Chapter 3- Cells and tissues

Question 1

what are cells

Answer 1

cells are the structural units of all living things

Question 2

What is a generalised cell?

Answer 2

A generalised cell is a cell that contains the three main regions or parts, the nucleus, cytoplasm and plasma membrane.

Question 3

Describe the structure of the plasma membrane?

Answer 3

The plasma membrane consists of two phospholipids (fats) layers that are arranged “tail to tail” with cholesterol and floating proteins scattered among them. Some phospholipids also have sugar groups attached to them, to form glycolipids. The phospholipid bilayer contains polar heads called hydrophilic “water loving” and nonpolar “tails” called hydrophobic “water fearing”

Question 4

What are the functions of the proteins in lipid layer of the plasma membrane

Answer 4

Some proteins are enzymes
Most are receptors for hormones/other chemical messengers
Binding sites for anchoring the cell
Most protein are involved in transport
Some cluster together to form protein channels for water soluble molecules or ions to move
Others act as carriers that bind to a substance and move it through the membrane
Some act as receptors for bacteria, viruses or toxins can bind to
Some determine your blood type
Play a role in cell recognition and interactions

Question 5

How are cells bound together

Answer 5

Glycoproteins in the glycocalyx act as an adhesive or cellular glue.
2. Wavy contours of the membranes of adjacent cells fit together in a tongue-and-groove fashion.
3. Special cell membrane junctions are formed (Figure 3.2). These junctions
vary structurally depending on their roles

Question 6

What are the functions of tight junctions

Answer 6

Tight junctions are impermeable junctions that encircle the cells
and bind them together into leak proof sheets. The adjacent plasma membranes
fuse together tightly together like a zipper, which prevents substances from passing
through the extracellular space between the cells.

Question 7

Give an example of a tight junction

Answer 7

An example would be in the small intestine, the junctions prevent digestive
enzymes from leaking into the bloodstream.

Question 8

What are the functions of desmosomes

Answer 8

Desmosomes are anchoring junctions that are scattered like rivets
along the sides of adjacent cells. They prevent cells subjected to mechanical stress
(such as heart muscle cells and skin cells) from being pulled apart. These junctions
are buttonlike thickenings of adjacent plasma membranes (plaques) that are
connected by fine protein filaments

Question 9

What are the functions of gap junctions

Answer 9

The main function of gap junctions is communications. These
junctions are mainly found in the heart and between embryonic cells. In gap
junctions the neighbouring cells are connected by hollow cylinders composed of
proteins (called connexons) that span the entire width of the abutting membranes.

Question 10

Why do phospholipids (which form the bulk of plasma membranes) organize
into a bilayer, tail to tail, in a watery environment?
,

Answer 10

The phospholipids have both polar (heads) and non polar (tails) regions.
Polar aligns with polar (water and other polar molecules inside and outside the cell).
Non polar aligns with non polar in the membrane interior.
The external faces of some membrane proteins have sugar groups attached to them

Question 11

what are 3 roles these sugar-coated proteins play in the life of a cell?

Answer 11

They act as receptors, determine blood type, and play a role in cell-to-cell interactions.

Question 12

What are the functions of the nucleus

Answer 12

The nucleus is the control center of the cell.
● The genetic material (DNA- Deoxyribonucleic acid) is stored in the nucleus of
the cell, it contains all the instructions needed for the building of the whole
body.
● DNA has genes, which carry the instructions for building proteins.
● DNA is also necessary for cell reproduction.
● The nucleus forms the shape of the cell.
● The nucleus has three recognisable regions or structures

Question 13

What are the three regions or structures of the nucleus

Answer 13

Nucleolus
chromatin
Nuclear envelope

Question 14

What are the functions of the nuclear envelope

Answer 14

The nuclear boundary is a double membrane barrier which is called the nuclear envelope or nuclear membrane.
● At various points the two layers of the nuclear envelope fuse, generating openings called nuclear pores.
● The nuclear envelope allows some but not all substances to pass through it,
through the relatively large nuclear pores in the nuclear envelope.
● The nuclear membrane encloses a jelly-like fluid which is called the neoplasm in which other nuclear elements are suspended.

Question 15

What are the functions of the nucleolus

Answer 15

Nucleoli is plural for nucleolus. Nucleoli are the sites where cell structures
called ribosomes are assembled.

Question 16

What are the functions of the chromatin

Answer 16

When a cell is not dividing, its DNA is carefully wound around proteins called
histones to form a loose network of “beads on a string” called chromatin.
● Chromatin is scattered throughout the nucleus.
● When a cell divides by mitosis to form two daughter cells, the chromatin
condenses to form dense, rod-like bodies called chromosomes.

Question 17

What are the three main components of the cytoplasm

Answer 17

Cytosol
Inclusions
Organelles

Question 18

What is the cytosol

Answer 18

The cytosol is a semi- transparent fluid that suspends the other elements.
Dissolved in the cytosol, which is largely water, nutrients and a variety of
other solutes.

Question 19

What are inclusions

Answer 19

Are chemical substances that may or may not be present, depending on the cell type.
● Most inclusions are stored nutrients or cell products floating in the cytosol.
● They include the lipid droplets common in fat cells, glycogen granules
abundant in liver and muscle cells, pigments such as melanin in skin and hair
cells, mucus and other secretory products and various kinds of crystals.

Question 20

What are the functions of the mitochondria?

Answer 20

“Powerhouses” of the cell
Change shape continuously
Carry out reactions where oxygen is used to break down food
Provides ATP for cellular energy
Site of aerobic respiration
ATP Synthesis

Question 21

What are the functions of the ribosomes?

Answer 21

The site of protein synthesis

Question 22

What are the two locations in the cell where ribosomes are found

Answer 22

Free in the cytoplasm
As part of the rough endoplasmic reticulum

Question 23

What are the functions of the Rough ER?

Answer 23

The proteins that are made on the ribosomes which are on the rough ER migrate into the rough ER tunnels.
Rough ER is abundant in cells that make (synthesise) and export (secrete) proteins.

Question 24

What are the functions of the Smooth ER?

Answer 24

The smooth endoplasmic reticulum plays no role in protein synthesis, because it
does not have ribosomes.

The main function of the smooth ER is lipid metabolism and detoxification of drugs and pesticides.

Question 25

What are the functions of the Golgi Apparatus?

Answer 25

Its major function is to modify, package, and ship proteins (sent to it by the rough ER via transport vesicles) in specific ways, depending on their final destination It also packages hydrolytic enzymes into membrane- bound organelles called lysosomes that remain in the cell

Question 26

What are the functions of the Lysosomes?

Answer 26

They are membranous “bags” containing powerful digestive enzymes. Contain enzymes that digest worn-out or non-usable materials within the cell Site of intracellular digestion. the stomach of the cell

Question 27

What are the functions of the Peroxisomes?

Answer 27

Peroxisomes are membranous sacs containing powerful oxidase enzymes that use molecular oxygen (O2) to detoxify a number of harmful or poisonous substances, including alcohol and formaldehyde. ● Their most important function is to disarm dangerous free radicals they replicate themselves by pinching in half

Question 28

What are free radicals

Answer 28

Free radicals are highly reactive chemicals with unpaired electrons that can damage the structure of proteins and nucleic acids.

Question 29

What is the cytoskeleton

Answer 29

The cytoskeleton is an elaborate network of protein structures that extend throughout the cytoplasm. This acts as the cells “bones or muscles” by furnishing an internal framework that determines cell shape, supports other organelles and provides the machinery for intracellular transport and various types of cellular movements.

Question 30

what is the cytoskeleton made up of

Answer 30

Microtubules Microfilaments Intermediate filaments

Question 31

What is the function of the Microfilaments and give an example

Answer 31

an example of microfilaments are actin and they are mostly involved with the cells motility and in producing the changes in the cell shape. transport of cell products throughout the cytoplasm

Question 32

What is the function of the microtubules and give an example

Answer 32

They determine the overall shape of a cell and the distribution of organelles. These structures are very important for cell division. make up cilia and flagella. they help with tansport of substances within. the cell

Question 33

What is the function of the intermediate filaments and give an example

Answer 33

They help to form the desmosomes and provide the internal guy wires to resist pulling forces on the cell. gives the cell structural support resists mechanical stress

Question 34

what are the functions of the centrioles

Answer 34

Centrioles are best known for their role in generating microtubules and directing the formation of the mitotic spindle during cell division.

Question 35

what are flagella and where is it found

Answer 35

Are cilia projections that are longer found on a sperm cell

Question 36

what are cilia and where is it found

Answer 36

Are whiplike cellular extensions that move substances along the cell surface. For example mucus is carried up and away from the lungs on the ciliated cells lining the respiratory system,

Question 37

what are microvilli

Answer 37

Microvilli are tiny, fingerlike extensions of the plasma membrane that project from an exposed cell surface. They increase the cells surface area tremendously and are usually found on the surface of cells during active absorption such as the intestinal and kidney tubule cells.

Question 38

what are the different Cells that connect body parts and where are they found in the body.

Answer 38

Fibroblast- secretes cable like fibers Erythrocyte (Red Blood cells)- this cell carries oxygen in the blood

Question 39

what are the different Cells that cover and line body organs

Answer 39

Epithelial cells

Question 40

what are the different Cells that move organs and body parts

Answer 40

Smooth, cardiac and muscle cells

Question 41

what are the different Cells that store nutrients

Answer 41

Fat cells

Question 42

What are the different Cells that fight disease

Answer 42

White blood cells

Question 43

What are the Cells that gather information and control body functions

Answer 43

Nerve cells

Question 44

Define selectively permeable

Answer 44

Selective permeability means that a barrier allows some substances to pass through it while excluding the others

Question 45

what is a solution

Answer 45

A solution is a homogenous mixture of two or more components, for example the air we breathe is a mixture of gases, seawater is a mixture between salt and water etc

Question 46

what is a solvent

Answer 46

The substance that has the largest amount is called the solvent (or dissolving medium).

Question 47

what is a solute

Answer 47

Components or substances that are present but in smaller amounts

Question 48

define diffusion

Answer 48

Diffusion is the process by which molecules and ions move away from areas where they are more concentrated (with fewer of them). Diffusion is the process of molecules by which they move from a high concentration to a low concentration.

Question 49

what are the two types of diffusion

Answer 49

faciliated and simple

Question 50

what is intracellular fluid

Answer 50

Intracellular fluid (nucleoplasm and the cytosol) is a solution that contains small amounts of gases (Oxygen and Carbon dioxide), nutrients and salts that are dissolved in water.

Question 51

define osmosis

Answer 51

is the diffusion of water through a selectively permeable membrane such as the plasma membrane, because water is highly polar, it is repelled by the (NonPolar) lipid core of the plasma membrane, but it can and does pass easily through special pores called aquaporins created by proteins in the membrane.

Question 52

what is extracellular fluid

Answer 52

The extracellular fluid or interstitial fluid is the fluid that continuously bathes the exterior of our cells

Question 53

what are two types of passive processes

Answer 53

Diffusion Filtration

Question 54

The hydrophobic core of the plasma membrane is a typical barrier to diffusion. Molecules will only diffuse through the plasma membrane if:

Answer 54

● The molecules are small enough to pass through the membranes pores (channels formed by membrane proteins) ● The molecules are lipid-soluble ● The molecules are assisted by a membrane carrier.

Question 55

what is faciliated diffusion

Answer 55

facilitated diffusion provides a passage for certain needed substances (notably glucose) that are both lipid-insoluble and too large to pass through the membrane pores, or charged

Question 56

what is filtration

Answer 56

is the process by which water and solutes are forced through a membrane or capillary wall by fluid or hydrostatic pressure gradient is involved The gradient is a pressure gradient that actually pushes solute-containing fluid (filtrate) from the higher pressure areas through the filter to the lower pressure area. Filtration is not very selective, only blood cells and protein molecules too large to pass through the membrane pores are held back.

Question 57

when does the cell need to use active transport

Answer 57

This Happens When a cell uses ATP to move substances across the membrane, Substances moved actively are usually unable to pass in the desired direction by diffusion. They may be too large to pass through membrane channels, the membrane may lack special protein carriers for their transport and may not be able to dissolve in the fat core, or they may have to move “uphill” against their concentration gradients.

Question 58

what are the two most important active processes

Answer 58

Active transport (solute pumping) or Vesicular transport

Question 59

what is a solute pump

Answer 59

it is a protein carrier involved in active transport

Question 60

Describe the sodium potassium pump

Answer 60

the sodium potassium pump alternatively carries potassium ions and sodium ions in and out of the cell. there are more sodium ions outside the cells than inside, so some tend to remain inside the cell unless the cell uses ATP to force them out. ATP is split into ADP and p (inorganic phosphate) and the phosphate is then attached to the sodium potassium pump in a process called phosphorylation There are more potassium ions inside cells than in the extra-cellular fluid, and potassium ions that leak out of cells must be actively pumped back inside. Because each of the pumps in the plasma membrane transports only specific substances, active transport provides a way for the cell to be very selective in cases where substances cannot pass by diffusion. (No pump—no transport.)

Question 61

describe vesicular transport

Answer 61

Some substances cannot get through the plasma membrane by active or passive transport. ● Vesicular transport, involves help from ATP, to fuse or separate membrane vesicles and the cell membrane, it moves substances into or out of cells “in bulk” without their actually crossing the plasma membrane directly.

Question 62

what are the two types of vesicular transport

Answer 62

Exocytosis Endocytosis

Question 63

what is Exocytosis

Answer 63

"out of the cell" is the mechanism that cells use to actively secrete hormones, mucus, and other cell products or to eject certain cellular wastes.

Question 64

What is Endocytosis

Answer 64

"into the cell" which includes those ATP-requiring processes that take up, or engulf, extracellular substances by enclosing them in a vesicle

Question 65

what is phagocytosis

Answer 65

"Cell eating" Certain white blood cells, such as the macrophage, and other “professional” phagocytes of the body act as scavenger cells that police and protect the body by ingesting bacteria and other foreign debris.

Question 66

what is pinocytosis

Answer 66

"Cell Drinking" during which the cell “gulps” droplets of extracellular fluid.

Question 67

what is receptor mediated endocytosis

Answer 67

is the main cellular mechanism for taking up specific target molecules

Question 68

explain DNA replication

Answer 68

The precise trigger for DNA replication is unknown but once it starts, it continues until all the DNA has been replicated. ● The two strands of the double helix structure of the DNA unwinds. ● The weak hydrogen bonds between nitrogenous bases of each complementary base pair break and the two DNA strands unzip/separate. ● Each DNA –strand serves as a template on which its complement is built. ● Free-floating nucleotides in the nucleoplasm of the nucleus, attach to their complementary nitrogenous bases (A to T& C to G) ● This results in two identical DNA molecules. Each molecule consists of one original strand and one new strand.§

Question 69

what is mitosis

Answer 69

is the process of dividing a nucleus into two daughter nuclei with exactly the same genes as the “mother” nucleus.

Question 70

describe prophase of mitosis

Answer 70

● the chromatin threads begins to coil and shorten so that it becomes visible under a microscope. ● Because DNA has already been replicated, (each chromosome is actually made up of two identical strands called sister chromatids; they are held together by a small button-like body called a centromere). ● The centrioles separate from each other and begin to move toward opposite sides of the cell, directing the assembly of a mitotic spindle (composed of microtubules) between them as they move. ● By the end of prophase, the nuclear envelope and the nucleoli have broken down and temporarily disappeared ● the chromosomes have attached randomly to the spindle fibers by their centromeres.

Question 71

describe metaphase of mitosis

Answer 71

In this short stage, the chromosomes line up at the metaphase plate (the center of the spindle midway between the centrioles) so that a straight line of chromosomes is seen.

Question 72

describe Anaphase of mitosis

Answer 72

● During anaphase, the centromeres that have held the chromatids together split. ● The chromatids (now called chromosomes again) begin to move slowly apart, drawn toward opposite ends of the cell. ● This careful division of sister chromatids ensures that each daughter cell gets one copy of every chromosome. ● Anaphase is over when the chromosomes stop moving.

Question 73

describe Telophase of mitosis

Answer 73

Telophase is essentially prophase in reverse. ● The chromosomes at opposite ends of the cell uncoil to become threadlike chromatin again. ● The spindle breaks down and disappears, a nuclear envelope forms around each chromatin mass, and nucleoli appear in each of the daughter nuclei. ● Centriole replication is deferred until late interphase of the next cell cycle, when DNA replication begins before the onset of mitosis

Question 74

Describe cytokinesis

Answer 74

Is the division of the cytoplasm, which usually begins late anaphase and completes during telophase. A contractile ring made of microfilaments forms a cleavage furrow over the midline of the spindle, and it eventually squeezes, or pinches, the original cytoplasmic mass into two parts. ● Thus, at the end of cell division, two daughter cells exist. Each is smaller with less cytoplasm than the mother cell had but is genetically identical to the mother cell.

Question 75

what are enzymes

Answer 75

biological catalysts that speed up every chemical reaction that occurs in cells), are functional proteins.

Question 76

what is a gene

Answer 76

A gene is defined as a DNA segment that carries the information for building one protein.

Question 77

what are the three types of RNA used in protein synthesis

Answer 77

● Ribosomal RNA (rRNA) helps form the ribosomes, where proteins are built. ● Messenger RNA (mRNA) molecules are long, single nucleotide strands that resemble half of a DNA molecule. They carry the “message” containing instructions for protein syn- thesis from the DNA (gene) in the nucleus to the ribosomes in the cytoplasm. ● Transfer RNA (tRNA) molecules are small, cloverleaf-shaped molecules that escort amino acids to the ribosome.

Question 78

describe transcription

Answer 78

- The double helix DNA unwinds. - The double-stranded DNA unzips/weak hydrogen bonds break - to form two separate strands. - One strand is used as a template - to form mRNA - using free RNA nucleotides from the nucleoplasm. - The mRNA is complementary to the DNA. - mRNA now has the coded message for protein synthesis. - mRNA moves from the nucleus to the cytoplasm and attaches to the ribosome

Question 79

describe translation

Answer 79

- Each tRNA carries a specific amino acid. - When the anticodon on the tRNA - matches the codon on the mRNA - then tRNA brings the required amino acid to the ribosome. - Amino acids become attached by peptide bonds - to form the required protein

Question 80

what is histology

Answer 80

histology is the study of body tissues

Question 81

what is a tissue

Answer 81

A tissue is a group of cells with similar specialized structure and carry out specific functions

Question 82

what are the 4 main types of tissues

Answer 82

epithelial connective muscle nervous

Question 83

what is epithelial tissue

Answer 83

Epithelial tissue, or epithelium, is the lining, covering, and glandular tissue of the body. epithelium covers all free body surfaces, both inside and out, and contains versatile cells. epithelium forms the boundaries that separate us from the outside

Question 84

What are the 4 functions of epithelium

Answer 84

● Protection ● Absorption ● Filtration ● Secretion

Question 85

what are the locations of epithelial tissue

Answer 85

Body coverings Body linings Glandular tissue

Question 86

what are the characteristics of epithelium (CALAR)

Answer 86

Cells fit closely together and often form sheets The apical surface is the free surface of the tissue The lower surface of the epithelium rests on a basement membrane Avascular (no blood supply) Regenerate easily if well nourished

Question 87

where is Simple squamous epithelium found in the body

Answer 87

This type of epithelium usually forms membranes where filtration or exchange of substances by rapid diffusion occurs. This type of epithelium is found in the air sacs of the lungs (alveoli) and forms the walls of the capillaries. It also forms serous membranes or serosae

Question 88

where is Simple cuboidal epithelium found in the body

Answer 88

It is common in glands and their associated small tubes called ducts. it forms the walls of the kidney tubules and covers the surface of the ovaries.

Question 89

where is Simple columnar epithelium found in the body

Answer 89

Simple columnar epithelium lines the entire length of the digestive tract from the stomach to the anus. Epithelial membranes that line body cavities open to the body exterior are called mucosae, or mucous membranes.

Question 90

where is Pseudostratified epithelium (pseudostratified ciliated columnar epithelium) found in the body

Answer 90

It gives the false impression that it is stratified This variety mainly functions in absorption and secretion lines most of the respiratory tract

Question 91

where is Stratified squamous epithelium found in the body

Answer 91

Stratified squamous epithelium is found in sites that receive a good deal of abuse or friction, such as the surface of the skin, the mouth, and the oesophagus

Question 92

where is Stratified cuboidal epithelium found in the body

Answer 92

Very rare in the body and is mostly found in the ducts of large glands

Question 93

where is Stratified columnar epithelium found in the body

Answer 93

Mucous membrane (conjunctiva) lining your eyelids Pharynx Anus

Question 94

where is Stratified Cuboidal and Columnar found in the body

Answer 94

Very rare in the body and is mostly found in the ducts of large glands

Question 95

where is Transitional epithelium found in the body

Answer 95

that forms the lining of only a few organs—the urinary bladder, the ureters, and part of the urethra. In the bladder, the ability of transitional epithelium to stretch allows more urine to be stored without increasing pressure in the bladder.

Question 96

where are Glandular epithelium found in the body

Answer 96

Found in Exocrine and Endocrine glands

Question 97

what are the functions of connective tissue

Answer 97

Connective tissues perform many functions, but they are primarily involved in protecting, supporting, cushioning, and insulating other body tissues.

Question 98

what are the characteristics of connective tissue (BVAEM)

Answer 98

Variations in blood supply Some tissue types are well vascularized Some have a poor blood supply or are avascular Extracellular matrix Non-living material that surrounds living cells

Question 99

Where is the connective tissue Bone (osseous tissue) found in the body

Answer 99

Is composed of osteocytes sitting in cavities called lacunae. These pits are surrounded by layers of a very hard matrix that contains calcium salts in addition to large numbers of collagen fibers. Because of its rocklike hardness, bone has an exceptional ability to protect and support other body organs (for example, the skull protects the brain).

Question 100

where is Hyaline cartilage found in the body

Answer 100

Its major cell type is chondrocytes (cartilage cells). It is found in only a few places in the body. Most wide- spread is hyaline cartilage, which has abundant collagen fibers hidden by a rubbery matrix with a glassy, blue-white appearance. It forms the trachea, or windpipe, attaches the ribs to the breastbone, and covers bone ends at joints. The skeleton of a fetus is made largely of hyaline cartilage; but by the time the baby is born, most of that cartilage has been replaced by bone.

Question 101

where is Fibro cartilage found in the body

Answer 101

forms the cushion like disks between the vertebrae of the spinal column It is a tough, slightly flexible, supporting tissue. It is found as pads called the intervertebral discs between the bodies of vertebrae. It is found between the articulating surfaces of the bones of the knee joint called semilunar cartilages It is found on the rim of the bony sockets of the hip and shoulder joints

Question 102

where is Elastic cartilage found in the body

Answer 102

Elastic cartilage is found in structures with elasticity, such as the external ear It provides support and maintains the shape of, for example, the pinna or lobe of the ear, the epiglottis and part of the tunica media of blood vessel walls.

Question 103

where is Dense connective tissue found in the body

Answer 103

It is also called dense regular fibrous tissue, collagen fibers are the main matrix element Dense regular connective tissue forms strong, ropelike structures such as tendons (Tendons attach skeletal muscles to bones) and ligaments (ligaments connect bones to bones at joints) that withstand tension in one direction. makes up the lower layers of the skin (dermis), where it is arranged in sheets and withstands tension in many directions

Question 104

what are the four main types of loose connective tissue

Answer 104

The main types of loose connective tissues are: ○ Areolar ○ Adipose ○ Retricular ○ Blood

Question 105

where is Areolar connective tissue found in the body

Answer 105

A soft layer of areolar connective tissue called the lamina propria underlies all mucous membranes. Its fluid matrix contains all types of fibers, which form a loose network.It is a type of loose connective tissue Areolar tissue is also found in or around mucous membranes, and around blood vessels, nerves, and the organs of the body.

Question 106

where is Adipose Connective Tissue found in the body

Answer 106

Adipose tissue is commonly called fat. Adipose tissue forms the subcutaneous tissue beneath the skin, where it insulates the body and protects it from bumps and extremes of both heat and cold. Adipose tissue also protects some organs individually—the kidneys are surrounded by a cap- sule of fat, and adipose tissue cushions the eyeballs in their sockets. There are also fat “depots” in the body, such as the hips, breasts, and belly, where fat is stored and available for fuel if needed.

Question 107

where is Reticular connective tissue found in the body

Answer 107

Reticular tissue is limited to certain sites: It forms the stroma (literally, “bed” or “mattress”), or internal frame- work of an organ. The stroma can support many free blood cells (largely white blood cells called lymphocytes) in lymphoid organs such as lymph nodes, the spleen, and bone marrow

Question 108

describe the tissue Blood

Answer 108

Also called vascular tissue It is considered a connective tissue because it consists of blood cells surrounded by a nonliving, fluid matrix called blood plasma. The “fibers” of blood are soluble pro- teins that become visible only during blood clotting. Blood is the transport vehicle for the cardiovascular system, carrying nutrients, wastes, respiratory gases, white blood cells, and many other substances throughout the body.

Question 109

what is the function of skeletal muscle

Answer 109

to produce movement

Question 110

what are the three types of muscle tissue

Answer 110

Skeletal tissue Cardiac tissue Smooth tissue

Question 111

Describe skeletal tissue

Answer 111

Skeletal muscle tissue is packaged by connective tissue sheets into organs called skeletal muscles, which are attached to the skeleton. Muscle tissue are tissue controlled voluntarily Contracts to pull on bones or skin Produces gross body movements or facial expressions

Question 112

what are the characteristics of skeletal muscle tissue

Answer 112

The cells of skeletal muscle are long, cylindrical, and multinucleate (more than one nucleus), and they have obvious striated (stripes). skeletal muscle cells are elongated to provide a long axis for contraction, they are often called muscle fibers.

Question 113

describe cardiac tissue

Answer 113

The cardiac muscles are only found in the heart wall As it contracts, the heart acts as a pump to propel blood through the blood vessels. Cardiac muscle has striations cardiac cells have only a single nucleus and are relatively short, branching cells that fit tightly together (like clasped fingers) at junctions called intercalated discs. These intercalated discs contain gap junctions that allow ions to pass freely from cell to cell. Cardiac muscle is under involuntary control, which means that we cannot consciously control the activity of the heart.

Question 114

describe smooth muscle tissue

Answer 114

Smooth muscle have no striations. The individual cells have a single nucleus and are tapered at both ends. 43 ● Smooth muscle is found in the walls of hollow organs such as the stomach, uterus, and blood vessels. ● As smooth muscle in its walls contracts, the cavity of an organ alternately becomes smaller (constricts when smooth muscle contracts) or enlarges (dilates when smooth muscle relaxes) so that substances are mixed and/or propelled through the organ along a specific pathway. ● Contractions of smooth muscle are longer and slower than the other two muscle types. Peristalsis, a wavelike motion that keeps food moving through the small intestine, is typical of its activity.

Question 115

what is nervous tissue

Answer 115

Nervous tissue is composed of Neurons, which send and receive electrochemical impulses from one part of the body to another. Thus irritability and conductivity are the teo major functional characteristics.