Unit 2 Flashcards
Ways to categorize muscle
location, appearance, control.
Red muscle, white muscle, and pink muscle
Red: high concentration of hemoglobin. Slow twitch, meant for sustainable use, less powerful, aerobic, used for things like swimming or jogging.
White: Fast twitch, meant for short bursts and burn out quickly. More powerful and anaerobic (uses glycosis). Used in sprinting or heavy weightlifting.
Pink: mixture of red and white muscle.
What happens when muscles are longer? Wider?
Longer: Muscles have longer muscle fibers, faster, more sacromeres.
Wider: More sacromeres parallel to each other, increases amount of power available.
Functions of the digestive system
Obtain food, process food, absorb nutrients, pass digested food.
Alimentary Canal
Tube from the mouth to the anus.
Includes: mouth + esophagus, stomach, intestines, cloaca.
Buccal Cavity
Jaws, teeth: acquisition and processing.
Tongue, glands: lubricate food, begin digestion, specialized feeding functions.
chemoreceptors: Detect nutrients and signal toxins.
Pharynx (Anterior-most foregut)
Pharyngeal arches and their derivatives (gills, hyoid arch, eustachian tubes), powerful muscles for swallowing.
Accessory organs (digestive system)
Liver, gallbladder, pancreas.
Abduction vs Adduction
Ab: Moving away from the midline.
Ad: Moving towards the midline.
Flexion vs Extension
Flex: Bending decreases the angle between two bones.
Extension: Increases or straightens out the angle between two bones.
Circumduction
Movement of a body region in a circular manner.
Protraction vs Retraction
Protract: Moves anterior to the body.
Retract: Moves medial to the body.
Elevation vs Depression
Elevation: Moves vertically up, superiorly, elevates.
Depression: Moves down, inferiorly, decreases.
Axial Musculature (Agnathans)
Arranged into myomeres and separated by myosepta; origin in the notochord and inserts in the connective tissue under the skin.
Epaxial Muscles
Dorsal to septum vertebrae and aid in stride length while supporting the head, body, and move tail.
Hypaxial Muscles
Located below the septum of the vertebrae, ventrally, are dominant in tetrapods and aid in respiration.
What happened to muscles as organisms evolved from aquatic habitats to terrestrial habitats?
Muscles specialization increases, external and internal obliques further aid movement, muscles differentiate and become more prominent as need for locomotion increases.
Appendicular Musculature
Limb Specializations: Pectoral and Pelvic Girdles
Pectoral: Brachial adaptations: rhomboideus, pectoralis (attaches limbs to trunk, brings limb forward, backward, and towards body), serratus ventralis (supports trunk, carries trunk forward and back). Trapezius: elevates shoulder and moves scapula towards head and tail.
Muscle differentiation in pectoralis for tetrapods
Present in early tetrapods as large sheet of muscle, need for more mobility causes selective pressure that causes muscle differentiation, facilitates increased control and fine movements around a joint.
What becomes the neck muscles in tetrapods?
The myomeres in the heads of agnathans; hypobrachial muscles become incorporated into the tongue.
Some important human muscle evolutions
constrictor colli (facial muscles), thumb muscles, and the glutes.
Integument and Functions
Beneath the skin (Epidermis: epiderm, dermis: mesoderm, and basement membrane: epiderm) = superficial facia (connective tissue, muscles, adipose tissue).
Functions: Gas exchange facilitation and protection, facilitate movement, house specialized structures and sensory adaptations, communication.
Pigment cells
Cells which synthesize and assemble pigments, often into membrane bound organelles.
Color change mechanism in vertebrates
Facilitated by melanosome transport; more spread out = more light absorbed = darker pigment.
Iridophore orientation - overlapping or angling can change the light being reflected.
Structural Coloration
Coloration provided by biomaterials aligned to reflect or absorb various wavelengths of light. Some might change iridophore orientation with temperature, like lizards turning green or blue.
What structure facilitates skin movement?
Collagen: Fibers are stacked and layered. If fibers are parallel to forces, skin will resist deformation.
Hair cells
Help with balance, lateral line in fish.
Protochordate Skin Structure
Outermost layer: Mucus membrane/muscosa - reduces drag, first layer of defense for pathogens, houses microbiota.
Epidermis: One cell layer thick - house pigments and secretes mucus.
Dermis: composed of collagen fibers arranged into layers, facilitates bending.
Agnathans and fish integument development
Epidermis develops specialized cells (unicellular glands).
Dermal bone can develop at the intersection of the epidermis and dermis.
Collagen fibers develop a more complex morphology, spiraling layers.
Tetrapod Integument Development: Keratinization
Develop extensive keratinization
- Epidermal cells form in stratum basale.
- As they age, they move outward and undergo apoptosis.
- As that happens, create and accumulate protein: keratin.
- Add lipids to keratin layer stopping dessication.
Integumental “Organs”
Specialized tissues created by combinations of the dermis, epidermis, and stratum corneum.
- I. e. feathers, hair, teeth, scales, mammary glands, horns and antlers.
Teeth and jaws
Teeth: Made up of enamel (extremely hard but brittle) and dentine (resilient).
Jaws help amplify and focus forces through: shape, insertion and origin, size, number of joints, location.
Incisiform Teeth
Chisel shaped, broad and flat with sharp cusp, front of the mouth. Good for nipping, biting, slicing.
Molariform Teeth
Large but flat with texture, back of the mouth, used for crushing and chewing.
Carnisal Teeth
Triangular, sometimes serrated, slicing through tissue and bones.
Conical Teeth
May include canines, pointy cone shaped teeth, specialized for piercing and sometimes crushing.
Pharyngeal Structures: Digestive System
Arches, gills (spiracles), jaws, tubotympanic recess, hyoid + derivatives, pharynx, trachea, larynx, pectoral girdle.
Alimentary Canal Functions
Keep food moving, continue food breakdown, absorb nutrients, eliminate indigestible components.
Alimentary Canal Functions: Individual Parts
Mouth, Esophagus, Stomach, Intestines, Rectum/Cloaca
Mouth: Mechanical + some chemical digestion.
Esophagus: Transports food to the stomach via contractions (peristalsis).
Stomach: Chemical digestion with enzymes and acids.
Small intestine: Duodenum receives enzymes from pancreas and bile from gallbladder, jejunun - nutrient absorption, Ileum absorbs salts and vitamins.
Large Intestine: Absorbs water and electrolytes.
Rectum/Cloaca: Stores and expels feces.
Alimentary Canal Basics
Derived from endoderm.
Connective tissue, blood vessels, and nerves from autonomic nervous system.
Sheets of smooth muscle oriented at 90 degrees.
Structure: Mucosa, submucosa, muscularis externa.
Sphincters
Help control the flow of food, humans have 6 primary sphincters.
Esophagus
Connects stomach to pharynx, lubricates food with mucus, changes size to accommodate food, can serve as temporary storage.
Stomach Origins
In gnathostomes, may have evolved as food storage compartment while acid may have been used as a preservative.
Stomach Anatomy
Contains gastric juice: enzymes, mucous, and hydrochloric acid.
Rugae in stomach increase stomach area.
HA secreted by gastric glands and neutralized by pyloric glands.
Stomach Specializations: Gizzards and Ruminant Stomach
Gizzards: Muscular walls in reptiles and birds, facilitates more mechanical digestion for harder objects like stones that may have been swallowed.
Ruminant Stomach: 4 ‘chambered’ stomach in cow-like animals, designed for efficient breakdown of cellulose.
Intestines
End products of digestion absorbed into the bloodstream here. Absorption determined by amount of area available to absorb food, time food items spend in the digestive tract. Glands secrete enzymes while villi increase surface area for absorption.
Intestinal Specializations
Goal: increase the amount of time nutrients spend in digestive tract.
Spiral valves increase the time spent in the intestines.
Herbivores tend to have larger digestive tracts and cecums.
Hepatic Portal
Capillaries throughout the intestines absorb chemicals (nutrients, toxins, macromolecules).
Drain into the hepatic portal, which transports them to the liver.
Other organs in the digestive system: Liver and pancreas
Liver: removes substances from blood, releases bile to digestive tract, stores macromolecules, develops from endoderm, can be buoyancy organ in marine organisms like sharks.
Pancreas: Develops from liver, creates enzymes and delivers them to the duodenum, neutralizes acids, endocrine functions related to digestion and sugar regulation like insulin, glucagon, and somatostatin.
Transduction
Cell generates action potential by opening and closing NA or K channels, different for different senses, carries info about presence, intensity, frequency, duration, and variation.
Chemoreception
~400 receptors for specific chemicals, certain odors come from combinations of these, include g-coupled receptors (amino acids, macromolecules, sugars), sodium channels, and H+ channels to sense acidity.
G-coupled Protein
Receive signal molecule and open ion channels which releases neurotransmitters to nearby nerves; different activation of different receptors gives tastes/smells, intensity determined by how many cells receive signal molecule.
Thermo Sensation
Detects potentially harmful stimuli, contribute to object identification.
Free nerves detect hot and cold as well as some ion channels.
Intensity coded by rate of firing different neuron types.
Light Reception
Photoreceptors present on the surface with nerve that runs to CNS, eye has lens that focuses light onto a light sensitive surface (retina, which contains cones and rods).
Intensity = rate of firing, color = rods and cones, different opsins sense different wavelengths of light.
How cones and rods work
In darkness = depolarized, let off glutamate.
When retina in rhodopsin is hit with light, cell is polarized - cells detect reduction in glutamate and transmit to ganglion cells. Ganglion cells integrate input from multiple photoreceptors.
Phototransduction facilitated by change in rhodopsin.
Hair Cells (Balance)
Have stereocilia which stick up from cell into a medium (fluid or air), movement of medium opens K and Na channels which depolarizes the cells which releases neurotransmitters to the brain.
Hair Evolution in Verts
- In early verts (lateral line)
- present in otic placodes, which forms a hollow structure lined with hair cells; bands of hair move there as the structure moves internally.
-In gnathostomes, otic capsule becomes more complex and specilized.
Semicircular Canals and Otolith Organs
Canals: Detect rotational movement
Utricle: Horizontal movement
Saccule: Vertical movement
Tetrapod Evolution for Sound
Elements of the hyoid become associated with otic capsule.
Stapes = bone for hearing, with tympanic membrane can amplify sound.
As the jaw articulates, bones in jaw were freed up and become incus and maleus.
Hearing Process
Sound = pressure waves vibrating in the air.
Location of hair cells stimulated along cochlea tells pitch; degree of displacement of hair cells give loudness.
Non-human senses
Extra chemoreceptors (vomeronasal organ for information analysis like in cats or dogs, also in reptiles and amphibians), external taste buds, electroreception in 2sharks, infrared receptors, magnetoreceptors.
Sliding Filament Theory
Myosin slides past actin during muscle contraction. When the two overlap, the muscle fibers shorten. This controls cellular movement.
Myosin binds to actin, ,myosin contracts + moves the actin, release + relaxes and the cycle repeats.
Skeletal, cardiac, and smooth muscle
Skeletal: Cells fused into muscular fibers, banded pattern.
Cardiac: Short, mononucleate, branched. Z disks make the muscle striated.
Smooth: organized into sheets and surrounds viscera.
