El hombro del gigante: septiembre 2021

jueves, 30 de septiembre de 2021

Epitelium

Covering epitelium

Covering epithelium shows almost :

no extracellular matrix and
epithelial cells are tightly attached to one another by macromolecular adhesion complexes.
Some epithelia show a high rate of cell turnover where cell death and cell proliferation are frequent.
Some epithelial cells can have apical specializations that allow them to function as sensory receptors, and some animals show complex structures in their epithelial layer, such as hair, feathers or scales.

Epithelia are usually classified according to two features: the number of cell layers and the shape of the cells of the more superficial layer

Simple epithelia are single cell layers where all the cells contact the underlying basal lamina and have an apical free surface. The shape of the cells can be flat (wider than high), cuboidal (as wide as high), or columnar (higher than wide).
Pseudostratified epithelia are simple epithelia where all cells contact the basal lamina, but not all cells reach the superficial layer because some are shorter than the others. Thus, this is a simple epithelium that looks stratified.
Stratified epithelium contains two or more layers of cells. Only cells of the deeper layer are in contact with the basal lamina and only cells of the upper layer show free surfaces.

Stratified epithelia can be classified as

squamous,

cuboidal and

columnar, depending on the shape of the cells of the upper layer when observed in transverse view.

Epithelium.

KERATINIZED STRATIFIED SQUAMOUS

Basal lamina: The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits.

Secretion is the release of substances from cells to the extracellular milieu, having these substances a physiological purpose. Secretory cells are usually grouped to from glands, although it is not always so.

Exocrine glands release their products to the external surfaces of the body (for example, skin, respiratory ducts and digestive duct).

If the products are released into inner tissues and blood stream they are called endocrine glands.

Exocrine glands release their products to internal cavities or to the exterior of the body.

Salivary gland

The classification of living organisms: Taxonomy

Human taxonomy

What are the characteristics of a scientific name?

The scientific name of a species is formed by the combination of two terms The first name (capitalized) is the genus of the organism, the second (not capitalized) is its species…. The genus name is written first. The genus name is always underlined or italicized. The first letter of the genus name is always capitalized.

What does a scientific name tell you?

Scientific names are also designed to tell you something about the animal’s relationships with other animals. The scientific name of each species is made up of a generic name (generic epithet) and a specific name (specific epithet). Scientific names are often descriptive also, suggesting something about the animal.

What two characteristics must a useful scientific name have?

A useful scientific name must have two characteristics: Each name must refer to only one species. Everyone must use the same name.

Hybridization

Speciation: is the evolutionary process by which populations evolve to become distinct species

martes, 28 de septiembre de 2021

The nutrition function

Claves sobre las moléculas polares/apolares/anfipáticas

La polaridad del agua: Propiedades derivadas de su polaridad

LA POLARIDAD DEL AGUA.

Intercambio de sustancias con el ambiente

Sin gasto de energía: Transporte pasivo Difusión: Simple o facilitada

Ósmosis

Transporte Activo

Endocitosis : Entrada de sustancias

Exocitosis

Explicación en vídeo

lunes, 27 de septiembre de 2021

Exchange with the environment

Passive transport

Diffusion

Facilitated diffusion

Osmosis

Schrink: Encogerse

Swell: Hincharse

Crenation: A process resulting from osmosis in which red blood cells, in a hypertonic solution, undergo shrinkage and acquire a notched or scalloped surface

Notched: Con muescas

Scalloped: Festoneada

Active transport

Endocytosis: the taking in of matter by a living cell by invagination of its membrane to form a vacuole

Pinocytosis: the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane.

Phagocytosis: the ingestion of bacteria or other material by phagocytes and amoeboid protozoans.

Phagosome: a vacuole in the cytoplasm of a cell, containing a phagocytosed particle enclosed within a part of the cell membrane.
Osmosis, the spontaneous passage or diffusion of water or other solvents through a semipermeable membrane (one that blocks the passage of dissolved substances—i.e., solutes

Conective Tissues

Connective tissues have been regarded as a supporting tissue because

they connect and keep together many organs of the body,
they provide mechanical support to different parts of the body and to the whole body as well,
and protect and isolate many organs.

Furthermore, they allow communication between different parts of the body. For example, the molecules absorbed by epithelia must cross the connective tissue before they reach other tissues, so that some connective tissues are considered internal environment of the body.

Histology