Bio 2 Final

what is the role of the nervous system?

• animal repro + dev

• immune system + species interactions

• behavioral ecology

What does the nervous system give the ability to do?

sense + respond to environmental changes

which animals do not have nerve cells but rely on a nerve net?

porifera (sponges)

What are the different types of sensory receptors?

mechanoreceptor, thermoreceptor, nociception, electromagnetic(photoreception), chemoreception

How does a stimulus lead to a response?

PNS—>CNS—>PNS

What is an example of a stimulus—>response?

1. neurons (nose+mouth) detect stimuli (odor+taste) signals—>brain

2. neurons (brain) interpret signals as food

3. brain sends signals—>neurons in PNS that stimulate salivation response

mechanoreceptor

touch, pressure, stretch, movement, sound

thermoreceptor

external+internal temp

nociception

pain

chemoreception

chemicals-taste+smell

what are neurons

basic units(cells) of the nervous system

what do neurons do?

transmit electrochemical signals, long-lived cells, irreplaceable(amniotic), high metabolic rate, sensory motor interneurons

what do glial cells do?

provide support, nutrition, insulation, + help w/signal transduction

what are schwaan cells?

type of glial cell, provide myelin sheath

what are astrocytes?

type of glial cell-support neurons

synapse

the region where an axon terminal communicates with its postsynaptic target cell

How are signals moves through a neuron?

dendrites (input signal)—>cell body(integration)—>presynaptic axon terminal(output signal)

what is the nervous system organized into?

CNS + PNS

What does the CNS consist of?

brain + spinal cord

what does the CNS do?

analyze + interpret signals from stimuli

• protected by skull, vertebrae, meninges, + cerebral fluid

What does the PNS consist of?

Bunch O’ Nerves

how is the PNS organized?

somatic + autonomic (sympathetic + parasympathetic systems)

What does the PNS do?

collect + send info

How is information transported thru the PNS?

sensory (afferent) nerves: send info towards CNS

motor (efferent) nerves: send info away from CNS

What does the forebrain consist of in an adult brain?

cerebrum (hypothalamus, thalamus, epithalamus)

What does the hindbrain consist of in an adult brain?

cerebellum + pons, medulla oblongata

where does the signal travel across in a signal pathway?

sensory neurons—>interneurons—>motor neurons in a circuit (PNS—>CNS—>PNS)

What is the shortest circuit?

reflex arc

reflex arc: neuron pathways

sensory neurons(PNS) leave muscles to cell body-work with segment of spinal cord(CNS)-allows motor neurons(PNS) to leave spinal cord towards muscles

how does a signal pathway work?

• neurons use electrical signs to communicate with other neurons, muscle cells, or endocrine glands

• these signals involve changes in the amount of electrical charge on either side of a cell’s plasma membrane

• Na⁺/K⁺ pumps, Na⁺ and K⁺ channels, and the presence of Cl^- ions establish the gradients of charge

how does membrane potential lead to action potential

movement of ions across the plasma membrane of the axon 1st depolarizes and then repolarizes the cell via opening + closing of Na⁺ and K⁺ channels

• the wave of changes in potential transmits the signal

What are the steps in membrane potential —> action potential

1. resting membrane potential

2. depolarization to threshold

3. peak of action potential (refractory period)

4. repolarization (relative refractory period)

5. restoration of resting membrane potential

what is resting membrane potential (membrane—>action)

voltage-gated channels are closed

what is depolarization to threshold (membrane—>action)

• voltage gated Na⁺ channels open

• Na⁺ diffuses into the cell + depolarizes the membrane

• action potential is triggered if cell is stimulated

what is peak of action potential (membrane—>action)

• +30mv: voltage-gated Na⁺ channels —> inactivated and K⁺ open

• K⁺ exits the cell and repolarizes the membrane

what is repolarization (membrane—>action)

• Na⁺ channels inactivated—>closed

• K⁺ remain open - hyper-polarization of membrane

what is restoration of resting membrane potential (membrane—>action)

• K⁺ channels close

• resting potential is restored by Na⁺/K⁺-ATPase pump + leak channels

How is action potential created?

1. unstimulated neuron - Na⁺ channels closed

2. threshold potential is reached at axon hillock - Na⁺ channels are open + action potential is generated

3. entry of Na⁺ depolarizes membrane + opens channels toward axon terminal, generating action potential - Na⁺ channels are inactivated

4. Na⁺ depolarizes membrane + opens channels father down axon - Na⁺ channels are closed/K⁺ channels are open + restore resting potential

5. process cont. + action potential moves down axon

synapses may be ___ / ___

electrical, chemical

What are the steps of synapses?

1. presynaptic cell: action potential opens voltage-gated Ca²⁺ channels - Ca²⁺ enters cytosol

2. intracellular Ca²⁺ binds to vesicles + causes them to fuse w/the presynaptic cell membrane, releasing neurotransmitter into the synaptic cleft via exocytosis

3. neurotransmitter molecules diffuses across the synaptic cleft + bind to receptors in the post synaptic cell membrane

4. ion channel opens in response - allows Na⁺ —>post-synaptic cell, depolarizing membrane - EPSP

what hormone works with the sympathetic division?

norepinephrine

What does the sympathetic division (norepinephrine) do to the body?

• dilate pupils

• inhibits salivation

• increase heartbeat + force of contraction

• relaxes airways

• inhibits digestion + stomach activity

• stimulates release of glucose—> blood

• inhibits insulin release

• inhibits activity of sm intestine

• stimulates secretion of epinephrine + norepinephrine

• relaxes urinary bladder

what hormone works with the parasympathetic division?

acetylcholine

What does the parasympathetic division (acetylcholine) do to the body?

• constricts pupils

• stimulates salivation

• slows heartbeat

• constricts airways

• stimulates digestion + stomach activity

• increase glucose utilization by liver cells

• stimulates insulin secretion from pancreas

• increase activity of sm intestine to promote absorption of nutrients

• stimulates urinary bladder to contract

what does the skeletal system do?

• provides support + protection

• functions in locomotion (w/muscular system)

vertebrate endoskeletons are organized into ____ and ____

axial and appendicular skeletons

hematopoiesis

production of all cellular components of blood + blood plasma

where does hematopoiesis occur?

bone marrow, liver, spleen

what are the diff types of joints

pivot, hinge, ball + socket

what composes the axial skeleton?

skull, spinal column, ribs, tailbone

what composes the appendicular skeleton?

shoulders, arms, legs, hip

what are the types of muscles?

skeletal, smooth, cardiac

skeletal muscle

• striated, tubular, multi-nucleated

• voluntary

• attached to skeleton

smooth muscle

• non-striated, spindle-shaped, uni-nucleated

• involuntary

• wall of internal organs

cardiac muscles

• striated, branched, uni-nucleated

• involuntary

• heart wall

antagonists

2 or more muscles that produce oppositely directed movements at a joint

flexors do what?

bend a joint

extensors do what?

straighten a limb

sacromeres

repeating units of myosin + thin filaments (actin)

what do myofibrils contain?

think filaments (myosin) + thin filaments (actin)

What happens when muscles contract?

• sarcomeres shorten by the sliding filament mechanism

• thin filaments(actin) slide past the myosin filaments by action of cross-bridges

• the formation and conformational changes in cross-bridges require ATP

cross-bridge

regions of myosin that extend toward the thin filament (actin)

muscle contraction cross-bridges steps

1. binding: when Ca²⁺ concentration is high, energized cross bridge can bind to actin (ADP + Pi already bound)

2. power stroke: release of Pi causes cross bridge to move toward the H-zone of sarcomere, moves actin—>H-zone (ADP released)

3. detaching: ATP binds to myosin, cross-bridge detaches from actin filament

4. resetting: hydrolysis of ATP—>ADP+Pi provides energy, cross bridges move away from H-zone, ADP+Pi remain bound to the re-energized cross-bridge

what are tropomyosin and troponin?

2 proteins associated w/thin filaments(actin), regulate muscle contraction

how do tropomyosin and troponin work?

1. Ca²⁺ binds to troponin causing tropomyosin to move away from myosin-binding sites

2. myosin binding sites are exposed

3. energized cross-bridge binds to actin + generates force

   1. Ca²⁺ concentration and muscle contractions are coupled w/electrical excitation (action potential)

   2. electrical stimulation occurs at a neuromuscular junction where acetylcholine binds to receptors and Na⁺ influx establishes action potential

importance of osmotic balance

1. action potential propagate along the plasma membrane + down the transverse tubules

2. the depolarization produced by the action potentials open voltage-gated Ca²⁺ channels in the membranes of the sarcoplasmic reticulum (Ca²⁺ diffuses into cell cytosol)

3. Ca²⁺ binds to troponin in the myofibril initiating muscle fiber contraction

4. Ca²⁺ is then pumped back into the sarcoplasmic reticulum by ATP-driven Ca²⁺ transporters - muscle fiber relaxation

What are the types of skeletal fibers?

slow-oxidative, fast-oxidative, fast-glycolytic

slow-oxidative skeletal fibers

ATP source: oxidative phosphorylation

mitochondria: many

blood supply: high

myoglobin content: high(red)

rate of fatigue: slow

myosin ATPase activity: low

rate of contraction: slow

fast-oxidative skeletal fibers

ATP source: oxidative phosphorylation

mitochondria: many

blood supply: high

myoglobin content: high(red)

rate of fatigue: intermediate

myosin ATPase activity: high

rate of contraction: fast

fast-glycolytic skeletal fibers

ATP source: glycolysis

mitochondria: few

blood supply: moderate

myoglobin content: low(white)

rate of fatigue: fast

myosin ATPase activity: high

rate of contraction: fast

which type of repro requires more energy?

sexual repro

DNA repair hypothesis

incorporate pieces of free floating DNA into the genome to repair damaged regions of the DNA

Hunger Hypothesis

incorporate pieces of free floating DNA (double helix)

• use half of double helix

• use other half to repair damaged regions

transformation

bacterium donor donates DNA to bacterium recipient (half-half DNA)

transduction

virus infects bacterium donor, viral replication occurs, recipient incorporates DNA via viral transfer

conjugation

recipient + donor cell make contact - donor transfers a copy of its F plasmid to recipient

what are the similarities between female and males sex organs?

• pair of gonads (organs that produce gametes) - endocrine glands

• a system of ducts that store + deliver gametes

• structures that facilitate copulation

what does the anterior pituitary act on?

testes(FSH), ovaries(LH), adrenal cortex(ACTH), thyroid(TSH), bone+soft tissues(GH), melanocyte(MSH), mammary glands(prolactin)

what does the posterior pituitary act on?

kidney tubules(ADH), mammary glands+uterus(oxytocin)

importance of hypothalamus

controls the release of hormones from the pituitary

• releasing hormones—>stimulate pituitary—>pituitary hormones

urethra

tube urine + semen are conveyed thru

penis contains _____ that when filled w/blood → erection

erectile tissue

scrotum

an external sac that holds the testes + keeps them slightly cooler than body temp

FSH triggers testes to produce ____

sperm

LH triggers testes to produce ____

testosterone

sperm is a ____ cell formed by the meiotic division of a ____ cell

haploid, diploid

(testes) diploid cells divide via meiosis to produce _____

haploid sperm cells (23 chromosomes)

how does the hypothalamus release secondary sex characteristics?

• hypothalamus releases GnRH

• anterior pituitary releases LH

• (testis) Leydig cells —> testosterone —>secondary sex characteristics

ovary

female gonad, eggs are produced and released

oviduct (fallopian tube)

site where egg and sperm meet

uterus

site of pregnancy where embryo develops into baby

vagina(birth canal)

where sperm enters + baby exits

vulva

collective name for all external repro structures

an egg is a ____ cell formed by the meiotic division of a ____ cell

haploid, diploid

(ovary) a mature ___ egg (ovum) develops 23 chromosomes

haploid

ovulation

the release of an egg cell from the ovaries occurs around day 14

FSH on female repro system

matures one egg each month, stimulates ovaries to produce estrogen

LH on female repro system

triggers ovulation, stimulates ovaries to produce progesterone

what are the two types of fertilization reactions

acrosomal + cortical

acrosomal fertilization

permits the sperm nuclei to enter

• sperm cell contacts egg - acrosome releases hydrolytic enzymes dissolve jelly coat

• exposes sperm-binding proteins on the egg cell plasma membrane that binds to the sperm

• sperm and egg plasma membranes fuse sperm nucleus then enter egg