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Questions and Answers
What distinguishes humans from apes?
Which domain and kingdom do humans belong to?
What is the first step in the scientific method?
What is a hypothesis?
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When testing a hypothesis, what is the primary focus regarding variables?
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Which of the following is NOT a step in the scientific method?
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What is the purpose of background research in the scientific method?
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What type of reasoning is utilized to formulate a hypothesis?
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What are the primary roles of the cytoskeleton within a cell?
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Which type of cytoskeletal fibers acts as tracks for organelle movement?
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What is the function of cilia in the respiratory tract?
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Which protein is found in the extracellular matrix and helps resist stretching?
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During cell division, which cytoskeletal structure forms the spindle apparatus?
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What is the role of fibronectin in the extracellular matrix?
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What distinguishes flagella from cilia?
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Which statement about the cytoskeleton is correct?
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What is the primary product of glycolysis?
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Where does glycolysis occur within the cell?
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Which molecule is produced during glycolysis that acts as an electron carrier?
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What occurs to pyruvate when oxygen is not available?
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Which molecule enters the citric acid cycle derived from pyruvate?
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Which of the following is produced by the citric acid cycle?
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What is released as a byproduct of the citric acid cycle?
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Why is it important that energy is released slowly during cellular respiration?
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What is the primary function of the plasma membrane?
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Which statement is true regarding prokaryotic cells?
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Which of the following is found only in eukaryotic cells?
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What components are found in the plasma membrane?
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What role do glycoproteins and glycolipids serve in the plasma membrane?
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What differentiates archaebacteria from eubacteria?
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Which structure is involved in providing support to the plasma membrane?
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What is characteristic of the cytoplasm in both prokaryotic and eukaryotic cells?
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What type of cartilage is characterized by the presence of lots of elastic fibers?
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Which component is NOT part of the formed elements in blood?
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What type of bone tissue consists of cylindrical structural units known as osteons?
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Which muscle type is described as involuntarily controlled?
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Which type of connective tissue primarily supports and protects organs?
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What are the main components of the fluid matrix of blood?
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Which structure is found in spongy bone that differentiates it from compact bone?
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What distinguishes fibrocartilage from other types of cartilage?
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What are the four major classes of tissues?
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What is the function of connective tissue?
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What distinguishes between blood and lymph?
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What are the three types of muscle tissue?
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What is the role of epithelial cells?
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The three general categories of connective tissue are ____, ____, and ____.
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Skeletal muscle is involuntarily controlled.
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Cardiac muscle cells are striated and connected by intercalated disks.
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What are the three types of cartilage?
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What components make up blood?
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Match the types of epithelial tissue with their characteristics:
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Describe the structure and function of a neuron.
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What is neuroglia?
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What are the four major classes of tissues?
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What is the function of connective tissue?
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What does muscular tissue do?
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What is the role of epithelial tissue?
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What are the three types of muscular tissue?
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Describe the structure of a neuron.
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Which of the following is NOT a type of connective tissue?
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Smooth muscle is voluntarily controlled.
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Hyaline cartilage contains strong collagen fibers.
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Which type of epithelial tissue has multiple layers of cells?
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What are the three formed elements found in blood?
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What is the function of human skin?
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What are the two main regions of the skin?
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What is homeostasis?
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Which type of feedback mechanism is primarily used in the body?
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The dermis is the outermost layer of the skin.
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What are the four types of body membranes?
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What are keratinocytes?
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What does a melanocyte produce?
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What is the role of the endocrine system in homeostasis?
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The body cavities include the ______ cavity and the ______ cavity.
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What is the function of mucous membranes?
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What are the two main regions of the skin?
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What type of cells produce melanin?
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The dermis is the outermost layer of the skin.
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What is the primary function of the mucous membranes?
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The ______ cavity contains the thoracic, abdominal, and pelvic cavities.
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Which cavities are separated by the diaphragm?
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What is homeostasis?
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Match the following body membranes with their functions:
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What are the two parts of the internal environment?
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Positive feedback mechanisms increase the output of a system in the opposite direction of the stimulus.
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What is the function of human skin?
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What are the two main regions of the skin?
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What type of cells produce melanin in the skin?
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Basal cell carcinoma is the most common type of skin cancer.
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Which layer of skin contains collagen and elastic fibers?
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What types of body membranes are mentioned?
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Define homeostasis.
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What are the two main body cavities?
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What feedback mechanism is primarily used to maintain homeostasis?
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The nervous system is slower than the endocrine system.
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Study Notes
Types of Tissues
- Tissues are collections of similar cells performing a specific function.
- Four major types: connective, muscular, nervous, and epithelial.
Connective Tissue
- Function: Binding and supporting body parts
- Components: Specialized cells, ground substance, and protein fibers.
- Ground substance: Noncellular material between cells; varies in consistency from solid (bone) to fluid (blood).
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Protein fibers:
- Collagen fibers: Flexible and strong
- Reticular fibers: Thin, highly branched collagen fibers
- Elastic fibers: Contain elastin, a protein that stretches and recoils
- Types: Fibrous, Supportive, Fluid
Fibrous Connective Tissue
- Types: Loose and Dense
- Components: Fibroblasts surrounded by matrix (ground substance and fibers)
Loose Fibrous Connective Tissue
- Types: Areolar, reticular, and adipose tissue
- Function: Supports epithelium and internal organs
Adipose Tissue
- Function: Stores fat, acts as insulation and cushioning
- Cells: Adipocytes - cells filled with liquid fat
- Location: Primarily under the skin and around organs.
Dense Fibrous Connective Tissue
- Function: Tensile strength
- Location: Tendons (muscles to bones) and ligaments (bones to bones)
Supportive Connective Tissue
- Function: Provides structure, shape, and protection
- Types: Cartilage and Bone
Cartilage
- Cells: Chondrocytes, located in spaces called lacunae
- Matrix: Solid but flexible, lacks a direct blood supply, heals slowly
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Types:
- Hyaline cartilage: Fine collagen fibers, found in the tip of the nose, ends of long bones, and the fetal skeleton.
- Elastic cartilage: Lots of elastic fibers, found in the outer ear
- Fibrocartilage: Strong collagen fibers, found in the disks between vertebrae
Bone
- Matrix: Made of collagen and calcium salts
- Types: Compact and spongy
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Compact bone: Makes up the shafts of long bones
- Contains cylindrical units called osteons
- Central canal contains blood vessels and nerves
- Bone cells are located in lacunae
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Spongy bone: Inside the ends of long bones
- Lighter than compact bone, but strong
Fluid Connective Tissue
- Types: Blood and Lymph
Blood
- Matrix: Plasma
-
Cellular components: Formed elements
- Red blood cells (erythrocytes): Carry oxygen
- White blood cells (leukocytes): Fight infection
- Platelets (thrombocytes): Pieces of cells that clot blood
Lymph
- Function: Transports white blood cells, absorbs excess interstitial fluid, and returns lymph to the cardiovascular system.
Muscular Tissue
- Function: Contracts to move the body and its parts
- Cells: Muscle fibers
- Types: Skeletal, smooth, and cardiac
Skeletal Muscle
- Function: Moves the skeleton , under voluntary control
- Location: Attached to the skeleton by tendons
- Structure: Long muscle fibers, can run the length of the muscle, contain multiple nuclei, striated appearance.
Smooth Muscle
- Function: Involuntary control
- Structure: No striations, spindle-shaped cells with one nucleus
- Location: Walls of viscera
Cardiac Muscle
- Function: Involuntary control
- Location: Walls of the heart
- Structure: Striated, single nucleus, cells connected by intercalated disks
Nervous Tissue
- Function: Senses, integrates, and transmits information
- Components: Neurons and neuroglia
Neurons
- Function: Conduct nerve impulses
-
Structure: Dendrites, cell body, and axon
- Dendrites: Carry information toward the cell body
- Cell body: Contains the nucleus and other organelles
- Axon: Conducts nerve impulses away from the cell body
- Myelin: Fatty substance that covers some axons
- Nerves: Bundles of axons traveling to and from the brain and spinal cord
Neuroglia
- Function: Support and nourish neurons
- Structure: Take up more than half the volume of the brain
Epithelial Tissue
- Function: Covers body surfaces, lines body cavities, forms glands
- Structure: Tightly packed cells, anchored by a basement membrane on one side, free on the other side
- Types: Simple and stratified
- Categorized by: Number of cell layers and shape of cells
Simple Epithelium
- Structure: Single layer of cells
Types of Simple Epithelium
- Simple squamous epithelium: Single layer of flattened cells (found in lungs for gas exchange)
- Simple cuboidal epithelium: Single layer of cube-shaped cells
- Simple columnar epithelium: Single layer of column-shaped cells
- Pseudostratified columnar epithelium: Appears stratified, but all cells touch the basement membrane (often has cilia)
Stratified Epithelium
- Structure: Multiple layers of cells
Types of Stratified Epithelium
- Stratified squamous epithelium: Forms the outer layer of the skin, lines the mouth and esophagus
- Transitional epithelium: Cells change shape in response to tension, found lining the urinary bladder
Distinguishing Humans from Apes
- Humans and apes share a common ancestor but have evolved distinct features
- Humans have a larger brain size, walk upright (bipedalism), and have complex language skills
Domain and Kingdom of Humans
- Humans belong to the domain Eukarya and the kingdom Animalia
- This classification highlights their complex cell structure and multicellular nature
First Step in the Scientific Method
- Observation: The initial step involves observing the natural world and identifying a phenomenon or question
Hypothesis
- A hypothesis is a testable explanation or prediction about a phenomenon or relationship
- It forms the basis for further experimentation
Variable Focus during Hypothesis Testing
- When testing a hypothesis, the focus is on manipulating independent variables and observing their effect on dependent variables
Non-Step in the Scientific Method
- Assumption is not a formal step in the scientific method
- While assumptions can be helpful in forming hypotheses, they need to be tested and verified through experiments.
Purpose of Background Research
- Background research helps gather existing knowledge about a topic
- It allows researchers to build upon prior findings, identify gaps in understanding, and design relevant experiments
Reasoning for Hypothesis Formulation
- Inductive reasoning: This type of reasoning draws a general conclusion based on specific observations
Cytoskeleton Functions
- Provides structural support for the cell
- Helps maintain cell shape
- Facilitates movement of organelles within the cell
Tracks for Organelle Movement
- Microtubules act as tracks for motor proteins that transport organelles within the cell
Cilia Function in the Respiratory Tract
- Cilia, tiny hair-like structures, sweep mucus and trapped particles out of the respiratory tract, protecting the lungs
Protein Resisting Stretching
- Elastin is a protein found in the extracellular matrix that allows tissues to stretch and return to their original shape
Spindle Apparatus Structure
- The microtubules form the spindle apparatus during cell division
Fibronectin Role
- Fibronectin plays a role in cell adhesion, migration, and tissue repair within the extracellular matrix
Flagella vs. Cilia
- Flagella are longer and usually occur singly or in pairs, propelling the cell
- Cilia are shorter and more numerous, beating in a coordinated manner
Cytoskeleton Statement
- The cytoskeleton is dynamic and can be rearranged to meet a cell's needs.
Primary Product of Glycolysis
- The primary product of glycolysis is pyruvate, a three-carbon molecule
Glycolysis Location
- Glycolysis occurs in the cytoplasm of the cell
Electron Carrier Produced During Glycolysis
- NADH, a reduced form of nicotinamide adenine dinucleotide, is produced as an important electron carrier during glycolysis
Pyruvate Fate Without Oxygen
- When oxygen is not available, pyruvate is converted into lactate.
Citric Acid Cycle Entry Molecule
- Acetyl-CoA, a two-carbon molecule derived from pyruvate, enters the citric acid cycle
Citric Acid Cycle Products
- ATP, NADH, and FADH2 are produced during the citric acid cycle.
Citric Acid Cycle Byproduct
- Carbon dioxide is released as a byproduct of the citric acid cycle
Slow Energy Release Importance
- Slow energy release helps prevent damage to cells and allows for greater energy efficiency
Plasma Membrane Function
- The plasma membrane regulates the passage of substances in and out of the cell, maintaining cellular homeostasis
Prokaryotic Cell Characteristics
- Prokaryotic cells lack a nucleus and other membrane-bound organelles
Eukaryotic Cell Exclusives
- Nucleus is only found in eukaryotic cells, housing the cell's genetic material (DNA)
Plasma Membrane Components
- The plasma membrane consists of a phospholipid bilayer embedded with proteins
Glycoproteins and Glycolipids
- Glycoproteins and glycolipids help with cell recognition and communication, contributing to cell interaction and signaling
Archaebacteria vs. Eubacteria
- Archaebacteria differ from eubacteria in their habitats, cell wall composition, and other structural and genetic features, reflecting their adaptation to extreme environments
Plasma Membrane Support
- The cytoskeleton provides support to the plasma membrane, contributing to its shape and stability
Cytoplasm Similarity
- Both prokaryotic and eukaryotic cells contain cytoplasm, a gel-like substance where various cellular processes take place
Elastic Cartilage Characteristic
- Elastic cartilage is characterized by the presence of abundant elastic fibers, providing flexibility and resilience
Non-Formed Element in Blood
- Plasma is not considered a formed element in blood, it's the fluid component.
Osteon Structure
- Compact bone tissue consists of cylindrical structural units called osteons
Involuntary Muscle Control
- Smooth muscle and cardiac muscle are involuntarily controlled, meaning they are not under conscious control.
Organ Support Connective Tissue
- Loose connective tissue provides support and protection to organs
Blood Matrix Components
- The fluid matrix of blood, plasma, consists of water, proteins, and dissolved substances
Spongy Bone Distinction
- Spongy bone is characterized by open spaces called trabeculae, which differ from the solid matrix of compact bone
Fibrocartilage Distinction
- Fibrocartilage is characterized by dense collagen fibers, providing resistance to compression and tensile forces, distinguishing it from other types of cartilage
Tissue Classes
- The four major classes of tissues are epithelial, connective, muscle, and nervous tissue.
Connective Tissue Function
- Connective tissues provide support, bind together, and protect other tissues and organs
Blood vs. Lymph Difference
- Blood circulates within blood vessels while lymph circulates in lymphatic vessels, and lymph lacks red blood cells and platelets
Muscle Tissues
- The three types of muscle tissue are skeletal, cardiac, and smooth muscle.
Epithelial Cell Role
- Epithelial cells form coverings and linings of organs and cavities, providing protection, secretion, absorption, and filtration
Connective Tissue Categories
- The three general categories of connective tissue are connective tissue proper, supporting connective tissue, and fluid connective tissue.
Skeletal Muscle Control
- Skeletal muscle is voluntarily controlled meaning it can be consciously contracted and relaxed
Cardiac Muscle Features
- Cardiac muscle cells are striated and connected by intercalated disks
Cartilage Types
- The three types of cartilage are hyaline cartilage, elastic cartilage, and fibrocartilage
Blood Components
- Blood consists of formed elements (red blood cells, white blood cells, and platelets) suspended in a fluid matrix called plasma
Epithelial Tissue Characteristics
- Simple squamous epithelium: Thin and flat, allows for diffusion and filtration
- Stratified squamous epithelium: Multiple layers, provides protection
- Simple cuboidal epithelium: Cube-shaped cells, involved in secretion and absorption
- Stratified cuboidal epithelium: Multiple layers of cube-shaped cells, provides protection
- Simple columnar epithelium: Tall, column-shaped cells, involved in secretion and absorption
- Stratified columnar epithelium: Multiple layers of column-shaped cells, provides protection
- Transitional epithelium: Stretchable, lines the urinary bladder
Neuron Structure and Function
-
Neuron: The basic functional unit of the nervous system
- Cell body (soma): Contains the nucleus and other organelles
- Axon: Long, slender extension that transmits signals away from the cell body
- Dendrites: Branching extensions that receive signals from other neurons
- Function: Neurons transmit electrical signals to other neurons, muscles, or glands, allowing for communication and coordination throughout the body
Neuroglia
-
Neuroglia: Supporting cells in the nervous system that provide structural support, insulation, and nutrition to neurons
- They also help maintain the blood-brain barrier.
Tissues Types
- Tissues are collections of similar cells performing a shared function.
- Four primary tissue types exist: Connective - supports and binds, Muscular - enables movement, Nervous - transmits nerve impulses, Epithelial - covers surfaces and lines cavities.
Connective Tissue
- Connective tissue comprises three main components: specialized cells, ground substance (non-cellular material), and protein fibers.
- Ground substance varies in consistency ranging from solid (bone) to fluid (blood).
- Three types of protein fibers are found in connective tissue: Collagen - flexible and strong, Reticular - thin and highly branched collagen fibers, Elastic - contains elastin and can stretch and recoil.
- Connective tissue is categorized into fibrous, supportive, and fluid.
Fibrous Tissue
- Fibrous tissue occurs in two forms: Loose and Dense. Both contain fibroblasts embedded in a matrix composed of ground substance and fibers.
- Loose fibrous connective tissue includes areolar, reticular, and adipose tissue.
- Dense fibrous connective tissue is found in tendons (connecting muscle to bone) and ligaments (connecting bone to bone).
Loose Fibrous Tissue
- Loose fibrous tissue supports epithelium and internal organs.
- Adipose tissue stores fat, has minimal extracellular matrix and contains adipocytes (fat-filled cells).
- Adipose tissue functions in energy storage, insulation, and cushioning, primarily found under the skin and around organs.
- Dense fibrous tissue contains densely packed collagen fibers.
Supportive Connective Tissue
- Supportive connective tissue includes cartilage and bone, providing structure, shape, and protection.
Cartilage
- Contains chondrocytes (cells residing in lacunae) within a solid yet flexible matrix.
- Cartilage lacks a direct blood supply, resulting in slow healing.
- Three types of cartilage exist: Hyaline - with fine collagen fibers (found in the nose, ends of long bones, and fetal skeleton), Elastic - with abundant elastic fibers (found in the outer ear), Fibrocartilage - with robust collagen fibers (found in vertebral discs).
Bone
- Bone, the most rigid connective tissue, has a matrix composed of collagen and calcium salts.
- Two types of bone tissue exist: Compact (forms shafts of long bones) and Spongy (located inside ends of long bones).
- Compact bone consists of cylindrical units called osteons, with a central canal containing blood vessels and nerves. Bone cells reside in lacunae.
- Spongy bone is lighter than compact bone but still strong.
Fluid Connective Tissue
- Fluid connective tissue includes blood and lymph.
Blood
- Blood consists of a fluid matrix called plasma and cellular components called formed elements.
- The three formed elements of blood are: Red blood cells (erythrocytes) - carry oxygen, White blood cells (leukocytes) - fight infection, Platelets (thrombocytes) - cell fragments responsible for blood clotting.
Lymph
- Lymph is a fluid that circulates through the lymphatic system and contains white blood cells.
- Lymphatic vessels absorb excess interstitial fluid and return lymph to the cardiovascular system.
Muscular Tissue
- Muscular tissue specializes in contracting.
- Cells of muscular tissue are known as muscle fibers.
- Three types of muscular tissue exist: Skeletal, Smooth, and Cardiac.
Skeletal Muscle
- Skeletal muscle is attached to the skeleton by tendons.
- Contraction of skeletal muscle moves the skeleton, and it is voluntarily controlled.
- Skeletal muscle fibers are very long, extending the entire length of the muscle, with multiple nuclei.
- Skeletal muscle has a striated (striped) appearance.
Smooth Muscle
- Smooth muscle lacks striations.
- Cells are spindle-shaped with a single nucleus.
- Smooth muscle is involuntarily controlled and found in the walls of viscera.
Cardiac Muscle
- Cardiac muscle is found exclusively in the heart wall.
- Cardiac muscle is striated and involuntarily controlled.
- Each cardiac muscle cell has a single nucleus and cells are connected by intercalated disks.
Nervous Tissue
- Nervous tissue is composed of neurons and neuroglia.
- Three main functions of nervous tissue: sensory input, integration, and motor output.
Neurons
- Neurons comprise three parts: dendrites, a cell body, and an axon.
- Dendrites carry information towards the cell body.
- The cell body contains the nucleus and other organelles.
- The axon conducts nerve impulses away from the cell body.
Neuroglia
- Neuroglia occupy over half the brain's volume. Their primary role is to support and nourish neurons.
Epithelial Tissue
- Epithelial tissue (epithelium) is tightly packed and lines body cavities, covers body surfaces, and is found in glands.
- Epithelium is anchored to a basement membrane on one side and is free on the other.
- Epithelium is classified based on the number of cell layers and the shape of the cells.
Epithelial Tissue Classification
- Epithelium is classified as either simple (single layer) or stratified (multiple layers).
Simple Epithelia
- Simple squamous epithelium is a single layer of flattened cells found in the lungs, facilitating gas exchange.
- Simple cuboidal epithelium is a single layer of cube-shaped cells.
- Simple columnar epithelium is a single layer of column-shaped cells.
- Pseudostratified columnar epithelium appears layered due to nuclei position, but all cells contact the basement membrane. It often contains cilia for moving mucus.
Stratified Epithelia
- Stratified squamous epithelium forms the outer layer of skin and lines the mouth and esophagus.
- Transitional epithelium consists of cells that change shape in response to tension, transitioning from cuboidal to squamous. It lines the urinary bladder.
Integumentary System
- The integumentary system includes the skin and accessory organs, including hair, nails, and glands.
- It protects underlying tissues from trauma, pathogen invasion, and water loss.
- It plays a role in regulating body temperature.
- Contains sensory receptors for touch and temperature.
Skin Structure
- Skin is made up of two main layers: the epidermis and the dermis.
- Underneath the skin lies a subcutaneous layer (hypodermis).
Epidermis
- The epidermis is the thin, outermost layer of the skin.
- It's composed of stratified squamous epithelium.
- Stem cells in the deepest layer produce new epidermal cells.
- If stem cells are destroyed due to injury, skin regeneration requires replacement through autografting (from another area of the body), allografting (from another person), or laboratory skin growth.
Epidermal Cells
- Keratinocytes are found in the upper epidermis layers, forming a waterproof barrier.
- Langerhans cells are white blood cells found in the epidermis.
- Melanocytes produce melanin, which determines skin color and provides protection from UV light.
- While everyone has the same number of melanocytes, melanin production varies.
Epidermis and Vitamin D
- Epidermal cells produce vitamin D when exposed to UV rays.
- Vitamin D is critical for regulating calcium and phosphorus levels in the human body.
Skin Cancer
- Ultraviolet rays from the sun cause skin cancer.
- Basal cell carcinoma, the most common type, is a cancer of epidermal stem cells and is usually easily curable.
- Melanoma, a cancer of melanocytes, is extremely serious.
Dermis
- The dermis, the thick inner layer of skin, is made of dense fibrous connective tissue.
- It contains collagen and elastic fibers providing strength and elasticity.
- It houses blood vessels, sensory receptors, and glands.
Subcutaneous Layer
- The subcutaneous layer is not technically part of the skin but is composed of loose connective tissue and adipose tissue.
- It stores energy, provides insulation, and offers protection.
Organ Systems and Body Cavities
- An organ is a group of tissues working together to perform a specific function.
- Organ systems are groups of organs with similar functions.
- Organ systems often occupy specific body cavities, while others are distributed throughout the body.
Body Membranes
- Body membranes line cavities and the internal spaces of organs and tubes that open to the outside.
- There are four types of body membranes: mucous, serous, synovial, and meninges.
Mucous Membranes
- Mucous membranes line the tubes of the digestive, respiratory, urinary, and reproductive systems.
- They consist of epithelium over a layer of loose fibrous connective tissue.
- Goblet cells within these membranes secrete mucus.
Serous Membranes
- Serous membranes line closed body cavities and cover the surfaces of the organs within those cavities.
- Pleurae line the thoracic cavity and cover the lungs.
- Pericardium forms the pericardial sac and covers the heart.
- Peritoneum lines the abdominal cavity and covers its organs.
Synovial Membranes
- Synovial membranes are composed only of loose connective tissue.
- They line freely moveable joints.
- They secrete synovial fluid for lubrication.
Meninges
- Meninges are made of connective tissue found in the dorsal cavity (around the brain and spinal cord).
- Meningitis is an inflammation of the meninges.
###Â Homeostasis
- Homeostasis is a state of relatively constant internal body environment.
- It maintains a narrow range of normal values for various conditions, including blood glucose, pH, and body temperature.
- Deviation from these normal values can lead to illness.
Internal Environment
- The internal environment has two main components: blood and interstitial fluid.
- Blood delivers oxygen and nutrients to the tissues and removes carbon dioxide and waste products.
- Interstitial fluid surrounds body cells, facilitating the exchange of substances between cells and the bloodstream.
- Body systems work together to maintain the normalcy of these substances.
Body Systems and Homeostasis
- The nervous and endocrine systems coordinate the other organ systems in maintaining homeostasis.
- The nervous system is faster, but the effects of the endocrine system last longer.
- The endocrine system secretes hormones, chemical messengers that travel in blood.
Negative Feedback
- Negative feedback is the primary mechanism used by the body to maintain homeostasis.
- It consists of a sensor and a control center.
- The output of the system decreases or shuts down production.
- Examples include how a furnace works and temperature regulation in the body.
Positive Feedback
- Positive feedback causes change in the same direction as the original stimulus.
- An example is childbirth, where the baby's head pushes against the cervix, triggering signals to the brain.
- The brain releases oxytocin, which causes stronger contractions. This leads to the release of more oxytocin, creating a cycle until childbirth occurs.
Integumentary System
- The integumentary system protects underlying tissues from trauma, pathogens, and water loss.
- It also regulates body temperature and contains sensory receptors for touch and temperature.
- The skin consists of two main regions: the epidermis and the dermis. The subcutaneous layer (hypodermis) is situated below the dermis.
The Epidermis
- The epidermis is the thin, outermost layer of the skin composed of stratified squamous epithelium.
- Stem cells in the deepest layer produce new epidermal cells. If these stem cells are destroyed, the skin needs to be replaced.
- Autografts are skin grafts taken from another area of the body, while allografts are taken from another person.
- Skin can also be grown in a lab.
Cells of the Epidermis
- Keratinocytes, found in the upper layers of the epidermis, are dead and filled with keratin, forming a waterproof barrier.
- Langerhans cells are a type of white blood cell found in the epidermis.
- Melanocytes produce melanin, which determines skin color and protects against UV light.
- The amount of melanin produced varies between individuals, even though everyone has the same number of melanocytes.
Epidermal Cells and Vitamin D
- Epidermal cells produce vitamin D upon exposure to UV rays.
- Vitamin D is crucial for regulating calcium and phosphorus levels in the body.
Skin Cancer
- Skin cancer is caused by ultraviolet radiation from the sun.
- Basal cell carcinoma, the most common type of skin cancer, develops from epidermal stem cells and is typically easily curable.
- Melanoma, a cancer of melanocytes, is extremely serious.
The Dermis
- The dermis is the thick, inner layer of skin composed of dense fibrous connective tissue.
- It contains collagen and elastic fibers for strength and elasticity.
- It also houses blood vessels, sensory receptors, and glands.
- Sensory receptors are specialized for touch, pressure, pain, heat, and cold.
The Subcutaneous Layer
- The subcutaneous layer, technically not part of the skin, is composed of loose connective tissue and adipose tissue.
- It stores energy, provides insulation, and offers protection.
Organ Systems, Body Cavities, and Body Membranes
- An organ is a group of tissues working together for a common function.
- Organ systems are formed by groups of organs with similar functions.
- Some organ systems (e.g., respiratory system) occupy specific cavities, while others (e.g., muscular system) are found throughout the body.
- Organs and cavities are lined with membranes, many of which secrete fluids.
Body Cavities
- There are two main body cavities: the ventral and dorsal cavities.
- The ventral cavity contains the thoracic, abdominal, and pelvic cavities, with the diaphragm separating the thoracic and abdominal cavities.
- The dorsal cavity includes the cranial cavity and vertebral canal.
Body Membranes
- Body membranes line cavities and internal spaces of organs and tubes that open to the outside.
- The four main types of body membranes are mucous, serous, synovial, and meninges.
Mucous Membranes
- Mucous membranes line the tubes of the digestive, respiratory, urinary, and reproductive systems.
- Composed of epithelial tissue overlying loose fibrous connective tissue.
- Contain goblet cells that secrete mucus.
Serous Membranes
- Serous membranes line closed cavities (not open to the environment) and cover the surface of the organs within them.
- For instance, pleurae line the thoracic cavity and cover the lungs, pericardium forms the pericardial sac and covers the heart, and peritoneum lines the abdominal cavity and covers its organs.
Synovial Membranes and Meninges
- Synovial membranes, composed only of loose connective tissue, line freely moveable joints and secrete synovial fluid for lubrication.
- Meninges, also composed solely of connective tissue, are located within the dorsal cavity, surrounding the brain and spinal cord.
- Meningitis is an inflammation of the meninges.
Homeostasis
- Homeostasis is the maintenance of a relatively constant internal environment.
- Various body conditions (blood glucose, pH, body temperature) are maintained within a narrow range of normal values.
- A significant deviation from normal conditions can lead to illness.
The Internal Environment
- The internal environment consists of blood and interstitial fluid.
- Blood carries oxygen and nutrients to tissues, removing carbon dioxide and waste products.
- Interstitial fluid surrounds body cells and facilitates the exchange of substances.
- Body systems work together to keep these substances within the normal range.
Body Systems and Homeostasis
- The nervous and endocrine systems coordinate other organ systems to maintain homeostasis.
- While the nervous system acts faster, the endocrine system's effects are longer-lasting.
- The endocrine system secretes hormones, chemical messengers that travel through the bloodstream.
Mechanisms for Maintaining Homeostasis
- Homeostasis is maintained through negative and positive feedback mechanisms.
- Negative feedback, the primary mechanism used in the body, has two components: a sensor and a control center.
- The output of the system reduces or shuts off the production. An example is how a furnace works.
- Temperature regulation is also a good example of negative feedback.
Positive Feedback Mechanisms
- Positive feedback brings about a change in the same direction as the original stimulus.
- Childbirth, for example, illustrates positive feedback: the fetus's head presses against the cervix, stimulating signals to the brain.
- The brain then secretes oxytocin, causing stronger contractions. This, in turn, leads to the release of more oxytocin.
- Childbirth eventually stops the positive feedback.
Integumentary System
- The integumentary system, aka skin, consists of skin and accessory organs such as hair, nails, and glands.
- Functions include protecting underlying tissues from trauma, pathogen invasion, and water loss; regulating body temperature; and containing sensory receptors.
- Two main regions: epidermis and dermis.
- Subcutaneous layer (hypodermis) lies beneath the skin.
The Epidermis
- Thin, outermost layer of skin made of stratified squamous epithelium.
- Deepest layer contains stem cells to produce new epidermal cells; if destroyed, skin needs to be replaced.
- Autograft: skin from another area of the body.
- Allograft: skin from another person.
- Epidermal cells can also be grown in the lab.
Epidermis Cells
- Keratinocytes: upper layers of epidermis that are dead and filled with keratin, forming a waterproof barrier.
- Langerhans cells: a type of white blood cell.
- Melanocytes: produce melanin which determines skin color and protects from UV light.
- All humans have the same number of melanocytes, but the amount of melanin produced varies.
The Dermis
- The thick inner layer of skin, made of dense fibrous connective tissue.
- Contains collagen and elastic fibers for strength and elasticity.
- Contains blood vessels, sensory receptors, and glands.
- Sensory receptors are specialized for touch, pressure, pain, hot, and cold.
The Subcutaneous Layer
- Not technically part of the skin.
- Composed of loose connective tissue and adipose tissue.
- Stores energy, insulates, and protects.
Organ Systems
- Organ: a group of tissues performing a common function.
- Organ systems: groups of organs with a similar function.
- Some organ systems occupy specific cavities (e.g., respiratory system) while others are found throughout the body (e.g., muscular system).
- Organs and cavities are lined with membranes, many of which secrete fluid.
Body Cavities
- Two main cavities: ventral and dorsal.
- Ventral cavity: contains the thoracic, abdominal, and pelvic cavities.
- Thoracic and abdominal cavities are separated by the diaphragm.
- Dorsal cavity: contains the cranial cavity and vertebral canal.
Body Membranes
- Line cavities and the internal spaces of organs and tubes that open to the outside.
- Four types: mucous, serous, synovial membranes, and meninges.
Mucous Membranes
- Line the tubes of the digestive, respiratory, urinary, and reproductive systems.
- Composed of epithelium overlying loose fibrous connective tissue.
- Contain goblet cells that secrete mucus.
Serous Membranes
- Line closed cavities (not open to the environment) and cover the surface of the organs contained within.
- Pleurae: line the thoracic cavity and cover the lungs.
- Pericardium: forms the pericardial sac and covers the heart.
- Peritoneum: lines the abdominal cavity and covers its organs.
Synovial Membranes and Meninges
- Synovial membranes: composed only of loose connective tissue.
- Line freely moveable joints.
- Secrete synovial fluid for lubrication.
- Meninges: composed only of connective tissue.
- In the dorsal cavity (around the brain and spinal cord).
- Meningitis: inflammation of the meninges.
Homeostasis
- A relatively constant internal environment.
- Body maintains various conditions within a narrow range of normal values (e.g., blood glucose, pH, body temperature).
- Illness can result if conditions vary too much.
The Internal Environment
- Two parts: blood and interstitial fluid.
- Blood delivers oxygen and nutrients to tissues and carries away carbon dioxide and wastes.
- Interstitial fluid surrounds body cells and facilitates substance exchange.
- Body systems work together to keep these substances within the range of normalcy.
Nervous and Endocrine Systems in Homeostasis
- Nervous and endocrine systems coordinate other organ systems.
- Nervous system is faster, but endocrine effects last longer.
- Endocrine system secretes hormones: chemical messengers that travel in blood.
Negative Feedback Mechanisms
- Primary mechanism used in the body.
- Two components: sensor and control center.
- Output of the system turns down or off production.
- Examples: how a furnace works, temperature regulation.
Positive Feedback Mechanisms
- Bring about a change in the same direction as the original stimulus.
- Example: childbirth - fetus' head pushes against the cervix, stimulating signals to the brain, which releases oxytocin, causing stronger contractions and more oxytocin release. Childbirth stops the positive feedback.
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Test your knowledge on key concepts in biology, including the scientific method and the functions of cellular components. This quiz explores distinctions between humans and apes, hypothesis formulation, and the roles of cytoskeletal fibers. Challenge yourself and enhance your understanding of essential biological principles.
