-pulls air into the lungs (inhalation) by varying the volume + pressure
-reduces air pressure in the lungs
-lung volume increases (ribs + diaphragm contract)
what is tidal volume and residual volume?
-tidal = volume of air inhaled
-residual volume = volume of air after exhalation
how do birds breathe?
-8 or 9 air sacs that keep air flowing through the lungs
-air passes the lungs in only one direction
-every exhalation renews the air in the lungs
what are the 2 main breathing control centers in humans?
-medulla oblongata
-pons
what does the medulla oblongata regulate?
-the rate + depth of breathing
-in response to pH changes (CO2 levels in the cerebrospinal fluid)
-does so to match metabolic demands
what does the pons regulate?
-the tempo of breathing
what prevents the lungs from overexpanding?
-negative feedback mechanism
-sensors during inhalation detect stretching of the lung tissue
-will send nerve impulses to the medulla to stop further inhalation
what is used as a secondary control over breathing? what is this important for?
-sensors in the aorta and carotid arteries monitor O2 + CO2 concentrations in blood
-important for modulating breathing in response to changes in oxygen levels
what are the partial pressures of blood arriving in the lungs relative to the air in the alveoli?
-low partial pressure of O2
-high partial pressure of CO2
-O2 from air goes to blood
-CO2 from blood goes to air
what do the partial pressure gradients favour in tissue capillaries?
-favour diffusion of O2 into the interstitial fluids and CO2 into blood
what are respiratory pigments?
-proteins that transport oxygen
-increase the amount of oxygen that blood can carry
what respiratory pigment do arthropods use?
-hemocyanin with copper as the oxygen binding component
what respiratory pigment do vertebrates and some invertebrates use?
-hemoglobin
where is hemoglobin contained within vertebrates?
-erythrocytes (RBC)
how many O2 molecules can a single hemoglobin molecule carry?
-4
-one per iron containing heme group
what can be shown in hemoglobin dissociation curves?
-a small change in the partial pressure of oxygen can result in a large change in the delivery of O2
what is the bohr shift?
-when CO2 produced during cellular respiration lowers the blood pH and decreases O2’s affinity for hemoglobin
how does hemoglobin help in CO2 transportation?
-some CO2 from respiring cells will diffuse into the blood and be transported
-they will bind to the hemoglobin as is or be transported as bicarbonate ions (HCO3-)
-the partial pressures in the lungs will favour diffusion of CO2 out of blood
what adaptions atre present in diving mammals such as seals?
-high blood to body volume ratio
-stockpile O2 + deplete it slowly
-store oxygen in their muscles in myoglobin proteins
what are the 3 ways diving mammals can conserve oxygen?
-change their buoyancy to glide passively
-decrease blood supply to muscles
-derive ATP in muscles from fermentation once oxygen is depleted
