#4: Locomotion Homeostasis & Ecology Flashcards
Animals movement dependent upon:
(most) Contractile proteins: actin & myosin
Types of movement
- Amoebic: amebas, WBCs
- Ciliary & flagellar: ciliates, epithelial surfaces (dep on proteins-tubulin & dynein
- muscular: muscles of all animals exert same force/X-sectional area
Cilia & flagella
- project from cell
2. 9 pairs of microtubules. surround a central pair: 9+2 (universal for all cilia/flagella in animal kingdom)
Pseudopodia
Extensions of cell cytoplasm, means fake foot
Sarcomere
- functional unit of muscle fiber
- holds Actin & myosin filaments
- filaments linked by molecular cross bridges that slide to shorten the sarcomere wh/ contracts the muscle
Control of Muscle Contraction
- W/out stimulation, fiber does not contract due to presence of TROPOMYOSIN
- Tropomyosin blocks binding sites on Actin where Myosin attach.
- Upon stimulation , Ca++ ions bind to Troponin, pull it away as Tropomyosin. Now myosin can bind to Actin (ATP is required); sliding can begin–> contraction
Neuromuscular junction
- where muscle fiber joins motor nerve
- When motor nerve is stimulated, Ach releases, acts on fiber & releases Ca++ ions (stored in sarcoplasmic reticulum)
3 types of muscle
- skeletal
- smooth
- cardiac
Skeletal
- Striated due to alternating myosin and actin proteins
- Many nuclei
- Fibers tied together by connective tissue
- Under voluntary control
Smooth
- Unstriated
- single nuclei
- organized as sheets
- found in walls of blood vessels, and around hollow organs
- under INVOLUNTARY CONTROL
Cardiac
- found only in heart
- one or two nuclei
- under involuntary control
ATP sources for muscle contraction
- Glucose: both transported to muscle via blood and derived from glycogen stored in muscle
- Creatine phosphate
Def. of Oxidative fibers
Muscles wh/ rely on aerobic metabolism of glucose for ATP
Def. of Glycolytic fibers
muscles wh/ rely on anaerobic metabolism of glucose (glycolysis) for ATP
Glycolytic fibers
- fast (bec use glycolysis)
- fatigue quickly (bec of lactic acid accumulation)
- don’t need extensive blood supply (appear white)
- used for short bursts of heavy exertion
Oxidative fibers
- slow (bec use aerobic metabolism)
- Don’t fatigue easily
- require extensive blood supply; get additional O2 via myoglobin
- appear red
- Used for slow, sustained activities.
Fast oxidative fibers
have best of both worlds
Homeostasis (tendency toward internal stabilization)
- recognized by Claude Bernard
- Metabolism depletes supplies/ produces wastes
- Influenced by external environment
- Reproductive system: only system not part of homeostatic mechanism of body
Set point
Point at which all other body systems function in an integrated manner to maintain the internal environment around (homeostasis)
Negative feedback regulation
Any deviations from set point that activate physiologic mechanisms to return environment to its set point
Animals living in open sea
- some do not experience large changes in salinity (stenohaline).
- Are in osmotic equilibrium w/ their environment
- Body fluid concentration changes with changes in seawater concentration
- Osmotic conformers
Animals living near coasts
- some have to tolerate large changes in salinity (euryhaline)
- Body fluid concentration remains steady even with concentration changes in surrounding water.
- Osmoregulators
Freshwater organisms
Need to excrete water/conserve salt
Saltwater organisms
Need to conserve water/excrete salt
Hyperosmotic regulation
- maintaining body fluids more concentrated than surrounding water
- In freshwater, water enters body by osmosis and salt is lost outward by diffusion.
- Water is pumped out by the kidney, forming dilute urine. Salt absorbing cells in gills pump salt ions from water to blood.
Hyposmotic regulation
- maintaining body fluids less concentrated than surrounding water).
- Drink sea water to get water and salt, secreting cells in gills pump salt ions from blood to water
- Solution to saltwater problem where water is lost and salt is gained
Contractile vacuole
- Expels excess water gained by osmosis
2. Excretory structure found in protozoans and sponges
Nephridium
- Consists of tubules wh/ collect fluids, move fluids thru duct system where they are excreted thru pores on body surface.
- Fluid is modified along way via reabsorption and secretion.
- Found in flatworms, annelids, molluscs, ete.
Malpighian tubules
- Salts secreted into tubules from hemolymph, creating an osmotic drag that pulls water, nitrogenous waste, etc., which then drain into rectum
- Found in insects, spiders
Nephron
functional unit of kidney
Parts of nephrons
- glomerulus: a mass of capillaries where incoming blood is filtered and filtrate passed down into renal tubule
- Renal tubule: all valuable material is reabsorbed as filtrate passes thru it and further wastes are secreted into it. Fluid then empties into a collecting duct.
- Collecting duct carries away waste via the ureter to the urinary bladder
Function of kidneys
- Regulate osmotic pressure of blood
- If fluid intake high–> kidneys excrete dilute urine, saving Na++, excreting H2O
- If fluid intake low –> kidneys excrete concentrated urine, saving H2O
Countercurrent Multiplier System
- Process thru which kidney is able to concentrate urine
2. Takes place at portion of tubule called Loop of Henle
Vasopressin
- Anti-diuretic (hormone (ADH)
- Controls absorption vs excretion of H2O (diuretic)
- Released by pituitary gland in response to high blood osmotic pressure or low blood volume
- increases permeability of collecting duct and tubule walls
- Controls urine concentration: dilute vs concentrated
Ectothermy
Body temp determined by environment.
Most animals are ectotherms
Endothermy
Body temperature determined internally, by generating and retaining metabolic heat.
- Only true endotherms are birds and mammals
- Allows them to remain active in winter.
How ectotherms adjust temperature
- Behavioral thermoregulation: seek areas where temperature is favorable (ie lizard stays warm in water in morning, moves under a rock to protect from hot sun midday, out in cooler sun in afternoon
- Temperature compensation: adjusts metabolic rate to prevailing temperatures so that metabolic intensity remains constant
How endotherms regulate temperature
- Heat production: by metabolism and muscle contraction (ie shivering).
- Bec most of food eaten by endotherms is used to generate heat, endotherms need more food than ecotherms of same size
- Heat loss: thru radiation, conduction, convection, evaporative cooling
Countercurrent heat exchange
- happens in extremeties: arms/hands and legs/feet
2. allows for adaptation to cold environments
Adaptive hypothermy
- Since endothermy is energenically expensive esp. in smaller animals (ie hummingbirds, pygmy mice, marmots), homeothermy is temporarily and routinely abandoned for a period of time.
Examples: - daily torpor in hummingbirds (rest and reduce body temp; not seasonal related)
- Hybernation in marmots
- Summer estivation in pygmy mice
Internal fluids
- increase in body size required specialized circulatory system to transport nutrients, wastes, hormones, heat, etc.
Multicellular animals internal fluids are:
two main compartments:
intra-cellular
extra-cellular
In animals with closed circulatory systems (vertebrates, annelids)
Extracellular fluid subdivided into:
- blood plasma
- interstitial (intercellular) fluid
Review of Fish vascular system
- Single Path of blood: Heart –> Gills–> body organs–> heart to get reoxygenated
- Since heart has to provide enough pressure to push blood through 2 systems (gills, body organs), blood pressure is greatly reduced.
Review of vertebrate vascular system
- Lungs evolved
- Double circulation:
a) systemic circuit takes blood to body organs
b) pulmonary circuit takes blood to lungs
Respiration facts
- Air > O2 than water; gas molecules diffuse > rapidly in air. So cost of getting O2 much lower for terrrestrial animals (living on land)
- Respiratory surfaces should be:
a) large surface area
b) thin and wet to allow efficient diffusion of gases
Four types of gas exchange
- direct diffusion
- Through tubes
- through gills in water
- lungs
Gas exchange by direct diffusion
- Also called cutaneous respiration
- seen in small bodied animals ie protozoans, sponges, cnidarians
- Used by amphibians/fishes as supplement
Gas exchange through tubes
- branching system of tubes (trachae) that terminate directly on the cells
- simple; highly effecient
- insects, terrestrial arthropods
Gas exchange in water thru gills
Countercurrent flow of blood and water provides maximum exchange of gases
Countercurrent flow
Water arrives oxygenated and leaves low in oxygen whereas blood leaves oxygenated and arrived deoxygenated
If not countercurrent, not good
Both water and blood arrive oxygenated and leave deoxygenated
Lungs
- Negative pressure is created in lungs by increasing volume of thoracic cavity (pull ribs outward and diaphragm downward)
- Air rushes in
- Exits through reverse process.
- as compared to amphibians: they use a positive pressure to inhale
Gas exchange in lungs
- takes place at alveoli
- Alveoli have more O2, less CO2 than blood in capillaries
- Through diffusion, O2 moves from alveoli to blood and CO2 moves from blood to alveoli.
Transport of Respiratory Gases
- Solubility of O2 is low in water so respiratory pigments are required to transport gases.
Hemoglobin (Hgb)
- Most common respiratory pigment (red, iron-containing protein)
- Holds O2 in a loose, reversible combination so can be easily released to tissues
Shape of hemoglobin controls amount of O2 taken up or given up. What factors affect shape?
Affected by several factors:
- Concentration of O2 in its surroundings
a) if more O2 (as in lung), Hgb binds oxygen
b) if less O2 (as in tissues), Hgb releases O2 (Bohr Effect)
Bohr effect
CO2 and/or a lower pH shift the Hgb saturation to the right, causing Hgb to unload more O2 into tissues.
