M1: L3: Animal Characteristics and Development

When did the most recent common ancestor of all living things first formed?

about 3.5 BYA

When did the two other kingdom (eukarya and archaea) formed?

about 3 BYA

When did animals first formed?

about 700 MYA

What are the characteristics of animals?

1) multicellular eukaryotes

2) heterotrophic

3) sexually reproducing

4) highly mobile (in at least 1 stage of life)

5) have tissues

a) muscle

b) nerve

heterotrophic means eating other organisms

T/F - Muscle and nerve tissues is not unique to animals.

false

define tissues.

specialized cells that func tgt

T/F - Sponges do have tissues.

false

T/F - Cnidarians are triploblastic.

false - they’re diploblastic

how many tissues do other animals have besides the sponges and cnidarians?

triploblastic

What are the 3 tissue layers? What do they give rise to?

ectoderm becomes the outer covering (epidermis)

endoderm becomes the digestive tract

mesoderm becomes the muscle and most of the other organs

define bilateral symmetry.

cut in only ONE DIRECTION in the middle of any organism and it gives mirror images

What are the stages of animal development?

zygote —> cleavage: 2 cells —> 4 cells —> 8 cells —> morula —> blastula —> gastrulation: gastrula

define morula.

solid ball of cleaved cells

define blastula (blastocyst).

outside: cleaved cells

inside: inner mass of cells or blastocoel

define cleavage.

1) a form of mitosis where identical copies of cells are made 

2) volume of the cells do not change either

define blastocoel.

empty space inside the blastula (blastocyst)

define gastrulation.

the formation of a gut

grastrula means belly

What are parts of the gastrula?

1) blastopore

2) archenteron

3) endoderm

4) blastocoel

5) ectoderm

define blastopore.

the opening of the gastrula

define archenteron.

the tunnel inside the gastrula

what are the 3 types of tripoblastic animals?

acoelomate, coelomate, and pseudocoelomate (or hemocoelmate)

define acoelmate

tissue-filled region completely filled by the mesoderm

define coelomate.

true body cavities completely lined by the mesoderm

define coelom.

an empty cavity that suspends (holds) internal organs

define pseudocoelomate (hemocoel).

animals that have a fluid-filled cavity which is not completely lined by the mesoderm

What makes up the muscle?

a bundle of muscle fibers —> made of a single muscle fiber —> (made of a single cell with multiple nuclei) —> surrounded with p.m —> made of myofilaments

define sacromere.

a contractible, functional unit of muscle cells

What are the two types of muscle filments?

thin filament made of actin

thick filament made of myosin

Rank the stages of muscle contraction from the shortest sacromere to the longest sacromere.

1) fully contracted muscle

2) contracting muscle

3) relaxed muscle

T/F - When muscle contracts, the sarcomere elongates.

false - it shortens

How do muscles contract?

How does a neuron tell a muscle to move?

What are the 3 types of muscles?

1) smooth

2) skeletal

3) cardiac

What are the func.s of the skeletal (striated) muscle?

1) voluntary

2) attaches to the skeleton

3) used for movement

voluntary means the brain can control the movement of muscles

What are the func.s of the cardiac muscle?

1) has striations, but not as pronounced

2) involuntary

3) ONLY found in the heart

What are the func.s of the smooth muscle?

1) slower, but more sustained

2) involuntary

3) lining of the digest tract, bld vessels, urinary tract, etc.

Give an example of how skeletal muscle moves.

What is the func of a dendrite?

receive signals from other neurons

func of axon 

deliver signals to other neurons

func of synapse

neuron to neuron communication

What is the structure of a neuron?

1) synapse

a) presynaptic cells

b) postsynaptic cells

What is the resting potential of a neuron?

diff in charge across the plasma membrane of a neuron

inside cell/neuron: more neg ions 

outside cell/neuron: more positive ions

at ~ 90 mV

what maintains the resting potential of a neuron?

Na⁺/K⁺ pump —> slow process by ACTIVE transport

3 Na⁺ out of the cell and 2 K⁺ inside the cell

Ion channels (open pores) —> fast process by PASSIVE transport

more K⁺ channels, so the K⁺ molecules rapidly diffuse out

What is happening at the resting state of the neuron?

What is happening at the depolarization stage?

What is happening at the rising phase of the action potential?

What is happening at the falling phase of the action potential?

How does the action potential spead down the axon?

How do neurons communicate with each other?

1) action potential moves down the acon

2) voltage-gated channels open and allows the flow of calcium in

3) synaptic vesicle binds with membrane, releasing neurotransmitter

4) neurotransmitters bind with the ligand-gated ion channels, triggering an action potential in postsynaptic cell