Zoology 2: Histology of Vertebrate Animals

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Questions and Answers

What is the function of adipocytes in connective tissue?

Storage of fat, support some organs (e.g., kidney), heat insulator

What is the origin of adipocytes?

Umbilical cord

Undifferentiated mesenchymal cells (correct)

Blood cells

Monocytes

Macrophage cells originate from __________.

monocyte

Match the following cell types with their functions:

Plasma cells = Formation and secretion of antibodies Mast cells = Secretion of histamine and heparin Macrophage cells = Engulf and digest micro-organisms, trap antigens for lymphocytes Signup and view all the answers

What is histology?

Histology is the study of the anatomy of cells and tissues of animals using microscopy. Signup and view all the answers

Which of the following are the four main types of tissues forming body organs?

Muscular tissue Signup and view all the answers

Epithelial tissue arises from the three germ layers: , , and __.

ectoderm, mesoderm, endoderm Signup and view all the answers

Epithelial tissue is vascular and penetrated by blood and lymph vessels.

False Signup and view all the answers

Match the following types of epithelial tissues with their characteristics:

Simple squamous epithelium = Adapted to allow substance transport and exchange Simple cubical epithelium = Found in secretory units of exocrine glands Simple columnar epithelium = Found in most of the digestive tube Pseudo-stratified columnar epithelium = Lining the upper respiratory tract with motile cilia Signup and view all the answers

What are the two major divisions of glands based on the presence or absence of ducts?

Exocrine and endocrine glands Signup and view all the answers

Which type of glands release their secretions (hormones) directly into the blood?

Endocrine glands Signup and view all the answers

What is the origin of skeletal (striated) muscle?

fusion of many mono-nucleated embryonic mesodermal cells Signup and view all the answers

What is the function of skeletal muscles?

Voluntary, forcible short contraction Signup and view all the answers

Smooth muscles are called smooth or visceral muscles.

True Signup and view all the answers

Each skeletal muscle fiber is enclosed by ______.

endomysium Signup and view all the answers

Match the following types of neurons with their descriptions:

Unipolar neurons = Have a single process close to the cell body Bipolar neurons = Have one dendrite and one axon Multipolar neurons = Have one axon and many dendrites Signup and view all the answers

Study Notes

Aim and Description of the Course

The aim of the course is to demonstrate the basic concepts of histology of vertebrate animals.
Students will be able to define the types of tissues and the correlation between structure and function of different tissue types.

Introduction to Histology

Histology is the study of the anatomy of cells and tissues of animals using microscopy.
It is an essential tool of biology and medicine.

Types of Tissues

There are four main types of tissues:
- Epithelial tissue
- Connective tissue
- Muscular tissue
- Nervous tissue
These tissues are associated together to form organs.

Epithelial and Connective Tissues

Epithelial tissue covers the body's surface and lines its internal tubes.
Connective tissue underlies epithelial tissue, supports and connects body parts.

Origin of the Tissues

The four basic tissues arise from the three germ layers of the embryo:
- Ectoderm
- Mesoderm
- Endoderm
Each tissue type originates from a specific germ layer.

Epithelial Tissues

General characteristics:
- Arises from the three germ layers.
- Very little intercellular substance.
- All cells rest on a basement membrane.
Functions:
- Forms sheets or membranes that cover a surface or line a cavity.
- May modify to form secretions, act as receptors, or contract.
Classification:
- Surface epithelium
- Glandular epithelium (secretion)
- Neuroepithelium (sensation)
- Myoepithelium (contraction)

Surface Epithelium

Simple epithelium:
- Squamous
- Cubical
- Columnar
- Pseudostratified columnar
Stratified epithelium:
- Squamous
- Cubical
- Columnar
- Transitional
Characteristics and functions of each type of surface epithelium.

Glandular Epithelium

Definition: A collection of epithelial cells specialized to produce secretion.
Classification:
- Exocrine glands (with ducts)
- Endocrine glands (without ducts)
- Mixed glands (both exocrine and endocrine parts)

Connective Tissues

Origin: Mesoderm
Characteristics:
- Formed of widely separated cells with large amounts of ground intercellular substance.
- Penetrated by blood vessels, lymphatics, and nerves.
Fixed cells:
- Fibroblasts
- Adipocytes
- Undifferentiated mesenchymal cells
Free cells:
- Macrophages
- Plasma cells
- Mast cells
Fibers:
- White collagenous fibers
- Yellow elastic fibers
- Reticular fibers
Ground substance (matrix):
- Inter-cellular substance
- Amorphous, jelly-like, and translucent
- Functions: allows exchange of nutrients and waste, and acts as a physical barrier

Types of Connective Tissues

Proper connective tissue:
- Loose connective tissue (areolar, adipose, reticular, mucous)
- Dense connective tissue (fibrous, elastic)
Characteristics and functions of each type of connective tissue.### Skeletal Connective Tissues
Cartilage and bone are two types of skeletal connective tissues.
Cartilage:
- Rigid but flexible matrix with widely separated cells
- Non-vascular, nourished by diffusion of O2 and nutrients from surrounding tissues
- No lymph vessels or nerves
- Functions: supports soft tissues, smooth sliding surface for joints, shock-absorbing, and involved in bone development and growth
Composition of cartilage:
- Cells: chondroblasts and chondrocytes
- Fibers: collagen and elastic fibers embedded in ground substance
- Matrix: abundant, firm, and compact
Types of cartilage:
- Hyaline cartilage: translucent, glassy appearance, found in nose, larynx, trachea, and articular surfaces of bones
- Elastic cartilage: yellow in fresh state, opaque, flexible, found in ear pinna, Eustachian tube, and epiglottis
- Fibrocartilage: important in bone-to-bone attachment, found in intervertebral discs and mandibular joints

Bone

Characterized by:
- Solid matrix with embedded collagen fibers
- Formed of bone cells, fibers, and solid matrix
- Covered by periosteum on the external surface and lined with endosteum on the internal surface
Functions:
- Forms adult skeleton
- Supports fleshy structures
- Protects vital organs (brain, heart, and lungs)
- Serves as a reservoir for calcium and phosphorus
Structure of bone:
- Bone matrix
- Bone cells (osteoblasts, osteocytes, and osteoclasts)
- Periosteum (nutrition, muscle attachment, and repair of fractures)
Types of bone:
- Compact bone: highly organized, hard connective tissue, dense, and mature, found in shafts of long bones
- Spongy bone: irregular type of bone, doesn't have a lamellar structure, found in the center of flat and irregular bones

Muscular Tissues

General characteristics:
- Originates from mesoderm
- Muscle cells are differentiated into elongated cells called muscle fibers
- Sarcolemma: cell membrane of muscle fibers
- Sarcoplasm: cytoplasm of muscle fibers, contains cell organelles and inclusions
Types of muscular tissues:
- Skeletal (striated and voluntary)
- Cardiac (striated and involuntary)
- Smooth (non-striated and involuntary)

Nervous Tissue

Divided anatomically into:
- Central nervous system (brain and spinal cord)
- Peripheral nervous system (nerve fibers, nerve ganglia, and nerve endings)
Neurons:
- Responsible for reception, transmission, and processing of stimuli
- Consists of 3 parts: cell body, dendrites, and axon
Types of neurons:
- Unipolar: single process close to cell body, found in spinal ganglia
- Bipolar: one dendrite and one axon, found in retina and olfactory mucosa
- Multipolar: one axon and many dendrites, found in spinal cord, cerebral cortex, and cerebellar cortex
Synapses:
- Site of functional contact between neurons or between neurons and effector cells
- Consists of presynaptic side, synaptic cleft, and postsynaptic side
Neuroglia cells:
- 10 times more abundant in mammalian brain than neurons
- Types: astrocytes, oligodendrocytes, microglia cells, ependymal cells, and Schwann cells

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Description

This course covers the basic concepts of histology in vertebrate animals, including the types of tissues and the correlation between structure and function. By the end of this course, students will be able to demonstrate their understanding of histology and its applications.