Exam 2 Zoology

As evolution continues

complexity increases

Cells

basic unit of organisms
simplest animals have only this level

Tissues

groups of cells of one type with one function

Organs

multiple tissues organized to perform a single function

Organ systems

multiple organs linked to perform major functions like gas exchange, circulation, digestion, etc.

4 main types of tissues

1. epithelial
2. connective
3. muscle
4. nervous

Dipoblastic

2 layers
ancestral
limited in tissue development

Tripoblastic

3 layers (endo, ecto, meso)

Sponges and cnidarians are

dipoblastic

mollusks, urochordates, and vertebrates are

tripoblastic

Epithelial tissue

-line and cover organs
-form skin
-make up glands
-can combine with connective tissue to form membranes
-may arise from any of the 3 embryonic germ layers

Simple squamous cells may be found in

the lining of the lungs

cuboidal epithelial cells may be found in the

kidneys

columnar epithelial cells may be found in the

gut

pseudostratified columnar epithelial cells may be found in

the esophagus

Exocrine glands

duct secretes product

Endocrine glands

secrete into blood

Connective tissue

cells + extracellular matrix

The matrix consists of

protein, ground substance, and fluids

Types of connective tissue

loose, dense, cartilage, bone, blood

Adipose tissue

loose connective tissue

Dense connective tissue examples

tendons, ligaments

3 types of muscle tissues

smooth, skeletal, cardiac

Homeostasis

organisms try to maintain constant internal conditions because their enzymes are optimized for certain conditions

Positive feedback

stimulus triggers response that increases stimulus
examples: blood clotting, childbirth, orgasm
-does not maintain homeostasis

Negative feedback

stimulus triggers response that decreases stimulus
examples: body temp, glucose, pH
-maintains homeostasis

Feedback involves

sensors, integrating centers (brain), and effectors (actions)

Example of negative feedback

Stimulus: room temperature changes from set point
Sensor: wall thermometer detects change
IC: thermostat compares temp with set point
Effector 1: below set point - AC off, furnace on
Response 1: room warms, temp goes toward set point
Effector 2: above set point - AC on, furnace off
Response 2: room cools, temp goes away from set point

Example of positive feedback

Stimulus: fetus is pushed against uterine lining
Sensor: receptors in uterus detect stretch
IC: brain receives stretch info, compares with set point
Effector: above set point - pituitary gland secretes oxytocin
Response: oxytocin causes increased uterine contractions
Cycle repeats.

Temperature regulation feedback

negative

Body heat:

heat produced + (heated gained-heat lost)

Body heat also:

heat produced -/+ heat transferred

4 mechanisms of heat transfer

radiation, conduction, convection, evaporation

Evaporation always

cools organisms

Body size / temp relationship

1. smaller organisms warm/cool faster
2. larger organisms maintain temp easier
3. easier for large organisms to be warm-blooded

Homeotherm ~

warm blooded

Poikilotherm ~

cold blooded

Homeotherms temperature regulated

at a set point

Poikilotherms temperature regulated by

environment

Endotherm ~

homeotherm

Ectotherm ~

poikilotherm

Heliotherm

an animal that obtains its body heat by basking in the sun

poikilotherm insulation

low

poikilotherm metababolism

low

poikilotherm temperature stability

low

poikilotherm environmental influence

high

homeotherm insulation

high

homeotherm metabolism

high

homeotherm temperature stability

high

homeotherm environmental influence

low

Butterflies and moths have hair because

1. it keeps moths warm because they are nocturnal
2. it keeps butterflies cool because they are diurnal

The nervous system facts

1. present at some level in all animals but sponges
2. sense stimuli
3. integrate sensory input
4. integrates output
5. sends signals to effectors

Sensory neurons / peripheral system

sense stimuli

Interneurons / central nervous system (CNS)

integrates sensory input/output

Motor neurons / peripheral nervous system (PNS)

sends signals to effectors

Autonomic nervous system parts

1. parasympathetic division
2. sympathetic division

Somatic nervous system

stimulate skeletal muscles

Nerve impulse transmission

membrane potential: inside of nerve cell negative compared to outside
resting potential: -70 mV inside - developed by sodium/potassium pump

Potassium out

sodium in

Triggering a nerve impulse

1. gated channel vs. leakage channel
2. leakage channels set up resting potential
3. gated channels cause nerve firing

Gated channels can be opened by

chemical or electrical signals

Chemical signals come from

neurotransmitters

Electrical signals come from

axons of adjacent neurons

Action potential

1. all or nothing
2. can't fire again until resting potential reestablished
3. caused by passive diffusion (no ATP)

Sodium-potassium pump needs

ATP

Sodium-potassium pump

reestablishes resting potential

Speed up impulses

1. large diameter
2. myelinated sheath

Synapses

transmission from one neuron to another

Electrical synapse

depolarization of one cell leaps to next
-more common in invertebrates

Chemical synapse

release of neurotransmitters from presynaptic cell which bind to receptors on postsynaptic cell and trigger action potential
-more common in vertebrates

More action potentials

more neurotransmitters

Neurotransmitters must be

1. broken down quickly
2. taken back up by neurons or glial cells

Excitatory neurotransmitters

open gates

inhibitory neurotransmitters

close gates

Central nervous system is more evident in

bilaterally symmetrical organisms
cephalization

Fish brain is

tripartite
1. hindbrain (rhombencephalon)
2. midbrain (mesencephalon)
3. forebrain (prosencephalon)

Visual images created

in the back of the brain

Spinal cord is part of the

CNS

Acetylcholine

excites motor nerves

Norepinephrine

inhibits motor nerves

Olfactory cranial nerve

smell

optic cranial nerve

vision

oculometer cranial nerve

motor control of eye and eyelid

trochlear cranial nerve

motor control of eye

trigeminal cranial nerve

chewing muscles and facial sensation

abducent cranial nerve

motor control of eye

facial cranial nerve

motor control of facial muscles, salivation, taste, and cutaneous sensations

acoustic cranial nerve

hearing and equilibrium

Glossopharyngeal cranial nerveq

salivation, skin, taste, viscera

vagus cranial nerve

motor control of the heart, sensation from the thorax and pharynx

accessory cranial nerve

motor impulses to the pharynx and shoulder

hypoglossal cranial nerve

motor control of the tongue, some skeletal, sensation from skin, viscera

Mechanoreception

touch, pressure, proprioception, hearing, motion

The senses

mechanoreception
chemoreception
vision
temperature
nocireceptors
electrical/magnetic
exteroreceptors
interoreceptors

Nocireceptors

pain

Brain conveying sensory information

1. Stimulation: physical stimulus reaches sensor
2. Transduction: potentials created in dendrites
3. Transmission: AP generated and propagated
4. Interpretation: signals translated into sensory perception in the brain

Transduction

stimulus-gated ion channels in sensory cells
-graded potentials

When graded potentials exceed threshold

action potential generated

Thermoreceptors

temperature

Electromagnetic receptors

light energy