BISC 101 Lecture Notes - Lecture 6: Symporter, Hypothalamus, Antiporter

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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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