mammals and their environment Flashcards
what are common features of mammals?
- four chambered hearts (atria and ventricles)
- warm-blooded (endotherms), high and constant body temperature
- muscular diaphragm used in breathing
- lower jaw made up of a singular bone
- three bones in the middle ear
- hair at some point in development
- milk producing glands in females
what are the classifications of mammals?
monotremes - egg
marsupials - pouch
placentals - placenta
what is the development of young in monotremes?
the embryo is in an egg which is laid
the young are known as monotremes
example is duck billed platypus and spiny ant eaters
what is the development of marsupials?
- the embryo develops within the uteris with the placenta connected to a yolk sac
the young are known as viviparous
examples are kangaroos
what is the development of placentals?
- the embryo develops in the female uterus in the female uterus and gains nutients and oxygen via blood in the placenta
- waste materials are also removed through the placenta
- the embryo is retained in the body until it reaches an advanced state of development e.g. human- 266 days and elephants - 670 days
- the young are called viviparous
what are the bodily responses to extreme cold?
- cold- to retain body heat and maintain body temperature
- heat- to limit water loss and maximise ingested water
- low oxygen - to maximise oxygen intake
- variations in seasons - to maintain body heat, reduce metabolism e.g. hibernation (winter dormancy), torpor or aestivation (summer dormancy)
what are the mammalian adaptations to cold temperature (in polarbears)?
- insualting layers- thick fur and greasy, thick layer of fat
- small surface area - volume ratio minimises heat loss
- white camoflage
- large feet to distribute load on ice
what are the mammalian responses to extreme heat (in humans and animals)?
humans- sweating
animal i.e. camel
- adaptations to kidbeys to prevent water loss
- sweat glands rarely sweat
- large flat feet, slit like nostrils, double row of eyelashes, thick eyebrows
- ability to tolerate body temperature above 42 degrees
- thick top layer of fur
- hump for storage of fat which is then broken down into water
what is the importance of water?
its needed for bodily functions
mammals can obtain water through their food and some can drink sea water, but they could end up ingesting 3x as much salt as is in the blood stream
what is the 2 step process for salt and water management in mammalian kidneys?
- glomular filtration - blood passes through a biological microfilter in part of the kidney; water, salt and small molecules pass thorugh but larger molecules dont
- reabsorption - the filtered plasma then passes through a long tube called the loop of henle where the water is reabsorbed
what happens when there is low oxygen availability such as when marine animals make prolonged dives into the depths for food?
- efficient exchange of air at the water surface, take up more oxygen into blood cells and its stored in muscles, reduction of blood supply to the extremities
- a slow heart rate to conserve oxygen and ensure the flow to vital organs e.g. the brain and the heart
- in the absence of oxygen, anarobic respiration takes place in muscles which produces lactic acid and they’ve evolved to cope with it
- they also have higher concentrations of haemoglobin and myoglobin
what is haemoglobin?
its involved in oxygen and gas exchange
its a protein found in red blood cells and 1 Hb molecule can bind up to 4 oxygen molecules
when 1 oxygen binds, it enhances the binding of the next oxygen molecule
- CO2 can also bind to Hb
- each one case a central Fe2+ that binds to a single O2 molecule
- each globin chain contains a haem molecule
- the O2-Hb dissociation curve forms a sigmoidal curve
what is myoglobin?
- it forms oxygen storage in muscles
- Mb is a small O2 carrying pigment found in muscle tissues
- Mb consists of a single polypeptide chain of 153 amino acids and a single prosthetic group (haem)
- diving mammals like whales have muscles with high abundances of Mb
- Mb releases O2 during periods of hypoxia or anoxia
what is hibernation?
- state of winter dormancy
- conservation of energy when food stores are low
- its the slowing down of metabolism and heart rate
- oxygen consumption falls and breathing rate also falls
- dropping of body temperature, regulated hypothermia
- regulation of enzyme activity e.g. the TCA cycle
this can last months but doesn’t have to be continuous
its an example of torpor
what is torpor?
its hypometabolic state (35% of basal metabolic rate)
it’s regulated by circadian rhythm and can occur every few hours
