11.1.1

How does blood clot?

11.1.2

How does the principle of challenge and response contribute to immunity?

When the immune system is attacked (or challenged) a chain of events is set off in response.  The result of this chain of events is a built up immunity for that particular pathogen or antigen.

11.1.2

How does the idea of clonal selection contribute to immunity?

Clonal selection is the idea that leukocytes can identify specific cells which can help fight a specific pathogen.  It also means that multiple cell divisions occur so that many cells of that type are produced 

11.1.2

How do memory cells contribute to immunity?

These cells provide long term immunity.  When the immune system fights a pathogen, memory cells are produced.  This means that if the immune system ever faces that pathogen again, it has the specific cells in 'memory' and can fight it off easily

11.1.3

What is active and passive immunity?

Active immunity is when your body uses lymphocytes to make antibodies to fight pathogens.

Passive immunity is when the antibodies are already supplied, such as some vaccinations and the passing of antibodies in mother's milk.

11.1.4

How are antibodies produced?

Antigen Presentation - a macrophage will identify and ingest and break up and antigen.  It then displays the parts of the antigen on its surface.

activation of t helper cells - these cells have receptors on their surface which bind to the presented antigens.  The macrophage then passes a message onto the t helper cell, thereby activating it.

activation of B cells - when inactive these cells have antibodies within their cell membrane.  If the antigen fits then it binds to these antibodies.  An activated T helper cell with the same receptors then binds to the B cell and activates it.  

Production of plasma cells - B cells then clone themselves by mitosis and these become known as plasma cells.

production of memory cells - these are T and B cells that are formed at the same time as the T helper cells.

11.1.5

How are monoclonal antibodies produced?

First an antigen is injected into a laboratory animal such as a mouse.  After some time, the spleen of the animal is harvested to gain access to blood cells.

Within these blood cells are the leukocytes cloned for the antigen.

The B cells are fused with cancerous cells, to form a hybridoma.  This means that the cells will stay alive longer and also divide rapidly.

The cells are cultured and they produce the desired antibody

11.1.5

What is the use of monoclonal antibodies?

In Diagnosis

The hormone HCG is produced during pregnancy.  When the antibody for this hormone is made it can be chemically bonded to an enzyme which catalyses a colour change when the antibody encounters HCG.

In Treatment

Because antibodies recognize specific antigens, they can be used to target cancer cells.  They could be used to directly target the cancer cells so that minimal treatment would be used.

11.1.6

What is the main principle of vaccination?

The main idea of vaccination is to provide long term immunity without the person having to experience the actual disease.

A vaccination will contain a weakened or dead form (the protein coat in the case of a virus) of the pathogen.  This sets of a primary immune response within the body which includes the production of memory cells.

Because memory cells are produced long term immunity is gained.

11.1.7

What are benefits of vaccination?

Some diseases can be completely eliminated - such as small pox

Immunity can be gained without experiencing the disease

Epidemics and pandemics can be prevented

The cost of healthcare drops because it is cheaper to vaccinate that treat a disease.

11.1.7

What are possible dangers of vaccination?

Some vaccines used to contain mercury which is toxic

Some people may have severe reactions to a vaccine

It has been thought that overloading the immune system may decrease its capacity to fight disease

There has been speculation that some vaccines (eg, MMR) can cause autism in young children

11.2.1

What structures in the body have a role in human movement?

Bones

Ligaments

Tendons

Muscles

Nerves

11.2.2

Label a diagram of the human elbow joint

11.2.3

What is the function of the Biceps and Triceps muscles?

The Biceps bends (or flexes) the elbow joint

The triceps extends the elbow joint

11.2.3

What are the functions of tendons and ligaments?

Tendons connect muscles to bone

Ligaments connect bone to bone

11.2.3

What are the functions of the synovial membrane and synovial fluid?

The synovial membrane secretes the synovial fluid.

The synovial fluid provides lubrication for the joint and also provides the cartilage with oxygen and nutrients

11.2.3

What is the function of cartilage in the elbow joint?

Reduces friction so that the bones move over each other smoothly rather than rubbing together.

Also acts as a shock absorber

11.2.3

What are the functions of the bones in the elbow joint?

All bones act as levers

Both the biceps and triceps muscles are attached to the humerus.

The biceps muscle is attached to the radius

The triceps muscle is attached to the ulna

11.2.3

What is the function of the capsule in the elbow joint?

Encapsulates the joint and encloses the synovial cavity

unites the connecting bones

11.2.4

What is the difference between the movement of the Hip joint and the movement of the knee joint?

Hip

Ball and socket joint

3 planes of movement

Can move rotationally

Knee

hinge joint

movement on 1 plane

can only flex and extend

11.2.5

What is the structure of striated muscle fibres?

Myofibrils - these are rod shaped bodies that run the length of the muscle cell.  They are made up of actin and myosin filaments that create light and dark bands.

Mitochondria - these are squeezed between the many myofibrils to provide energy for the power stroke.

Sarcoplasmic reticulum - type of ER filled with fluid and surrounds the myofibrils

Sarcolemma - this is the name for the cell membrane.

11.2.6

Draw and label a diagram of a sarcomere

11.2.7

How does skeletal muscle contract?

a motor neuron brings an action potential to the muscle

calcium ions are released from the sarcoplasmic reticulum

this makes binding sites on the actin available for myosin heads to bind

Myosin heads form cross bridges

ATP binds to the myosin head and cause the cross bridge to break

ATPase located on the myosin head hydrolyses ATP into ADP + P - now storing potential energy

the heads attach to the binding sites and powerstroke occurs as the ADP + P is released

11.2.8

Distinguish between contracted and relaxed muscle from an electron micrograph.

11.3.1

What is excretion?

The removal from the body of the waste products of metabolism

11.3.2

Draw and Label a Kidney

11.3.3

What is the function of the parts of the glomerlus and nephron?

[image]

Glomerulus - capillary bed which filters substances out of

the blood by using high pressure

Bowman's Capsule - Collects substances forces out of the glomerulus

Loop of Henle - main purpose is to reabsorb water

11.3.4

What is the process of Ultrafiltration?

The high pressure of the glomerulus forces plasma and other substances out.

The fenestrated blood cappillaries allow plamsa and other substances through

the basement membrane of the bowman's capsule prevents large molecules such as proteins from becoming part of the filtrate.

11.3.5

What is osmoregulation?

The control of water balance of the blood tissue and cytoplasm in a living organism.

11.3.6

How are water, glucose and salts reabsorbed by the kidney?

Reabsorption takes place in the proximal convoluted tubule.  The wall of this tubule is only one cell thick and has microvilli so diffusion is efficient.

Salt ions - actively transported into the cells of the tubule and then into the fluid outside the tubule.

Water - The movement of the salts causes the water to follow by osmosis

Glucose - active transport

11.3.7

What is the role of the loop of Henle in maintaining the water balance of the blood?

as water and dissolved solutes enter the descending arm of the loop some water leaves because this arm is mostly permeable to water but not salts.

The filtrate then enters the ascending loop which is relatively permeable to salts and not water.  Sodium ions are pumped out and enter the medulla.  This creates a hypertonic region (area with lots of salts)

11.3.7

What are the roles of ADH and the collecting duct in osmoregulation?

The collecting duct can be either permeable or impermeable to water depending on the presence of ADH.

When ADH is present the collecting duct is permeable to water and water moves into the hypertonic medulla by osmosis.

When there is no ADH the water remains in the urine.

ADH is present when the water levels in the blood are low because it stimulates the kidneys to conserve more blood.

11.3.8

How does the concentration of proteins vary between the blood plasma, glomerular filtrate and urine?

Plasma - high - filtrate/urine - none

Proteins are too big to fit through the basement membrane of the Bowman's capsule therefore they never enter the filtrate.

11.3.8

How does the concentration of Urea vary between the blood plasma, glomerular filtrate and urine?

same concentration in plasma and filtrate - very high concentration in urine

The high concentration in the urine is cause by the reabsorption of water.

11.3.8

How does the concentration of glucose vary between the blood plasma, glomerular filtrate and urine?

Same concentration in plasma and filtrate but none in the urine

glucose is reabsorbed in the proximal convoluted tubule because it is a necessary part of life.

11.3.9

Why is glucose found in the urine of an untreated diabetic?

People who have diabetes and are not treated for it normally have very high levels of sugar in their blood.

The active transport mechanism which reabsorbs glucose in the proximal convoluted tubule has a maximum rate at which it can work.  If there is too much glucose then the mechanism can't keep up and some glucose remains in the filtrate.

11.4.1

What is the location and function of interstitial cells, germinal epithelium cells, developing spermatozoa and Sertoli cells in testis tissue?

Interstitial cells - also known as Leydig cells, responsible for the production of testosterone

germinal epithelium cells - the initial stage in spermatogenesis 

developing spermatozoa - intermediate stage in spermatogenesis

Sertoli cells - nourishes the sperm, allows them to differentiate

11.4.2

What processes are involved in Spermatogenesis?

Mitosis ensures that there are always plenty of spermatogonia (cells that later become sperm)

The spermatogonia undergo Cell Growth so that they can undergo mitosis many times without getting smaller.

Four sperm result from two divisions of meiosis.  Each one is very small.

Each resulting cell must undergo differentiation to become a fully motile sperm.  This happens at the sertoli cells

11.4.3

What is the role of LH, FSH and Testosterone in Spermatogenesis?

LH - stimulates Leydig cells to produce Testosterone

FSH- stimulate meiosiis

Testosterone - simulate meiosis

11.4.4

Annotate a Diagram of the Ovary to show location of germinal epithelium, primary follicles, mature follicle and secondary oocyte.

11.4.5

What are the processes in Oogenesis?

The germinal epithelial cells undergo Mitosis repeatedly.  Follicle cells also undergo mitosis so that a layer of cells is formed around each primary oocyte.

When the germinal epithelial cells (or oogonia) undergo Cell Growth they become known as primary oocytes.  Each primary Oocyte begins to undergo meiosis but is arrested during prophase 1.  This along with the follicle is known as the primary follicle.  During a menstrual cycle a few primary follicles finish Meiosis 1 resulting in 1 large cell and a polar body.  The large cell starts meiosis 2 but is once more arrested at prophase.  During this time the follicle also divides so that there are 2 rings of follicle cells with a fluid filled gap.  This entire structure is now called a graafian follicle.

The secondary oocytes is released with the inner ring of follicle cells during ovulation.  Meiosis 2 is not completed until fertilisation.

11.4.6

Draw and label a mature sperm

11.4.6

Draw and label a mature egg

11.4.7

What is the role of the epididymis in the production of semen?

The epidiymis is a long coiled tube where the sperm become motile and are stored.  At this point there is no semen.

11.4.7

What is the role of the seminal vesicle in the production of Semen?

Produces 70% of the semen which contains fructose for energy and nutrients

11.4.7

What is the role of the prostate gland in the production of semen?

Contributes about 30% of the semen

provides a fluid that is alkaline to protect the sperm in the acidic environment of the vagina.

11.4.8

What are similarities between spermatogenesis and oogenesis?

Both occur in the gonads

Both use meiosis

Mature gametes are released after puberty

both are controlled by hormones

11.4.8

What are differences between spermatogenesis and oogenesis?

4 small sperm are produced/1 large egg is produced

sperm is constantly released/only 1 egg in released in a menstrual cycle

Production occurs for whole lifetime/production stops at menopause

millions of gametes formed/only limited amount of gametes

11.4.9

What happens during fertilisation?

Many sperm are required to break through the follicle.

when a sperm cell gains access to the glycoprotein layer (zona pellucida) around the egg, the acrosomal cap is released along with hydrolytic enzymes.

When a sperm cell reaches the cell membrane of the egg, the membranes fuse and the genetic material is released into the cytoplasm of the egg.  This initiates the cortical reaction.

Cortical granules in the egg fuse with the membrane and release their enzymes to the outside.  These enzymes alter the zona pellucida so that it becomes impenetrable to any more sperm.  This ensures that only one sperm gains access to the egg

11.4.10

What is the role of HCG in early pregnancy?

HCG (or Human Chorionic Gonadotrophin) is produced by the embryo shortly after fertilisation.  This hormone stimulates the corpeus luteum to continue secreting oestrogen and progesterone longer than the usual 14 days so that pregnancy will be maintained.

11.4.11

What happens in embryo development up to the implantation of the blastocyst?

The zygote begins to divide mitotically - the first division usually occurs within the first 24 hours of fertilisation.

During the first 5 days the early embryo is dividing and moving towards the uterus

By the time the embryo reaches the uterus it is approximately 100 cells.

At this stages this is a ball of cells known as a blastocyst.  This is made up of a ring of cells (later becomes the placenta) and a mass of cells to one side of this ring (later becomes body of the embryo) and a fluid filled cavity.

11.4.12

How does the structure and function of the placenta maintain pregnancy?

the placenta allows materials to be exchanged between the foetus and the mother's blood.

The placenta acts as an endocrine organ - secreting oestrogen and progesterone.

11.4.13

What is the purpose of the amniotic sac?

To hold amniotic fluid which supports and protects the foetus

11.4.14

What happens in the placenta?

Materials are exchanged between the blood of the mother and the foetus

11.4.15

What are the hormone changes that occur during birth?

When it is time for a foetus to be born there is a rapid drop in levels of oestrogen and progesterone.

At the same time a hormone called oxytocin is secreted by the pituitary gland.

Low oxytocin levels begin the contractions of the uterus - labour.

Mechanoreceptors detect the uterine contractions and stimulates more oxytocin to be produced.  This cause the contractions to become more frequent and more intense.

This is positive feedback.

When there is nothing for the uterus to contract on, oxytocin is no longer produced.