Biology Module 3 Vocabulary

Porifera

simple, asymmetrical animals (sponges)

Cnidaria

radial symmetry and stinging cells (jellyfish, corals, sea anemones)

Bilateria

animals with bilateral symmetry (humans and worms)

Asymmetry

no symmetry (sponges)

radial symmetry

symmetry around a central axis (starfish, jellyfish)

Bilateral symmetry

symmetry where the body can be divided into two equal halves (humans, fish)

Cephalization

concentration of nerves/sensory organs in the head (e.g., in bilaterally symmetric animals)

Segmentation

division of the body into repetitive sections (e.g., worms, arthropods)

Gastrulation

Formation of three germ layers: ectoderm, mesoderm, endoderm, during embryonic development (muscle & gut)

Ectoderm

outer germ layer, forms digestive tract and internal organs (epidermis and brain)

Mesoderm

middle germ layer, forms muscles, bones, and circulatory system

Diploblast

two germ layers (ectoderm & endoderm) (e.g., cnidarians)

Triploblast

three germ layers (ectoderm, mesoderm, & endoderm) (e.g., humans, other bilaterians)

Blastopore

the opening in the early embryo that develops into either the mouth or anus

Protostome

animals where the blastopore becomes the mouth (e.g., mollusks, annelids)

Deuterostome

Animals where the blastopore becomes the anus (e.g., vertebrates, echinoderms)

Endocrine gland

glands that secrete hormones directly into the bloodstream (e.g., thyroid, pancreas (insulin))

Exocrine gland

glands that secrete substances through ducts (e.g., sweat & salivary glands)

Actin & Myosin

protein filaments responsible for muscle contraction

Neuron

nerve cell that transmits electrical signals

Neuroglia

support cells in the nervous system

Dendrite

Branch-like extensions of a neuron that receive signals

Cell body

the central part of the neuron containing the nucleus

Axon

long extension of a neuron that carries signals away from the cell body

Axon terminal

the end of an axon where neurotransmitters are released

Neurotransmitter

chemicals that transmit signals across synapses (e.g., dopamine, serotonin)

Resting Membrane Potential

the electrical potential of a neuron at rest (~-70mV, prepares neuron to fire)

Hyperpolarization

a less negative membrane potential inhibiting action potential (makes neuron less likely to fire)

Depolarization

a less negative membrane potential after depolarization (more positive, occurs during action potential firing)

Repolarization

return to resting membrane potential, triggering an action potential (resets the neuron to fire again)

action potential

electrical impulse that travels along neurons ( sends signal to muscle for contraction)

IPSP (inhibitory postsynaptic potential) vs EPSP (excitatory postsynaptic potential)

IPSP reduces the likelihood of an action potential ( brain balances), whereas EPSP increases it (control activity)

Oligodendrocyte

glial cell that forms myelin in the CNS (insulates neurons in the brain and spinal chord)

Myelin Sheath

fatter layer that insulates axons, speeding up signal transmission (like insulation on electrical wires)

Saltatory conduction

fast transmission of action potentials along myelinated axons (speeds up nerve impulses)

Continuous Conduction

slower transmission along unmyelinated axons

NS Divisions

Structural: central nervous system (CNS, brain and spinal cord, receives information) and peripheral nervous system (PNS, nerves outside the CNS, transmitting signals for movement and sensation)

functional:

sensory: carries info to CNS

motor: sends commands from CNS to effectors

somatic (voluntary; walking, skeletal muscle)

automatic (involuntary; breathing, smooth/cardiac muscle, glands)

sympathetic: "fight or flight"

parasympathetic: "rest and digest"

Effector

a muscle or gland that responds to a nerve signal

sensory transduction

the conversion of sensory stimuli unto electrical signals

Receptor types

stimulus origin:

Exteroceptors: external stimuli (vision, touch, smell)

interceptors: internal stimuli (blood pressure)

stimulus types:

mechanoreceptors: pressure, touch (ears, skin)

photoreceptors: light (eyes)

thermoreceptors: temperature

chemoreceptors: chemicals (nose, taste)

nociceptors: pain

Simple vs Compound eye

simple eye: single lens, e.g., human eye

compound eye: many lenses, e.g., insects

Accommodation

the ability of the lens to change shape for focusing (focus on nearer objects)

Opsin

protein in photoreceptor cells that detect light

Rods

photoreceptors for low vision (light intensity)

Cones:

photoreceptors for color and sharp vision

Statocyst organ

organ used by some animals to detect gravity and orientation

Lateral line

sensory system in fish for detecting vibrations and movement in water

Hair cell

sensory cells in the ear and lateral line that detect sound and movement

Vestibular system

part of the inner ear responsible for balance

Cochlea

spiral structure in the inner ear responsible for hearing

Complete vs incomplete gut

complete gut: has 2 openings (mouth and anus)

incomplete gut: has 1 opening

GI tract regions

mouth --> esophagus --> stomach --> small intestine --> large intestine --> rectum --> anus

GI tract vs accessory organs

GI tract: continuous tube where food travels, from mouth to anus

accessory organs: aid in digestion, but food doesn't directly pass through them (liver, pancreas, gallbladder)

4 layers of GI tract wall

mucosa: secretes mucus and absorbs nutrients

submucosa: blood vessels, nerves

muscularis: smooth muscle for movement

serosa: protective outer layer

Ingestion

the intake of food

Physical digestion

breaking food into smaller pieces (stomach churning, chewing)

Endoderm

inner germ layer; forms gut lining and organs (lining of stomach and intestines)

4 animal tissues

epithelial: covers surfaces (skin, gut lining)

connective: supports (bone, blood)

muscle: movement (skeletal, cardiac, smooth)

nervous: signals (brain, spinal cord)

Chemical digestion

breaking down food w/ enzymes (amylase breaking down starch)

Absorption

nutrients entering the blood from the intestines

Amylase

Enzyme that breaks down starch into sugars (found in saliva and pancreas)

Bolus

soft mass of chewed food ready to swallow

Peristalsis

wave-like muscle contractions that move food

Chyme

partially digested food & stomach acid

Villi

fingerlike projections in the small intestine that absorb nutrients (increase surface area for absorption)

Microvilli

tiny projections on villi cells for even more absorption

Hydrolytic enzyme

enzyme that uses water to break down molecules (lipase breaks fats into fatty acids)

Emulsification

breaking up fat droplets into smaller ones (bile emulsifies fats in the small intestine)

Bile

digestive fluid made by the liver, stored in the gallbladder (helps digest fats)

Pancreatic juice

Enzyme-rich fluid that neutralizes stomach acid and digests all food types (contains: amylase, lipase, and proteases)

Bulk Flow

movement of fluids (air, food) driven by pressure (blood pumped by the heart through the vessels)

Ventilation

movement of air in and out of the lungs or gills (breathing in oxygen and out CO2)

Circulation

movement of blood through the body (delivers oxygen and nutrients)

Operculum

protective flap over fish gills that helps pump water (opens and closes as the fish breathes)

Countercurrent Exchange

blood flows opposite to water flow in fish gills, maximizing oxygen uptake (helps fish extract more O2 from water)

Boyle's Law

pressure and volume in inversely related (inhalation increases lung volume, lowering pressure to draw in air)

Tidal ventilation

air moves in and out via same path (no-flow-through system) (mammal lungs)

Diaphragm

muscle under lungs that contracts to help inhale (when it contracts, lung expand)

Alveolus (plural alveoli)

tiny air sacs where gas exchange occurs (oxygen enters blood here, CO2 leaves)

Hemocyanin

oxygen-binding protein in some invertebrates (blue blood, found in horseshoe crabs)

Hemoglobin

Protein in red blood cells that carries oxygen (makes blood red, binds oxygen in lungs)

Myoglobin

oxygen-storage protein in muscles, especially in diving animals

Open circulatory system

blood flows freely around organs (not in vessels) (e.g., insects, mollusks)

Closed circulatory system

blood stays in vessels (e.g., humans, fish, mammals)

Artery

carries blood away from the heart

Arteriole

small branches of arteries leading to capillaries (control blood pressure and flow)

Vein

carries blood toward the heart

Venule

small veins leaving capillary beds (merge into larger veins)

Capillary

tiny vessels where gas/nutrient exchange happens (found in all tissues)

Endothelium

inner lining of blood vessels (smooth to reduce resistance)

Hypotension/Hypertension

Hypotension: low blood pressure

Hypertension: high blood pressure

Ischemia

lack of blood flow (oxygen) to tissue (can cause heart attack or stroke)

Atrium

upper heart chamber; receives blood (right atrium receives from the body)

Ventricle

Lower heart chamber; pumps blood out (left ventricle pumps to the body)

Cardiac cycle

sequence of heart contraction and relaxation (includes systole and diastole)

Systole

contraction phase (pumps blood out) (ventricle squeezes blood into arteries)

Diastole

relaxation phase (chambers refill) (atria refill during diastole)

Homeostasis

maintaining stable internal conditions (keeping body temperature or blood sugar steady)

Negative feedback

response that reverses a change ( insulin lowers blood sugar when its high)

Positive feedback

responses that amplifies a change (oxytocin increases contractions during childbirth)