IB Biology Topic B2.3.9 Adaptations of Cardiac Muscle Cells and Striated Muscle Fibres Revision Notes (HL)

IB Biology Topic B2.3.9 Adaptations of Cardiac Muscle Cells and Striated Muscle Fibres Revision Notes (HL) | RevisionDojo

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Cardiac and Skeletal Muscle: Same Striations, Different Adaptations

Cardiac muscle cells and striated (skeletal) muscle fibres are both striated, because both are packed with myofibrils showing repeating sarcomeres.
Their differences in shape, nuclei, and control reflect their very different jobs in the body.
1. Cardiac muscle powers the continuous, tireless pumping of the heart.
2. Skeletal muscle powers voluntary movement of the body under conscious control.

Definition

Myofibrils

Contractile units within muscle cells, composed of actin and myosin filaments that allow for muscle contraction.

Tip

Both muscle types contract using the sliding filament theory.
Actin and myosin filaments slide past each other to shorten the sarcomere and generate force.

Cardiac Muscle: Branched Cells Wired for Synchronised Beating

Branched Cells Joined by Intercalated Discs

Cardiac muscle cells are branched, so they interconnect into a continuous network.
Neighbouring cells are joined end to end by intercalated discs.
1. Intercalated discs contain gap junctions that let electrical impulses pass directly between cells.
2. This rapid electrical coupling makes the whole heart contract in a synchronised wave.

One Central Nucleus and Many Mitochondria

A cardiac muscle cell is uninucleate, usually with a single, centrally placed nucleus.

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Cardiac and Skeletal Muscle: Same Striations, Different Adaptations

Cardiac muscle cells and striated (skeletal) muscle fibres are both striated, because both are packed with myofibrils showing repeating sarcomeres.
Their differences in shape, nuclei, and control reflect their very different jobs in the body.
1. Cardiac muscle powers the continuous, tireless pumping of the heart.
2. Skeletal muscle powers voluntary movement of the body under conscious control.

Definition

Myofibrils

Contractile units within muscle cells, composed of actin and myosin filaments that allow for muscle contraction.

Tip

Both muscle types contract using the sliding filament theory.
Actin and myosin filaments slide past each other to shorten the sarcomere and generate force.

Cardiac Muscle: Branched Cells Wired for Synchronised Beating

Branched Cells Joined by Intercalated Discs

Cardiac muscle cells are branched, so they interconnect into a continuous network.
Neighbouring cells are joined end to end by intercalated discs.
1. Intercalated discs contain gap junctions that let electrical impulses pass directly between cells.
2. This rapid electrical coupling makes the whole heart contract in a synchronised wave.

One Central Nucleus and Many Mitochondria

A cardiac muscle cell is uninucleate, usually with a single, centrally placed nucleus.

Definition

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anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B2.3.9: Adaptations of Cardiac Muscle Cells and Striated Muscle Fibres Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

Cardiac and Skeletal Muscle: Same Striations, Different Adaptations

Cardiac Muscle: Branched Cells Wired for Synchronised Beating

Branched Cells Joined by Intercalated Discs

One Central Nucleus and Many Mitochondria

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Cardiac and Skeletal Muscle: Same Striations, Different Adaptations

Cardiac Muscle: Branched Cells Wired for Synchronised Beating

Branched Cells Joined by Intercalated Discs

One Central Nucleus and Many Mitochondria

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account