ICBA Unit 4

Animal Form and Function

  • All animals have similar needs

    • Obtain nutrients & oxygen

    • Fight infection

    • Survive & reproduce

  • Same needs, varying anatomy

  • Anatomical variation = outcome of evolution

  • Function & form are correlated

    • Evolution results in close match of form to function

    • Anatomy results in physiology

    • Seals, penguins, & tuna have fusiform (tapered on both ends)

      • B/c water is dense & causes drag

      • Allows animals to swim quickly

  • What limits animal shape and size?

    • Physical & structural constraints

      • Skeletal and muscular system might not grow enough to support large animal

      • Requires very efficient ways to move nutrients & oxygen

    • Energetic constraints

      • More energy needed to maintain larger animal

    • Evolutionary trade-offs

    • Need to exchange nutrients, waste, gasses, etc. with environment

  • Organization of body plans - organism, organ, tissue

  • Tissues: groups of cells with similar appearance & common function

    • Building blocks of organs

  • Organs: functional units composed of many different tissue types

  • Organ systems: groups of organs that work together

  • Epithelial tissues: tissue covering outside of body & lining organs + cavities inside body

    • Closely packed cells due to likelihood of abrasions

    • Different shape = different function

  • Connective tissue:  holds many tissues + organs together and in place

    • Sparsely populated cells scattered in extracellular matrix

    • Matrix = web of fibers

  • Types of connective tissue

    • Loose  - holds organs in place

    • Fibrous - found in tendons & ligaments

    • Bone - skeleton

    • Adipose - insulation & fuel (fat pads)

    • Cartilage - strong & flexible support

    • Blood - technically connective tissue (will not be discussed in class)

  • Muscle tissue: responsible for movement

    • Regulated by actin-myosin contraction

  • Types of muscle tissue

    • Skeletal/striated - voluntary movement

    • Smooth - involuntary movement

    • Cardiac - heart contractions

  • Nervous tissue:   detects, processes, and transmits information

  • Organs built from limited set of cell & tissue types

  • 4 categories of tissue →  build organs

    • Epithelial tissue: covers outside of body & lines organs + cavities

    • Connective tissue:  holds many tissues + organs together & in place

    • Muscle tissue: control movement in the body

    • Nervous tissue: receives, processes, and transmits information

  • Animals use many organ systems to manage internal environment

    • Temp, glucose levels, pH, solute concentration, etc.

  • Regulator:  uses internal mechanisms to control internal environment

    • Does not change based on external environment

  • Conformer:  internal condition changes based on external environment

    • Changes with external environment

  • Homeostasis: maintenance of internal environment 

    • Physiological activity responds to stimuli & brings it back to baseline

  • Negative feedback: increasing response reduces stimuli then returns itself to normal

    • Ex: insulin produced to control blood sugar, then reduces to prevent body from leaving homeostasis

  • Endocrine & Nervous systems register stimuli

  • Endocrine system controlled by hormones

    • Hormone: secreted chemicals that travel through body fluids and act on specific target cells in the organism

  • Hormone balance can change over time

    • Ex: hormone fluctuations responsible for menstrual cycle

    • Circadian rhythm: physiological changes that regulate sleep-wake cycle

      • ↑ [melatonin] = ↑ tiredness

  • Animals differ in whether body temp is variable or constant

    • Poikilotherm: body temp varies w/ environment

    • Homeotherm: body temp is constant

  • Animals have many ways to balance heat loss + gain

    • Radiation: release of heat over absolute zero

    • Evaporation: removal of heat from surface of liquid (cooling effect)

    • Convection

    • Conduction: heat transfer between two touching objects

  • 5 adaptations for regulation

    • Insulation: reduces heat flow between body & environment

      • Via fur, fat layers

    • Circulatory adaptations: constriction & dilation, vessel arrangement

      • Constriction of arteries reduces blood flow to extremities

        • Keeps blood warmer for longer

      • Dilation of blood vessels bring more blood towards skin

        • Cools blood 

      • Vessel arrangement of many birds & marine mammals allows for countercurrent exchange

        • Heat transfer between opposing currents

    • Cooling by evaporative heat loss: evaporation keeps body temp from rising

      • Ex: sweat in humans evaporates off of body & cools it

      • Ex: panting in dogs creates moisture around mouth that evaporates & cools it

    • Behavioral responses: change behavior to maintain homeostasis

      • When cold - seek warm places, orient towards heat, huddle together

      • When hot - bathe, move to cooler areas, orient away from heat 

  • Thermogenesis: adjust metabolic heat production to maintain body temp

    • Increased by muscle activity (moving/shivering)

    • Nonshivering - takes place when mitochondria 



From maga mak-quan-zie number 1 milf <3 

Nervous System

  • Nervous System consists of circuits of neurons & supporting cells

    • Neurons: process & transmit information through electrical & chemical signals

    • Action Potential: rapid, temporary change in a membrane potential

      • Membrane Potential: voltage difference across a cell membrane, resulting from the unequal distribution of ions inside & outside the cell

        • Measured in millivolts

        • **line at top is threshold potential

  • Nervous Systems consist of circuits of neurons & supporting cells

    • Simplest animals with nervous systems, the cnidarians (ex. jellyfish), have interconnected neurons arranged in nerve nets

      • Decentralized, no clear brain

    • More complex animals have nerves, in which the axons of multiple neurons are bundled together

  • Bilaterally symmetrical animals exhibit cephalization (clustering of sensory organs at the front end of the body)

    • In vertebrates:

      • Central Nervous System: brain & spinal cord

        • Brain & spinal cord (CNS) contain

          • Gray Matter: consists of neuron cell bodies, dendrites, & unmylenated axons

          • White Matter: consists of bundles of myleninated axons

            • Can send signals faster

      • Peripheral Nervous System: nerves & ganglia → transmits information to and from the CNS

        • Afferent neurons transmit information to the CNS

        • Efferent neurons transmit information away from the CNS

          • Motor System: carries signals to skeletal muscles

          • Autonomic Nervous System: carries signals to smooth & cardiac muscles

            • Sympathetic: arousal & energy generation (“flight or fight response”)

              • Heart beating faster

              • Adrenaline secretion

            • Parasymathetic: calming & return to self-maintenance (“rest & digest”)

              • Slows heart

              • Construct eye pupil

        • Regulates movement & internal environment

  • The vertebrate brain is regionally specialized

    • Forebrain: processing of olfactory input, regulation of sleep, learning, and any complex processing

    • Midbrain: coordinates routing of sensory input

    • Hindbrain: involuntary activities & coordinates motor activities

    • Size differences between species reflect relative importance of the particular brain function



  • Multiple organisms exhibit vocal communication

    • Whales, elephants

  • Human language based on similar features

    • Phonemes

    • Morphemes

  • fMRI detects brain activity via changes in oxygen concentration

  • Cerebral cortex: region of brian that controls voluntary movement and cognitive functions

    • Divided into four lobes

      • Frontal lobe - cognitive function

      • Parietal lobe - controls movement

      • Temporal lobe - hearing

      • Occipital lobe - sight

  • “Tan” patient case study

    • Patient could only say “tan” after a brain injury - non-fluent aphasia

      • Non-fluent aphasia: inability to produce coherent speech

    • Dr. Broca found that “Tan” and other patients with similar symptoms had damage to a region in the left interior frontal lobe

      • Broca’s area: area in the left interior frontal lobe that regulates speech output

  • Damage to the temporal lobe causes fluent aphasia

    • Fluent aphasia: inability to understand language coherently

      • Verbal output present

      • Sound substitutions (girl instead of curl)

      • Word substitutions

      • Difficulty comprehending what they read or hear

    • Damage to Wernicke’s area 

  • Babies rapidly acquire local language w/o need of formal instruction

  • Specialized mechanisms for language acquisition have a clear cut sensitive period 

  • Many nervous systems disorders can be explained in molecular terms

    • Schizophrenia, depression, drug addiction, Alzheimer’s, Parkinson’s

    • Genetic and environmental factors contribute to diseases

  • Invertebrates use statocysts to sense gravity

    • Statocysts: organs in most invertebrates containing mechanoreceptors used to maintain equilibrium

      • Mechanoreceptors detect movement of granules called statoliths

  • Insects can use body hairs or localized organs w/ tympanic membrane to detect sound

  • In most terrestrial vertebrates, sensory organs for hearing and equilibrium are closely associated in the ear

    • Outer ear (pinna)

      • Ear canal funnels sound into middle ear

    • Middle ear

      • Stapes: bone of the middle ear that 

    • Inner ear

      • Cochlea: coiled tube with a set of internal membranes that divide into three chambers.

        • Fluid filled chambers

  • Hair cells bending cause ion channels to open or close

    • Causes increase/decrease of neurotransmitter intake depending on structure

  • Organs in the inner ear detect body movement, position, and balance

    • Semicircular canals: detect angular head movements (direction of head wrt body)

    • Utricle & saccule: detect position wrt gravity 

    • Otoliths: free moving granules that move within the inner ear

      • Position of otoliths informs organism of position wrt gravity 

      • Helpful for burrowing mammals 

  • Lateral line systems in fish contain mechanoreceptors that detect & respond to water movement

    • Detect & respond to water movement based on movement of hair cells

    • Important model for understanding hair cells in humans & other complex organisms

  • Behaviors that result from sensory input require muscle activity

  • Muscle contraction relies on intrxns between protein structures

    • Thin filaments: composed of actin

    • Thick filaments: staggered arrays of myosin

  • Vertebrate skeletal muscle moves bones + the body

    • Skeletal muscle consists of bundle of single celled fibers that runs length of muscle

    • Muscle fiber composed of longitudinally arranged myofibril bundles

      • Sarcomere: unit that makes up the muscle fiber

  • Thick and thin filaments ratchet past each other longitudinally to contract muscle

    • Powered by myosin

    • Does not change length of filaments

      • Filaments overlap, which pulls muscle in 

  • Steps of muscle contraction - must repeat itself to continue movement

    • ATP binds to myosin head

      • Head released from thin filament

    • ATP hydrolyzed to ADP

      • Myosin head pivots and binds to new actin subunit

    • Inorganic phosphate released

      • Head pivots while holding onto thin filament (drags with it)

    • ADP released

      • Cycle can repeat itself

  • Varying # of fibers that contract can impact strength of contraction

    • Motor unit: single motor neuron and the muscle fibers it controls

    • Recruitment: process by which more motor neurons are activated

  • Rate of muscle fiber stimulation also regulates muscle contraction

    • Tetanus: state of smooth and sustained muscle contraction produced

      • Muscles cannot relax between stimuli

      • Symptom of the disease tetanus (different things)

  • Skeletal muscles cannot work without bones as framework

    • Wouldn’t pull anything with it 

  • Skeletal systems transform muscle contraction into locomotion

    • Exoskeleton: hard covering deposited on animal’s surface

      • No hard structure within the body

    • Endoskeleton: hard structure buried within soft tissue

    • Hydrostatic skeleton:  fluid within body held by high pressure in closed body cavities

      • Movement of fluid moves organism

  • Skeletal muscles attached in antagonistic pairs

    • Cooperate to control movement

  • Hydrostatic skeletal muscles change shape of fluid filled compartments to move

    • Called peristalsis 

      • How food moves down the esophagus in humans


Stolen from Makenzie again :3 :3 :3 :3 :3 :3 

  • Discrete sensory inputs can stimulate both simple and complex behaviors

    • Behavior: actin carried out by muscles under control of the nervous system

    • Behaviors and the anatomical structures related to their performance are subject to natural selection

    • A fixed action pattern is a sequence of unlearned acts directly linked to an external cue (sign stimulus)

      • Ex: stickleback fish showing territorial response to red color

      • Unchangeable & must be carried to completion

    • Migration: regular, long-distance change in location guided by environmental cues

      • Animals can orient themselves through unfamiliar territory using their position relative to

        • The sun

        • The North Star

        • Earth’s magnetic field


  • Animals that communicate with odor/taste emit chemical substances called pheromones

    • Not just related to reproductive behavior