Biology II FINAL EXAM (endocrine, musculoskeletal, sensory systems, cardiovascular and respiratory )

chemosensory

taste and smell

mechanoreceptor systems

touch, hearing, balance

electromagnetic receptors

sight
-respond to electrical, magnetic, and light stimuli

sensory receptor cells

rely on membrane receptors:
-embedded in cells that communicate with neurons

sensory organs

Consists of the eyes, ears, nose, skin, and tongue.

sensory transduction

the conversion of physical or chemical stimuli into nerve impulses

stimulated membrane sensory receptor

causes ion channels in the plasma membrane to open
-sensory receptors then either fire action potentials themself or connect with neurons that do
-the signals are interpreted in the CNS

smell

chemosensitive projections of neurons extend into the mucus that line the upper part of our nasal passage

taste

taste buds on our tongue are specialized cells that synapse with sensory neurons
-use the same general mechanisms as taste

mechanoreceptors

-respond to physical deformation of the plasma membrane
-opens sodium channels causing an action potential to fire
-responsible for our sense of touch (specific receptors for different types of touch)

epidermis mechanoreceptors

merkels discs
meissners corpuscles

dermis mechanoreceptors

ruffini endings
pacinian corpuscles

hair cells

give us a sense of hearing and balance
-sense mechanical vibration using hair-like projections on their surface
-do not fire action potentials but do synapse with neurons
-stimulations of hair cells alter the rate at which neurons fire

cochlea

a coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses
-contains hair cells that are responsible for hearing

steps by which hearing works

1. hair cells that are responsible for hearing in vertebrates are contained in the cochlea
2. sound vibrations enter the outer ear and vibrate the tympanic membrane
3. the tympanic membrane then moves bones in the middle ear
4. middle ear bones then vibrate the oval window in the cochlea

the vestibular system

in the inner ear; detects gravity, acceleration, and deceleration using 3 semicircular canals

semicircular canals

each semicircular canal detects angular momentum in one plane that the head can turn (nodding, turning, or moving side to side)
when the body moves, fluid in the canals moves hair cells which are converted into nerve impulses

photoreceptors

most common electromagnetic receptors

ospin

light-sensitive protein that converts light energy into electrical signals
-each contains a pigment called a retinal

eyecups

most primitive; flatworms can only detect light intensity and direction

compound eyes

found in insects
and crustaceans
• consist of up to several thousand
light detectors called ommatidia
• function as acute motion detectors
• usually provide excellent color vision

single-lens eyes

humans, reptiles, birds, and mammals
very large eyes with high visual acuity

rod cells

a type of photoreceptor specialized for low levels of light intensity, such as those found at night
black and white vision

cone cells

work best in bright light and enable you to see colors

muscle purpose

to move the body
convert chemical energy to mechanical energy (ATP to force)

force

A push or pull exerted on an object

muscle fiber

individual muscle cell
-main unit of focus
-contain contractile proteins (actin and myosin)

skeletal muscle

voluntary
-striated
-multiple nuclei

cardiac muscle

involuntary
-striated
-branched
-can twist

smooth

involuntary
-lines internal bodily tubes and eyes
-not striated
-rippling motion
-spindly

striations

from actin and myosin filaments
-skeletal and cardiac have a regular distribution
-smooth has an irregular distribution

muscle organization

-individual muscles are made of muscle bundles
-muscle bundles are made of muscle fibers
-muscle fibers are made of myofibrils (contractile units in individual cells)

thin filament

ACTIN
surrounded by a double helix of tropomyosin (regulatory protein that controls contractions)

thick filament

myosin

z-disc

coin-shaped sheet of proteins that anchors the thin filaments and connects myofibrils to one another

sarcomere

contractile unit; area from one z-disc to the next

how sarcomeres contract

change the relation of thick and thin filaments, reducing the distance between z-disc

sliding filament model

states that the thick and thin filaments slide past each other so that their degree of overlap increases.

cross-bridge cycling

-Myosin head attaches to actin binding site, forming cross-bridge
-Myosin cross-bridge pulls thin filament toward center of sarcomere
-ADP and phosphate are released from myosin
-New ATP binds to myosin
-Linkage between actin and myosin cross-bridge break
-ATP splits
-Myosin cross-bridge goes back to original position

motor unit

A motor neuron and all of the muscle fibers it connects to

myofibrils

-action potential from nerves connects to the muscles at the motor endplate
-causes sarcoplasmic reticulum to release Ca2+
-Ca2+ binds with troponin which moves the tropomyosin to expose actin-binding sites; allows myosin heads to bind

Ecxitation-contraction coupling

excitation of the muscle cell is coupled to the contraction of the muscle

antagonist muscles

paired muscles that cause the exact opposite movement of each other when they contract

flexion

muscle contraction that causes a bending motion

extension

muscle contraction that causes a straightening movement

agonists (prime movers)

muscles that contract to provide the main force to move or rotate a bone through its joint

muscle contraction speed

the slower the contraction, the more power the muscle has

isometric contraction

muscle tenses but does not shorten

lengthening contraction

occurs when the force applied to the muscle exceeds the force that the muscle is producing
-the muscle lengthens

twitch

muscle contraction of a specific force, from one action potential

tetanus

a sustained muscular contraction resulting from a rapid series of nerve impulses
-muscle cannot relax
-max contraction for an extended period of time

slow-twitch muscle fibers

red muscle fibers that are fatigue resistant but have a slow contraction speed and a lower capacity for tension; usually recruited for endurance activities
-marathon running, posture or long-term movement

fast-twitch muscle fibers

white muscle fibers that contract rapidly and forcefully but fatigue quickly; usually recruited for actions requiring strength, power, or speed
-sprinters
-rapid movement

why are slow-twitch fibers red?

because the myoglobin content, carries oxygen to the mitochondria

hydrostatic skeleton

A fluid skeleton in many soft-bodied invertebrates, including annelids, that allows an organism to change shape but not volume.

exoskeleton

A body covering, typically made of chitin, that provides support and protection

exoskeleton limitations

-animals are vulnerable after molting until the chitin hardens
-if damaged, the entire skeleton must be regrown
-prone to breaking if surface area is too large (football is max size)

endoskeletons

Internal skeletons (those in humans)
-made of relatively few cells and extracellular matrix

tendons

Connect muscle to bone
-made of collagen

axial skeleton

The portion of the skeleton that supports and protects the head, neck, and trunk

appendicular skeleton

Bones of the limbs and limb girdles that are attached to the axial skeleton

osteoBLASTS

bone forming cells

Hydroxypapatite

what bones are made of, a hard extracellular, calcium and phosphate-containing tissue embedded in the matrix of collagen fibers.

osteoCLASTS

Bone-destroying cells

osteocytes

mature bone cells

spongy bone

-composed of small plates and rods
-found at the end of the bones
-reduces bone weight
-increases ability to resist deformation from force

compact bone

-form the walls of bone shafts
-contains dense mineralized bones and a network of blood vessels
-provides a strong but brittle structure
-breaks from hitting the side, but provides strength from the top down

diaphysis

shaft of a long bone

epiphysis

knobby end of a long bone

growth plate

the area just below the head of a long bone in which growth in bone length occurs
-women stop growing at 18, men at 21
-in mammals and birds growth continues until maturity
-amphibians grow throughout their lives but at a slower rate

bone formation

membranous bones- skull and ribs: EMBRYONICALLY produced by osteoblasts with no soft tissue model
-other bones are embryonically first formed as cartilage, and later become bone as blood vessels invade the cartilage as fetus matures

ball-and-socket joint

three-dimensional motion: more likely to be damaged or dislocated
shoulder and hip

hinge joint

Joint between bones (as at the elbow or knee) that permits motion two-dimensionally
-less likely to be damaged

horomones

Chemicals produced by your glands that regulate the activities of different body cells

endocrine system regulates

responses to the environment, growth and development, homeostasis, reproduction

environmental responses

often triggered by sensory input from the nervous system
-predator presence: release adreneline
-mate presence: release of sex hormones

growth regulation

-sex hormones are released to trigger secondary sex characteristics as an animal approaches adulthood
-molting and metamorphosis in insects triggered by the release of hormones in tissues of the head

growth regulation (in the brain of insects)

PTTH initiates molting (amount stays the same)
juvenile hormone controls size (decreases in amount over time)

corpora allata

example of neurosecretory hormones
-these are neurons that secrete hormones and not neurotransmitters
-DIRECT RELEASE

growth regulation in humans

growth regulation is primarily controlled by the pituitary gland, which produces human growth hormone
-TRIGGERED RELEASE

homeostasis regulation

hormones regulate a large number of bodily processes including:
-circadian rhythms
-metabolism
-fight, flight, freeze
-blood sugar

blood sugar regulation

endocrine-putting hormones into the blood stream
pancreas-a gland and endocrine organ that regulates blood sugar via negative feedback loops

negative feedback loops

when a system responds to change by returning to its original state, or at least by decreasing the rate at which the change is occurring
-stabilize the body system

positive feedback loop regulation

destabilize
-permanent change in body position
-used to precipitate a particular event like childbirth

hormones targeting specific cells

-only affects cells that have a receptor for the hormone
-allows hormones to be released in the blood and trigger cells in different parts of the body

hormone receptors

-may be on the cells surface
-may be inside a cell
-depends on the molecular make up of the hormone

hydroPHILIC homrone

cannot cross the cell membrane
-ex: peptides and amines

hydroPHOBIC hormone

can cross the cell membrane
-ex: steroids like cholesterol

amines and peptide hormones

-can't enter cell membrane
-more diverse
-more abundant
-work in minutes to hours
-typically initiate signal cascades that activate or repress enzymes
-changes cell shape, size, division, or triggers release of another hormone

hormone amplification

hormones are typically released in small amounts but are amplified along a hormonal pathway

hormonal pathway

one gland releases a hormone that triggers a second gland to release a hormone
-stops once the change occurs or the hormone needed is produced
-usually begin with a releasing hormone from the hypothalamus that is triggered to release by stress or predators

evolutionary conservation of hormones

-hormones evolved early in the evolution of life
-vertebrates and invertebrates share a number of hormones but they differ in function
-some hormones also function as neurotransmitters

vertebrate endocrine system

1. responds to sensory input from the nervous system
2. hypothalamus responds by releasing hormones
3. releasing hormones signal anterior or posterior pituitary
4. pituitary then releases hormones to regulate the rest of the endocrine system

anterior pituitary gland

formed from epithelial cells in the roof of the mouth

posterior pituitary gland

forms from neural tissue at the base of the brain

pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.

hypothalamus

contain neurosecretory cells that release hormones into the blood vessels that supply the anterior pituitary
-synapse directly with the posterior pituitary gland

tropic hormones

hormones that stimulate other glands to release their hormones

hormones released by the anterior pituitary

TSH-targets thyroid, controls metabolism
FSH-signals gonads for sexual development
LH- signals gonads to produce sex hormones
ACTH-signals adrenal glands to produce cortisol in times of stress, raises blood sugar and suppresses immune function

hormones released by the posterior pituitary

oxytocin and antidiuretic hormone (ADH)