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Animal Eukaryotic Cells and Organelles

• Nucleus: Holds genetic material. Protected by a double membrane that separates it from the cytoplasm.

• Vacuoles: Small sacs that store different substances.

• Lysosomes: Made by the Golgi apparatus; digest materials inside the cell.

• SER (Smooth Endoplasmic Reticulum): Produces lipids and helps remove toxic substances.

• Mitochondria: Have two membranes; break down glucose to release energy (cellular respiration).

• Cytoplasm: Jelly-like fluid with the cytoskeleton that supports and gives shape to the cell.

• RER (Rough Endoplasmic Reticulum): Stores and transports proteins made by ribosomes attached to it.

• Ribosomes: Smallest organelles, no membrane; make proteins, free or attached to RER.

• Cell membrane: Made of lipids

पारिभाषिक शब्दावली: अर्थ और स्वरूप

अर्थ

पारिभाषिक शब्दावली से तात्पर्य ऐसे शब्दों से है जिनका प्रयोग किसी विशेष विषय, क्षेत्र या विद्या में एक निश्चित और स्थिर अर्थ में किया जाता है। ये शब्द उस क्षेत्र की तकनीकी भाषा का हिस्सा होते हैं और सामान्य बोलचाल की भाषा से अलग होते हैं।

उदाहरण

• गणित

Understanding Reflexes

A reflex is an involuntary motor response. The reflex arc follows this path: receptor → afferent nerve → CNS → efferent nerve → effector.

Deep Tendon Reflexes (Monosynaptic)

• Biceps (C5–C6, musculocutaneous): Elbow flexion.
• Triceps (C6–C7, radial): Elbow extension.
• Brachioradial (C5–C6, radial): Elbow flexion.
• Patellar (L3–L4, femoral): Knee extension.
• Achilles (S1–S2, tibial): Plantar flexion.

Superficial Reflexes (Polysynaptic)

• Corneal: CN V–VII.
• Abdominal: T7–T12.
• Cremasteric: L1–L2.
• Anal: S4–S5.

Plantar Reflex and Lesions

The normal plantar reflex results in toe flexion. A Babinski sign (big toe extension + fanning) indicates an Upper Motor Neuron (UMN) lesion.

• UMN Lesions: Hyperreflexia, clonus, Babinski

Skeletal Joints: Structure and Classification

Joints: These structures, also known as articulations or knuckles, consist of tissues that unite different parts of the skeleton. More technically, a joint is defined as the set of hard and soft parts that constitute the union of two or more contiguous bones.

Joints can be classified into two large categories based on:

• Structure (morphology).
• Function (physiology).

Morphological Joint Types

Morphologically, different types of joints are classified according to the connecting tissue into several categories:

• Fibrous joints
• Cartilaginous joints
• Synovial joints (Diarthroses)

Physiological Joint Types

Physiologically, the human body features several joint types:

• Synarthrosis: Immobile joints.
• Symphysis: Joints allowing

Cytoplasm:

The cell space between the nuclear envelope and plasma membrane. Comprising cytosol, cytoskeleton, and organelles.

Cytosol:

The internal environment of the cytoplasm (75-85% water). It performs the synthesis of ribosomes and protids (enzymes, small molecules, or proteins). It forms filaments of the cytoskeleton. Due to the presence of many enzymes, there are numerous metabolic reactions.

Cytoskeleton:

In eukaryotes, it forms a network of protein filaments. Features:

• Maintaining the shape of the cell and the possibility of changing it.
• The possibility of moving the cell.
• Contraction of muscle.
• Transport and organization of organelles.

Microfilaments:

Actin filaments are the main components of the cytoskeleton. Usually, they partner with other... Continue reading "Understanding Cytoplasm and Its Key Components" »

Structure of the Plasma Membrane

Membrane Amphipathic Properties

The plasma membrane is amphipathic:

• Fatty acid tails are hydrophobic (repel water).
• Phosphate head groups are hydrophilic (attract water).

Transport Through the Membrane

Factors Affecting Transport

• The concentration of substances.
• The type of molecules.

Transport Mechanisms

Based on these factors, transport can occur by three phenomena:

• Passive transport
• Active transport
• Vesicle-mediated transport

Passive Transport

In passive transport, molecules move down their concentration gradient: from regions of higher concentration to regions of lower concentration. The cell does not expend energy; the process occurs spontaneously.

Types of Passive Transport

• Simple diffusion
• Osmosis
• Facilitated diffusion

Simple

Nutrition, Mobility and Cell Characteristics

Nutrition

Nutrition: Variety — plants (autotrophs), animals (heterotrophs).

Mobility

Mobility: Variety — plants (immobile), animals (mobile).

Growth

Growth: Plants (often indeterminate / unlimited), animals (typically determinate / limited).

Cellular Coverings

Cell coverings: Plants: cell wall and cell membrane; Animals: plasma membrane.

Similarities of Living Beings

Similarities: assimilation, sensitivity, autoregulation and reproduction.

Cell Composition and Organelles

Cell composition: Life composed of abundant protoplasm; cells possess a cell membrane, cytoplasm, and a nuclear membrane (karyotheca) with a nucleus.

There are a variety of structures in the cytoplasm (organelles): ribosomes, endoplasmic

7-As nadadeiras dos peixes podem apresentar funções variadas de acordo com adaptações ocorridas ao longo dos tempos. Podem ser usadas para, exceto: Respirar

8- Na reprodução dos vertebrados inferiores, predominam os processos de: Fecundação externa

9-No Aparelho excretor dos peixes, os rins são do tipo: Mesonéfrico

1- Entre os peixes e os primeiros anfíbios foram necessários 40 milhões de anos de lenta e constante evolução.

Todas as alternativas contêm adaptações surgidas durante essa evolução, exceto : Manutenção da pele úmida, Termo regulação.

4- Os únicos animais que apresentam, ao longo da vida, respiração branquial, cutânea e pulmonar são os: Pererecas

7- um animal, vivendo no ambiente terrestre e utilizando a pele... Continue reading "Cola" »

Catabolism. breaking down of complex substances into simples ones to obtain energy.

Relative dating.is a way of using geometric relationship between rocks bodies to determine the sequence of geological events in an area.

Marine trangression. is a geologic events during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in floading.

Facies fossils. a fossil which exist only in a very specific environment. They show the original conditions of the position.

Anabolism. is the termi given to all the chemical reactions where simple substances are joines together to form more complex ones.

Mass extinction. is the extinction of one or more species in a short period of geological time, this is a consequences... Continue reading "Chemical oxygen generators are used to furnish oxygen to the" »