Cells, tissues, muscle, bone

Question 1

What does DNA stand for and what is it?

Answer 1

Deoxyribonucleic acid, it is the blueprint for a living thing. It is a molecule making the shape of a long spiralling ladder, found in the nucleus of a cell in the form of chromosomes.

It tells AMINO ACIDS how to form the perfect protein shape.

It is made up of 4 different types of chemicals (NUCLEOTIDES)

A single strand of DNA is millions of letters long, spending most of it’s life coiled up like a noodle inside a cells nucleus.

Question 2

What is RNA?

Answer 2

These are special chemicals inside the nucleus that make partial copies of the DNA code (TRANSCRIPTION).

They look a lot like DNA but shorter and only 1 side (of the ladder)

Their small shape and size allows them to fit through tiny pores in the nucleus, into the cytoplasm, and into the ribosome.

Question 3

What are ribosomes?

Answer 3

They are PROTEIN BUILDING MACHINES.

They read the RNA code 3 letters at a time, suck amino acids out of their surroundings, and stick them together according to RNA code. As the chain grows, it bends, folds and sticks to itself to form a perfectly shaped protein.

Every 3 letters of the code tell the ribosome which of the 20 different kinds of amino acids go next.

Eg. CAA = Glutomine

Question 4

What is the sequence from DNA?

Answer 4

DNA creates RNA which creates PROTEINS which form LIFE

Question 5

What are nucleotides?

Answer 5

They are the 4 bases found in DNA.

A - Adenine
G - Guanine
T - Thymine
C - Cytosine

They are arranged in a precise order along the DNA molecule. Each base along one strand of DNA pairs with a base on the other strand in a precise way (known as complementary base pairing)

Adenine pairs with Thymine
Cytosine pairs with Guanine
(The exception here is in mRNA as there is no thymine in RNA, so uracil is added instead to pair with adenine)

The bases run down the middle of the helix and are joined via hydrogen bonds

Question 6

What is transcription?

Answer 6

It is the process of the DNA template being partially copied to form RNA. It occurs in the nucleus and is catalysed via the enzyme polymerase.

Polymerase unravels the double helix to expose the bases so the code can be read, then produces another strand.

It reads one strand of the dna (the template strand) & uses the strand it has produced to complement the base codes with one change - URACIL is paired with ADENINE instead of thymine.

Question 7

What is translation?

Answer 7

It is the synthesis of the final protein using information carried on mRNA. It occurs in the cytoplasm, but more specifically the ribosomes. It is the process of a nucleotide sequence being ‘read’ by a ribosome which specifies the amino acid sequence of a protein.

The ribosome slides along the mRNA reading the codons & adding the appropriate amino acid to the growing protein molecule. It carries on until it arrives at a stop codon, where it terminates, synthesises & releases the new protein. Some new proteins are used within the cell itself and some are exported.

Question 8

Name the 3 types of RNA

Answer 8

mRNA - Messenger RNA. Acts as the messenger between DNA & protein production.

tRNA - Transfer RNA. RNA is generally single stranded, but tRNA folds it into a t shape. It’s responsible for bringing amino acids together during translation to form a peptide chain which becomes a protein. It binds to an amino acid and holds it in place on the ribosome until it is incorporated into a protein.

rRNA - Ribosomal RNA . This is the main component of ribosomes. rRNA combines with special proteins to form ribosomes which then read mRNA to form proteins.

Question 9

Explain what mitosis is

Answer 9

It is a type of cell division done by most of our body cells, and results in 2 new identical cells with the same number of chromosomes as the original cell.

It is responsible for repair of damage and growth (nails, height etc)

Does NOT create egg or sperm cells.

Question 10

Where are chromosomes found and how many are they? What are they made out of?

Answer 10

They are found in the nucclei, and there are 46 of them. They are made of DNA and protein.

Question 11

Summarise the process of mitosis

Answer 11

The initial phase (interphase) is G1 (The cell grows in size and volume), S (Chromosomes replicate making 2 identical copies of DNA. There are now 92 chromatids, but still 46 chromosomes - there is now enough DNA for 2 cells, G2 (further growth and prep for cell division)

Prophase - The replicated chromatin becomes tightly coiled, making it more visable under a microscope. The 46 chromatids pair with the identical chromatid it replicated during interphase, attaching via the centromere creating a double unit chromosome. The mitotic apparatus appears. The centrioles move to opposite ends of the cell and the nuclear envelope dissapears.

Metaphase - The chromatids align in the centre of the spindle and are attached via their centromeres.

Anaphase - The sister chromatids separate along with their centromeres and move to either side of the spindle. The microtubles that form the spindle shorten.

Telophase - The chromosomes are now at 2 opposite ends. The mitotic spindle dissapears and the nuclear envelope develops around each bundle of chromosomes. The chromosomes uncoil, and then cytokinesis occurs. The cytosol, intracellular organelles and plasma membrane split forming 2 identical daughter cells.

Question 12

Where would you find smooth muscle?

Answer 12

In all the organ systems eg. GI tract, blood vessels

Question 13

What is an example of a hinge joint and whats its range of motion?

Answer 13

Elbow. There is flexion and extension of the forearm, uni axial movement.

Question 14

What is an example of a condyloid joint and whats its range of motion?

Answer 14

The wrist. There is flexion, extension, abduction, adduction and circumduction. Bi-axial movement.

Question 15

What is an example of a ball and socket joint?

Answer 15

The shoulder. Wide range of movement.

Question 16

What is an example of a saddle joint and what range of motion does it have?

Answer 16

The thumb joint, Bi-axial movement

Question 17

What are types of synovial joints?

Answer 17

Planar joints
Hinge joints
Pivot joints
Condyloid joints
Saddle joints
Ball & socket joints

Question 18

What specialised tissue is found on the end of long bones?

Answer 18

Articular Cartilage.

Question 19

Describe an endocrine gland.

Answer 19

An organ that makes hormones that are released directly into the blood and travel to tissues and organs all over the body. Endocrine glands help control many body functions, including growth and development, metabolism, and fertility. Some examples of endocrine glands are the pituitary, thyroid, and adrenal glands.

Question 20

What is a dermatome?

Answer 20

They are areas of skin on your body that rely on specific nerve connections on your spine

Question 21

What is an example of a pivot joint, and what range of motion does it have?

Answer 21

In the neck that allows your head to rotate. It has rotational movement.

Question 22

What are the islets of Langerhans?

Answer 22

A pancreatic cell that produces hormones (e.g., insulin and glucagon) that are secreted into the bloodstream.

Question 23

What is the blood brain barrier?

Answer 23

It is a highly selective semipermeable membrane barrier that separates the circulating blood from the brain’s extracellular fluid in the central nervous system (CNS). It selectively allows essential nutrients, oxygen, and certain molecules to enter the brain while preventing the entry of potentially harmful substances, pathogens, and toxins.

Question 24

What are the 2 types of scwann cells?

Answer 24

Myelinating cells, and nonmyelinating cells.

Question 25

What are plexuses?

Answer 25

They are networks of interwoven nerve fibers from different spinal nerves. Examples include the Cervical plexus - provides nerve connections to the head, neck and shoulder Brachial plexus - located in the neck and shoulders which distributes nerves throughout the chest, shoulders and arms Lumbar plexus - distributes nerves to back, abdomen, groin, knees, thighs and calves Sacral plexus - nerves to the pelvis, buttocks, genitals, thighs, calves, feet

Question 26

What is meiosis?

Answer 26

It's a process which occurs in the ovaries and testes, producing gametes with half the number of chromosomes (haploid = 23 chromosomes, diploid = two haploids joined).

Question 27

What is selective permeability?

Answer 27

It is the characteristic which enables the plasma membrane to be selective with which substances enter or leave the cell, therefor regulating the internal composition of the cell.

Question 28

What is diffusion?

Answer 28

It's where particles move from a higher concentration to a lower concentration, down a concentration gradient.

Question 29

What factors effect diffusion?

Answer 29

Temperature, molecular size, speed

Question 30

What is diffusion through a lipid bilayer?

Answer 30

Non polar hydrophobic molecules such as oxygen, carbon dioxide, carbon dioxide, fatty acids and fat soluble vitamins diffuse freely through a plasma membrane.

Question 31

Explain diffusion through ion channels

Answer 31

Ion channels are transmembrane proteins that allow small ions to pass through. eg. potassium (K+) and sodium (Na+). These molecules are too hydrophilic to pass through a phospholipid bilayer without a channel. As there are fewer channels in a membrane the process is slightly slower. Channels can be gated or plugged as the protein changes shape to allow more of fewer ions into or out of a cell. Ions diffuse down an electrochemical gradient.

Question 32

What is osmosis?

Answer 32

The passive movement of water from a high concentration to a low concentration.

Question 33

What is osmotic pressure?

Answer 33

The pressure that develops when two solutions of different concentrations are separated by a semi-permeable membrane, and water molecules move through the membrane to equalize the concentration of solutes on both sides. It is a measure of the force required to stop this flow of water. The greater the difference in solute concentration between the two solutions, the higher the osmotic pressure. It's like the "push" that water exerts on the side with higher solute concentration, trying to dilute the more concentrated solution and achieve equilibrium.

Question 34

What is the function of a ribosome in a cell?

Answer 34

Protein synthesis

Question 35

What are the three functions of endoplasmic reticulum (rough and smooth)?

Answer 35

Synthesis of fatty acids and steroids Synthesis of glycoproteins and phospholipids Intracellular storage of calcium

Question 36

What is the function of a mitochondrion?

Answer 36

Aerobic cellular respiration and the production of ATP

Question 37

How many chromosomes does a haploid cell have?

Answer 37

23

Question 38

What is an example of ciliated simple columnar epithelium?

Answer 38

Uterine tubes

Question 39

What does an endocrine gland drain into?

Answer 39

Directly into the blood

Question 40

Name some examples of a serous membrane

Answer 40

Pleura, Peritoneum, Pericardium

Question 41

What is serous membrane?

Answer 41

The outer lining of organs and body cavities of the abdomen and chest, including the stomach - made of smooth muscle. Secretes serous fluid to allow lubricated sliding movements between opposing surfaces.

Question 42

What is hemopoiesis?

Answer 42

The production of blood cells

Question 43

Which part of the long bone contains yellow bone marrow in adults?

Answer 43

Diaphysis (the shaft of central part of a long bone)

Question 44

What is red bone marrow?

Answer 44

Red bone marrow contains blood stem cells that can become red blood cells, white blood cells, or platelets.

Question 45

What is yellow bone marrow?

Answer 45

Yellow bone marrow is made mostly of fat and contains stem cells that can become cartilage, fat, or bone cells.

Question 46

What movement does the levator palebrae superioris muscle create?

Answer 46

Raises the eyelid

Question 47

What is ossification?

Answer 47

Bone formation

Question 48

Which proteins are involved in muscle contraction?

Answer 48

Actin, Myosin and Troponin

Question 49

What do fibroblasts do?

Answer 49

Manufacture collagen and elastin fibres - contributing to the formation of connective tissue.

Question 50

What three things effect bone growth?

Answer 50

Minerals, hormones and vitamins

Question 51

What is facilitated diffusion?

Answer 51

It's the process by which solutes that are two polar or too highly charges to pass through passively, bind to a specific transporter on one side of the membrane and are released on the other side (hitching a lift) Still a passive process, determined by a concentration gradient.

Question 52

What is active transport?

Answer 52

It is where transporter proteins (PUMPS) move solutes across a membrane against the concentration gradient and ENERGY (ATP) is required. Ions that are moved in this way are Na+, K+, amino acids

Question 53

How does a sodium/potassium pump work and which cells have it?

Answer 53

All cells possess this pump. Sodium and potassium diffuse down their concentration gradient which results in higher potassium levels on the outside and higher sodium levels on the inside. The pump forces the ions to move from an area of low concentration to an area of high concentration using ATP. It moves soidum ions out of the cell, and potassium ions into the cell to enable to keep the unequal concentrations on either side of the plasma membrane. Nerve impulses use this electrical gradient.

Question 54

Transport in vesicles

Answer 54

This is an active process as it requires ATP. Substances are either transported into or out of a cell in a vesicle.

Question 55

What is phagocytosis?

Answer 55

It translates to 'cell eating'. It brings in larger particles into a cell such as cell fragments, foreign material and microbes, into a vacuole and is processed in the same way as pinocytosis.

Question 56

What is pinocytosis?

Answer 56

It translates to 'cell drinking'. the cell membrane wraps around liquid and larger particles that are outside of the cell, and brings them inside the cell. The membrane breaks off and it becomes a vacuole. Lysosome then binds to the vacuole membrane and releases enzymes to digest the contents, then the waste materials are released back through the membrane in a phase known as exocytosis.

Question 57

What are the functions of the plasma membrane?

Answer 57

Protecting the contents of the cell Communicating with other cells Regulating the flow of materials in and out of the cell Maintains the appropriate environment within the cell

Question 58

What is the lipid bilayer?

Answer 58

The lipid bilayer is a type of membrane that separates the cell from the environment and is made of two layers of phospholipids. Also known as the phospholipid bilayer, the cell membrane surrounds the cell and forms a flexible barrier that allows the cell to be separate from the extracellular space. It is composed of two back to back layers of lipids: Phospholipids Cholesterol Glycolipids This layer occurs because the lipids are amphipathic (polar and non polar regions). The fatty acid tails (non-polar areas) are in the centre of the bilayer, away from the water in the cytosol and extracellular fluid.

Question 59

What are membrane proteins and whats their function?

Answer 59

They provide channels for non-lipid soluble substances and electrolytes as they pass all the way through the membrane. They also act as receptors to hormones and c hemical messengers. Some are enzymes. Some have branches that carbohydrate molecules attach to outside of the cell, giving the cell it's immunological identity.

Question 60

What is the cytoplasm?

Answer 60

The cells contents (including the cytosol and organelles, it EXCLUDES the nucleus). It serves as a medium for important reactions and molecule transport.

Question 61

What is cytosol?

Answer 61

The watery fluid inside a cell which suspends organelles. It gives the cell its shape and structure, and is resposible for metabolic reactions eg. glycolosis

Question 62

What are organelles?

Answer 62

They are the 'small organs' inside the cell. Includes the nucleus, mitochondria, ribosomes, endoplasmic reticulum, golgi apparatus, lysosomes and cytoskeleton. They are enclosed within their own membrane in the cytosol. They all have individualised and highly specialised functions.

Question 63

What is the cytoskeleton

Answer 63

A network of tiny protein fibers. It's an internal support system for the cell.

Question 64

Centrosome

Answer 64

This is made up of a pair of centrioles (small clusters of microtubules). Plays an important part in cell division.

Question 65

Cilia and flagella

Answer 65

Cilia is microscopic hair like projections containing microtubules that lie along the borders of some cells. They beat in unison to move substances along the surface. Flagella are single, long, whip like projections containing microtubules which form the tails of spermatozoa.

Question 66

Golgi complex

Answer 66

Present in all cells but larger in ones that synthesise and export proteins. Made of stacks of closely folded flattened membranous sacs. Proteins move from the endoplasmic reticulum to the golgi complex where they are packaged into membrane bound vesicles. The vesicles are stored, and when needed get expelled using exocytosis.

Question 67

Lysosome

Answer 67

Small membranous vesicles pinched off from the golgi complex. They contain enzymes involved in breaking down fragments of organelles and large molecules inside the cell into smaller particles that can then be recycled or exported.

Question 68

Mitochondrion

Answer 68

Membraneous sausage-shaped structures in the cytoplasm. The powerhouse of the cell. Produces energy in the form of ATP through cellular respiration.

Question 69

Nucleus

Answer 69

All body cells have this expect for mature red blood cells. Found in the nuclear envelope. Contains the bodys genetic material in the form of DNA, also contains RNA.

Question 70

Give an example of a positive feedback system

Answer 70

Childbirth. The release of oxytocin creates a hormonal stimulation of contractions in the uterus - this moves the babies head into the cervix, stimulates stretch receptors within the cervix which triggers the release of more oxytocin. This strengthens contractions and maintains the state of labour. Once the baby is born, the uterus and cervix are no longer stimulates and so the release of oxytocin is stopped.

Question 71

Give an example of a negative feedback system.

Answer 71

Core body temperature. If the body temperature falls below 37 degrees, specialised temperature sensitive nerve endings found in the skin pick up on this and send a notification to the hypothalamus in the brain. The hypothalamus issues the effectors, activating mechanisms to raise the body’s temperature (stimulation of skeletal muscles to induce shivering, narrowing of the blood vessels to reduce blood flow to and heat loss from the peripheries, and of course behavioural changes, e.g. putting more clothes on). When the body temperature rises to its normal range, the temperature-sensitive nerve endings are no longer stimulated and their signals to the hypothalamus stop.

Question 72

Location and function of simple squamous epithelium

Answer 72

Heart (endocardium), blood vessels & lymph vessels Made of a single layer of flattened cells, they fit closely together like paving stones forming a thin & smooth membrane where diffusion easily occurs.

Question 73

Location and function of simple cuboidal epithelium

Answer 73

The walls of the kidney tubules some glands such as the thyroid. Cube-shaped cells fitting closely together & lying on a basement membrane. Involved in secretion, absorption and excretion.

Question 74

Location & function of non ciliated simple columnar epithelium

Answer 74

Found in many organs, the lining of the stomach & the lining of the small intestine. It's a single layer of tall, thin cells on a basement membrane.

Question 75

Location & function of ciliated simple epithelium

Answer 75

Trachea and uterine tubes. Ova are propelled along towards the uterus in the uterine tubes by cilia.

Question 76

Location & function of stratified squamous epithelium

Answer 76

Outer layers of skin, mouth, vagina Protects against drying out, abrasion, infection

Question 77

Transitional epithelium location & function

Answer 77

Urinary tracts including bladder Made up of several layers of pear shaped cells, allows for stretching as bladder fills.

Question 78

What is the function of an exocrine gland?

Answer 78

They secrete substances onto a surface or into ducts. EG. sweat, saliva, digestive enzymes.

Question 79

What are three types of fibres found in connective tissues?

Answer 79

Collagen, elastic and reticular fibres

Question 80

What cells are involved in connective tissue?

Answer 80

Fibroblasts Macrophages Plasma cells Mast cells Adipocytes White blood cells

Question 81

Location and function of areolar connective tissue

Answer 81

Almost every part of the body. Provides elasticity and tensile strength. Connects and supports other tissues (under the skin, between muscles).

Question 82

Location and function of adipose tissue

Answer 82

There is white and brown. White is found in the kidneys and the eyeballs, between muscle fibres and under the skin. Brown is found in the upper chest an neck areas. White is a thermal insulator and energy store. Brown has more mitochondria and generates more heat than white adipose tissue - essential in keeping newborn babies warm.

Question 83

Location of reticular connective tissue

Answer 83

Lymph nodes and lymphatic organs.

Question 84

Location & function of dense connective tissue

Answer 84

Found in tendons, ligaments, the respiratory tract, blood vessel walls They stabilize & support surrounding tissues and organs

Question 85

Location & function of elastic connective tissue

Answer 85

In organs where strecthing or alteration of shape is required. To allow extension and recoil

Question 86

Hyaline cartilage location & function

Answer 86

On the ends of long bones that form joints, the costal cartilages that attach the ribs to the sternum Provides flexibility, support and smooth surfaces

Question 87

Fibrocartilage location & function

Answer 87

Found as the pads between the body's vertebrae A tough slightly flexible supporting tissue

Question 88

Elastic fibrocartilage location & function

Answer 88

The epiglottis Provides support and maintains the shape

Question 89

Location and function of bone in relation to connective tissue

Answer 89

They are surrounded by a matrix of collagen fibres, strengthed by calcium and phosphate. They bring strength and rigidity to the human body.

Question 90

What does an epithelial membrane consist of? (2 layers)

Answer 90

An epithelial layer and an underlying connective tissue layer

Question 91

What are the differences between mucous and serous membranes?

Answer 91

Mucous membranes = line exposed surfaces such as digestive and respiratory tracts, they secrete mucous for protection. Made up of stratified or simple columnar epithelium. Defend against external threats, aid nutrient absorption. Serous membranes = Found in closed body cavities like the thoracic and abdominal cavities, produce a lubrication serous fluid. Made up of simple squamous epithelium. Reduce friction during organ movements.

Question 92

How is tissue repair carried out?

Answer 92

New cells form via mitosis from the stroma, or the parenchyma.

Question 93

Latin name for Head region

Answer 93

Cephalic

Question 94

Latin name for neck region

Answer 94

Cervical

Question 95

Latin name for armpit region

Answer 95

Axillary

Question 96

Latin name for arm region

Answer 96

Brachial

Question 97

Latin name for front of elbow region

Answer 97

Antecubital

Question 98

Latin name for Forearm region

Answer 98

Antebrachial

Question 99

Latin name for wrist region

Answer 99

Carpal

Question 100

Latin name for Palm region

Answer 100

Palmar

Question 101

Latin name for fingers region

Answer 101

digital

Question 102

Latin name for thigh region

Answer 102

femoral

Question 103

Latin name for anterior surface of of knee

Answer 103

Patellar

Question 104

Latin name for leg

Answer 104

crural

Question 105

Latin name for ankle region

Answer 105

Tarsal

Question 106

Latin name for foot region

Answer 106

Pedal

Question 107

Latin name for toes

Answer 107

digital

Question 108

Latin name for Chest region

Answer 108

Thoracic

Question 109

Pubis

Answer 109

Pubic

Question 110

Hands

Answer 110

Manhs

Question 111

Groin

Answer 111

Inguinal

Question 112

Hip

Answer 112

Coxal

Question 113

Naval

Answer 113

Umbillical

Question 114

Breast

Answer 114

mammary

Question 115

Chin

Answer 115

Mental

Question 116

Mouth

Answer 116

Oral

Question 117

Nose

Answer 117

Nasal

Question 118

Cheek

Answer 118

buccal

Question 119

Ear

Answer 119

Otic

Question 120

Eye

Answer 120

Orbital

Question 121

Forehead

Answer 121

Frontal

Question 122

Shoulder

Answer 122

Acromial

Question 123

Shoulder blade

Answer 123

Scapular

Question 124

Spinal collumn

Answer 124

Vertebral

Question 125

Between hips

Answer 125

Sacral

Question 126

Buttock

Answer 126

Gluteal

Question 127

Hollow behind knee

Answer 127

Popliteal

Question 128

Calf

Answer 128

Sural

Question 129

Sole of foot

Answer 129

Plantar

Question 130

Heel

Answer 130

Calcaneal

Question 131

Directional term - Intermediate

Answer 131

Between 2 structures (eg. the knee is intermediate between the foot and hip)

Question 132

Directional term - Ipsilateral

Answer 132

On the same side of the body

Question 133

Directional term - Contralateral

Answer 133

On opposite sides of the body

Question 134

Directional term - Proximal

Answer 134

The closest point to the attachment of a limb

Question 135

What are the functions of bone and the skeletal system?

Answer 135

Support Protection Assistance in movement Mineral homeostasis - minerals are released into the blood to maintain homeostasis Blood cell production Triglyceride storage (in yellow bone marrow)

Question 136

Osteoblasts

Answer 136

Are bone-forming cells. They deposit both inorganic salts and esteoid in bone tissue. They are present at sites where bone is growing, repairing or remodelling

Question 137

Osteocytes

Answer 137

These are mature bone cells that do not divide. They monitor and maintain bone tissue.

Question 138

Osteoclasts

Answer 138

These cells break down bone, releasing calcium and phosphate. They are giant cells with upto 50 nuclei. Found where bone is growing, repairing, remodelling.

Question 139

What is compact bone?

Answer 139

It is the strongest form of bone Forms bulk diaphysis of long bones Found in all bones throughout the human body. Compact bone forms the hard, dense outer covering of bones, Provides protection and support for movement *Blood, lymph vessels and nerves penetrate compact bone through perforating canals

Question 140

Spongy bone

Answer 140

Isn't actually spongy It forms short, flat and irregular bone shapes Forms epiphyses of long bones Provides support and protection bone marrow

Question 141

Ossification

Answer 141

is bone formation. There are 2 tyes: intramembranous - where bone forms within mesenchyme in sheet like layers endochondral ossification where bones form with hyaline cartilage

Question 142

Bone growth in length

Answer 142

Occurs at the epiphyseal plate up until 18 years old in females and upto 21 years old in males. At this point cartilage cells at the epiphyseal plate stop dividing and become bone.

Question 143

Bone growth in thickness

Answer 143

This is through a process called appositional growth. Osteoblasts deposit new bone tissue on the external surface. Simultaneously osteoclasts remove old or damaged bone tissue from the inner layer (endosteum). It is these opposing processes which create outward expansion of bone.

Question 144

What are the 3 main factors affecting bone growth?

Answer 144

Hormones, exercise and diet

Question 145

What are the 3 types of muscular tissue?

Answer 145

Skeletal muscle tissue Cardiac muscle tissue Smooth muscle tissue

Question 146

Describe skeletal muscle tissue

Answer 146

It moves the bones of the skeleton Is striated Is voluntary through part of the somatic nervous system

Question 147

Describe cardiac muscle tissue

Answer 147

Forms the heart wall Is striated Involuntary

Question 148

Describe smooth muscle tissue

Answer 148

Forms the walls of hollow internal structures (eg blood vessels, abdominal organs) Nonstriated Involuntary

Question 149

What are the four main functions of muscular tissue?

Answer 149

MOVEMENT - Muscles enable voluntary and involuntary movements of the body. They allow for conscious movements such as walking etc. Smooth muscle contributes to involuntary movement in internal organs like the digestive system. SUPPORT - Muscles provide support to the body and help maintain posture. Core muscles play a key role in stabilising the spine. HEAT - Muscular contraction releases energy in the form of heat, this contributes to the bodies temp regulation. Especially important in cold environments. JOINT STABILITY - Muscles stabalize joints by surrounding and supporting them. The contraction of muscles around joints help prevent excessive movement - reduced risk of injuries.

Question 150

What is a sarcolemma

Answer 150

The cell membrane of a muscle fiber (cell). It surrounds and encases the muscle cell, plays a crucial role in transmitting signals for muscle contraction.

Question 151

What is a sarcoplasm

Answer 151

The cytoplasm of a muscle cell. It contains organelles including myofibrils, glycogen and myoglobin.

Question 152

What is myoglobin

Answer 152

A protein found inside muscle cells that binds with oxygen, facilitating its storage and release. It plays a vital role in providing oxygen to muscle tissues during periods of increased activity.

Question 153

What are myofibrils

Answer 153

They are long, cylindrical structures within muscle cells composed of repeating sarcomeres. They contain contractile units of muscle, namely actin and myosin filaments and are responsible for muscle contraction.

Question 154

What is the sarcoplasmic reticulum

Answer 154

Specialised endoplasmic reticulum found in muscle cells. It stores and releases calcium ions, which are essential for muscle contraction. The release of calcium triggers the sliding of actin and myosin filaments during muscle contraction.

Question 155

What are filaments

Answer 155

They are the thin protein strands (actin & myosin) that make up the myofibrils. During muscle contraction these filaments slide past eachother, causing the muscle to shorten.

Question 156

What is the sarcomere

Answer 156

It is the structural and functional unit of a myofibril. It is the segment of myofibril between 2 Z-lines. The interaction of actin and myosin filaments within the sarcomere leads to muscle contraction.

Question 157

Myofibrils are built from which 3 kind of proteins?

Answer 157

Contractile proteins - generate force during contraction Regulatory proteins - which help switch contraction on and off Structural proteins - keep filaments aligned, give elasticity and extensibility, links the myofibril to the sarcolemma and extracellular matrix

Question 158

What is Excitation-contraction coupling?

Answer 158

It is the process that links the electrical signal (action potential) in a muscle cell to the actual muscle contraction: 1. Nerve signals stimulate the muscle cell membrane (sarcolemma), leading to the generation of an action potential. 2. Action potential travels along the sarcolemma into the Ttubules (these are deep into the muscle cell) 3. T-tubules signal sarcoplasmic reticulum to release stored calcium ions into the cytoplasm. 4. Calcium binds to troponin (bike lock). This causes a change in troponin, which moves tropomyosin (bike chain) away from the myosin-binding sites on the actin filaments 5. Now the binding sites are exposed, myosin heads on the thick filaments can attach to actin, forming cross-bridges. 6. ATP powers the movement of myosin heads, leading to the sliding of actin and myosin filaments past eachother. This results in muscle contraction. 7. Calcium is pumped back into the SR, troponin returns to it's original conformation. Tropomyosin covers the myosin-binding sites on actin, leading to muscle relaxation.

Question 159

What is the neuromuscular juntion?

Answer 159

It is the synapse between the somatic motor neuron and the skeletal muscle fibre. It is where muscle action potentials arise. the action potential jumps the gap (synaptic cleft). Neurotransmitters are used to communicate between the two cells.

Question 160

Describe the process of what happens at the NMJ

Answer 160

It begins with the arrival of an action potential (nerve impulse) at the motor neurons axon terminal. The action potential triggers the opening of voltage-gated calcium channels in the neurons axon terminal. The influx of calcium stimulates the release of acetylcholine from synaptic vesicles into the synaptic cleft. Acetylcholine diffuses across the synaptic cleft and binds to the nicotinic acetylcholine receptors on the sarcolemma of the muscle fibre. ACh binding to receptors causes the opening of ligandgated sodium channels on the muscle cell membrane. The influx of sodium generates endplate potential (a depolarization of the muscle cell membrane). The EPP triggers an action potential that moves along the sarcolemma into the T-tubules. The action potential signals the SR to release calcium ions into the cytiplasm of the muscle cell. Calcium binds to troponin, initiating the sliding actin and myosin filaments - leading to muscle contraction. Acetylcholinesterase (an enzyme in the synaptic cleft) breaks down ACh, terminating the signal and preventing continuous muscle stimulation.

Question 161

How do muscles produce ATP?

Answer 161

Aerobic respiration = mitochondria within muscle cells utilize oxygen to metabolize glucose and fatty acids, producing ATP Anaerobic processes = glycolysis breaks down glucose to generate ATP without oxygen

Question 162

What is muscle fatigue?

Answer 162

Where muscles work at a level that exceeds the supply of oxygen and fuel such as glucose. The muscle response decreases with fatigue.

Question 163

What is muscle tone?

Answer 163

A sustained partial muscle contraction that allows maintenance of posture without fatiguing the muscles involved. eg. keeping the head upright.

Question 164

Summarise the processes of mastication and deglutition.

Answer 164

Chewing and swallowing. Mastication = physical breakdown of food Deglutition = Oral buccal phase, pharyngeal phase, oesophageal phase.

Question 165

How are alveoli suited to gas exchange?

Answer 165

They are single-cell walled, great for facilitating diffusion They have elastic properties They are fluid-lined which facilitates gases exchange as well as assisting with the elastic recall Alveoli have a large surface area and a close association with blood vessels

Question 166

Compare pulmonary and systemic circulation

Answer 166

Pulmonary = carries deoxygenated blood from the heart to the lungs, oxygenated blood from the lungs to the heart. Systemic = Carries oxygenated blood from the heart to the body, then deoxygenated blood back to the heart. Pulmonary artery - the only artery that carries deoxygenated blood. Pulmonary vein - the only vein that carries oxygenated blood. 2 Systems are similar = Both components of double circulation, both occur in many mammals, they are both closed circuit systems, functions are that respiratory gases nutrients and metabolic wastes get to their final destinations, both comprised of arteries and veins.

Question 167

Describe function and structure of lymph nodes

Answer 167

Small bean-shaped masses of lymphoid tissue, enclosed by a capsule. Could draw the difference between lymph nodes and lymph nodules. They filter blood They provide areas where antigens can be trapped and exposed to the immune system for destruction or education. Found in the junctions of major lymphatic vessels (neck, groin, armpits) Capsule and cortex - 2 regions of a lymph node. Lymph drains into the lymph vessels but they can also drain from one node to another.