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Today • Looking at “Form fits function” – Human Body Review • Have out notes, etc. that you need

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Today. Looking at “Form fits function” Human Body Review Have out notes, etc. that you need. Form fits function. Examples. Enzyme specificity Viral specificity Pollinators/flowers Pollen/stigma Adaptations/environment. Nervous System. Action potential. - PowerPoint PPT Presentation

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Today

• Looking at “Form fits function”– Human Body Review

• Have out notes, etc. that you need

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Form fits function

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Examples

• Enzyme specificity• Viral specificity• Pollinators/flowers• Pollen/stigma• Adaptations/environment

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Nervous System

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Transmission across synapses

• http://outreach.mcb.harvard.edu/animations/synaptic.swf

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter14/animation__transmission_across_a_synapse.html

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Muscular System

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Muscle Tissue

• Skeletal – attached to bone (Ex. Biceps)

• Smooth – blood vessels and internal organs (stomach)

• Cardiac – heart• Reflex arc – pictured

to the left

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Vertebrate Skeletal Muscle• Contract/relax: antagonistic pairs

w/skeleton• Muscles: bundle of….• Muscle fibers: single cell w/ many nuclei

consisting of….• Myofibrils: longitudinal bundles composed

of….• Myofilaments:

•Thin~ 2 strands of actin protein and a regulatory protein •Thick~ myosin protein

• Sarcomere: repeating unit of muscle tissue, composed of….

• Z lines~sarcomere border• I band~only actin protein• A band~actin & myosin protein overlap• H zone~central sarcomere; only myosin

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Muscle contraction

• http://bcs.whfreeman.com/thelifewire/content/chp47/4702001.html

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Muscular contraction

• Action potential travels from neuron to muscle• Action potential is generated on the

sarcolemma• Sarcoplasmic reticulum releases Ca++• Ca++ binds to troponin on the actin filaments

– Conformational change exposes myosin binding sites

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Muscular Contration

• ATP binds myosin head (high-energy head)• If Ca++ present, myosin binding sites on the

actin are exposed (myosin heads bind to actin filaments) – form cross bridges

• ADP and P are released, causes conformational change in myosin, causes sliding movement towards center of sarcomere (2 Z lines come together)

• Muscle fibers contract

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Muscle contraction regulation, I

• Relaxation: tropomyosin blocks myosin binding sites on actin

• Contraction: calcium binds to troponin complex; tropomyosin changes shape, exposing myosin binding sites

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Muscle contraction regulation, II

• Calcium (Ca+)~ concentration regulated by the….

• Sarcoplasmic reticulum~ a specialized endoplasmic reticulum – releases Ca+

• Stimulated by action potential in a motor neuron

• T (transverse) tubules~ travel channels in plasma membrane for action potential

• Ca+ then binds to troponin

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Endocrine System

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Mode of Action: Chemical Signaling• 1- Plasma membrane reception •

signal-transduction pathways (neurotransmitters, growth factors, most hormones)

• 2- Cell nucleus reception • steroid hormones, thyroid hormones, some local regulators

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TROPIC HORMONES

T3/T4 Calcitonin

TestosteroneEstrogen

ProgesteroneShort-termEpinephrine

Long-termGlucocorticoids

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QuickTime™ and aCinepak decompressor

are needed to see this picture.

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Respiratory

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• Countercurrent exchange – allows diffusion to occur along the entire length of capillary

• 80% efficient• On land, gills would dry out and collapse (need

moist surface for diffusion)

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Regulating breathing• Regulation: monitors CO2

levels in blood (medulla oblongata)

• CO2 + water = carbonic acid = lowers pH

• Slight drop in pH triggers a breathing response

• O2 levels have little effect on breathing unless O2 is severely depleted

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Respiratory pigments: gas transport• Needed for efficient transport of

oxygen• Oxygen transport-• Hemocyanin: found in hemolymph of

arthropods and mollusks (Cu) – blue blood

• Hemoglobin: vertebrates (Fe)

• Carbon dioxide transport-• Blood plasma (7%)• Hemoglobin (23%)• Bicarbonate ions (70%)• Deep-diving air-breathers-• Myoglobin: oxygen storing protein

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Protein review• Cooperativity – the

binding of one oxygen to hemoglobin, causes the other 3 active sites to have a HIGHER AFFINITY for oxygen

• Similar to allosteric activation

• What do you think the optimal pH is for hemoglobin?

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Bohr shift• Hemoglobin releases oxygen (has less affinity

for oxygen) at lower partial pressure for oxygen and at lower pH’s (more CO2)

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Circulation system evolution, I • Gastrovascular cavity (cnidarians, flatworms)• Open circulatory •hemolymph (blood & interstitial fluid) •sinuses

(spaces surrounding organs)• Closed circulatory: blood confined to vessels• Cardiovascular system •heart (atria/ventricles) •blood vessels

(arteries, arterioles, capillary beds, venules, veins) •blood (circulatory fluid)

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Circulation system evolution, II• Fish: 2-chambered heart; single circuit of blood flow• Amphibians: 3-chambered heart; 2 circuits of blood flow-

pulmocutaneous (lungs and skin); systemic (some mixing)• Mammals: 4-chambered heart; double circulation; complete separation

between oxygen-rich and oxygen poor blood

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The heartbeat• Sinoatrial (SA) node (“pacemaker”): sets rate and timing of cardiac

contraction by generating electrical signals• Atrioventricular (AV) node: relay point (0.1 second delay to ensure

atria empty) spreading impulse to walls of ventricles• Electrocardiogram (ECG or EKG)

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Why do the blood vessels have different structure?

• Capillaries•endothelium (lining of smooth cells = less resistance to blood flow); basement membrane – cell attachment & selective permeability

• Arteries•thick connective tissue;

thick smooth muscle; endothelium; basement membrane

• Veins •thin connective tissue; thin smooth muscle; endothelium; basement membrane

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Blood• Plasma: liquid matrix of blood in which cells are suspended (90% water)• Erythrocytes (RBCs): transport O2 via hemoglobin• Leukocytes (WBCs): defense and immunity• Platelets: clotting• Stem cells: pluripotent cells in the red marrow of bones• Blood clotting: fibrinogen (inactive)/ fibrin (active); hemophilia; thrombus

(clot)

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Digestion

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Feeding mechanismsSuspension-feeders

Bulk-feedersFluid-feeders

Substrate-feeders

Deposit-feeders

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Intracellular Digestion

• Ingestion – phagocytosis, pinocytosis

• Digestion – hydrolytic enzymes contained in lysosomes

• Absorption – simple diffusion

• Elimination - exocytosis

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Extracellular Digestion – can eat larger preyGastrovascular cavity

Complete digestive tracts(alimentary canals) – allow for systematicFood processing in specialized regions

1 opening2 openings

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Gastric Pits

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Positive feedback mechanism

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Hormonal Regulation• Gastrin - found in stomach

– released when we sense food– Stimulates gastric juice production

• Secretin – found in duodenum– Acid chyme stimulates production of secretin– Secretin stimulates the pancreas to release bicarbonate

(offset acid)• CCK (cholecystokinin) – duodenum

– Presence of fatty acids/amino acids stimulates release of CCK

– CCK stimulates the gall bladder to release bile and the pancreas to release other enzymes

– CCK slows peristalsis if meal is high in fat (fat takes longer to digest)

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• Excretion

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OsmoregulatorsSaltwater fish – lose water to the environment, need to drink salt water, actively transport salt out of gills & release salt in urineFreshwater fish - opposite

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Aquatic organisms can afford to

lose water ammonia

• most toxic• Able to dilute it

Terrestrial need to

conserve water urea

• less toxic/can store at high conc. (ENERGY)

• Energy tradeoff Terrestrial egg

layers need to conserve

most water uric acid

• least toxic• Less soluble• Waste in paste-form

Nitrogen waste – toxic ammonia vs energy loss

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Mammalian System• Key functions

– filtration• fluids from blood collected • includes water & solutes

– reabsorption• selectively reabsorb needed

substances back to blood– secretion

• pump out unwanted substances to urine

– excretion• remove excess substances & toxins

from body

blood filtrate

urine

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Excretory SystemsProduction of urine by 2 steps: • Filtration (nonselective) • Reabsorption (secretion of solutes)Protonephridia ~ flatworms (“flame-bulb” systems)Metanephridia ~ annelids (ciliated funnel system)Malpighian tubules ~ insects (tubes in digestive tract)Kidneys ~ vertebrates

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Osmotic control in nephron• How is all this re-absorption achieved?

– tight osmotic control to reduce the energy cost of excretion

– use diffusion instead of active transportwherever possible

the value of acounter current exchange system

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Kidney regulation: hormonesAntidiuretic hormone (ADH) ~ secretion increases permeability of distal tubules and collecting ducts to water (H2O back to body); inhibited by alcohol and coffee, caused by osmolarity changesJuxtaglomerular apparatus (JGA) ~ reduced salt intake--->enzyme renin initiates conversion of angiotension (plasma protein) to angiotension II (peptide); increase blood pressure and blood volume by constricting capillaries Angiotension II also stimulates adrenal glands to secrete aldosterone; acts on distal tubules to reabsorb more sodium, thereby increasing blood pressure (renin-angiotension-aldosterone system; RAAS)