Chapter 6
Growth
To this point, we have considered problems in biomechanics, which deals with the
mechanical response of cells and tissues to applied loads. We now turn to the topic
of mechanobiology, which involves the biological response to mechanical loads. As
discussed in Chap. 1, mechanobiology consists of three primary processes: growth
(change in volume), remodeling (change in material properties), and morphogenesis
(change in shape). This chapter focuses on growth.
In mechanobiology, mechanics and biology are often coupled. In growing tissues,
for example, stress affects growth and growth affects stress. Both directions will be
considered here.
During the last 25 years, interest in the mechanics of growth has “grown”
enormously. This chapter offers only a relatively brief introduction to this highly
complex subject. A more thorough treatment of growth mechanics can be found
in the outstanding monograph by Goriely (The mathematics and mechanics of
biological growth. Springer, New York, 2017).
6.1 Types of Growth
Biological growth occurs through a variety of processes. Hard tissues (bone, teeth,
horns, etc.) grow by surface growth, which involves deposition or resorption of
material on external or internal surfaces. Mathematical models show that surface
growth governed by relatively simple rules can produce highly complex and
interesting shapes (Skalak et al. 1997; Goriely 2017). This type of growth will not
be considered in this book, however.
In contrast, soft tissues grow by volumetric growth, which usually involves
adding volume by cell division (hyperplasia), cell enlargement ( hypertrophy), or
creation of extracellular matrix. Soft tissues also can grow by influx of cells (through
© Springer Nature Switzerland AG 2020
L. A. Taber, Continuum Modeling in Mechanobiology,
https://doi.org/10.1007/978-3-030-43209-6_6
253
Growth
To this point, we have considered problems in biomechanics, which deals with the
mechanical response of cells and tissues to applied loads. We now turn to the topic
of mechanobiology, which involves the biological response to mechanical loads. As
discussed in Chap. 1, mechanobiology consists of three primary processes: growth
(change in volume), remodeling (change in material properties), and morphogenesis
(change in shape). This chapter focuses on growth.
In mechanobiology, mechanics and biology are often coupled. In growing tissues,
for example, stress affects growth and growth affects stress. Both directions will be
considered here.
During the last 25 years, interest in the mechanics of growth has “grown”
enormously. This chapter offers only a relatively brief introduction to this highly
complex subject. A more thorough treatment of growth mechanics can be found
in the outstanding monograph by Goriely (The mathematics and mechanics of
biological growth. Springer, New York, 2017).
6.1 Types of Growth
Biological growth occurs through a variety of processes. Hard tissues (bone, teeth,
horns, etc.) grow by surface growth, which involves deposition or resorption of
material on external or internal surfaces. Mathematical models show that surface
growth governed by relatively simple rules can produce highly complex and
interesting shapes (Skalak et al. 1997; Goriely 2017). This type of growth will not
be considered in this book, however.
In contrast, soft tissues grow by volumetric growth, which usually involves
adding volume by cell division (hyperplasia), cell enlargement ( hypertrophy), or
creation of extracellular matrix. Soft tissues also can grow by influx of cells (through
© Springer Nature Switzerland AG 2020
L. A. Taber, Continuum Modeling in Mechanobiology,
https://doi.org/10.1007/978-3-030-43209-6_6
253