The Cells, Tissues, and Organization of the Body Flashcards
zygote
results from the fusion of the ovum (female egg cell) and the spermatozoon (male sex cell)
from it the human body develops
cell consists of
plasma membrane inside which are a number of organelles
(small working parts/small organs) suspended in a watery fluid called cytoplasm
What are Organelles
have individual and highly specialized function, and are often enclosed in their own membrane within the cytoplasm
Types of Organelles
include the nucleus, mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and the cytoskeleton
plasma membrane
consists of two layers of phospholipids (fatty substances) with protein and sugar molecules embedded in them & lipid cholesterol
The membrane proteins perform several vital functions:
- Branched carbohydrate molecules attached to the outside of some membrane protein molecules give the cell its immunological identity
- They can act as specific receptors (recognition sites) for hormones and other chemical messengers
- Some are enzymes
- Some are involved in transport across the membrane
nucleus
largest organelle and is contained within the nuclear envelope, a type of membrane similar to the plasma membrane but with tiny pores through
which substances can pass through
contains the body’s genetic material, which directs all the metabolic activities of the cell.
46 chromosomes, which are made from deoxyribonucleic acid (DNA).
nucleolus
involved in manufacturing (synthesis) and assembly of the components of ribosomes
Mitochondria
membranous, sausage-shaped structures in the cytoplasm of the cell, sometimes described as the “power house” of the cell
involved in aerobic respiration, the processes by which chemical energy is made available in the
cell
Ribosomes
e tiny granules composed of RNA and proteins.
create proteins from amino acids using RNA as the template.
- including the enzymes required for metabolism
endoplasmic reticulum (ER)
s an extensive series of interconnecting membranous canals in the cytoplasm of the cell.
types of endoplasmic reticulum (ER)
smooth and rough
smooth ER
synthesizes lipids and steroid
hormones, and is also associated with the detoxification of some drugs.
rough ER
studded with ribosomes which are the site of synthesis of proteins, some of which are exported from the cell.
Golgi apparatus
consists of stacks of closely folded flattened membranous sacs
present in all cells but is larger in those that synthesize and export proteins
Lysosomes
one type of secretory vesicle with membranous walls, which are
formed by the Golgi apparatus.
contain a variety of enzymes involved in breaking down fragments of organelles and large molecules inside the cell into smaller particles that are either recycled, or extruded from the cell as waste material.
cytoskeleton
consists of an extensive network of tiny protein fibers.
These fibers are microfilaments,
microtubules, centrosomes
, cell extensions
microfilaments
the smallest fibers which provide structural support
microtubules
large contractile protein fibers that are involved in the movement of organelles within the cell, chromosomes, and cell extensions
centrosomes
directs organization of microtubules within the cell
cell extensions
project from the plasma membrane in some types of cells, allowing for movement of the cell
mitosis
a process that results in two new genetically identical daughter
cells
gametes
sex cells
cell cycle
period between two cell divisions
has two phases, these being interphase and mitosis
Interphase
considered the longer of the two phases
divided into three separate stages:
* First gap phase - the cell grows in size and volume.
- Synthesis of DNA - the chromosomes replicate forming two identical copies
of DNA. - Second gap phase - there is further growth and preparation for cell division.
Mitosis phases
continuous process which involves four distinct phases, these are:
- Prophase - chromatin replicates and becomes tightly coiled
- Metaphase - chromatids align on the centre of the mitotic spindle, attached at
their centromeres - Anaphase - the centromeres separate, and one of each pair of sister chromatids
migrates to each end of the spindle - Telophase - the mitotic spindle disappears, the chromosomes uncoil and a
nuclear envelope reforms
Prophase
chromatin replicates and becomes tightly coiled
Metaphase
chromatids align on the centre of the mitotic spindle, attached at
their centromeres
Anaphase
the centromeres separate, and one of each pair of sister chromatids
migrates to each end of the spindle
Telophase
the mitotic spindle disappears, the chromosomes uncoil and a
nuclear envelope reforms
active transport
transport of substances up their concentration gradient (uphill), or rather, from a lower to a higher concentration.
chemical energy in the form of ATP drives specialized protein carrier molecules that transport substances across the membrane in either direction.
The carrier sites are specific and can be used by only one substance, therefore the rate at which a substance is transferred depends on the number of sites available.
Types of active transport
bulk transport &
bulk transport
via a sodium potassium pump that maintains the unequal concentration of sodium and potassium ions on either side of the plasma membrane.
may use up to 30% of cellular ATP requirements
In the cell potassium levels are much higher than outside, and sodium levels are much high outside of the cell.
four main types of body tissue
Epithelial tissue or Epithelium
Connective tissue
Muscle tissue
Nervous tissue
Epithelial tissue or Epithelium
covering the whole body and the lining of various cavities, hollow organs, and tubes.
also found in glands
functions of epithelium
- Protection of underlying structures
- Secretion
- Absorption
Simple epithelium
consists of a single layer of identical cells and is divided into
three main types (squamous epithelium, cuboidal epithelium, and columnar epithelium).
It is usually found on absorptive or secretory surfaces where the single layer enhances these processes, and not usually on surfaces subject to stress
Stratified epithelia
consist of several layers of cells of various shapes.
The main function of stratified epithelium is to protect underlying structures from mechanical wear and tear. There are two main types: stratified squamous and transitional.
Connective tissue
abundant tissue in the body.
The connective tissue cells are more widely separated from each other than in epithelial tissues, and the intercellular substance (matrix) is present in considerably larger amounts.
There are usually fibers present in the matrix, which may be of a semisolid jelly-like consistency or dense and rigid.
Connective tissue functions
- Binding and structural support
- Protection
- Transport
- Insulation
Loose (areolar) connective tissue
most generalised type of connective tissue.
providing elasticity and tensile strength.
Adipose tissue
consists of fat cells, containing large fat globules, in a matrix of
areolar tissue which falls into two types (white and brown)
Lymphoid tissue
also known as reticular tissue
has a semisolid matrix with fine
branching reticulin fibers.
contains reticular cells and white blood cells and is found in the lymph nodes and all organs of the lymphatic system
Dense connective tissue
contains more fibers and fewer cells than loose connective
tissue and has two types which are fibrous and elastic tissue.
made up mainly of closely packed bundles of collagen fibers with very little matrix
what does Dense connective tissue do
- Forming ligaments which bind together bones
- As an outer protective covering for bone
- As an outer protective covering for some organs
- Forming muscle sheaths, called muscle fascia
Elastic tissue
capable of considerable extension and recoil.
the matrix consists mainly of masses of elastic fibers secreted by fibroblasts.
found in organs where stretching or alteration of shape is required such as in large blood vessel walls, the trachea, the bronchi, and the lungs.
Cartilage
another connective tissue
firmer than other connective tissues;
the cells are called chondrocytes and are less numerous.
They are embedded in
matrix and enforced by collagen and elastic fibers.
There are three types of cartilage:
hyaline
fibro
elastic
bone
Bone cells (osteocytes) are surrounded by a matrix
of lagen fibers strengthened by inorganic salts, especially calcium and phosphate.
This provides bones with their characteristic strength and rigidity.
Bone tissue is
regenerated throughout life
two types of bone
- Compact bone - solid or dense appearance
- Spongy or Cancellous bone - spongy or honeycomb like appearance
Muscle contraction - three types of specialized contractile cells
Skeletal muscle tissue
Smooth muscle tissue
Cardiac muscle tissue
Skeletal muscle tissue
forms muscles that move the bones because of striations.
These muscles are voluntary, meaning they are under conscious control
Smooth muscle tissue
non-striated, visceral, or involuntary.
not under conscious control and has the intrinsic ability to contract and relax.
This type of tissue is found in the walls of hollow organs and are used to regulate the diameter of blood vessels, propel contents of the ureters, ducts of glands,
and the alimentary tract, and are also what expels the contents of the urinary bladder and uterus
Cardiac muscle tissue
this type of muscle is found only in the heart wall and is not under conscious control.
Nervous tissue
consist of excitable cells such
as neurons, and non excitable cells known as glial cells (this will be covered more
in depth in the section on the nervous system)
regeneration depends on
The extent to which regeneration is possible depends on the normal rate of turnover of particular types of cells
a rapid turnover regenerate most effectively
rapid regeneration in
in the skin, mucous membrane, and uterine lining
infrequent regeneration
liver, kidney, and smooth muscle cells
tissues they are normally unable to replicate
nerve cells and skeletal and cardiac muscle cells
Extensively damaged tissue is usually replaced by
fibrous tissue, meaning that the
functions carried out by the original tissue are lost
Median Plane:
When the body, in the anatomical position is divided longitudally through the midline into right and left halves it has been divided in the median plane
Directional Terms:
These paired terms are used to describe the location of body parts in relationship to others.
Regional Terms:
describe parts of the body.
Medial:
Structure is nearer to the midline.
“The heart is medial to the humerus”
Lateral
Structure is further from the midline or at the side of the body.
“The humerus is lateral to the heart”
Proximal
Nearer to a point of attachment of a limb, or origin of a body part.
“The femur is proximal to the fibula”
Distal
Further from a point of attachment of a limb, or origin of a body part.
“The fibula is distal to the femur”
Anterior or ventral
Part of the body being described is nearer the front of the body.
“The sternum is anterior to the vertebrae”
Posterior or dorsal
Part of the body being described is nearer the back of the body.
“The vertebrae is posterior to the sternum”
Superior
Structure nearer the head
“The skull is superior to the scapula”
Inferior
Structure further from the head
“The scapula are inferior to the skull”
Cranial Cavity
contains the brain, and its boundaries are created by the bones of the skull
- Anteriorly - 1 frontal bone
- Laterally - 2 temporal bones
- Posteriorly - 1 occipital bone
- Superiorly - 2 parietal bones
- Inferiorly - 1 sphenoid, and 1 ethmoid bone and parts of the frontal, temporal,
and occipital bones.
Thoracic Cavity - boundaries
upper part of the trunk
- Anteriorly - The sternum and costal cartilages of the ribs
- Laterally - 12 pairs of ribs and the intercostal muscles
- Posteriorly - The thoracic vertebra
- Superiorly - The structures forming the root of the neck
- Inferiorly - The diaphragm, a dome-shaped muscle
Thoracic Cavity - contains
- The trachea, 2 bronchi, 2 lungs
- The heart, aorta, superior and inferior vena cava, numerous other blood vessels
- The esophagus
- Lymph vessels and lymph nodes
- A variety of important nerves (reviewed in the section on the nervous system)
Abdominal Cavity - boundaries
largest cavity in the body and is oval in shape
- Superiorly - The diaphragm, which separates it from the thoracic cavity
- Anteriorly - The muscles forming the anterior abdominal wall
- Posteriorly - The lumbar vertebra and muscles forming the posterior abdominal
wall - Laterally - The lower ribs and parts of the muscles of the abdominal wall
- Inferiorly - It is continuous with the pelvic cavity
Abdominal Cavity - contains
- The stomach, small intestine, and most of the large intestine
- The liver, gall bladder, bile ducts, and pancreas The spleen
- 2 kidneys and the upper part of the ureters 2 adrenal glands
- Numerous blood vessels, lymph vessels, nerves, and lymph nodes
Pelvic Cavity - boundaries
roughly funnel shaped and extends from the lower end of the abdominal cavity
- Superiorly - It is continuous with the abdominal cavity
- Anteriorly - The pubic bones
- Posteriorly - The sacrum and coccyx
- Laterally - The innominate bones
- Interiorly - The muscles of the pelvic floor
Pelvic Cavity - contains
- Sigmoid colon, rectum, and anus
- Some loops of the small intestine
- Urinary bladder, lower parts of the ureters, and the urethra
- In the female - the organs of the reproductive system: The uterus, uterine tubes, ovaries, and vagina
- In the male, some of the organs of the reproductive system: the prostate gland,
seminal vesicles, spermatic cords, deferent ducts, ejaculatory ducts, and the urethra
