Week 4 - Skeletal, Muscular, Circulatory Systems

Skeletal system function

support/rigidity, muscle attachment, protection of organs

cartilage

formed by chondrocytes surrounded by gel-like matrix made up of protein and fiber

bone

formed by osteocytes, surrounded by calcium-phosphate matrix, living structure

exoskeleton

outer covering for protection, mainly insects

appendicular skeleton

pectoral and pelvic girdles, appendages

axial skeleton

skull, vertebrae, ribs, sternum

squamosal dentary jaw

mammalian jaw

endoskeleton

internal skeleton, can grow and function without shedding

endochondral bones

begin as cartilage then ossify into bones, most common type

dermal bone

no cartilage precursor

smooth muscle

around organs, involuntary

major innovations of skeletal system

locomotion (sprawl to limbs under body), jaw articulation (fish), mammalian jaw and middle ear

muscular system function

locomotion, eating/digestion, circulation of blood, breathing, communication

skeletal muscle

attaches to bones through tendons

cardiac muscle

foudn only in the heart, involuntary control

Structure of muscles (big to small)

muscle, fascicle, muscle fiber, myofybril, myofilaments (actin and myosin)

Motor neurons

controls skeletal muscles by sending signals to contract

Circulatory function

transport gases, nutrients, waste, hormones, antibodies, regulate temperature, maintain homeostasis

atrium

heart chamber, thin walled, recieves blood from veins

ventricle

heart chamber, thicker walled (muscle), pumps blood out to arteries

arteries

carry blood AWAY from heart, thick walls to sustain pressure

arterioles

smaller vessels, subdivide to take blood to all body parts

capillaries

very narrow vessels responsible for material exchange with tissues

Venules

smaller vessels that collect into larger vessels, taking blood from body back to heart

Veins

carry blood back to heart, tend to be larger in diameter than arteries but with thinner walls

plasma

mainly water, contains nutrients, salts, hormones, proteins, wastes, antibodies

erythrocytes

red blood cells, have hemoglobin, iron inside binds to O2

leukocytes

white blood cells, immune function

thrombocytes

blood clotting (platelets in mammals)

lymphatic system function

return lymph to cardiovascular, filter foreign particles in lymph nodes, contribute to immune system

closed circulatory system

blood stays in the vessels in the body

two chambered heart blood pathway

body, atrium, ventricle, gills, body

three chambered heart pathway (amphibians)

body, R atria, ventricle, lungs, L atria, ventricle, body

three chambered heart (reptiles)

more efficient than amphibians, ventricle is partially subdivided by incomplete septum; crocs have valve that basically gives them four chambers

four chambered heart pathway

body, R atrium, R ventricle, lungs, L atrium, L ventricle, body

Gene Tbx5

higher expression leads to ventricle separation in the heart