Midterm 1 Flashcards
How do animals provide tissue stability without cell walls?
Animals use an extracellular matrix (ECM) and cell junctions
Animal Body Plans
Describe the way animals are structured and serve as a blueprint for cellular organization.
What are the three main factors that influence an animal’s body plan?
- Embryonic development pattern (Protostomes vs. Deuterostomes)
- Germ layers (Diploblasts vs. Triploblasts)
- Body symmetry (Radial vs. Bilateral)
What are the differences between protostomes and deuterostomes?
Protostomes: Spiral, determinant cleavage; mouth develops first.
Deuterostomes: Radial, indeterminate cleavage; anus develops first.
Ectoderm
Forms skin and nervous system
Endoderm
Forms digestive and respiratory systems
Mesoderm
Forms muscles, circulatory system, and other organs
What is gastrulation?
process in early embryonic development; blastula folds inward, forming the three germ layers.
Radial Symmetry
Body parts arranged around a central axis (e.g., jellyfish).
What are the main differences between diploblastic and triploblastic animals?
Diploblastic: Have only two germ layers (ectoderm & endoderm) (e.g., cnidarians like jellyfish).
Triploblastic: Have three germ layers (ectoderm, mesoderm, endoderm) (e.g., flatworms, chordates).
Bilateral symmetry
Can be divided into left and right halves (e.g., humans, insects).
What is segmentation in animals, and why is it important?
repetition of body structures along the anterior-posterior axis, allowing for greater mobility and specialization (e.g., annelids, arthropods, chordates).
What are the three types of body cavities in animals?
- Acoelomates
- Pseudocoelomates
- Coelomates
What is the evolutionary advantage of bilateral symmetry?
Bilateral symmetry allows for cephalization (concentration of sensory organs in the head), which improves movement, navigation, and predatory behavior.
Acoelomates
No body cavity (e.g. flatworms)
Pseudocoelomates
Body cavity between mesoderm and endoderm (e.g. roundworms
Coelomates
True body cavity within the mesoderm
What does negative feedback do?
It reduces changes to bring the body back to normal (e.g. sweating)
example of positive feedback
childbirth (oxytocin increases contractions until birth)
what I positive feedback
amplifies changes instead of stopping them (pushes body away from normal, which can be dangerous)
feedforward control
body prepares for changes before they happen
What is thermoregulation?
The process of keeping body temperature stable.
What are the two types of thermoregulation?
Endothermy and ectothermy.
What is an ectotherm?
An animal that gets heat from the environment (e.g., reptiles).
What is an endotherm?
An animal that generates its own heat (e.g., mammals, birds).
What does vasoconstriction do?
Narrows blood vessels to keep heat in.
What is countercurrent heat exchange?
Blood vessels are arranged so warm blood heats cold blood, saving heat.
How do animals keep warm with fur or fat?
Fur traps heat, and fat insulates the body.
How does shivering help?
Muscle contractions generate heat.
What is torpor?
A temporary drop in body temperature to save energy.
What is hibernation?
Long-term torpor during winter.
What happens during a fever?
The body raises its temperature to fight infections.
Why can high fevers be dangerous?
Too much heat damages proteins and organs.
thermoreceptors do what
detect change in temperature
hypothalamus
body’s thermostat, maintains core homeostatic functions (more than temp)
What does the thyroid need to produce T3 and T4
iodine
hypo / hyper thryroidism refers to
T3 and T4 production, not thyroid size
What are the four levels of organization in animals?
Cells → Tissues → Organs → Organ Systems.
What is a tissue?
A group of similar cells that work together.
What are the four main types of tissues?
Epithelial, connective, muscle, nervous.
What is the function of epithelial tissue?
Covers surfaces, lines organs, protects, absorbs, and secretes.
What are the five types of epithelial cells?
Simple squamous, stratified squamous, cuboidal, columnar, pseudostratified.
What is the difference between endocrine and exocrine glands?
Endocrine glands release hormones into the blood, while exocrine glands release substances through ducts (e.g., sweat, saliva).
What is the function of connective tissue?
Supports, connects, and protects body parts.
Name six types of connective tissue.
Cartilage, bone, blood, loose connective tissue, fibrous connective tissue, adipose tissue
What is the extracellular matrix (ECM)?
A network of proteins and molecules that provides support in tissues.
What are the three types of muscle tissue?
Skeletal, cardiac, smooth.
Which muscle type is voluntary?
Skeletal muscle.
Which muscle type is only found in the heart?
Cardiac muscle.
What are the two main types of nervous system cells?
Neurons and glial cells.
What is the function of neurons?
Send electrical and chemical signals.
What is the function of glial cells?
Support and protect neurons.
What are the two major systems for coordination in animals?
Nervous system & endocrine system.
What are the three major roles of the nervous system?
Collect, process, and transmit information.
What is a neuron?
A single nerve cell.
What is a nerve?
A bundle of axons.
What is membrane potential?
Unequal charge distribution across a cell membrane.
What is the resting membrane potential of a neuron?
About -70 mV.
Which ions are primarily responsible for membrane potential?
Sodium (Na⁺) and Potassium (K⁺).
What does the Na+/K+ ATPase pump do?
Moves 3 Na⁺ out and 2 K⁺ in.
What are the three types of membrane potentials?
Resting, electrotonic, and action potentials.
What is depolarization?
When the inside of a neuron becomes more positive.
What is hyperpolarization?
When the inside of a neuron becomes more negative.
What triggers an action potential?
A stimulus reaching the threshold potential.
What is saltatory conduction?
Action potential jumping between nodes in myelinated axons.
What happens during repolarization?
K⁺ channels open, K⁺ leaves, membrane returns to negative.
What prevents action potentials from going backward?
The refractory period.
What is a synapse?
A junction between two neurons.
What are the two types of synapses?
Electrical and chemical.
What is a neurotransmitter?
A chemical that transmits signals across a synapse.
What ion is necessary for neurotransmitter release?
Calcium (Ca²⁺).
What is an EPSP?
Excitatory post-synaptic potential (depolarizes).
What is an IPSP?
Inhibitory post-synaptic potential (hyperpolarizes).
What is summation in synapses?
The combination of multiple EPSPs and IPSPs.
What is the role of acetylcholine?
It is a neurotransmitter for muscle contraction.
Where do action potentials start?
The axon hillock.
What is the function of voltage-gated Na+ channels?
They initiate and propagate action potentials.
How do neurotransmitters leave the synaptic cleft?
Diffusion, enzymatic breakdown, or reuptake.
What is the refractory period?
A period where a neuron cannot fire another action potential.
What is the role of myelin in synaptic transmission?
It speeds up signal transmission.
What neurotransmitter is involved in pleasure and reward?
Dopamine.
What is the main inhibitory neurotransmitter in the brain?
GABA.
Extracellular fluid always has
High Sodium, low potassium (HIGHER SODIUM OUTSIDE)
Intracellular fluid always has
High Potassium, Low Sodium (HIGHER POTASSIUM INSIDE)
Which ion causes an EPSP?
Na⁺ (Sodium) entering the neuron.
Which ions cause an IPSP?
K⁺ (Potassium) leaving or Cl⁻ (Chloride) entering.
What is summation?
The combination of multiple PSPs to determine if a neuron fires.
What is bioelectricity?
Electrical activity in living organisms due to ion movement.
What are the two divisions of the autonomic nervous system (ANS)?
Sympathetic and Parasympathetic.
What is the function of the sympathetic nervous system?
“Fight or flight” response.
What is the function of the parasympathetic nervous system?
“Rest and digest” response.
Which neurotransmitter is used by the sympathetic system?
Norepinephrine.
Which neurotransmitter is used by the parasympathetic system?
Acetylcholine.
What happens to the heart during sympathetic activation?
Heart rate increases. (Fight or flight)
What happens to digestion during sympathetic activation?
Digestion slows down. (fight or flight)
What is the main site of integration for the ANS?
The hypothalamus.
What are ganglia in the ANS?
Clusters of nerve cell bodies where pre- and post-ganglionic neurons synapse.
What are the five main types of sensory receptors?
Mechanoreceptors, Thermoreceptors, Nociceptors, Electromagnetic receptors, and Chemoreceptors.
What do mechanoreceptors detect?
Mechanical stimuli like touch and sound.
What do photoreceptors detect?
Light.
What is the role of the retina?
Converts light into neural signals.
What are the two types of photoreceptors?
Rods and Cones.
What do rods detect?
Low light and black & white vision.
What do cones detect?
Color and sharp vision.
What is the optic chiasma?
The point where optic nerve fibers cross in the brain.
What do chemoreceptors detect?
Chemical stimuli like taste and smell.
Where are taste receptors located?
In taste buds on the tongue.
What is the function of the olfactory bulb?
Processes smell information.
What are pheromones?
Chemicals used for communication between organisms.
What is nociception?
The detection of pain.
Which sensory system helps animals navigate using electrical fields?
Electroreception (found in sharks and some fish).
What is the function of the auditory system?
Detects sound waves and converts them into neural signals.
What are opsins?
Proteins in photoreceptors that detect light.
How many types of cone cells do humans have?
Three (for red, green, and blue light).
What is the function of rod cells?
Detect low-intensity light (night vision).
What is rhodopsin?
A light-sensitive pigment found in rod cells.
What happens when light hits retinal?
It changes shape, triggering a nerve signal.
What is the optic chiasma?
The point where optic nerve fibers cross in the brain.
What are mechanoreceptors?
Sensory receptors that detect mechanical stimuli like touch and pressure.
What are thermoreceptors?
Receptors that detect temperature changes.
What are nociceptors?
Pain receptors that detect tissue damage.
What are chemoreceptors used for?
Detecting chemicals (e.g., in taste and smell).
How do taste and smell work together?
Smell enhances taste perception by detecting airborne molecules.
What are pheromones?
Chemical signals used for communication between animals.
What is the function of the olfactory bulb?
Processes smell information in the brain.
What is electroreception?
The ability to detect electrical fields (e.g., in sharks).
What role does the parietal lobe play in sensory processing?
It processes taste and touch sensations.
What are the three types of skeletons in animals?
Hydrostatic, Exoskeleton, and Endoskeleton.
What is a hydrostatic skeleton?
A skeleton that uses fluid pressure for movement.
Example: worms, jellyfish.
What is an exoskeleton?
A rigid external covering that provides protection and support.
Example: arthropods.
What is an endoskeleton?
An internal skeleton made of bone or cartilage.
Example: vertebrates.
What is the main component of vertebrate bones?
Calcium phosphate.
What are the two types of bone tissue?
Compact bone and spongy bone.
What are the three types of muscle tissue?
Skeletal, cardiac, and smooth muscle.
Which type of muscle is voluntary?
Skeletal muscle.
What is the functional unit of a muscle?
The sarcomere.
Which two proteins are involved in muscle contraction?
Actin and myosin.
What is the sliding filament theory?
Muscle contraction occurs when myosin pulls actin filaments closer together.
What ion is required for muscle contraction?
Calcium (Ca²⁺).
What neurotransmitter is released at the neuromuscular junction?
Acetylcholine (ACh).
What is ATP’s role in muscle contraction?
It provides energy for myosin to detach from actin and reset.
What is the difference between fast-twitch and slow-twitch muscle fibers?
Fast-twitch fibers contract quickly but fatigue fast, while slow-twitch fibers contract slowly but sustain activity longer.
What is the biological definition of an animal?
all members of the kingdom Animalia (Metazoa)
What is the common ancestor of animals
A colonial flagellated protist from the Precambrian (~700 million years ago).
What group of modern organisms is most similar to the common ancestor of animals?
Choanoflagellates
What are the three main features used to classify animals?
body plans, embryonic development, and germ layers.
as environmental temp decreases, what happens to an Endotherm?
metabolic rate increases causing body temperature to increase
as environmental temp decreases what happens to an Ectotherm?
body temp also decreases, causing physiological processes to slow down
Oligodendrocytes / Schwann cells
form insulating layers around axons (myelin)
Astrocytes
help maintain ion balance surrounding neurons
