Bio 2 exam 3
Monoecious plants -
- two types of flowers (male & female) occurring on the same plant. This occurs in the "cucurbits" (i.e. pumpkins & squashes).
Know the steps of fertilization in Sea Urchins
. Sperm cell contacts the jelly coating of the egg & the acrosome releases enzymes. 2. Acrosomal enzymes digest a hole in jelly coating allowing penetration of sperm cell. 3. Species-specific proteins on sperm cell bind to species-specific receptor proteins on the egg. 4. Sperm & egg cell plasma membranes fuse, allowing sperm nucleus to enter egg cell (time zero). 5. Egg cell plasma membrane becomes impenetrable to other sperm cells (< 2 sec.). 6. Vitelline layer hardens & separates from plasma membrane, becoming impenetrable to sperm (20 sec); meiosis II finishes; nuclei fuse (20 min); 1st cell division (90 min). 7. Sperm & egg nuclei fuse.
What are the four ways antibodies mark antigens for elimination?
1. Neutralization (blocks viral binding sites; coats bacteria) 2. Agglutination (of microbes) 3. Precipitation (of dissolved antigens) 4. Activation of the complement system
Know the steps of tracking an action potential and what happens in each.
1. Resting state: Voltage-gated Na+ and K+ channels are closed;resting potential is maintained by ungated channels 2. depolarization 3. Additional Na+ channels open, K+ channels are closed; interior of cell becomes more positive 4. repolarization 5. The K+ channels close relatively slowly, causing a brief undershoot. 6. return to resting state
How do cytotoxic T cells destroy infected body cells, (know the steps)?
1.A cytotoxic T cell binds to an infected cell. 2. Perforins form holes in the infected cell's membrane, and enzymes trigger cell death. 3. The infected Cell dies. 4. Cytotoxic T cell detaches and can destroy other cells infected by the same pathogen.
Know the mechanism of filament sliding. slides 20 through 27.
1.ATP binds to myosin head, resulting in the low energy (detached) configuration. 2.Myosin hydrolyzes ATP to ADP & Pi; both remain bound to myosin; energy released causes the myosin head to extend to the actin filament. 3.Myosin head latches onto its actin binding site forming a cross bridge between the two filaments. 4.ADP & Pi are released, and the myosin head reverts back to its low-energy configuration (i.e. the "power stroke"), causing the actin filament to move toward the center of the sarcomere. 5.The cross bridge remains attached until another ATP binds to the myosin head, thereby repeating the above process. 6.The sequence: detach, extend, attach, pull, detach repeats many times; the combined action of hundreds of heads results in the contraction of the entire muscle
How do neurons communicate at the synapses? What happens if you get botulism?
1.Action potential arrives at synaptic terminal. 2.Action potential causes some synaptic vesicles filled with neurotransmitter to fuse with plasma membrane of synaptic terminal; Neurotransmitter is released into synaptic cleft. 3.Neurotransmitter diffuses across synaptic cleft & binds to ion channel receptor proteins in receiving cell dendrite membrane. 4.An influx of (Na+) ions may trigger an action potential in the receiving cell. 5.Neurotransmitter is taken back into sending neuron (or is degraded or diffuses away) & ion channels close. Botulism is weakness of muscles and can weaken muscles involving breathing which can lead to death
What are the 4 steps of allergies?
1.Allergen enters the bloodstream. 2.Virgin B Cells are recruited to produce antibodies. 3.B Cells develop into plasma cells that release antibodies. 4.Antibodies attach to mast cells
Heat is gained or lost in 4 ways
1.Conduction — the transfer of heat by direct contact. 2.Convection — the transfer of heat by movement of air or liquid past a surface. 3.Radiation — the absorption or emission of electromagnetic waves. 4.Evaporation — the loss of heat from the surface of a liquid that is losing some of its molecules as a gas.
what are the three stages of childbirth?
1.Dilation of the Cervix. Longest stage of labor (6-12+ hrs). Short, mild contractions every 10 min. Cervix dilates to 10 cm. Amnion ruptures. 2.Expulsion (delivery). Lasts ~ 20 - 60 min. Strong rhythmic uterine contractions (1 min., every 2 - 3 min.) Infant is forced down & out uterus & vagina. 3.Delivery of the Placenta. Expulsion of the "afterbirth". Normally within 15 min. of delivery.
the two main types of immunity and describe in detail the components and their functions of each.
1.Innate Immunity Aka non-specific, genetic, or natural immunity. Involves a set of defenses that are immediately active, and independent of previous encounters with a given pathogen or substance. Are the same, whether or not the pathogen has been previously encountered. Found in both vertebrates & invertebrates. 2.Adaptive Immunity Aka acquired immunity. Involves a set of defenses developed for, and activated by specific pathogens or substances. Immune system "remembers" (or specifically recognizes) a previously encountered pathogen.
Know the main components of the urinary system, and it major roles in homeostasis. Two main functions.
1.Kidneys - produce urine. 2.Renal Artery & Vein - transport blood to & from the kidneys. 3.Ureter - conducts urine from the kidney to urinary bladder. 4.Urinary Bladder - stores urine until voided from the body. 5.Urethra - conducts urine from the urinary bladder to the exterior of the body. Two Main Functions: 1.Form & excrete urine. 2.Regulate water & solute content in body fluids.
How are helper T cells, cytotoxic T cells, and B cells activated
1.Macrophage ingests & degrades foreign cells or material, and breaks it into antigenic fragments. 2.Self proteins bind to foreign non-self molecules/antigens. 3.Self/non-self complexes are displayed at cell surface. 4.Virgin helper T cells bind to self/non-self complexes (= recruitment /activation). 5.Signal molecules stimulate division of activated Helper T cells to form memory T cells and effector T cells. 6.Activated Helper T cells secrete Interleukin-2 which . . . AND: Activated HT cells bind to "presented antigens" on B cells, which activates them to promote division & formation of plasma cells that release antibodies. Interluekin-1 tends to stimulate the inflammatory response, while IL-2 tends to stimulate proliferation of HT cells. 7. Activates B cells (& the humoral response), and Cytotoxic T Cells (& the cell-mediated response
5 methods of adaptions that balance heat gain or loss.
1.Metabolic Heat Production - increased rates of metabolism give off more heat (e.g. vigorous exercise & shivering). 2.Insulation - such as hair, feathers, fat. 3.Circulatory System Adaptations: Counter current heat exchange. Changes in blood flow to/from skin. 4.Evaporative Cooling: Sweating, panting, spreading saliva. 5.Behavioral Responses: Movement to warm vs. cool environments. Bathing, seasonal migrations.
How is an action potential propagated along the axon?
1.Once an action potential is initiated, Na+ channels open, resulting in the influx of Na+ ions; this triggers a similar influx of Na+ in adjacent regions of the plasma membrane. 2.Once the influx of Na+ is completed, Na+ channels close & K+ channels open, resulting in an efflux of K+ ions. 3.Migrating action potential continues along the entire length of the axon; Na/K pump re-establishes correct membrane resting potential. Impulse travels @ 50-60 m/sec.
What are the 3 main functions of the nervous system
1.Sensory Input - conduct signals from receptors to CNS. 2.Integration - analysis & interpretation of sensory signals, & formation of appropriate responses. Motor Output - conduct signals from CNS to effectors that execute a response.
What are the 3 main types of neurons and what are the 4 steps of the reflex arch?
1.Sensory neurons - receive stimuli, convey signals from sensory receptors to the CNS. 2.Interneurons - are located entirely in the CNS, integrate information & send it to motor neurons. 3.Motor neurons - convey signals to effector cells. Knee-Jerk Reflex Arc 1.Sensory receptor detects stretch stimulus. 2.Sensory neuron sends impulse to the CNS (spinal cord). 3.Impulse is transferred from the CNS to motor neurons . . 4.And interneurons.
How do motor neurons stimulate muscle contraction? Why is acetylcholine important in this function? What is the function of acetylcholine and how do the myosin heads cause actin filaments to "slide" relative to myosin filaments? S28-30
Acetylcholine triggers an action potential in the muscle cell plasma membrane. Carry nerve impulses (action potentials) from the CNS to muscles. Axons of each motor unit branches out to synapse with many muscle fibers (cells). Synaptic terminals release acetyl-choline into the synaptic cleft. Acetylcholine initiates a muscle contraction
Adaptive immunity, how can it be acquired?
Active Immunity - long-term immunity that occurs when an individual produces their own supply of antibodies, either by exposure to a foreign entity or by immunization. e.g. Exposure to Chickenpox or Measles. e.g. Vaccination for Smallpox or Tetanus. Passive Immunity - temporary immunity that occurs when an individual is given previously prepared antibodies to prevent a disease. e.g. Treatments for rabies & snakebites (anti-venom). Mother's antibodies protect unborn children. can be acquired through vaccinations
What are the structures and functions of the blood brain barrier, (BBB)?
Blood-Brain Barrier - the selectively permeable barrier between the capillaries of the brain & the surrounding cellular matrix of the brain. -Tight junctions between endothelial cells. -Allows passage of nutrients & oxygen, but not metabolic wastes from other parts of the body. -Helps to maintain a stable chemical environment for the brain. Remember - Astrocytes are "transfer cells" that transfer glucose & other nutrients from the blood vessels into nerve cells.
What are the parasympathetic and sypathetic divisions of the nervous system? What does each one do? What do they control?
Both are a part of the autonomic nervous system (involuntary) Parasympathetic Division - Prepares the body for activities that gain & conserve energy (aka "Rest & Digest"). Sympathetic Division - prepares the body for intense energy-consuming activities (aka "Fight or Flight").
Where do B & T cells form and where they mature? Describe the development of B cells versus T cells.
Both originate in bone marrow from stem cells. B cells mature in marrow. T cells mature in thymus.
What are the processes that give form to the developing animal? Know each and why each is important.
Cell Migration - where cells move by amoeboid motion along chemical signal trail. Apoptosis - i.e. Programed Cell Death - where unnecessary cells or tissues are induced to "self destruct" by nearby cells that also remove cellular debris. Embryonic Induction - individual cells (or groups of cells) induce other nearby cells (groups) to switch on/off certain genes that cause the receiving cells to differentiate Pattern Formation - the emergence of a body form with specialized tissues, organs & limbs forming at the correct time & in the correct locations.
What are some examples of diuretics? What causes kidney stones?
Common diuretics include beverages containing caffeine & alcohol; some foods/herbs (e.g. hawthorn, dandelion & celery) Kidney Stones - crystallized precipitates of calcium oxalate, uric acid or cystine that variously form in the ducts of the kidney.
Describe the complement system, Inflammatory response and the steps.
Complement System A group of about 30 kinds of serum proteins that can act with (i.e. "complement") or help antibody & phagocyte defense mechanisms. 1. Enhance Inflammation Bind to mast cells & trigger more histamine release. Mast cells are bone marrow-derived cells that are found resident in tissues throughout the body, particularly in association with structures such as blood vessels and nerves, and close to surfaces that interface the external environment. 2. Help Target Cells for Destruction Bind to cells coated with antibodies as extra signal to phagocytes. Mast cells release histamines that trigger the inflammatory response. 3. Form Membrane Attack Complexes. Channels formed by the Membrane Attack Complexes pass through the membrane(s) and cell wall of the microbe; cells cannot control the entry & exit of water & solute which leads to cell lysis and/or death. Inflammatory Response The characteristic redness, swelling, pain and heat exhibited by a tissue when it is damaged by physical or chemical agents, or by infection. ª1.Tissue injury allows entry microbes. ªMast cells release histamines - cause capillary dilation; attracts neutrophils. ªMacrophages release cytokines - promote blood flow into area. ªDamaged cells release prosta-glandins - stimulate local pain. ª2. Capillaries dilate, become leaky, allow fluids into tissue. ªTissue swells, becomes red & warm. ªMore neutrophils are attracted to infected area. ªPlatelets & clotting factors bind to damaged tissue & initiate clotting. ª3. Neutrophils & macrophages phagocytize microbes & damaged cells ªBlood clot forms & tissue heals.
Oviparous
Eggs hatch outside the mother's body
the different types of thermoregulation strategies
Endotherms - "warm-blooded" animals that warm themselves via heat derived from their own metabolism (e.g. mammals, birds & most vertebrates). Ectotherms - "cold-blooded" animals that warm themselves by absorbing heat from their surroundings (e.g. fish, amphibians, lizards, snakes, most invertebrates).
Know the different types of joints and what they do and an example of each. S15-16
Fibrous Joints - tight immovable joints, where separate bones are held together by connective fibers (e.g. bones of skull and tooth & socket joints). Cartilaginous Joints - slightly movable joints between bones that are joined together by strips or disks of cartilage (e.g. in ribs, vertebrae & hip bones). Synovial Joints - freely movable joints that are enclosed in a fibrous capsule; bones are separated by a fluid-filled cavity and stabilized (held together) by ligaments. Ball-and-socket joints - enable rotation in the arms and legs. Hinge joints - in the elbows and knees permit movement in a single plane. Pivot joints - enable the rotation of the forearm at the elbow.
In innate immunity, what comprises the 1st and 2nd line of defenses and their functions?
First Line of Defense - Barriers to Entry: Skin - dead, keratinized cells form an impermeable barrier. Mucous membranes - form a sticky trap for microbes; ciliated cells sweep mucus & microbes into throat. Second Line of Defense (if above fails) - Innate Immune Cells: Neutrophils - "first-responder" phagocytes circulate freely in blood; are attracted to infection sites; squeeze between cells of capillary wall, which is called extrasalvation. Macrophages - "large" phagocytes that reside in, & wander through the interstitial fluids. Natural Killer Cells - attack cancer cells and virus-infected cells.
The types of asexual reproduction
Fission - as in Prokaryotes & Anemones. Cell Division (binary fission) - as in unicellular protists. Budding - as in yeasts & hydras. Fragmentation & Regeneration - as in Starfish & Sponges. Parthenogenesis - seen in fish, arthropods, amphibians, and lizards. An egg develops without being fertilized Binary Fission - the separation of a parent organism/cell into two (or more) individuals of about equal size
Understand cleavage, gastrulation, and the derivatives of the three embryonic layers
Formation of the blastopore, followed by the formation of the gastrula. Varies from one species to another. Animal Pole - region of small rapidly dividing cells; thought to become the three germ layers. Vegetal Pole - region of large slowly dividing cells; thought to become the yolk & placenta. Blastopore - becomes the embryonic anus.
Know the structure and function of the nervous system components.
Functionally divided into . . . The Central Nervous System - comprised of the brain & spinal cord. Peripheral Nervous System - comprised of nerves outside the CNS that carry signals into & out of the CNS
What are the different parts of the human skeleton, functions, names of bones. Why are bones complex living organs? What do bone cells do throughout life? Name and define the different cells. S11-14
General Functions -Rigid -Protection -Storage -Production -Provides -Levers •all bone marrow is red at birth, but red marrow gradually converts to yellow marrow as we become adults. After adulthood, only flat bones and ends of long bones (i.e. "spongy bone tissue") contains red marrow. is yellow because it is enriched in & stores fat that can be used as a last resort as a source of food/energy during extreme starvation. can convert back to red bone marrow in 1-2 days in cases of severe blood loss. Osteogenic cells - stem cells that give rise to all other bone cells. Osteoblasts - bone-forming cells; remove calcium from blood & deposit Ca2+ salts into forming bone. Osteocytes - mature bone cells trapped or located in lacunae of bone that maintain bone tissue; thought to be the "mechanosensor cells" that control the activities of osteoblasts & osteoclasts. Osteoclasts - bone-absorbing cells; breakdown bone & return calcium to blood.
Describe the different types of skeletons. S5
Hydrostatic Skeleton - A skeleton made up of fluid held under pressure in a closed body compartment; the shape of the compartments controls the animal's form. Found in worms and Cnidarians. Exoskeletons - rigid "non-living" external skeletons (or shells) that are found in arthropods & Molluscs. They consist of . . . Chitin and protein in Arthropods. Must be shed to permit growth. Endoskeletons - hard or leathery supporting elements situated among the soft tissues of an animal. They are made of . . . Cartilage or cartilage and bone (vertebrates).
how is pregnancy induced
Induced by hormones and other chemical signals. Highest levels of estrogen are reached late in pregnancy. Estrogen stimulates the formation of oxytocin receptors in uterus. Fetal cells & mother's pituitary gland secrete increasing amounts of oxytocin. Oxytocin stimulates . . . Uterine contractions. Placental synthesis & release of prostaglandins. Prostaglandins stimulate more contractions of the uterus.
know spermatogenesis in the human male
It takes about 2.5 - 3 months for sperm cells to fully mature. occurs in seminiferous tubules •During maturation, sperm cells finish flagellum development (i.e. become motile), develop receptor proteins to be able to recognize an egg; and form the acrosome (the anterior structure with digestive enzymes required to penetrate the egg for fertilization). Once ejaculated, they live for only about 5 - 6 days
4 methods of thermoregulation
Kleptothermy is any form of thermoregulation by which an animal shares in, or steals from, the metabolic thermogenesis of another animal Poikilothermic animals are ectotherms which have no control over their body temperature; their core body temperature conforms to ambient temperature of it surroundings and environment.
the types of osmoregulation in land animals with examples
Land animals lose water by . . . Evaporation & waste disposal. Gain water by drinking and eating. Land animals conserve water by . . . Reproductive & behavioral adaptations. Waterproof skin & efficient kidneys. •Laying eggs & fertilization in watery habitats. •Development of the "amniotic egg" (w/a waterproof coating or shell).
differences between freshwater and marine fishes in osmoregulation
Marine fishes- Gains water, food, and salt ions through drinking salt water. EXCRETES salt through gills. Osmotic water loss through gills. Excretion of salt and SMALL amounts of water through concentrated urine in kidneys. Freshwater fishes- gains water and food from drinking fresh water. UPTAKE of salt ions through gills. Osmotic water gain through gills. Excretion of salt and LARGE amounts of water through diluted urine in kidneys.
Nerve function depends on??
Nerve Function Depends on Charge Differences Across Neuron Membranes. Outside = positive. Inside = negative. Na+ high outside of neuron K+ high inside of neuron
Advantages of asexual reproduction
Normally faster than sexual reproduction - allows rapid population growth into new or vacated habitats; early populations have a competitive advantage. Beneficial in stable, unchanging habitats - no new selective pressures, new adaptations are not beneficial; genetic stability if favored. Beneficial for sparse populations or where individuals do not move - allows reproduction where mates are not available.
Know oogenesis in the human female.
Primary Oocyte In Prophase I (from fetal development) 1. Epithelial cells become organized around a primary oocyte to become a primary follicle. 2. Meiosis I is completed to form a secondary follicle containing a secondary oocyte & 1st polar body 3. Meiosis II follows; Follicle swells with follicular fluid to form a vesicular follicle. 4a. Follicle continues to swell & distend the surface of the ovary. 4b. Ovulation - the Vesicular follicle bursts to release secondary oocyte ("egg"). Meiosis stops at Metaphase II. 5. Follicular remains develop into the corpus luteum. 6. Corpus luteum degenerates. Corpus luteum starts to produce & secrete estrogen & progesterone. 7.Estrogen & progesterone . . . Feed back to inhibit release of FSH & LH by anterior pituitary. Promote thickening of endo-metrium & secretion of mucus. 8.Decrease in LH causes corpus luteum to degenerate & gradually quit producing estrogen & progesterone. 9.Low levels of estrogen & progesterone . . . Trigger the disintegration & shedding of endometrium (i.e. menstruation). Cause the hypothalamus to promote the release of FSH & LH by the anterior pituitary, thus initiating another cycle.
What happens in each of the three trimesters of pregnancy
The First Trimester - the period of greatest change. The embryo forms, but looks like other vertebrate embryos. Extra-embryonic membranes form. All major organ systems (except circulatory & respiratory systems) are established. The Second Trimester (13 - 27 weeks) Fetus greatly increases in size (from ~ 5 to 19 cm) & weighs ~ 0.5 kg ( 1 lb.); assumes the "fetal position". Human features become well-defined, including facial, hand & feet features; eyes are open at end of 2nd trimester. The Third Trimester (28 weeks - birth) Also a time of rapid growth where . . . The circulatory and respiratory systems mature. Muscles thicken and the skeleton hardens.
Describe clonal selection.
The process whereby genetically unique (naïve or virgin) lymphocytes react with (recognize) their specific antigen for the very first time. Stimulates their mitotic proliferation. Leads to the production of Effector B Cells (aka Plasma Cells) and Memory Cells. Effector/Plasma cells produce & secrete massive amounts of antibodies (2000/sec). Memory Cells migrate to lymph nodes to respond to subsequent invasions. Last for decades. Activated by Helper T cells. Macrophages destroy antigens bound to antibodies.
How do helper T cells stimulate the humoral and cell mediated immune responses?
They must first be "activated" (or "recruited) into action - i.e. "naïve" or "virgin" cells must encounter their first antigen. Involves complex self/antigen receptors. First exposure to antigen only occurs via macrophage "antigen presenting cells". Antigen-Presenting cells include: Macrophages & B cells. Activated Helper T Cells then activate . . . B cell lymphocytes (Humoral Response). Cytotoxic T Cells (Cell-mediated response).
Know the types of muscle contraction and skeletal/muscle interactions in movement, 3 classes. S18-19
Three Types of Muscle: 1.Cardiac - involuntary muscle of the heart. 2.Smooth - involuntary muscles of the internal organ systems (except the heart). 3.Skeletal - voluntary muscles attached to the skeletal system for movement & locomotion
What is important about language as a form of communication?
Types of Communication: Spoken words = 7% Tone of voice = 38% Body language = 55% BODY LANGUAGE MOST IMPORTANT
Describe the different types of movement versus the different types of locomotion. What are their functions? What do they provide?
Types of Locomotion Swimming - Supported by water; nominal effects of gravity; slowed by friction. Walking -Less overall friction between air and the animal; must resist gravity; requires good balance. Running - " Hopping - " Crawling (& Burrowing) - Some unique considerations : Most of the animal's body is in contact with the ground. Thus, there are nominal effects due to gravity, but major effects due to friction. Flying
What are the 3 types of nitrogenous wastes? Which one is for humans, why?
Urea (mammals), Uric acid (birds, reptiles, insects), ammonia (most aquatic animals) Urea is produced by humans
What is metabolic water?
Water produced during oxidative phosphorylation. Glucose + O2 --> C02 +H20
What is important about the homeotic genes?
What is important about the homeotic genes?
how does the structure of an antibody match its function?
Y-shaped protein receptor molecules (aka Immunoglobins) produced by B cell lymphocytes. Comprised of four polypeptide chains: Two heavy + two light chains, Each with variable & constant regions. Each recognizes or binds only one specific antigen. All function to "neutralize" antigens and/or mark them for destruction via phagocytes Phagocytes recognize & bind/attach to base of "Y". Humoral - refers to non-cellular substances that occur in the fluids (especially blood) of the body. Antibodies are the most common "non-cellular" substance.
Which organisms have or do not have these types of immunity?
all animals have innate immunity Only vertebrates have adaptive immunity
hermaphrodite
an organism that has both male and female reproductive organs.
oviviparous
eggs stay in female body in till hatched
3 osmotic systems or scenarios
hypotonic, isotonic, hypertonic
Know the parts of the human kidney and the four key processes of the urinary system. Know the flow and what happens in the kidney, from Bowman's capsule, proximal tubules, loop of Henle, distal tubules, and the collecting duct, renal pelvis, ureter, bladder, urethra.... What molecules are reabsorbed, and which one are released.
nephron- functional unit of kidney Four Key Processes of the Urinary System 1.Filtration (at Bowman's capsule) 2.Reabsorption (by capillaries surrounding proximal & distal convoluted tubules.) 3.Secretion (- by capillaries surrounding proximal & distal convoluted tubules. Includes harmful compounds not filtered into the glomerulus (e.g. residual ammonia, uric acid). 4.Excretion (from kidney, bladder, urethra, ureter). Some Important Notes: Active reabsorption of NaCl results in passive reabsorption of water via osmosis. Reabsorption of HCO3- & secretion of H+ helps to control blood pH.
viviparous
producing living young (not eggs)
cloaca
the posterior opening that serves as the only such opening for the combined intestinal, reproductive, and urinary tracts. All amphibians, birds, reptiles, and monotremes possess a cloaca, from which they excrete both urine and feces
Dioecious plants -
two types of flowers: male flowers on "male plants"; female flowers on female plants
Know the 2 types of osmoregulation strategies
ªOsmoconformers - animals with body fluids having a solute concentration equal to that of seawater, thus without major challenges in water balance. •Includes many marine invertebrates (e.g. squids, star fish, anemones etc.). ªOsmoregulators -animals with body fluids having solute concentrations that greatly differ from their environment. •Includes land animals, freshwater fish, marine vertebrates.
What is the difference between an unmylenated and myelinated neurons and where are each of them found?
•Myelinated neurons occur mainly in the peripheral nervous system where impulses must normally travel further. •Unmyelinated neurons occur mainly in the CNS as interneurons, where impulses travel much shorter distances between sensory & motor neurons.
how is it determined how much of the brain controls parts of the body?
•Parts of the human body are proportionally distorted to represent which parts receive the most precise control with the greatest number of both sensory & motor neurons.