BISC 101 Lecture Notes - Lecture 6: Symporter, Hypothalamus, Antiporter
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8 Aug 2016
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Nutrient: A substance that an organism needs to remain alive
● Humans require essential nutrients (Nutrients that cannot be made and must be
obtained in diet)
Food: Any material that contains nutrients
Four Steps to Obtain Nutrients
● 1) Ingestion: Take in food
● 2) Digestion: Breakdown of food into smaller molecules
● 3) Absorption: Uptake of nutrients
● 4) Elimination: Disposal of waste (absorb water)
Food Getting Techniques
●Suspension Feeders: Filter small organisms/bits of organic debris from water
using cilia/mucus lined nets and other structures
○ Example: Sponges/Tubeworms
●Deposit Feeders: Swallow organic rich sediments and other deposited material
○ Example: Sea Cucumber/Earthworms
●Fluid Feeders: Suck or lap up fluid (blood/nectar/sap)
●Mass Feeders: Seize/manipulate chunks of food by using mouthparts such as
jaws/teeth/beaks/special toxin-injecting organs
○ Majority of animals
Mouthparts as Adaptations:
● Mammals only animal to chew food and swallow distinct packets
○ Diversification in jaw size to exploit wide range of food
○ Complex multipart skull/jawbones have evolved in snakes
● Natural selection is strong for food capture because obtaining nutrients is vital for
fitness (Offspring)
● Evolution is not progressive (Do not get better overtime)
● Adaptation is not perfect (Example: Wisdom teeth)
DIgestion Tract
●Mouth: Mechanical/Chemical Processing of carbohydrates
○Salivary Glands: Make salivary amylase for carbohydrates and lubricating
mucus
■Salivary lipase
●Esophagus: Transport food to stomach through peristalsis (muscle contractions)
●Stomach: Mechanical/Chemical processing of proteins (acidic environment)
○Gastric Glands: Produce HCL/Pepsinogen/mucus
●Small Intestine: Chemical processing/absorption of proteins/fats/carbohydrates
(nutrients/water)
○ S/F Relationship:
■ Long: Get as much nutrients through absorption
■ High surface area: Along small intestine to get as much nutrients (villi)
■ Blood Capillaries in villi: Absorption right into the bloodstream
■ Short diffusion distance between lumen/blood
■ Transporter proteins bring ions into blood
■ Concentration gradient maintained
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■ Pancreas is upstream from small intestine: Get enzymes to there
faster
○Liver: Secretes molecules (bile) for fats
○Gall Bladder: Stores secretion from liver to small intestine
○Pancreas: Secretes enzymes into small intestine (trypsin/pancreatic lipase)
●Large Intestine: Absorbs water of indigestible food and forms feces (to hepatic
portal vein to liver to veins)
●Rectum: Temporary storage of feces
●Anus: Defecation
Homeostasis: Stability in the chemical/physical conditions within animal cells/tissues/organs
(always kept in tolerable range)
● Equilibrium with environment is DEATH
●Two Ways:
○Conformation: Temperature remains constant (conforms to temperature of
surrounding which shows little variation)
○Regulation: Mechanisms that adjust internal state to keep in limits that are
tolerable
●Epithelium: Forms internal environment that can be dramatically different from
external environment to maintain physical/chemical conditions inside animal
● To achieve homeostasis, animals have regulatory systems that monitor internal
conditions such as blood pressure/glucose/ph/enzymes
○ Has a set point (a normal or target value)
○Homeostatic system is based on 3 components: CONSTANT
■Sensor: Sense aspect of external/internal enviro.
■Integrator: Evaluates incoming sensory info and decides whether a
response is needed to achieve homeostasis
■Effector: Restores the desired internal condition
○Based on negative feedback: Occurs when effectors reduce/oppose change
in internal conditions (RETURN TO SET POINT)
■Example: A rise in blood pH triggers effectors that reduce rise
Thermoregulate: Control body temperature (How animals obtain heat/whether body
temperature is constant)
●Endotherm (inner heat): Produce heat from metabolism to warm tissues (32
degrees)
●Ectotherm (outer heat): Heat gained from enviro./external sources (require less
food) (22 degrees)
○ Behaviorally but still regulate environment
● Most animals are a mixture of these two
●Homeotherms (alike heat): Keep body temperature constant
●Heterothermy (different heat): Allow body temperature to rise/fall
●Examples:
○ Humans/Mammals are endothermic homeotherms
○ Small desert animals allow body temperature to rise in hotter temperatures of
the day
○ Small mammals in cold climates reduce metabolic rate/allow body temp. To
drop (torpor and for longer time = hibernation)
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