Plant Epidermis: Deposits, Cells, and Trichome Secretion
Plant Epidermis: Deposits, Cells, and Secretion Mechanisms
Cuticular and Epidermal Deposits
In epidermal cells, various salt deposits manifest as crystals. These deposits are located both on the cuticle surface and permeating it, even within the cell wall itself. Many plants exhibit significant mineralization of the cell wall, with silica joining other salt deposits. These salts distribute evenly between cellulose and cutin. Calcium carbonate mineralization appears coarser than silica, with a granular
Darwin, Lamarck, and Neo-Darwinism: Evolution Theories
Darwin’s Theory of Evolution
Darwin’s theory posits that populations evolve over time through a process of natural selection. Key points include:
- Organisms produce more offspring than can survive.
- Despite overpopulation, population sizes generally remain constant.
- This leads to a struggle for resources (food, space).
- Individuals within a species vary in their traits (some are more “fit”).
- The fittest individuals are more likely to survive and reproduce.
Conclusions of Darwin’s Theory
- Individuals with traits
Plant Hormone Mechanisms: Auxins, Amylases, Ethylene
Rhizobium-Legume Symbiosis: Infection Process
- Union of *Rhizobium* to a radical emergent hair by chemotaxis.
- The hair grows curved, and bacteria grow inside.
- Degradation of the cell wall allows infection.
- The infection cord reaches the base of the hair.
- *Rhizobium* is freed in the apoplast and initiates the formation of a new cord.
- The infection branches and releases vesicles into the cytosol. Nodule differentiation occurs.
Auxin Action Mechanism: Cell Elongation and Growth
Auxins induce cell growth and
Read MoreNervous Impulse Transmission: Synapse and Invertebrates
Nervous Impulse Transmission
From Neuron to Neuron: Synapse
Neurons are independent; they are not in physical contact with each other (synaptic cleft). The synapse is the process of functional communication between two neurons.
- Presynaptic Area: This is the axon of the neuron from which the information arrives.
- Postsynaptic Area: This is the specialized part of another neuron to which the information is directed.
- Synaptic Cleft: This is the space separating the two areas.
The transmission of nerve impulses
Read MoreHuman Interaction, Nervous and Endocrine Systems
1. The Interaction Process
This function includes a series of processes whose objectives are:
- To adapt the body to changing conditions, in the internal as well as external environment.
- To connect and coordinate the different parts of our body so that they work together.
1.1. Homeostasis
Homeostasis processes maintain the body’s stability when there are changes in the internal environment.
Homeostasis processes work like a feedback device. This means that when a variation is detected in a particular element,
Read MoreKidney Anatomy and Physiology: Calyces, Pelvis, Nephron
The kidneys are complex organs responsible for filtering blood and maintaining homeostasis. This document details their key anatomical structures and physiological processes.
Kidney Anatomy
Calyces and Renal Pelvis
Calyces: These are smaller, cup-shaped structures where urine collection begins. Minor calyces surround each renal papilla (the tip of a renal pyramid). They are small membranous ducts that open into the major calyces.
Major Calyces: Typically, there are three major calyces: superior, middle,
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