Module 1 - Biological Foundations Sept 10

Motor Neuron structures

• dendrites

• cell body(soma)

• axon

• myelin sheath

• axon terminals

Dendrites

receive info from other cells

Cell body (Soma)

contains nucleus and integrates incoming info

Axon

conducts electrical signals away from cell body

Myelin Sheath

insulates axon and increase speed of signal conduction

Axon Terminals

communicates with skeletal muscle fibres

Motor neurons activates……

skeletal muscle

Motor Neuron - Form Support Function

a long axon allows a motor neuron to transmit info over long distances from the spinal cord to the skeletal muscle

Sensory (afferent) Neuron

carries sensory info towards the CNS

Motor (efferent) Neuron

carries commands away from the CNS and to the effectors

Interneuron

processes/integrates indo within the CNS

Skeletal Muscle Fibre generates…

force

Skeletal Muscle Fibre Characteristics/Parts

• cylindrical cell

• multiple nuclei

• myofibrils

• actin and myosin

• mitochondria

• sarcolemma

• sarcoplasmic reticulum

Skeletal Muscle Fibre - Cylindrical cell function

allows force to be generated along the length of the fibre

Skeletal Muscle Fibre - multiple nuclei function

supports the large volume and protein demands of the fibre

Skeletal Muscle Fibre - myofribrils function

contains the contractile machinery

Skeletal Muscle Fibre - actin and myosin function

interacts to produce force

Skeletal Muscle Fibre - mitochondria function

sites of aerobic ATP re-synthesis

Skeletal Muscle Fibre - sarcolemma function

cell membrane surrounding the muscle fibre

Skeletal Muscle Fibre - sarcoplasmic reticulum

stores and releases Ca2+ to regulate contraction

Skeletal Muscle Fibre - Form Supports Function

a skeletal muscle fibre is packed with contractile machinery allowing it to generate force

Osteocyte function

maintains bone

senses machanical load

Osteocyte structures

• embedded within mineralized bone matrix

• long cellular processes

• mechanosensitive

• cellular network

Osteocyte - Embedded within mineralized bone matrix function

maintains surrounding bone tissue

Osteocyte - long cellular processes function

communicates with other bone cells

Osteocyte - mechanosensitive function

detects mechanical loading/strain

Osteocyte - cellular network function

helps coordinate responses to mechanical loading

Osteocyte - Form Supports Function

osteocytes form a communication network within bone that can sense mechanical loading

Osteocyte - Movement Connection

movement/loading —> mechanical strain on bone —> osteocytes sense load —> signals contribute to bone remodeling

Osteogenic

undifferentiated cells that divide and develop into osteoblasts

stem cells

Osteoblasts

responsible for forming new bone and is found in the growing portion of the bone

build up

Osteocytes

differentiated from osteoblasts into osteocytes and maintain bone tissue

Osteoclasts

perform bone reabsorption

break down

Bone Remodelling Cycle

• formation

• reabsorption

• reversal

Bone Reabsorption (osteoclasts)

• begins when osteoclasts remove a portion of the bone to be replaced later by the action of osteoblasts

• this signals for bone formation

Bone Formation (osteoblasts)

• lay down collagen and mineral deposits over the area previously re-modelled by osteoclasts

• vital for maintaining bone mineral density and bone strength

Fibroblast builds and……

maintains ECM (extracellular matrix)

Fibroblast structures/characteristics

• spindle shaped cell with extensions

• abundant rough ER

• golgi apparatus

• produces collagen and other ECM components

Fibroblast - Spindle shaped cell function

interacts with surrounding extracellular matrix

Fibroblast - Abundant rough ER function

produces proteins for secretion

Fibroblast - golgi apparatis function

processes/packages secreted proteins

Fibroblast - produces collagen and other ECM components function

builds and maintains connective tissue

Fibroblast - Form Supports Function

• fibroblasts produce and maintain the ECM that gives tendons and other connective tissues their mechanical properties

Fibroblast - Movement Connection

muscle generates force —> tendon transmits force —> bone moves

Specialized Cells for Sustained Movement

• cardiac muscle cell - generates force to pump blood

• adipocyte - triglyceride storage

• red blood cell - transport O2

Cardiac Muscle Cell generates…

force to pump blood

Cardiac Muscle Cell structres/characteristics

• branched cells

• myofibrils

• intercalated discs

• numerous mitochondria

Cardiac Muscle Cell - Branched cells function

forms an interconnected network

Cardiac Muscle Cell - Myofibrils function

• actin and myosin

• generates force

Cardiac Muscle Cell - Intercalated discs function

connect adjacent cells mechanically and electrically

Cardiac Muscle Cell - Numerous mitochondria function

supports continuous aerobic ATP re-synthesis

Cardiac Muscle Cell - Form Supports Function

• interconnected, contractile, mitochondria-rich cells allow rhe heart to contract repeatedly throughout life

Cardiac Muscle Cell - Movement Connection

• heart contracts —> blood flows —> O2 and nutrients delivered to working muscle

Red Blood Cell function

transports oxygen

Red Blood Cell structures/characteristics

• biconcave shape

• flexible membrane

• packed with hemoglobin

• no nucleus

• no mitochondria

Red Blood Cell - biconcave function

large surface area to volume ratio facilitates diffusion of O2 and CO2

Red Blood Cell - flexible membrane function

allows passage through very small capillaries

Red Blood Cell - packed with hemoglobin

binds and transports O2

Red Blood Cell - no nucleus function

provides more internal space for hemoglobin

Red Blood Cell - no mitochondria function

does not consume the O2 it transports

Red Blood Cell - Movement Connection

exercising skeletal muscle requires increased O2 delivery

Adipocyte function

triglyceride storage

Adipocyte structure/characteristics

• large lipid droplet

• nucleus towards edge

• specialized metabolic machinery

Adipocyte - large lipid droplet function

stores triglycerides

Adipocyte - nucleus on edge function

allows most of the cell volume to be occupied by lipid droplet

Adipocyte - specialized metabolic machinery function

store triglycerides and mobilizes fatty acids in response to metabolic signals

Adipocyte - Form Supports Function

large lipid droplets allow adipocytes to store substantial amounts of chemical energy as triglyceride

Adipocyte - Movement Connection

adipocyte triglyceride —> fatty acids released into blood —> can be used as fuel by active skeletal muscle

Specialized Cells that Produce and Control Movement

• motor neuron

• skeletal muscle fibre

Specialized Cells that transmit and support movement

• fibroblast

• osteocyte

Specialized Cells that sustain movement

• red blood cell

• cardiac muscle cell

• adipocyte

Cardiac Muscle Cell function

generates force to pump blood

Cardiac Muscle Cell characteristics/structures

• branched cells

• myofibrils

• intercalated discs

• numerous mitochondria

Cardiac Muscle Cell - Branched Cells function

forms an interconnected network

Cardiac Muscle Cell - myofibrils

• actin and myosin

• generates force

Cardiac Muscle Cell - intercalated discs functions

connect adjacent cells mechanically and electrically

Cardiac Muscle Cell - numerous mitochondria

supports aerobic ATP re-synthesis

Red Blood Cell function

transpor O2

Red Blood Cell parts/structures

• biconcave shape

• flexible membrane

• hemoglobin

• no nucleus or mitochondria

Red Blood Cell - biconcave shape function

large surface area to volume ratio facilitates diffusion of O2 and CO2

Red Blood Cell - flexible membrane function

allows passage through very small capillaries

Red Blood Cell - hemoglobin function

binds and transports O2

Red Blood Cell - no nucleus or mitochondria

• provides more internal space

• does not consume O2 it transports

Adipocyte function

triglyceride storage

Adipocyte parts/structures

• large lipid droplet

• nucleus toward edge

• specialized metabolic machinery

Adipocyte - large lipid droplet function

stores triglycerides

Adipocyte - nucleus towards edge function

allows most of the cell volume to be occupied by lipid droplet

Adipocyte - metabolic machinery function

stores triglycerides and mobilizes fatty acids in response to metabolic signals

What specialized cells produce and control movement?

• motor neuron

• skeletal muscle fibre

What specialized cells transmit and support movement?

• fibroblasts

• osteocyte

What specialized cells sustain movement?

• red blood cells

• cardiac muscle cell

• adipocyte