Exam 3 Flashcards
Mycorrhizal Fungi and its significance
Relationships with other organisms help a plant to obtain essential nutrients
So plants form mycorrhizae
In exchange the fungus receives some nutrients from the plant
What is mycorrhizal fungi
A network of fungal threads that act to increase the plants absorptive capacity
What are the two types of mycorrhizal fungi
1) endomycorrhizae - found inside of the root (most common)
2) ectomycorrhizae - Fungus is located on the root surface (associated with woody plants)
Explain nitrogen dependency
Plants depend on bacteria to supply nitrogen
Atmospheric nitrogen is in the form N2 which plants cannot use
Because of the nitrogen in the air cannot be used how do plants get nitrogen
Supplies are in the soil
Soil bacteria convert N2 from the air into forms utilizable by the plant
Ie) nitrate ions and ammonium ions
Define nitrogen fixation
The process of converting nitrogen from the atmosphere into alternate forms
Explain plant parasites
A plant that is not capable of photosynthesis may tap into another plants vascular system and absorb organic molecules from the plant
Carnivorous plants obtain some nutrients from …
Animal tissues
Ie) use insects as a source of nitrogen
Are Epiphytes parasitic plants? What do they do
Not parasitic
Use other plants to anchor themselves for support
Ie) orchids
what is an animal
multi-cellular heterotrophic eukaryotes most are diploid and reproduce sexually lack cell walls
how do animals obtain nutrients
obtained by ingestion
eats food not like absorption digestion occurs within the body
how do animals move
muscle cells for movement and nerve cells for conducting impulses
animal reproductive cycle
1) male and female haploid gametes are produced by meiosis
2) egg and sperm fuse producing a zygote
3) the zygote divides by mitosis
4) enters early embryonic stage called blastula and it folds inward forming a gastrula
5) internal sac formed during gastrulation becomes the digestive tract lined by the endoderm
what is the blastula
a hollow ball of cells that is an early embryonic stage
what is the ectoderm
outer cell layer that gives rise to the outer covering of the animal and if present also the central nervous system
what is the mesoderm
the third embryonic layer that forms the muscles and most internal organs
after the gastrula most animals will develop into what
what do others develop into
adults
others develop into one or more larval stages
what is larva
an immature individual that looks different then the mature adult body form
in order for the larva to become an adult that reproduces sexually it undergoes a major change in body form called
metamorphosis
this is controlled by special gene sets
explain the animal ancestor
1) an aggregate of identical cells formed few cells
2) larger colonies likely formed hollow spheres
3) eventually cells in the colony became specialized for certain functions such as reproduction and locomotion
4) a simple multicellular organism likely formed from infolding of one side of the colony
5) a gastrula like proto animal eventually would have formed
when is the common animal ancestor thought to have lived
1 billion years ago
are there any fossils to document the evolutionary process of the animal ancestor
NO Fossils to document
the oldest fossil is 575 million years old
define invertebrates
refer to animals lacking a vertebral column
define vertebrates
animals that have a vertebral column
how many phylums of animals are there how many of them are invertebrates
approx. 35 phylums
34 of the phylums are invertebrates
1 of the phylums are vertebrates
how are animals categorized
by their body plans
what are the two types of body plan symmetry
radical symmetry
- body parts radiate from the center the animal has a top and a bottom but not right and left sides
bilateral symmetry
- mirror image right and left sides
a distinct head, tail, a back and a bottom
animals body structure correlates with lifestyle how?
radial animals are usually sedentary meeting their environment equally on all sides
bilaterally structured animals have all of their sense organs located within the head region (eyes brain mouth) this arrangement facilitates mobility
what are the three types of body cavities
true coelom
psuedocoelom
acoelomates
what is a true coelom
animals that have a body cavity lined entirely by tissue from the mesoderm
ie) segmented worm
what is a psuedocoelom
a body cavity lined with tissues that were not completely derived from mesoderm tissue
these function just like true coeloms
ie) roundworms
what is a acoelomates
no body cavity
animals that have three tissue layers can be characterized by what
the presence or absence of a body cavity
what is a body cavity
a fluid filed space between the digestive tract and the outer body wall
cushions the internal organs and enables them to grow and move independently of the body wall
what do soft bodied animals have
a hydrostatic skeleton
what is a hydrostatic skeleton
a non compressible fluid in the body cavity of soft bodied animals
provides a rigid structure that muscles contract against
what is protostomes
the opening formed during gastrulation becomes the mouth
what are deuterostomes
the opening formed during gastrulation becomes the anus and the mouth develops from the second opening
what are eumetazoans
animals with true tissues
what are sponges
have no tissues
sedentary animals
most are marine some are freshwater
some are radial but most are asymmetrical
ore complex sponges have branching water canals
do most animals have radial or bilateral symmetry
bilateral symmetry
what are the holes used for in sponges
water is drawn through pores into a central cavity which then flows out through a larger opening
what are the two cell layers of a sponge separated by
a gelatinous region
what are the choanocytes and where are they located
inner layer of the flagellated cells of sponges
the choanocytes help to sweep water through the sponges body
what are amoebocytes in sponges
wander through the middle body region
produce supportive skeletal fibers composed of flexible protein called spongin and mineralized particles called spicules
what can sharp spicules do
may protect the large opening
sponges are __ feeders
suspension
what does it mean to be suspension feeders
animals that collect food particles from the water
the food is passed through some sort of food trapping equipment
what do the choanocytes and amoebocytes do for the sponges food
the choanocytes trap food particles in mucus on membranes that surround the base of their flagella and then engulf the food by phagocytosis
the amoebocytes pick up food packaged in food vacuoles from choanocytes and digest it carrying the nutrients to the other cells
adult sponges are ___ what does this mean
sessile
anchored in place
they are unable to esc ape from predators
consequently sponges produce defensive compounds such as antibiotics and toxins to deter pathogens parasites and predators
what is the simplest animal what characteristics make it the simplest
sponges
no nerves or muscles
individual cells can sense and react to environmental changes
no true tissues
thought to have evolved from a flagellated protest ancestor
what are cnidarians
eumatozoan (one of the oldest types)
radial symmetry
only has two tissue layers
have contractile tissues and nerves in their simplest forms
what are some examples of cnidarians
hydras jellyfish and corals
what are the two tissues of cnidarians
outer epidermis and inner cell layer that lines the digestive cavity
jelly filled middle region which may contain scattered amoebid cells
explain cnidarians incomplete gut
mouth and no anus single opening
how do cnidarians feed
tentacles surround the mouth opening to assist the trapping and intake of food
there are two main body forms of cnidarians what are the two forms can a cnidarian ever be in both forms in their life
medusa
polyp
yes they are exist in both forms during their life cycle
explain the medusa body form
motile by swimming
the mouth faces downward
organism is umbrella shaped with a thick middle layer composed of viscous jelly like material (ie jellyfish)
explain the polyp body form
stationary tubular tentacles face up colonial aggregations are the most common (ie sea anemone)
what do cnidarians have to function in defense and capture prey
unique stinging cells called cnidocytes
where are cnidocytes found
throughout the epidermis and tentacles
what and how do cnidarians eat
nearly all are carnivorous
feeds predominantly on small crustaceans and other plankton that is captured by the tentacles
prey enters the gastrointestinal cavity via the mouth where digestion takes place using extracellular enzymes
what are Platyhelminthes
flatworms
what are the characteristics of Platyhelminthes
bilateral symmetry and three embryonic tissue layers
thin and ribbon like
simplest bilatarians
marine freshwater or damp habitats
one opening to the gastrointestinal cavity
what are the three major groups of Platyhelminthes
planarians - free living flatworms
flukes - parasitic
tapeworms - parasitic
describe planarians
free living flatworms
head with a pair of light sensitive eyespots
flap at each side of the head to detect chemicals
dense packs of nerve cells function as the brain
where do planarians live
undersurfaces of rocks in streams and freshwater ponds
how do planarians move
use cilia on their ventral surface to crawl also have muscles that enable them to twist and turn
how do planarians get food
sucks food in from the mouth at the tip of a muscular tube and has a highly branched GI tract
how do planarians have nerves that act as a brain
a pair of nerve cords connect with small nerves that branch throughout the body
describe flukes
parasitic
have a tough protective covering
suckers that attach to their host
reproductive organs occupy almost the entire interior of these worms
complex life cycles
intermediate hosts in which larva develop
larva infect final host where they will lived as adults
what is an example of flukes
blood flukes that cause schistosomiasis in humans spend a part of their life cycle in snails
describe tapeworms
inhibit the digestive tract of vertebrates as adults
ribbon like body
this is the most evolutionarily advanced of all the flatworms
lacks a gut
nervous system is reduced
how do tapeworms derive nutrients
nutrients are taken up form the host across the wall of the worm body
what are nematodes
roundworms
describe nematodes
cylindrical worms with a blunt head and a tapered tail pseudocoelomates free living soil dwelling body is composed of a fixed cell number some are parasitic
what are nematodes covered by
a tough non living cuticle
periodically shed
used as protection and to resist dehydration
how are some nematodes parasitic
big agricultural pests
attack animal and plant roots
some cause animal diseases such as heartworm
describe molluscs
most diverse group of invertebrates terrestrial marine and fresh water organisms have separate sexes bilateral symmetry 3 tissue layers have a true coelom
what is a molluscs body composed of
a small but well defined head large dorsal visceral mass and a broad flat ventral foot
visceral mass covered by the mantle which secretes the shell
the shell is the unique characteristic
what is the molluscs shell composed of
calcium carbonate
what do molluscs use for respiration
gills
do molluscs have a circulatory system
yes
how do molluscs feed
with a structure called a radula
what do a molluscs life cycle include
a ciliated larval stage called a trochophore
what are the three major classes of molluscs
gastropods
bivalves
cephalopods
describe gastropods
largest most diverse class marine fresh water and terrestrial only molluscs that live on land the terrestrial molluscs lack gills distinct head with eyes at tentacle tips
what are some examples of gastropods
snails and slugs
explain a gastropods shell what is it used for
has a single spiralled shell used for the animal to be able to retreat when threatened
in gastropods the lining of the mantle cavity functions as
a lung performing gas exchange with the air
describe bivalves
the shells are divided into two halves and hinged together
most are suspension feeders
sedentary living in sand or mud
muscular foot is used for digging and anchoring
what are some examples of bivalves
clams oysters and muscles
how do bivalves feed
gills in the mantle cavity used for feeding and gas exchange
mucus coated gills trap small food particles from the water
cilia sweeps particles to the mouth
describe cephalopods
adapted to lifestyle of fast agile predators
marine and most free swimming
carnivorous
highly developed nervous and locomotion systems
change color in response to threat
who is considered the most agile invertebrate
the octopus
give some examples of cephalopods
squids and octopus
how do cephalopods eat
use beak like jaws to radula to crush/rip prey apart
mouth is the base of the foot
drawn into several long tentacles to catch and hold prey
how do cephalopods swim
via a water jet propulsion from the mantle cavity
describe annelids
segmented body composed of a number of sections
marine freshwater and terrestrial
how do annelids move
their segmentation allows added mobility for swimming and burrowing
how do annelids eat and what
suspension feeders scavenging
herbivores and carnivores
what can medicinal leeches do
promote healing of tissue grafts and reattached appendages
what are the three major groups of annelids
polychaeta
earthworms
leeches
describe plychaeta
largest group
very diverse lifestyle function and form
secrete and occupy tubes
marine, burrow, bottom dwellers, live in rocks and shells and can swim when necessary
how do polychaeta move
paddle like parapodia function as gills and assist in locomotion
one appendage on each
how do polychaeta feed
search for prey on the seafloor or live within tubes and filter food particles
extend appendages coated in mucus to trap suspended food particles
describe earthworms
many body structures are repeated in each segment
the digestive tract is continuous but the nervous system has nerve clusters in each segment
each segment has bristles that offer traction
closed circulatory system
hermaphrodites
what muscles do the earthworms have
the segments have longitudinal and circular muscles
describe leeches
dorso-ventrally flattened ventral and posterior suckers parasitic that thrives off of host blood free living carnivorous species fresh water marine and terrestrial
what do leeches eat and how do they act as parasites
eat small invertebrates such as snails
have razor like jaws that split the animals skin and they secrete anticoagulant and anesthetic into the wound to prevent pain and blood clotting
describe arthropoda
the largest group of animals
segmented
exoskeletons made out of chitin
jointed appendages that are modified for many functions
open circulatory system
variety of specialized organs for gas exchange
what is the arthropoda’s ecdysis
a process in which the arthropoda grows and molts its exoskeleton
arthropoda’s have fluid filled with what
hemolymph that circulates into spaces surrounding tissues and organs
what is a subgroup of anthropods
chelicerates
describe chelicerates
named for claw like feeding appendages called chelicerates
most marine forms are EXTINCT however the horseshoe crab still exists
what is the most common form of chelicerates
arachnids
a group that includes spiders ticks mites and scorpions
what do anthropods include
millipedes
centipedes
crustaceans
arachnids
describe millipedes
have a large number of legs
each trunk segment has two pair of legs
describe centipedes
carnivores
contain jaw like mandibles
one pair of legs per trunk segment
describe crustaceans
usually have branched appendages that are specialized for feeding and moving
nearly all aquatic
jointed appendages project from the shell to strain food from water
what are some examples of crustaceans
lobster crayfish and barnacles
what do barnacles contain
a hardened shell containing calcium carbonate
crustaceans anchor themselves to what and how
to objects such as boats using adhesive that they produce that is stronger then any glue ever invented
describe insects
the most numerous and most successful
what are three parts of insects body
1) head- sensory antenna and eyes various mouth parts
2) thorax - three sets of legs and wings (but not all have wings)
3) abdomen
what are some examples of insects (with three body parts)
grasshoppers
beetles
moths
what is incomplete metamorphosis and what animal follows this
many insects have developmental processes that follow the transition from larva to adult and goes through many molts without forming a pupa
what is complete metamorphosis
larvae specialized for eating and growing
larvae look very different from adults
adults specialized for dispersal and reproduction
describe echinodermata
all marine deuterostomes radially symmetrical as adults but bilateral larvae have an endoskeleton slow moving or sessile mouth located on underside
what are some examples of echinodermata
sea stars sand dollars and sea urchins
what is a endoskeleton what do Echinodermata have on their endoskeleton
spines and plates found internally
a thin bumpy or spiny skin covers the endoskeleton of hard calcareous plates
what are used for respiration locomotion and feeding in Echinodermata
tube feet
chordate clades were constructed by analysis of __
molecular evidence
anatomical evidence
fossil evidence
who were thought to be the first group of chordates
what is different about these
tunicates
only chordate that does not have a brain
describe chordates
contain a head referred to as craniates
head consists of a brain at the anterior end of the dorsal nerve cord
contains a skull eyes ears nose
has a well defined backbone
what does the backbone and vertebral column function as
to protect the contents of the nervous system
what was some of the major evolutionary developments of the chordates
the jaws
the lungs
muscular lobed fins with skeletal support
what are tedtrapods and what group do they belong to
jawed vertebrates with two pairs of limbs
the first vertebrates on land
chordates
who were the first vertebrates on land
the tetrapods
what are amniotes
tetrapods with a terrestrially adapted egg
what was the last major adaptation to life on land for the chordates
the amniotes that adapted with an egg
who are the most primitive chordates
hagfishes and lampreys
are hagfishes and lampreys craniates
yes
they are both jawless
hagfish have a notochord, what is this
a strong flexible rod running the length of the fish body
do lampreys have a notochord
yes
are lampreys vertebrates
yes they have a vertebral column; a rudimentary vertebral column
describe hagfish
scavenge dead or nearly dead vertebrates
along the bottom of the ocean
almost blind
excellent senses of smell and touch
how do hagfish prey and eat
enter prey through existing holes
or creates holes using sharp structures on the tongue that resembles teeth
they grasp and tear flesh
how do hagfish act against threats
exudes slime from glands on the sides of its body
occurs when threatened
after the threat is removed the hagfish ties its tail in a knot and slides the knot forward to remove the layer of slime
how many species of hagfish
approximately 40
describe lampreys
oldest living vertebrates suspension feeders lived in freshwater streams and most of the time spent buried in sediment migration to the ocean or the sea occurs when they mature into adults most are parasitic attaches to the skin of prey using rasping tongue to penetrate feeds on blood and tissues
describe jawed vertebrates
have paired fins and a tail which allows them to swim to their prey
jaws enable them to catch and eat a diverse group of prey
contrast with suspension feeders
jawed vertebrates with paired fins and gill are commonly referred to as fish
when are jawed vertebrates said to have appeared
appeared on the fossil record 470 million years ago
what are the three lineages of jawed vertebrates
chondrichthyans
ray finned fish
lobe finned fish
describe the jawed vertebrates gills
initially skeletal rods supported the gill slits functioned to trap food particles
two pairs of skeletal rods near the mouth have become the jaws and their supports
gill slits were no longer needed for feeding remained for gas exchange
what are some examples of chondrichthyans
sharks and rays
describe chondrichthyans
flexible skeleton made of cartilage most are predators (some suspension feeders) quick swimmers with strong jaws sharp vision great sense of smell
electrosensors on the head of chondrichthyans do what
detect electromagnetic fields produced by muscle contractions of near by animals
describe sharks lateral line systems
have lateral line systems
a row of sensory organs that run along each side of the animal
sensitive to changes in water pressure
can detect very small vibrations caused by animals moving nearby
describe rays
are adapted for life at the bottom of the ocean
bodies are dorsoventrally flattened
eyes on top of the head
tail has sharp spines with venom glands at the base
suspension feeders that swim through the ocean filtering plankton
what are some examples of ray-finned fish
tuna trout and goldfish
describe ray-finned fish
skeleton made of bone reinforced with cartilage hard matrix of calcium carbonate usually flattened scales over the skin and secrete a mucus to reduce drag while swimming
what is operculum what animal has it
protective flap on each side of the head
covers the chamber housing the gills
movement of the operculum allows the fish to breathe without swimming
contrast; sharks need to swim to pass water over their gills
ray-finned fish
what are swim bladders what do they do and what animal has them
gas filled sac
a lung derivative
helps to keep the fish buoyant and evolved from balloon like lungs
ray finned fish have them
who are said to be the largest group of vertebrates with how many species
ray finned fish
27 000 species
describe lobe finned fish
rod shaped bones
found in muscular pectoral and pelvic fins
what are the three lineages of lobe finned fish
coelacanth - deep sea dweller
lungfish - inhibit stagnant waters, gulp air into lungs connected to the pharynx
tetrapods - adapted to life on land and give rise to terrestrial vertebrates
what are some examples of amphibians
salamanders and frogs
describe amphibians
tetrapods (vertebrates with two pairs of limbs)
most are found in damp habitats
moist skin supplements lungs for gas exchange
skin usually has poison glands used in defense
who are said to be the first vertebrates to have colonize the land
amphibians
distribution of most amphibians is limited because they require moisture because they are susceptible to dehydration
some amphibians live only on land such as toads
what are some examples of reptiles
lizards snakes turtles and birds
dinosaurs
what is a major characteristic that was derived by reptiles
The amniotic egg
describe the amniotic egg
embryo develops inside enclosed by a protective fluid filled sac called an amnion
allows reptiles to complete their life on land
similar to the role of the seed in plant evolution
snakes likely become limbless because their ancestors developed a burrowing lifestyle
what are some other adaptations to terrestrial life of reptiles
reptilian skin - covered with scales heavily keratinized to protect drying out,
therefore they breathe through lungs with an assisted ribcage
what are non bird reptiles referred to why?
cold blooded
do not use metabolism to generate body heat
to stay warm they stay in the sun or maintain contact with warm surfaces
previous reptiles such as dinosaurs are thought to have been endotherms
define ectothermic
absorbing heat rather then generating heart
what type of reptile is said to be a descendent of the dinosaurs
the bird group
what did birds evolve from
theropods
a small two legged group of dinosaurs suggested by fossil evidence
feathers are present on these dinosaurs but not used for flight but for insolation and courtship displays
what are the most primitive birds
the archaeopteryx
feathered wings
otherwise dinosaur like
teeth wing claws and tail with lots of vertebrae
what features of the bird reflect adaptations that enhance flight
reduce weight
no teeth
bones within the tail have only a few hollow vertebrae
feathers have hollow shaft
bones are honeycomb structure providing strength within a light weight structure
large breasts muscles provide power for flight
describe birds
have a high metabolism because flying requires a great deal of energy
endothermic - feathers to prevent heat loss
very efficient circulatory system and lungs (more efficient at gas exchange then mammalian lungs)
strong senses - amazing vision
have an amniotic eggs covered with hard shell
describe mammals
amniotes with hair and the ability to produce milk
hair functions to insulate
mammals are endothermic
mammary glands produce milk to nourish young
differentiation of teeth allows consumption of many different foods
larger brains then vertebrates of comparable size
long period of parental care
highly efficient circulatory and respiratory system
four chambered heart diaphragm assists in ventilation
probably nocturnal and eats small and insects
when did mammals approximately arose
200 million years ago
what are the three main groups of mammals
monotremes
marsupials
eutherians
describe monotremes
duck billed platypus only mammals that lay eggs female platypus usually lays two eggs incubates eggs in a nest once born the babies lick milk from the mothers fur
explain mammals birth
most are born not hatched
embryos are nourished inside of the mothers body
the lining of the uterus together with embryonic layers form a sac called a placenta which allows exchange of nutrients and wastes to and from the mothers body
describe marsupials
brief gestation
mother gives birth to tiny offspring that complete embryonic development attached to the mothers nipples
nourishing young are usually contained in an external pouch called a marsupium
where do most marsupials live
nearly all live in Australia new Zealand and south America
describe eutherians
called placental mammals
more complex then those of marsupials
entire embryonic development is completed with the placenta
they bear fully developed live young
what are some examples of eutherians
humans zebras elephants rodents and rabbits
what are the 3 dietary categories
herbivores- eat autotrophs such as plants
carnivores- eat other animals
omnivores- eat both plants and animals
what are the four mechanisms animals use to obtain and ingest food
suspension feeders
substrate feeders
fluid feeders
bulk feeders
define suspension feeders
extract food particles suspended in the surrounding water
define substrate feeders
there organisms live within or atop their food source
they eat their way through the food source
ie) earthworms
define fluid feeders
suck nutrient rich fluids from their host
host can be plant or animals
ie) mosquitoes
define bulk feeders
ingest large pieces of food
utilizes utensils claws jaws or teeth
kill prey and tear off pieces
what are the four stages of food processing
ingestion
digestion
absorption
elimination
define ingestion
this is the actual act of eating
define digestion
this is the breakdown of food molecules small enough to be absorbed by the body
what are the two types of digestion
mechanical breakdown- occurs in the mouth of humans and many other animals, teeth break food into smaller pieces increasing surface area
enzymatic breakdown - enzymes breakdown the chemical structure of the molecules occurs via the addition of water
define absorption
the products of enzymatic digestion are absorbed into the cells lining the digestive tract
these products then enter the blood stream and are delivered to the cells of the body
define elimination
under digested material passes through the digestive tract
where does digestion occur
mostly in specialized compartments in order to avoids digestion of self tissues
most animals contain a internal compartment that permits extracellular digestion
what is the smallest digestive compartment
fuses with lysosome which contains digestive enzymes
what is an example of an internal digestive compartment in an animal
gastrovascular cavity
- digestive cubit with only one opening (the mouth)
describe the process of compartmentalized digestion
1) gland cells lining the cavity secrete digestive enzymes
2) enzymes break down soft prey tissues
3) other cells present engulf small food particles
4) food particles are broken down in food vacuoles
5) under digested material is expelled through the mouth
what is the alimentary canal
a compartment of digestion
has two openings a mouth and an anus
most mammals have this
what structures are apart of the alimentary canal
pharynx
esophagus - may lead to a crop, a gizzard or a stomach
small intestine
anus
what does the stomach or gizzard do
temporarily stores food
muscular
churns and grinds food
what does the small intestine do
bulk of enzymatic digestion and all nutrient absorption occurs here
what does the anus do
under digested materials are expelled through the anus
what are three examples of animals with alimentary canals
earthworm
grasshopper
birds
describe the earthworms alimentary canal
food enters pharynx from the mouth
passes through esophagus and is stored in the crop
the gizzard contains sand and gravel and digests the food
digestion and subsequent absorption occurs in the intestine
dorsal fold increase the surface area for absorption
describe the grasshoppers alimentary canal
uses a crop to store food also
digestion occurs in the mid gut region
gastric pouches here increase the surface area for absorption
hindgut is to absorb water and compact wastes
describe the birds alimentary canal
three separate chambers
a crop
a stomach
a gizzard - filled with gravel to pulverize food
chemical digestion and absorption occurs in the small intestine
human digestion - peristalsis
propels food through the GI tract by alternating waves of smooth muscle contraction and relaxation
human digestion - sphincters
regulate the passage of food into and out of the stomach
cardiac sphincter
pyloric sphincter
how does the human stomach increase surface area
has accordion like folds to increase absorptive surface area
the human stomach secretes what? what is it and what does it do?
gastric juice
composed of mucus strong acid and enzymes
hydrochloric acid begins the breakdown of chemical bonds in food
kills most bacteria that have enter with food
the ph= 2
mucus protects stomach lining from harsh acidity
HCI also converts certain enzymes into their active form
explain the humans stomachs hormonal control of digestion
gastrin is released from the stomach cells into the blood in response to food
circulates in the blood returning to the stomach to stimulate secretion of more gastric juice
where does the remainder of digestion occur after in the stomach, what else occurs here
the small intestine
absorption of nutrients
digestive enzymes used during digestion are synthesized by
the pancreas - pancreatic juice which is a mixture of digestive enzymes and bicarbonate
the liver- produces bile which contains salts that emulsify fats
the small intestine also produces digestive enzymes which aid in digestion
where is bile stored
stored by the gall bladder until it is required in the small intestine
what allows for the small intestine to increase absorptive surface area
the villi which are finger like projections lined with microvilli
extend into the lumen of the small intestine greatly increasing surface area
absorptive surface of the small intestine is approximately 300msquared (the size of a tennis court)
where is the liver located in humans
between the intestines and the heart
where does the hepatic portal vein receive blood from and what does it do
receives blood from capillaries of small and large intestine
transports nutrients absorbed by the intestines directly to the liver
what is the main function of the human liver
to remove excess glucose from the blood
coverts excess glucose into glycogen
glycogen is stored in the liver
liver also produces lipoproteins that transport fats and cholesterol to the cells of the body
liver is involved in detoxifying and modification of substance absorbed by the GI tract ie) alcohol
describe the human large intestine
1.5m long
outpocketings include a blind pouch called the caecum and the appendix
what is the main function of the large intestine in humans
to absorb any remaining water
waste products are referred to as feces
mainly undigestible plant fibers and normal flora from the colon
especially E. coli
feces are stored in the anus until elimination
how has natural selection effected evolutionary adaptations on different animals digestive systems
natural selection has favoured adaptations that fit an animals digestive system to be structured to digesting the kind of food that the animal eats
what is an evolutionary adaptation of carnivores digestive system
large expandable stomachs
what is an evolutionary adaptation of herbivores and omnivores digestive system
length of digestive tract
vegetation is more difficult to digest
longer canal provides more time for digestion
herbivores also usually have special chambers to house bacteria which helps the animal by digesting cellulose into simple sugars
how can an animal get nutrients
essential nutrients must be supplied by animal diet
animals cannot make essential nutrients from raw material
what are the four classes of essential nutrients
essential fatty acids - linoleic acid used to synthesize the plasma membrane
essential amino acids- 8/20 cannot be synthesized
vitamins
minerals
define undernourishment
diet chronically deficient in calories
define malnourishment
long term absence of one or more essential nutrients
what are the three main phases of gas exchange
breathing
transport of gases
bodily cells take up oxygen from the blood and release co2
define breathing in gas exchange
exposes a large moist internal surface to air
oxygen diffuses across the cells lining the lung into surrounding blood vessels
carbon dioxide diffuses out of the blood and into the lung
define the transport of gases
oxygen that diffused into the blood binds to hemoglobin in red blood cells
carbon dioxide is also transported in the blood from the tissues to the lungs
explain how bodily cells take up oxygen from the blood and release co2
oxygen is the terminal electron acceptor during cellular respiration in the mitochondria
where does gas exchange occur within the animal
the respiratory surface
composed of living cells that must be kept moist to maintain function
how does gas exchange occur
by diffusion
must have a large surface area
describe earthworms and their gas exchange
entire outer skin surface is used for gas exchange
no specialized organs
a capillary layer immediately below the surface receives oxygen
must live in damp places as the entire organism must be wet
organisms that ventilate this way are usually small and many are long and thin
what are some other mechanisms for gas exchange
gills
tracheal system
lungs
describe gills
extensions /outfoldings of the body surface
specialized for gas exchange
oxygen diffuses across the gill surface into a capillary bed
carbon dioxide diffuses out of the fish from the capillary bed out of the gill
maintaining a moist surface is not problematic
describe tracheal system
respiratory system is contained within the animal
extensive system of branching internal tubes
respiratory system is at the tips of the tubes
gases are exchanged directly with body cells
circulatory system is not required
describe lungs
found in most terrestrial vertebrates
internal sacs lined with moist epithelium
large amount of branching internally
the branching forms a large respiratory surface
gases are moved between the lungs and the body cells via the circulatory system
oxygen and gills
oxygen is present in water as dissolved gas
less oxygen in water then in air so gills must be very efficient
describe the gill structure
four gill arches on each side of the body
two rows of gill filaments project from each gill arch
each filament has many plate like structures called lamellae
what are lamellae
are the actual respiratory surfaces
they are full of tiny capillaries so small that the RBC’s must pass through single file
describe the process of gas exchange with gills
water goes into the mouth of the fish and out the side
the fish may simply open their mouth allowing water to flow
fish may also actively pump water across the gills by the opening and closing of the mouth and opeculum
define countercurrent exchange
blood flows opposite the movement of water past the gills
the transfer of material from a fluid moving in one direction to a fluid moving in the opposite direction
why is breathing air advantageous
much higher oxygen concentration
air is very light weight and requires less energy
what are the trachea
largest tubes
open to the outside of the animals
reinforced with chitin
enlarged portions form air sacs near organs that require high oxygen supply
what are tracheoles
the smallest branches extending to every cell in the animals body
tiny tips are closed and contain fluid
gas exchange with body cells directly across this surface
no circulatory system necessary
some insects alternately contract and relax flight muscles to pump rapidly through the tracheal system
where are the lungs located in mammals
In the thoracic cavity
separated from abdominal cavity by a thick mucus
what is the passage of air in mammals to the lungs
air enters through nostrils
filtered by cilia and warmed and humidified as it travels
moves through the pharynx to the larynx to the trachea
to the bronchi to the bronchioles to the alveoli sac
describe the epiglottis
covers the trachea when we swallow food in order to prevent choking
what houses the vocal cords
the larynx
describe the trachea
lined with cilia and a thin mucus layer
moist epithelial cells
cartilaginous rings keep trachea open
how many bronchi are there
two bronchi branch from the trachea and enter each lung
where is the site of gas exchange in the lungs
the alveoli
describe the alveoli
surrounded by a dense network of capillaries
oxygen diffuses across the alveolus and into the capillary network
alveolus covered with a thin layer of surfactant which decreases surface tension
how does blood transport respiratory gas
oxygen enters the blood at the lung and carbon dioxide is subsequently unloaded
this occurs by diffusion of gasses down their concentration gradient
what are the two basic types of circulatory systems
open circulatory system
closed circulatory system
define the open circulatory system
found in most invertebrates
fluid pumped through open ended vessels
flows out among cells
there is no distinction between blood and interstitial fluid
bodily movements help to circulate fluid throughout
fluid returns to the heart through several pores
each pore has a valve to protect against backflow
describe the closed circulatory system
vertebrate circulatory system
called cardiovascular system
blood is confined to vessels which keeps it distinct from interstitial fluid
what are the three types of vessels in the closed circulatory system
arteries - carry blood away from the heart to body tissues
veins- return blood to the heart
capillaries - convey blood between arteries and veins at the tissue level
give an example of a closed circulatory system
fish
2 chambered heart
atrium receives blood from veins
ventricle pumps blood to gills
after passing through gills large arteries carry oxygenated blood to the rest of the body
arteries become arterioles which become capillaries which exchange material between blood and interstitial fluid
c capillaries become venules which become veins
when is the double circulation used
after loosing pressure in the capillaries of the lung blood is pumped a second time
what are the two circuits of double circulation
pulmonary circuit- carries blood between heart and lung tissues
systemic circuit - carries blood between the heart and the rest of the body
what type of animals have three chambered hearts what does this mean
amphibians such as frogs
mixing of blood (oxygenated and deoxygenated) occurs in the ventricle
some animals such as turtles and snakes have the ventricle partially divided to minimize mixing
what types of animals have a four chambered heart and what does this mean
birds and mammals
two aria and two ventricles
right side of the heart handles deoxygenated blood
left side of the heart handles oxygenated blood
supports the high metabolic rate of endothermic mammals
describe the human circulatory system
right ventricle pumps deoxygenated blood into lungs via pulmonary arteries
blood flowing through the lung capillaries unloads co2 and picks up oxygen
oxygen rich blood returns to the heart via pulmonary veins into the left atrium which then flows into left ventricle
from the left ventricle this blood exits into systemic circulation via the aorta
describe the aorta
has branched called coronary arteries which supply the heart with blood
also has branches to supply the head neck and arms and into the abdomen
explain the path of the circulatory system in tissues
arteries lead into arterioles and then capillaries
capillaries become venules and then veins
veins coverage into the inferior and superior vena cava which return deoxygenated blood to the right atria of the heart
blood then flows into the right ventricle and back into pulmonary circulation
