Biology II: Exam 3
Organization of Animal Bodies
all animal cells share similarities in which they…
lack cell walls (instead have plasma membrane; gatekeepers)
exchange materials with surroundings
obtain energy from organic nutrients
synthesize complex molecules
reproduce themselves
detect and respond to signals in their immediate environment
levels of organization
Cellular - Phylum Porifera
Tissue - Phylum Cnidaria and Phylum Ctenophora
Organ - Phylum Platyhelminthes
Organ Systems - Phylum Annelida, Phylum Arthropoda, Phylum Mollusca, Phylum Echinodermata, Phylum Chordata
internal organization
cells with similar properties group together to form tissues
tissues combine together to form organs
organs are linked together to form organ systems
Tissues
tissues are an association of many cells that have similar structure
epithelial tissue
connective tissue
nervous tissue
muscle tissue
Epithelial Tissue
sheets of densely packed cells that…
covers body and encloses organs
lines walls of body cavities and organs
specialized to protect and secrete/absorb ions and organic molecules
cells have a variety of shapes
based on shape of cell
cuboidal - square shaped cells
squamous - flat-like cells
columnar - rectangular shaped cells
based on layers of cells
simple - one layer of cells
stratified - multiple layers of cells
pseudostratified - one layer, but looks like multiple
all epithelial cells are asymmetrical or polarized
one side of the cell rests on the basal lamina (basement membrane) and the other faces the environment
types of epithelial tissues
simple squamous - single layer of flat cells
simple cuboidal - single layer of square cells
simple columnar - single layer of rectangular cells
pseudostratified columnar - one cell thick with all cells connected to base membrane
stratified squamous - multiple layers of flat cells
transitional - stretchable tissue in urinary bladder
Connective Tissue
connects, surrounds, anchors, binds, transports, and supports
form extracellular matrix (ECM) around cells
provides scaffold for attachment
protects and cushions
mechanical strength
transmits information
types of connective tissue
blood - transports and protects
adipose (fat) - insulation, energy, support, and protection
bone - support and protection
cartilage - support and flexibility
loose - holds internal organs in place
dense - strength and support
Muscle Tissue
specialized cells that generate mechanical force
skeletal muscle
attach to bone or exoskeleton for locomotion
elongate fibers
voluntary control
smooth muscle
surrounds tubes and cavities for propulsion of contents
flattened cells
involuntary control
cardiac muscle
only in the heart
elongates fibers
involuntary control
Nervous Tissue
a complex network of neurons (nerve cells) and other cells
initiate and conduct electrical signals from one part of the animal body to another
electrical signals produced in one neuron may stimulate or inhibit other neurons to…
initiate new electrical signals
stimulate muscle cells to contract
stimulate glandular cells to release chemicals
contains neuroglial cells (more numerous than neurons)
provide metabolic support, maintenance, ion balance, and cleaning for the neurons
produces new glial cells and neurons
neurons CAN’T produce new neurons
Organs
composed of two or more of the major types of tissues
may form sheets, tubes, layers, bundles, or strips
organ systems - different organs that work together to perform an overall function
frequently work with other organ systems
EX. nervous, circulatory, and endocrine systems functions to influence how much water kidneys retain
spatial arrangement of organs into organ systems part of overall body plan
body plan controlled by highly conserved family of genes with homologs in all animals (Hox Genes) especially in vertebrate
Organisms
structure and function
organization of structure can usually predict the functions
EX. big structure, more complex functions
concentrate on increasing complexity of structure, thus increasing complexity of organismal functioning
mostly emphasis on vertebrate
Homeostasis
changing variables in environment
air temperature
water temperature
food supply
water supply
pH
O2 concentration
homeostasis is the process of adjusting to external environment and maintaining a stable internal environment
there is no set form of home; all animals may have a different versions
Integumentary System (Vertebrate Integuments)
skin and all other accessories
skin is the largest organ in vertebrates
consists of two layers
epidermis (outer)
dermis (inner)
Functions
protection from absorption
protects against water loss
barrier to disease
(little) protection from UV light
temperature regulation
contains sensory receptors (EX. touch pain)
(limited) excretion
Epidermis
thinner, outer layer
nutrients diffuse into here from the dermis
stratified squamous epithelium
most become dead cells from not enough nutrients
cell types
Langerhans Cells
defensive cells
Melanocytes
produces melanin pigment
skin coloration
protect from UV
Merkel Cells
touch receptors
Keratinocytes
PRIMARY cell type
produces insoluble protein keratin
amount of keratin increase from inside to out (more keratin on outside)
keratin fills cytoplasm and impairs nutrient diffusion causing cells to die
Dermis
inner layer of skin
thicker than epidermis
highly vascularized (blood vessels)
contains sensory structures, vessels, nerves, glands
origin of hair, feathers, scales
sensory structures
Meissner’s Corpuscles
light touch
Pacinian Corpuscles
deep pressure
vibration
Sweat Glands
temperature regulation
produces sweat (primarily water)
2.5 million glands in body
releases heat
Sebaceous Glands
all over body EXCEPT palms and soles
large on face, neck, and upper chest
produces sebum (oil); lubricates and softens hair and skin
aquatic animals have more sebum
Hypodermis (Subcutaneous Layer)
lies beneath dermis
NOT a layer of skin
contains adipose (fat) tissue
functions
body contour
insulation (holds in heat)
energy storage
females have thicker layers of adipose than males (softer skin)
Digestive System
Intro to nutrition
nutrients - any substances taken in by organisms that is needed for survival, growth, develop, maintenance, or reproduction
nutrition - process of consuming and using food and nutrients
animals get nutrients from consuming food
animals are heterotrophs
CAN’T manufacture own food
require synthesized organic compounds of plants or other animals to supply materials for…
survival
growth
maintenance
reproduction (highest amount of food/energy intake)
Gut Tracts
Blind Gut
NO CAVITY between gut and body wall
one opening
primitive form (jellyfish, flatworms)
Tube-within-a-Tube
flow through digestive tube
body cavity between gut and body wall
separate openings
allows for expansion
Digestive Enzymes (require H2O)
carbohydrates
proteases (proteins)
lipases (lipids)
nucleases (nucleic acids)
food processing in animals
occurs in five phases
Ingestion - food taken into body and moves into digestive cavity; usually called alimentary canal
Digestion - food is broken down into smaller molecules
Transportation
Absorption - ion, water, and small molecules diffuse or are transported into circulatory system
Egestion - undigested materials and other wastes are passed from the body
alimentary canal
digestive tract or tube (GI Tract)
single, elongated tube with opening at both ends
contains smooth muscle in cell walls
lined by simple epithelial tissue
synthesizes and secrete digestive enzymes
secrete hormones
transport digested materials
several specialized regions
different environments for different processes
storage area
structure of GI Tract
same general structure from midpoint of esophagus to anus (cloaca)
lumen lined by epithelium and gland cells
secretory cells release protective layers of mucus
other cells release hormones
glands release acid, enzymes, water, and ions
epithelial cells lined by tight junctions and surrounded by layers of tissue made of smooth muscles, neurons, connective tissue, and blood vessels
neurons activated by sight and smell of food, presence of food in tract
5 Regions of Alimentary Canal
Region of Reception
buccal cavity (mouth and accessory organs)
ingestion site and digestion site (chemical and mechanical)
jaws, teeth, muscles, tongues, salivary glands (saliva —> enzymes)
pharynx (back of mouth cavity)
where digestive and respiratory cross paths
Region of Conduction
esophagus
tube carrying materials from mouth to rest of alimentary canal
from neck region to the chest
conducts food from pharynx to stomach
peristalsis - rhythmic, wave-like contraction which propels food forward in GI Tract
squeezes food along the tract like toothpaste
Region of Storage and More Digestion
stomach (mostly)
muscular sac-like organ involved in storing food
muscle nature helps break up food; partial protein digestion
regulates rate of emptying into small intestine
secretions
hydrochloric acid - kills microbes; dissolves particulate matter (Parietal cells)
pepsinogen - converted to pepsin to begin protein digestion (Chief cells)
epithelium coated with alkaline mucus
lumen (cavity) stomach
pepsinogen + HCl —> pepsin (protein breakdown)
Region of Terminal Digestion and Absorption of Food
small intestine
nearly all digested food and absorption of food
hydrolytic enzymes found on apical surface of epithelial cells or secreted by pancreas into lumen
products of digestion absorbed across epithelial cells and enter blood
vitamins/minerals and water absorbed (glucose)
small intestine length = 8x height of organism
small intestine specialized to carry out bulk of digestion and absorption
mucosal infoldings
villi - finger-like projections
epithelial cells with microvilli create brush border (extensions of plasma membrane)
specializations increases surface areas 600-fold
increase likelihood of food particles encountering digestive enzymes and being absorbed
3 sections of small intestine
duodenum
jejunum
ileum
surface modifications that increase surface area for absorption
plicae circulares
large folds of epithelial lining
increase surface area 2-3 times
villus (villi)
finger-like projections
increases surface area 10 times
lined with epithelium
microvilli
folding of plasma membrane of cells lining the villus
increase 20 times
Region of H2O Absorption
large intestine
mammals - about 1.5 meters in length
lack plicae, villi, microvilli
H2O absorbed through epithelium
function - humans (~1400 mL of H2O/day)
compacts and solidates all eliminated feces
waste
water - 75%
inorganic substances - 5%
roughage - 8%
fat - 5% (very hard to break down)
undigested protein, dead cells, bile - 2%
most mammals end of large intestine is the anus
anus-opening at posterior end of alimentary canal for release of waste production
cloaca - some vertebrates; chamber receiving contents of digestive, reproductive, and urinary tracts; vent opening to the outside
accessory digestive glands
not part of alimentary canal (necessary for proper digestion)
salivary glands - secrete saliva
pancreas - secrete enzymatic juices through the pancreatic duct into the duodenum
liver - produces bile (assists enzymes in break down of large fat globules into smaller forms)
bladder - storage of bile; secrete bile into small as needed
biomolecules
carbohydrates - polysaccharides (starch) —> mono (glucose) & disaccharides (sucrose)
proteins - polypeptides —> amino acids (in stomach)
fats - glycerol & fatty acids
nucleic acids - nucleotides (individual subunits of nucleic acids)
*enzyme activity for chemical reaction at biological temperatures (breaks the bonds)
Nervous System
Central Nervous System (CNS) - brain and spinal cord in vertebrates
Peripheral Nervous System (PNS) - all neurons and their projections outside of CNS
*in certain invertebrates with simple nervous systems, the distinction is less clear btwn CNS and PNS
cellular components of nervous system
nervous system has two classes of cells (neurons and glia)
neurons - nerve cells; cells that send and receive electrical and chemical signals to and from each other and other cells throughout body
present in ALL animals EXCEPT sponges
number of neurons varies as a function of size and behavioral complexity; also varies on brain/body size
neuron structure
soma (cell body)
contains nucleus and organelles
dendrites
extensions of cell body, single or branching
receive incoming signals from nearby neurons
axons
extension of cell body
carries signals to other cells (AWAY from cell body)
may have branches and may be wrapped in myelin sheath
axon hillock near cell body (base)
axon terminals convey electrical or chemical signals to other cells (tips)
typically occur in bundles wrapped by connective tissue called nerves
glia - surrounds neurons and perform numerous functions (1000x more numerous than neurons)
astrocytes
metabolic support (nutrition)
maintain concentration of ions in extracellular fluid
microglia
participate in immune functions
remove cellular debris
myelin sheath
interrupted by non insulated nodes of ranvier
produced by oligodendrocytes (CNS) and Schwann cells (PNS)
radial glial cells
warehouse for cellular division
can divide into all the other types of glial cells
three main types of neurons
sensory neurons
detect info from outside world or internal body conditions
also called afferent neurons —> transmits TOWARDS the CNS
motor neurons
send signals AWAY from CNS to elicit responses
also called efferent neurons
interneurons
forms interconnections btwn other neurons
critical interpretation of info and elicited responses
reflex arc
stimulus from sensory neurons sent to CNS; little to no interpretation (fewer interneurons)
signal transmitted to motor neurons to elicit response (“automatic” signal sent)
EX. stimulus —> hand touches stove (receptor)
effector —> you move your hand (response)
quick and automatic responses
electrical properties of neurons
membrane potential (“gatekeeper”)
ONLY neurons and muscle cells generate electrical signals
cells are polarized due to membrane’s permeability
difference in ions btwn inside/outside of neuron (causes both chemical and electrical differences); imbalances within glial cells
resting membrane potential
when neuron is NOT sending signals
selectively permeable to cations (+) and anions (-)
inside is more (-), outside is more (+)
the membrane helps keep the imbalance (creates barrier)
anions on inside are drawn to cations on outside, so most ions are near the edge of membrane
electrochemical gradient
imbalance due to differences inside/outside of neuron
chemicals —> K+, Na+, Cl-
charge with chemicals + or -
3 factors contributing to resting membrane potential
sodium-potassium pump —> requires ATP
pumps 3 Na+ for every 2 K+
ion specific channels allow passive ion movement (high to low)
membrane is more permeable (favors) to K
K channels more frequently open at resting potential
polarity
more (-) inside neuron
gated ion channels
voltage-gated —> open/close in response to voltage charnes
chemical-gated —> open/close in response to chemical changes
nerve impulse
frequency - language of the message
higher frequency, greater excitation level (more immediate response)
resting potential —>imbalance btwn K+ and Na+
membrane selectively permeable to K, but channels closed for Na and Cl
outside neuron 10x more Na, 5x more Cl
inside neuron 30x more K
action potential - rapid brief change of nerve fibers
electric potential of impulse
self propagating
after passing a given point, membrane returns to resting
at given impulse point, channels for Na open and Na diffuses in
K is already diffusing out, but increased at impulse
sodium-potassium pump
complex of proteins in membrane (requires ATP)
pumps out Na, carries in K
return the imbalance (“normalcy”)
nerve impulse rate
variable-dependent on complexity of system and organism
EX. sea membrane (0.1 m/sec)
mammals (120 m/sec) —> nerves move really fast
invertebrate animals - speed is related to axon diameter
vertebrates - speed is combo of axon diameter and layers of myelin sheath
myelin sheath is in sections (Nodes of Ranvier)
“saltatorial locomotion” - jumping motion where animal moves a lot (ex. kangaroo)
evolution of nervous system
Phylum Cnidaria (jellyfish) - simplest neural organization
“nerve net” - not a system; simple primitive nerve cells
Phylum Platyhelminthes (flatworms)
2 anterior ganglia, each network branching off
weak PNS and CNS (no brain or spinal cord)
Phylum Annelida (segmented worms)
brain, ventral nerve cord, simple motor/sensory neurons
Phylum Mollusca (mollusks)
squids and octopus may be equal to fish
complex - more than earlier groups
Phylum Arthropoda (arthropods)
similar to annelids and most mollusks
EXCEPT “social insects” - well developed brain, complex social behaviors, learning, division of labor, communication (EX. ants)
vertebrate nervous system
spinal cord and brain = CNS
both are surrounded by meninges (layers) - 3 of these
dura mater - outer
arachnoid - middle
pia mater - inner
btwn each layer and within canal of spinal cord contains cerebrospinal fluid
spinal cord - always dorsal and hollow
enclosed within vertebral column
brain
increase in size with complexity of vertebrate evolution
3 divisions
hindbrain - where brain attaches to spinal cord
midbrain
forebrain - biggest part of the brain
brain : spinal cord ratio (ratio increases based on importance of brain)
fish —> 2 : 1 (EX. brain is 2x bigger than spinal)
amphibians —> 10 : 1
reptiles —> 25 : 1
birds —> 35 : 1
humans —> 55 : 1
*birds and mammals have the most complex bodies
Muscular - Skeletal Systems
types of animal skeletons
a skeleton is a structure that function in support, protection, locomotion (movement from one place to another)
three types of skeletons
exoskeletons
endoskeletons
hydroskeletons
found in soft-bodied invertebrates that use water pressure for propulsion (EX. jellyfish)
exoskeletons
internal structures
do not protect body surface, only some internal organs
found in echinoderms and vertebrates (deuterostomes)
minerals provide firmness
echinoderm skeletons composed of spiky networks of protein and minerals or mineralized plate-like structures
vertebrate skeletons composed entirely of cartilage (cartilaginous fishes) or of cartilage bone
advantage - skeleton is internal and grows with the body; composed of living tissue
other functions
blood cells and platelets are formed in marrow
calcium and mineral storage
provides attachment sites for skeletal muscle
Bone
lining, dynamic connective tissue
organic components
osteoblasts and osteocytes - cells that form bone
composed of collagen - triple helical structure provides strength and flexibility
osteoblasts - breakdown bone
mineral components (salts, phosphates)
crystalline mixture of Ca2+, PO4-, and other ions provide rigidity
continuously formed, broken down, and reformed
formation
endochondral - bone replaces cartilage (most bones)
intramembranous - bones forms with tissue membranes (skull plates, thin tissue)
one cubic inch of bone can sustain 19,000 lbs
one mm diameter fiber of collagen can hold 19 lbs of dangling weight
types of bone tissue (both provide strength and support)
compact bone (ground bone)
“dense”
composed of osteons
spongy bone
lacks osteons, lots of air spaces
consists of “bony spikes” called trabeculae
microscopy anatomy of compact bone
osteons - structural unit of spongy bone (doesn’t cover ends of bone)
osteonic canal - support and protection from damage, space for arteriole, venules, and nerves
trabeculae - spikes of spongy bones
periosteum - protective layer around outside of bone
lamellae - ring of bone tissues as it develops
lacuna - the space between each lamella where osteocytes are located
canaliculi - microscopic channels connecting lacunae
anatomy of long bone
epiphysis - ends of bone (has spongy bone)
diaphysis - shaft of bone (mostly compact bone)
medullary cavity
yellow bone marrow storage (adipose tissue) in diaphysis
red bone marrow in epiphysis of certain bones; site of blood cell production
compact bone on the outer portion of entire
articular surfaces of bone are capped with a layer of hyaline cartilage which acts as a shock absorption
periosteum - protective membrane covering external surface of a bone except articular surface
the vertebrate system
two parts
axial skeleton - mid longitudinal axis of body
appendicular skeleton - limb bones and glands (everything away from midline)
joints
formed where two or more bones come together (allow enhanced movement and better contact with substrate)
allow movement
pivot joints
ball-and-socket joints
hinge
axial skeleton
skull
ribs
sternum
vertebral column
cervical (neck)
thoracic (upper back/chest)
lumbar (lower back)
sacral (hip)
caudal (tail) (coccyx)
supports body, protection/support of nerve cord, flexibility
appendicular skeleton
forelimb bones
humerus (upper arm)
radius and ulna (lower arm)
carpals (wrist)
metacarpals (hand)
phalanges (fingers)
hindlimb bones
femur (thigh)
patella (kneecap)
tibia and fibula (lower leg)
tarsals (ankle)
metatarsals (foot)
phalanges (toes)
muscles
vertebrates have three types of muscles, classified according to structure, function and control mechanisms
cardiac - found only in heart
striated
involuntary
fibers of elongated tubes
possibly branched
multinucleated
smooth - surrounds and forms part of the lining of hollow organs and tubes
involuntary
ONE nucleus
skeletal - directly involved in locomotion
striated
voluntary
multinucleated
skeletal muscle
grouping of muscle fibers bound together in bundles (fascicles) by connective tissues
usually linked to bones by bundles of collagen fibers called tendons (dense connective tissue)
bones moves as muscle shortens
contracting muscle exerts only a pulling force - attach to bone, pulled toward or away from each other
requires ATP (from cell respiration)
example
muscle —> muscle fascicle —> skeletal muscle cells —> myofibrils —> thick and thin filaments (myofilaments)
thin filaments = actin
thick filaments = myosin
sarcomere
functional unit of skeletal muscle cells
distance from one z-line to the next
shortens during contraction
overlapping of thick and thin filaments produces striations
contraction
contracted muscle cell
myosin heads attach to actin filaments and pull together; shortening of sarcomeres=
*energy required - high energy bond of 3rd phosphate of ATP
adenosine P-P=P, where = is high energy bond, applied for sarcomere contraction
muscle cells
contains many mitochondria
powerhouse of cell
site of bulk ATP formation
requires oxygen for aerobic cellular respiration