Lamella (surface anatomy)

{{Short description|Anatomical structure}}

{{Other uses|Lamella (disambiguation)}}

image:Lamellae.jpg

In surface anatomy, a lamella is a thin plate-like structure, often one amongst many lamellae very close to one another, with open space between. Aside from respiratory organs such as book lungs, they appear in other biological roles including filter feeding and the traction surfaces of geckos.

{{cite journal |last=Santos |first=Daniel |author2=Matthew Spenko |author3=Aaron Parness |author4=Kim Sangbae |author5=Mark Cutkosky |journal=Journal of Adhesion Science and Technology |year=2007 |volume=21 |issue=12–13 |pages=1317–1341 |url=http://www.brill.nl/journal-adhesion-science-and-technology |quote=Gecko "feet and toes are a hierarchical system of complex structures consisting of lamellae, setae, and spatulae. The distinguishing characteristics of the gecko adhesion system have been described [as] (1) anisotropic attachment, (2) high force to preload ratio, (3) low detachment force, (4) material independence, (5) self-cleaning, (6) anti-self sticking and (7) non-sticky default state. ... The gecko’s adhesive structures are made from ß-keratin (modulus of elasticity [approx.] 2 GPa). Such a stiff material is not inherently sticky; however, because of the gecko adhesive’s hierarchical nature and extremely small distal features (spatulae are [approx.] 200 nm in size), the gecko’s foot is able to intimately conform to the surface and generate significant attraction using van der Waals forces.|doi=10.1163/156856107782328399 |title=Directional adhesion for climbing: Theoretical and practical considerations |s2cid=53470787 |url-access=subscription }}

Gecko feet consist of millions of setae made of β-keratin arranged into lamellate structures called spatula, which allow adhesion to walls due to creating more Van der Waals force between the gecko's feet and the wall.{{Cite journal |last1=Autumn |first1=Kellar |last2=Sitti |first2=Metin |last3=Liang |first3=Yiching A. |last4=Peattie |first4=Anne M. |last5=Hansen |first5=Wendy R. |last6=Sponberg |first6=Simon |last7=Kenny |first7=Thomas W. |last8=Fearing |first8=Ronald |last9=Israelachvili |first9=Jacob N. |last10=Full |first10=Robert J. |date=2002-09-17 |title=Evidence for van der Waals adhesion in gecko setae |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=99 |issue=19 |pages=12252–12256 |doi=10.1073/pnas.192252799 |doi-access=free |issn=0027-8424 |pmc=129431 |pmid=12198184}}

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In fish, gill lamellae are used to increase the surface area in contact with the environment to maximize gas exchange (both to attain oxygen and to expel carbon dioxide) between the water and the blood.{{Cite journal|last1=Evans|first1=David H.|last2=Piermarini|first2=Peter M.|last3=Choe|first3=Keith P.|date=January 2005|title=The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste|url=https://www.physiology.org/doi/10.1152/physrev.00050.2003|journal=Physiological Reviews|language=en|volume=85|issue=1|pages=97–177|doi=10.1152/physrev.00050.2003|pmid=15618479|issn=0031-9333|url-access=subscription}} In fish gills, there are two types of lamellae, primary and secondary. The primary gill lamellae (also called gill filament) extends from the gill arch, and the secondary gill lamellae extends from the primary gill lamellae. Gas exchange primarily occurs at the secondary gill lamellae, where the tissue is notably only one cell layer thick. Furthermore, countercurrent gas exchange at the secondary gill lamellae further maximizes oxygen uptake and carbon dioxide release. These gill lamellae are larger and have smaller pores in faster-swimming fish compared to slower-swimming fish.{{Cite book |url=https://books.google.com/books?id=yINDnV4mWi8C&dq=%2522FISH+PHYSIOLOGY+V10A%2522&pg=PA263 |title=Fish Physiology |date=1984-08-21 |publisher=Academic Press |isbn=978-0-08-058531-4 |pages=266 |language=en}}

In insects, some species feature antennae with a lamellate structure such as the members of the Scarabaeidae family.{{Cite web |title=Order Coleoptera - Beetles |url=https://entomology.unl.edu/order-coleoptera-beetles/ |access-date=2025-06-17 |website=entomology.unl.edu}} These antennae, covered in fine hairs (setae), are used to detect female pheromones, temperature, humidity, and to touch nearby objects.{{Cite web |title=Ten Lined June Beetle |url=https://entomology.wsu.edu/outreach/bug-info/ten-lined-june-beetle/ |access-date=2025-06-17 |website=Department of Entomology |language=en-US}}{{Cite book |last=Chapman |first=R. F. (Reginald Frederick) |url=http://archive.org/details/insectsstructure0000chap |title=The insects : structure and function |date=1998 |publisher=Cambridge, UK ; New York, NY : Cambridge University Press |isbn=978-0-521-57048-0 |pages=8–11}}

File:Ten Lined June Beetle.JPG