Sponges/Porifera vs. Cnidarians

Sponges/Porifera

• Choanocytes are specialized cells in sponges possessing a flagellum surrounded by a collar of microvilli.
• The flagellum generates water currents through the sponge, while the collar traps food particles.
• Sponges filter feed via tiny pores (Ostia), where choanocytes use flagella to create a current, trap food, engulf it, and pump water back out.
• Sponges lack true organs.

Cnidarians

• Cnidarians exhibit radial symmetry.
• Cnidarians possess tissue layers, including the epidermis for protection/sensation and the gastrodermis, which lines the gut and aids digestion/nutrient absorption.
• The mesoglea is a non-cellular layer that supports and provides buoyancy.
• Cnidarians use tentacles with cnidocytes to kill prey, then move the prey to the mouth for digestion.
• Digestion happens in the mouth.

Cnidarian vs. Sponge Traits

• Digestion Type: Cnidarians use extracellular and intracellular digestion, while sponges use intracellular digestion.
• Digestive System: Cnidarians have a gastrovascular cavity (one opening), while sponges have no cavity, just individual cells.
• Specialized Feeding Cells: Cnidarians use cnidocytes, while sponges use choanocytes.
• Tissues: Cnidarians have tissues, but sponges do not.
• Method of Feeding: Cnidarians are active predators using tentacles, whereas sponges are passive filter feeders.

Bilateria

• Bilaterians exhibit bilateral symmetry with mirror-image left and right sides.
• Cephalization, or a sensory organ/brain concentration, allows for directional movement.
• Bilaterians are triploblastic with ectoderm (skin/nervous system), mesoderm (muscles/organs/bones), and endoderm (digestive tract).
• Bilaterians have a complete digestive tract with a mouth and anus.
• Cephalization involves the development of a head region with a brain and sensory organs, enabling active movement.
• Organ systems arise from the mesoderm layer (circulatory, nervous, excretory, reproductive).
• Bilaterians divide into protostomes and deuterostomes.

Protostomes vs. Deuterostomes

• Blastopore Fate: Protostomes develop a mouth first, while deuterostomes develop an anus first.
• Cell Division: Protostomes exhibit spiral and determinant cleavage, while deuterostomes display radial and indeterminate cleavage.
• Body Cavity Development: Protostomes form a body cavity by splitting mesodermal tissue, while deuterostomes form the cavity by out-pocketing the primitive gut.
• Nervous System: Protostomes develop nerve cords from the bottom with ganglia, while deuterostomes develop nerve cords from the top with a centralized brain.
• Examples of protostomes include insects, snails, and segmented worms, while deuterostomes include birds, fish, starfish, and sea urchins.

Protostome Groups

• Protostomes include lophotrochozoans and ecdysozoans.

Lophotrochozoa

• Characterized by bilateral symmetry, they have feeding structures and a larval form.
• Annelid worms display a segmented body, a coelom as a hydrostatic skeleton, bilateral symmetry, and setae for locomotion.
• Annelids have a closed circulatory system, respiration through skin/gills, and repeated body segments with specialized functions.
• Mollusks are unsegmented with a distinct head-foot region and internal organs.
• Mollusks have a coelom, a mantle secreting a shell, a radula for feeding, and bilateral symmetry.
• Mollusks typically possess an open circulatory system, a shell, a highly developed nervous system, and exhibit diverse feeding modes.

Ecdysozoa

• Ecdysozoans share the trait of periodic shedding of an external cuticle or exoskeleton to grow.
• Nematodes are unsegmented with a pseudocoelom, bilateral symmetry, and a tough cuticle they molt as they grow.
• Nematodes have a complete digestive tract with a mouth and anus, but no circulatory system.

Arthropods

• Have segmented bodies (tagmata: head, thorax, abdomen), an exoskeleton, joint appendages, and bilateral symmetry.
• Arthropods possess an open circulatory system, compound eyes, and specialized appendages for specialized function.
• Segmented bodies and jointed appendages provide adaptability.
• Exoskeletons offer protection, support, and minimize water loss.
• Molting allows adaptibility in body shape and size.

Insects

• Traits of insects that explain their diversity is flight, a small size, and metamorphosis.
• Insects flight helps colonize habitats, find food, and escape predators.
• Insects small size exploits a variety of niches.
• Insects metamorphosis reduces competition between life stages.

Deuterostomes

• The blastopore becomes the anus during development.
• Display radial, indeterminate cleavage
• Enterocoely happens; the coelom is formed from the gut
• Hemichordates have bodies plan with bilateral symmetry, three-part bodies, pharyngeal slits, dorsal nerve cords and live below marine sediment.
• Echinoderm larvae are bilateral, but adults become pentaradial.
• Echinoderms have a water vascular system for movement and feeding, tube feet for locomotion, an endoskeleton, with no brain.
• Chordates include vertebrates.

Vertebrates

• Jawless fish lack jaws or paired fins and have a cartilaginous skeleton.
• Cartilaginous fish have jaws and paired fins.
• Cartilaginous skeletons are made of cartilage and lack a swim bladder.
• Bony fish, unlike cartilaginous, have a bony skeleton, swim bladders and operculum gills.
• Lobe-finned fish possess fleshy, lobed fins supported by bones and the ability to breathe air.
• Tetrapods include amphibians.

Tetrapods:

• Amphibians have aquatic larvae and terrestrial adults, moist skin for gas exchange, non-amniotic eggs.
• Amniotes exhibit features, including the amnion, chorion, allantois, and yolk sac.
• Amniotes development occurs away from water including reptiles, birds, and mammals.

Mammals

• Monotremes lay eggs.
• Monotremes lack nipples, but secrete milk through fur/skin.
• Marsupials give birth to underdeveloped young that develop in a pouch.
• Placental mammals develop inside in the uterus.
• Placental mammals have longer gestation and a wider diversification.

Evolution of Animals

• Over time animal complexity increases to include tissues, organs, etc.
• Symmetry shifts over time from radial symmetry to bilateral symmetry.
• Transition from water to land requires stronger skeletons, lungs/gills, and amniotic eggs.

Neurons

• Sensory neurons detect stimuli and sends information to the CNS.
• Interneurons process information within the CNS.
• Motor neurons send commands from the CNS to muscles/glands.

Direction of Signal

• Sensory Neurons: PNS to the CNS
• Interneurons: CNS only
• Motor Neurons: CNS to PNS

Location

• Sensory Neurons: Sensory organs (eyes, skin, ears).
• Interneurons: The Brain and Spinal Cord (CNS)
• Motor Neurons: connect to effectors in the PNS.

Connects To

• Sensory Neurons: Receptors to the CNS
• Interneurons: Sensory to motor.
• Motor Neurons: the CNS to muscles or glands

Reflexes

• Sensory Neurons: detect stimulus.
• Interneurons: processes stimulus and plans response.
• Motor Neurons: carries out response.

Neuron Components

• Cell Body (Soma): Contains organelles; performs basic maintenance.
• Dendrites: Receive incoming signals.
• Axon: Carries impulses to axon terminals.
• Axon Hillock: It is the "trigger zone" where potentials beings.
• Myelin Sheath: Insulates the axon, speeding up signal transmission.
• Nodes of Ranvier: Gaps in the myelin sheath where the signal jumps
• Axon Terminals: Sends signals to other neurons (via neurotransmitters).
• Synapse: Gap between neurons where neurotransmitters carry the signal.
• Neurotransmitters: Chemicals that transmit signals across the synapse.

Action Potentials

• Action Potentials: Individual action potentials cannot be stronger or weaker than another.
• Membrane Potential: differences in electrical charges.
• Resting membrane potential: Na+/K+ pump transports 3Na+ out and 2K+ in, creating an electrical gradient
• Selective Permeability: The membrane is more permeable to K+ than Na+, inside of the cell is more negative

Glial Cells & Action Potentials

• Glial cells support and protect neurons.
• Glial cells insulate neurons to speeds up signal transmission.
• Glial cells maintain homeostasis and help with healing.
• Glial cells do not transmit action potentials.

Action Potential Stages

• Resting Potential: Neuron is at rest.
• Depolarization: Na+ channels open. Na+ rushes into the cell, inside becomes less negative
• Rising Phase: More Na+ channels open, voltage spikes
• Repolarization: Na+ channels close, K+ channels open, K+ flows out, inside becomes negative again.
• Hyperpolarization: Na+/K+ pump and leak channels restore resting potential

Action Potential Propagation

• Moves along the neuron from the axon hillock to terminal.
• Myelin speeds & increases and conserves electrical signals.

Communication in Synapses

1. Action potentials reach the axon terminal.
2. Calcium channels open to flood inside.
3. Vesicles fuse with the presynaptic membrane.
4. Neurotransmitters released into the synaptic cleft.
5. Neurotransmitters bind to receptors on the postsynaptic neuron.
6. The signal is terminated once its received.

Neuron Information Coding

• Frequency Coding: More intense stimuli have higher frequencies that codes the brain to the strength of stimulus.
• Timing: Precise timing of spikes carries information.
• Population Coding: Many neurons work together.
• Labeled Line Coding: Brains knows what to expect from a type of neuron that tells the brain.

EPSP & IPSP

• EPSP make a neuron more likely to fire through slight depolarization.
• IPSP make a neuron less likely to fire, through slight hyperpolarization.
• Temporal summation happens when one neuron rapidly fires EPSPs or IPSPs to threshold.
• Spatial summation occurs when effects add up to boost or cancel each other.

PNS vs. CNS

PNS:

• Nerves: the bundle of cranial and spinal nerve axons.
• Ganglia: clusters of nerve cell bodies outside of the CNS.
  • Divided into sensory & motor divisions.

CNS:

Somatic vs. Autonomic Nervous Systems

• Somatic Nervous System enables voluntary control of skeletal muscles.
• Autonomic Nervous System regulates involuntary functions (sympathetic, parasympathetic).

Autonomic Nervous System

• Sympathetic: fight or flight response.
• Parasympathetic: rest and digest response.

Parts of the CNS

• Brain: control center for processing, memory, decision, and emotions.
• Spinal Cord: connects brain to the body, coordinates reflexes.

Lobes of the Cerebral Cortex

• Frontal: Decision making, problem solving, personality, voluntary motor control, speech.
• Parietal: Sensory processing, spatial awareness, coordination.
• Occipital: Visual processing.
• Temporal: Sides of the brain, auditory processing, language comprehension, and memory.

Gray vs. White Matter

Gray matter:

• Contains Neuron cell bodies, dendrites, synapses.
• Color is Grayish.
• Functions processing, integration, decision-making
• It is the Brain's Outer layer + inner nuclei.
• In the Spinal Cord it's Inner "butterfly" shape
• Very Little myelin

White matter:

• Contains myelinated axons
• Color is White
• It Communicates and sends signals between regions.
• It is the Brain's Deeper inside
• In the Spinal Cord it's Outer region
• Rich in myelin

Forebrain Components

• Cerebrum: higher cognitive ability, sensory processing and voluntary movement.
• Diencephalon: it acts sensory information, thalamus regulates hunger, thirst, and emotion.
• Limbic: memory/emotion regulation.

Hindbrain Structures

• Medulla Oblongata: autonomic functions that connects spinal cord & brain stem
• Pons: bridges Cerebrum & Cerebellum; responsible for sleep and breathing.
• Cerebellum: helps body movement.

SNS vs. ANS

SNS:

• Voluntary
• Sends messages via skeletal muscles.
• Needs one motor neuron between CNS & muscle
• No Subdivisions

ANS

• Involuntary
• Communicates Smooth muscles, cardiac muscles, glands
• Needs 2 neurons between CNS & destination
• Composed of Sympathetic & Parasympathetic

Stimuli: chemo-, mechano-, and photoreceptors

• Chemosensitive: chemical stimuli modify membrane potential.
• Mechanosensitive and light: use G-protein to activate hyperpolarization.

Neurotransmitters / Hormones

• Acetylcholine moves with Voluntary movement and reflexes
• Norepinephrine is stimulated by Regulation of automatic functions like heart rate and digestion.

Types of Sensory Receptors: Smell, Taste, Vision & Hearing

• Smell: Chemoreceptors -Chemical binding to GPCRs causing depolarization & action potentials
• Taste: Chemoreceptors- Chemical binding to receptors (GPCRs or ion channels) Vision: Photo receptor-Photo pigment activation leads to hyperpolarization Hearing: Mechanoreceptors-Vibration bends hair cells, depolarizing them and sending signals

Vision: Rods vs. Cones

Rods:

• It facilitates Night vision and light intensity
• Cylindrical shape
• Sensitive to light
• Peripheral vision
• Black and white

Cones:

• It facilitates Color vision.
• Conical shape
• Located in Central retina
• They use color Vision

Eye Structure

Single Len Eyes:

• It facilitates Images with focus that is limited

Simple Cup Structure:

• Wide, but no detailed image

Compound:

• Wide.
• They use Low resolution + motion detection

Endocrine vs. Nervous Systems

• Hormones controls slower.
• Nervous system controls faster.

Benefits of Hormone

A. Insulin lowers blood Glucose levels B. Glucagon releases more Glucose release from liver.

Functions o Negative feedback mechanisms a. Glucose lowers from insulin

o Positive Feedback Mechanisms:
           a. Baby causes birth

Types of Hormones

• Hormones*
• Steroids, peptides and Proteins

HPA’s: to control endocrine glands

Protein

  - Short

  - Works on surface to send enzymes

Steroids:

         - Made from cholesterol:

        - Works inside long term.

Definitions

• Endocrine: Transports to all parts of the body

• Paracrine: Local hormone cells

• Synaptic sends a messenger

• Exocrine: is a pheromone sender

Respiratory requirements to move

Diffusion to move if body isn't big. • Surface. Bigger bodies rely on bulk.

Types o Lungs o Gills

The Hemoglobin molecule has the higher affinity for Oxygen

The rate of breathing affects functions