Biology Flashcards
Define a cell:
Cells are the structural and functional units of the body.
What are the functions of the cell membrane?
The structure of a cell membrane is a phospholipid bilayer
The plasma membrane functions:
- defines the cell boundaries (barrier)
- governs cell interactions (communication)
- controls passage of materials into and out of the cell (gate keeper)
Explain how the cell membrane acts as selective permeable barrier?
Selective permeability: it is selective as to what it allows to go through
The plasma membrane is permeable to:
-small, non-polar, uncharged, molecules
Eg:
-Oxygen, carbon dioxide, steroids, alcohol
The plasma is not permeable to:
-large, charges, polar molecules and ions
Eg:
-glucose
What are the factors that determine solubility?
- lipid solubility
- size of particle
- charge of particles
- is there a carrier?
Describe the role and location of receptors in the cell?
Receptors are a cell recognition site that binds to:
-hormones, enzymes, neurotransmitters, drugs etc
and relays the message to the cell nucleus
Receptors can be found in membrane proteins in the plasma membrane
What is the nucleus and what does it do?
The nucleus is a cell organelle
It is the control centre of the cell
It contains DNA which is organised into chromosomes
chromosomes contain genes
What is the endoplasmic reticulum and what does it?
The ER is a cell organelle
- The ER is folding membrane which extends FROM the nucleus
- used for storage and synthesis of cell products
- smooth ER are the endoplasmic recticulum that don’t have ribosomes attaches to them
- rough ER are the endoplasmic recticulum that have ribosomes attached to them
What are ribosomes and what are it’s functions?
Are cell organelles
They are the sites for protein synthesis
Amino acids are joined by ribosomes to form proteins
What are lysosomes and what are their functions?
Lysosomes are a cell organelle
They are membranous sacks containing digestive enzymes
What is the peroxisomes and what is its function?
Peroxisomes is a cell organelle
It is membranous sacs containing detoxifying enzymes
Found in saliva and tears, helps clear bacteria cellular debris
What is the Golgi apparatus and what is it’s function?
This is a cell organelle
It receives proteins that have been synthesised by the ribosomes
It processes and packages and helps transport these to other parts of the cell within the cell itself
What is the mitochondria and what is it’s function?
A cell organelle
It’s the ‘powerhouse of the cell’
Site of cellular respiration, I.e it produces ATP
Oxygen and glucose are consumed to create energy
Carbon dioxide released as waste
What is the cytoskeleton and what is it’s function?
It’s a cell organelle
It is located just under the plasma membrane
It is a collection of protein rods and cylinders that give structural support to the cell
The rods are called microfilaments
The hollow cylinders are called microtubules
What is the Fluid Mosaic Model?
makes up the cell plasma membrane
consists of phospholipid bilayer
Hydrophilic phosphoric head
Hydrophobic lipid tails
What are the four primary types of tissue in the body?
Epithelial tissue
Connective tissue
Muscular tissue
Nervous tissue
What is the role of epithelial tissue and where can you find it?
-Epithelia tissue
forms sheets/ layers of tissue that cover the internal and external surfaces
Lines body cavities
———
-glands
Forms glandular tissue;
make glands which are structures that produce secretion
Ie saliva glands, sweat glands, milk
———
Epithelial is avascular, what does this mean?
It means it doesn’t have blood vessels, therefore there is no direct blood supply to the tissue. Epithelial get their nourishment from membrane relying on diffusion.
Blood oxygen etc are diffused from membrane
What are the functions of epithelial tissue?
Protection- e.g skin and mucous membranes
Absorption -e.g digestive tract (most likely simple epithelial)
Excretion- the process of eliminating or expelling waste matter
Filtration- e.g the blood vessels in your capillaries are made of epithelial tissue
Surface transport- w.g respiratory passages
Sensory functions- e.g epithelial tissue on the younger and nose
Secretion- e.g glands
What are the two types of epithelial glands? And what do they do?
Endocrine glands:
Release hormones INTO the body
-no ducts
Exocrine glands:
Produce and release secretions
-onto epithelial surfaces through ducts
Eg sweat, tears, saliva
What is the role of connective tissue?
- Connects epithelium to the rest of the body
- Binding, eg tendons bind to muscles to bones
- provides structure and protection, e.g bones
- stores energy and produces heat (e.g, fat)
- transports materials (e.g blood)
Where can you find connective tissue?
- Cartilage
Fibrocartilage: tough/ dense, forms intervertebral discs and pubic synthesis
Hyaline cartilage: has a smooth surface and covers the ends of bones
Elastic cartilage: is made of elastic forms outer ear - Bone
Spongy bone: inside of bone looks like sponge
Compact bone: hard surface of bone - Blood
Primarily fro transport
What are the three types of muscular tissue?
- skeletal muscle
- smooth muscle
- cardiac muscle
What do all muscles have the ability to do?
All muscles have the ability to contract and cause movement
As this requires a lot of ATP, muscle cells have lots of mitochondria
- What does skeletal muscle, as part of the muscular tissue group do?
- What does it look like?
- Is it voluntary or involuntary?
- Where is it located?
- Skeletal muscle moves the skeleton, produces heat
- Appears striated, cells/fibres are long, thin and multinucleated
- It is under voluntary control
- It is attached to bones via tendons
- What does smooth muscle do, as part of the muscular tissue group?
- What does it look like?
- Is it voluntary or involuntary?
- Where is it located?
- Churning and mixing action of the stomach
- Propulsion of food along the GI-Tract
- Contraction of uterus during childbirth
- Vasodilation/ constriction of blood vessels
- Lacks striation
- fusiform
- layered
- single nucleated
- Involuntary
- Forms layers in the walls of digestive, respiratory and urinary tracts, blood vessels, uterus etc.
- What does cardiac muscle do, as part of the muscular tissue group?
- What does it look like?
- Is it voluntary of involuntary?
- Where is it located?
- Other key characteristics?
- Makes up the heart, thick muscles of the heart contract to pump blood out, then relax to let blood in
- specialised muscle tissue that has properties of both smooth muscle and skeletal muscle
- Striated and branched
- Involuntary
- Localised to the heart
- Myoctyes are joined together via intercalated discs, cardiac muscle does not fatigue easily
What are the two types of cells found in nervous tissue?
- Neurons (nerve cells/ fibres)
2. Neuroglia
What are neurons inside nervous tissue?
Neurons (nerve cells/ fibres)
are excitable cells which generate and transmit nervous impulses
What is the neuroglia inside nervous tissue?
Neuroglia are the supporting cells
- They provide structural framework
- Protects and supports the neurons
- Insulates neurons for better propagation
- Unlike neurons, they don’t actually transmit electrical impulses directly
Where is nervous tissue found?
Nervous tissue is found in the peripheral nerves of the PNS throughout the body and organs of the CNS, the brain and spinal cord.
What are the two broad sub-types of epithelial tissue? What are their characteristics?
- Simple epithelium
- single layer of cells
- all cells are in contact with the basement of the membrane
- good for rapid diffusion
- Stratified epithelium
- two or more layers of cells, only the deepest layer sits on the basement membrane
- good for protection (cells can be packed tightly together)
(Pseudo stratified) - looks stratified but is actually simple
What is simple squamous epithilium?
Where is it found?
What is its function?
- Simple squamous epithilium is a single layer of flat cells
- very thin layer
- cells are in direct contact with each other
- It lines surface and inside of organs and body cavities
- i.e lining of the air sacs of the lungs, lining of blood vessels, lining of heart chamber - Controls absorption and rapid diffusion
What is stratified squamous epithelium?
Where is it found?
What is its function?
- Many layers for protection of underlying tissues. More durable than simple epithelium.
- Basal cells are normally columnar or cuboidal and continually make new cells which are pushed towards the surface to replace the old ones.
- Anywhere that acts as a protective layer, i.e nails, skin
- Protection
What are the characteristics of connective tissue?
-consists of few cells surrounded by an abundance of extra cellular material
-highly vascular
-contains lots of extra cellular matrix which are produced by cells
-can vary from solid to fluid
-solid extra cellular matrix- fibres (collagen, reticulum, elastin)
Fluid extra cellular matrix- ground substance (water, glycosaminoglycans, proteoglycans, etc)
Explain how epithelial and connective tissue combine to form four types of tissue membranes?
What are these types?
Each membrane consists of an epithelial sheet and an underlying connective tissue membrane that cover and protect other structures and tissues in the body.
- mucous
- serous
- cutaneous
- synovial
Where is mucous membranes found? What does it do?
Lines inside cavities that open directly to external environment, e.g GI, respiratory, reproductive and urinary tract
It secretes mucous which:
- is a defence mechanism
- traps dust/ pathogens
- lubricates contents of GI tract
Serous Membranes, what do they do? Where are found?
They line the cavities of the body that do not open to the external environment e.g lining of organs, the chest and abdominal cavities
They secrete serous fluid which decreases friction between organs during movement
What is the location and function of cutaneous membrane?
Found in the skin, it covers the entire body.
It is many layers of keratinised epithelial cells which functions include:
- protection
- storage
- sensation
- temperature regulation, etc
What is the location and function of synovial membrane?
- Surrounds the synovial joint
- Produces and secretes synovial fluid
- lubricates joints
- allows for frictionless movement
- nourishes cells of the cartilage
Define anatomy:
Define physiology:
Define histology:
Anatomy: Is the study of human body structures
Physiology: is the study of the functions and activities performed by the body’s structures
Histology: is the study of the tiny structures found in living tissue
Describe an atom?
Atoms are the smallest particle of material, also called chemical element, which still has the characteristics of that material.
What are the three subatomic particles in an atom?
Protons
- found in the nucleus
- positively charged
- large in size
Neutrons
- found in the nucleus
- neutral charge
- large in size
Electrons
- orbits in shell around nucleus
- negative in charge
- small in size
Differentiate between elements and molecules
Element:
An element is a substance that is made entirely from one type of atom, therefore it will have exactly the same number of protons
Molecule:
A molecule however, is a group of atoms bonded together to form a chemical compound
What is the biological importance of the element H?
- Hydrogen; forms organic compounds
- It is a component of water and most other compounds in the body
What is the biological importance of the element k
Potassium; is important for proper membrane function, nerve impulses and muscle contractions
What is the biological importance of the element Na?
Sodium is important for nerve impulses and fluid retention
What is the biological importance of the element C?
Carbon forms organic compounds
What is the biological importance of the element Ca?
Calcium is found in bones and teeth, important for nerve impulses
What is the biological importance of the element Fe?
Iron is a component of Hemoglobin
How do ions form?
If an atom gains or loses one or more electron it is then called an ion.
What is an anion?
An ion that gains electrons is called an anion
What is a cation?
An ion that loses electrons are called cations
What is the importance of the organic molecule carbohydrates?
Are a class of important organic molecule that provides energy and structure
Sugars are the building blocks for carbohydrates
What is the important of the organic molecule; lipids?
Lipids are large hydrophobic organic molecules
- Chemical messengers
- Storage and provision of energy
What is the importance of the organic molecule; proteins?
- made up of amino acids
- building tissues and muscles
- hormone production; Hormonal proteins such as insulin and oxytocin play a vital role like controlling blood sugar concentration and stimulating contractions during childbirth
- provides energy
- immune function; antibodies (specialised protein) that provides a specific immune defence against invaders.
What is the importance of the organic molecule; nucleic acids?
- Consist of long chains of nucleotides
- are the molecules of the genetic code
- are also important as energy carries
What are the three layers of the integumentary system?
Epidermis (including basal cells, melanocytes and keratinocytes) (top layer)
Dermis (directly below epidermis)
Hypodermis (subcutaneous layer) (just below skin connects the skin to surface muscles)
What is the function of the epidermis?
Outermost layer composed of epithelial cells
- Form a protective covering for all of the internal and external surfaces of the body
- Avascular, dependent on lower layers for nourishment
- keratinised stratified squamous epithelium
What is the role of DNA?
Human DNA contains thousands of genes that provide the information essential for heredity
What is the major cavity that contains the heart?
Thoracic cavity
Which organelle is important in detoxification and lipid synthesis?
Smooth endoplasmic reticulum
What is the main chemical in the structure of the cell membrane?
Phospholipids
Which cell is specialised for movement of food through the digestive tract?
Smooth muscle cell with contractile proteins
What is the structure of the cell membrane?
The cell membrane is made up of a phospholipid bilayer.
A phospholipid is made up of hydrophilic,water-loving, phosphate head, along with two, hydrophobic, water-hating, lipid (fatty) acid tails. parts and water hating (hydrophobic) lipid part.
Phospholipids spontaneously arrange themselves in a double-layered structure with their hydrophobic tails pointing inward and their hydrophilic heads facing outward.
Structural features that enable it to perform that feature:
lipids 98%
-phospholipids :make up the sea of the membrane
-cholesterol: essential for membrane structure, embedded between lipid tails, holds the phospholipids together, makes the membrane less fluid
-glycolipids: lipids that are attached to a carbohydrate group, only occurs in the outer facing side (ECF) of the mb
Proteins 2%
-can be integral or peripheral
Functions: receptors, enzymes, channel proteins, gated channels, cell identify markers, CAM’s
Explain how the body is organised?
Organ Systems
^
Organs
^
Tissue
^
Cells
^
ChemicalsHow is the plasma membrane a barrier and gatekeeper and why?
Because a cell membrane is semi-permeable it restricts diffusion of highly charged molecules, such as ions, and large molecules, such as sugars and amino acids
The passage of these molecules relies on specific transport proteins embedded in the membrane.
What can freely diffuse through the cell membrane?
Small hydrophobic molecules and gases like oxygen and carbon dioxide cross membranes rapidly.
Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly.
On the other hand, cell membranes restrict diffusion of highly charged molecules, such as ions, and large molecules, such as sugars and amino acids.
What are the major body systems?
Skeletal system Muscular system Cardiovascular system Lymphatic system Immune system Respiratory system Digestive system Urinary system Nervous system Integumentary system Endocrine system Reproductive system
What is the major structure and functions of the skeletal system?
Major structures: bones, joints and cartilage
Major functions: supports and shapes the body. Protects internal organs. Forms some blood cells and stores minerals.
Major structure and functions of the Muscular system?
Structures:
muscles
fascia (sheet of connective tissue)
tendons (fibrous collagen attaching muscle to bone)
Functions: holds the body erect, makes movement possible. Moves body fluids and generates body heat.
Major structure and functions of the cardiovascular system:
Structures: heart, arteries, veins, capillaries and blood.
Functions: blood circulates throughout the body to transport oxygen and nutrients to cells, and to carry waste products to the kidneys where waste is removed by filtration.
Major structure and functions of the lymphatic system:
Structure: lymph, lymphatic vessels, and lymph nodes
Function: removes and transports waste products from the fluid between cells. Destroys harmful substances such as pathogens and cancer cells in the lymph nodes. Returns the filtered lymph to the bloodstream where it becomes plasma again
Major structure and functions of the immune system?
Structure:
Tonsils, spleen, thymus, skin, and specialised blood cells
Function:
Defends the body against invading pathogens and allergens
Major structure and functions of the respiratory system?
Structures:
Nose, pharynx, trachea, larynx and lungs
Functions:
brings oxygen into the body for transportation to the cells. Removes carbon dioxide and some water waste from the body.
Major structure and functions of the Digestive system:
Structure:
Mouth esophagus, stomach, small intestines, large intestines, liver and pancreas
Functions:
Digest ingested food so it can be absorbed into the bloodstream. Eliminates solid waste
Major structure and functions of the urinary system?
Structures: kidney, ureters, urinary bladder and urethra
Functions: filters blood to remove waste maintains the electrolyte and fluid balance within the body
Major structure and functions of the nervous system?
Structures: nerves, brain and spinal cord
Functions: coordinates the reception of stimuli. Transmits messages throughout the body (pns) (cns)
Major structure and functions of the integumentary system?
Structures: skin, sebaceous glands, and sweat glands
Functions: protects the body against invasion of bacteria. Aids in regulating the body temp and water content.
Major structure and functions of the endocrine system?
Structures: adrenal glands, gonads, pancreas, parathyroids, pineal, pituitary, thymus, and thyroid
Function: integrates all body functions
Major structure and functions of the reproductive system?
Structures:
Males: penis and testicles
Female: ovaries, uterus, and vagina
Function: produces new life
What are the 7 body cavities?
- Cranial cavity
- vertebral cavity
- Pericardial cavity
- Abdominal cavity
- Pelvic cavity
- Pleural cavity
- Superior mediastinum
What is the location and function of the cranial cavity?
Location: Skull
Function: Lined by melinges, containing cerebrospinal fluids, to cushion blows and protect brain.
Explain the location and function of the dorsal cavity?
The dorsal cavity is located along the back of the body and head. It contains organs of the nervous system that coordinate body function.
Divided into two portions:
Cranial cavity
-within skull, surrounds and protects the brain
Spinal cavity
-located within the spinal column, surrounds and protects the spinal cord.
Briefly explain the role of DNA?
DNA carries genetic instructions to tell your cells how to: • Growth • Development • Functioning • Reproduction
Explain the basic structure of DNA? Where to find it, and what it stands for?
Deoxyribonucleic acid exists in all living things, even bacteria that isn’t considered living contains DNA.
DNA is packaged in the nucleolus
The nucleolus is inside the nucleus.
The nucleolus contains proteins, nucleic acids and all our DNA.
DNA is a long molecule like a twisted ladder called the double helix ladder.
Describe human chromosomes?
- DNA is long and thin
- it gets wrapped around histones
- which form nucleosomes and super coils
- these are then arranged into chromosomes
- chromosomes are housed inside the nucleus.
Describe human chromosomes with respect to number, autosomes and sex chromosomes?
Human somatic(body) cells have 46(known as diploid number) chromosomes
23 from mum
23 from dad
23 pairs of chromosomes: 22 pairs of homologous autosomes
1 pair of sex chromosomes
- females have XX - males have XY
Human gametes have 23(haploid) chromosomes
What’s the difference between human somatic cells and human gamete cells?
Somatic cells are basically every cell in the body besides the gametes. In humans, a diploid cell has 46 chromosomes. Gametes are sex cells, so the egg and sperm. They are considered haploid because each gamete contains half the number of chromosomes that an organism’s somatic cells will have.
Define a gene?
- A gene is a small segment of DNA on a chromosome
- they provide instructions for A PARTICULAR protein
- each chromosome carries thousands and thousands of genes
- each gene is always found in the same location of a chromosome.
Define a Genotype and phenotype:
Genotype= your chromosomes and genes, your unique genetic make up
Phenotype= your anatomy and physiology, the expression of your genotypes !WHAT IS EXPRESSED!
Phenotypes are determined by your genotype
They are also influenced by the environment
Define an allele:
Is when same populations may have different versions of gene
Different variation of one gene
Same corresponding genes on the chromosome found in the locus (plural)
I.e BB, Bb,
Distinguish between homozygous and heterozygous?
You inherit two copies of each gene:
If they are the same it is called homozygous
(eg black hair from mum black B hair from dad B child has black hair BB)
If they are different it is called heterozygous
(Eg black hair from mum B blonde hair from dad b child will be Bb)
Explain the relationship between genotype and phenotype?
Phenotypes (expression) are determined by your genotype (genetics)
For example your black hair is a phenotype resulting from dominant genotypes
Genotype= your chromosomes and genes, your unique genetic make up
Phenotype= your anatomy and physiology, the expression of your genotypes !WHAT IS EXPRESSED!
Explain the principals of inheritance with respect to recessive and dominant alleles:
Heterozygous of an allele you have two sets of instructions:
Dominant/recessive:
One allele is dominant and therefore its trait is expressed, the other allele is recessive and so the trait is masked by the dominant allele
They can still carry the recessive gene and pass it on to their offspring
In order for the recessive trait to be expressed they have to be homozygous
Co-dominance:
Both alleles are expressed, resulting in a mixture of the two traits,
Eg blood type A and B are both dominant
If one parent is blood type A and the other is blood type B the offspring will be blood time AB
Explain what autosomal recessive is?
Autosomal recessive are one of several ways that a trait, disorder, or disease can be passed down through families. An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.
Autosomal dominant disorder is similar to autosomal recessive disorders, except the dominant allele is the undesired condition
What are the cells of the Epidermis?
Cells of the Epidermis • Keratinocytes most abundant, produces keratin, arises from the deepest layer of the epidermis • Melanocytes spider-shaped cells, produces melanin, found in the deepest layer of the epidermis . Basal cells
———————-
Langerhan’s cells
star-shaped macrophage cells, activate immune system,
originate from bone marrow
• Merkel cells
present at the epidermis-dermis junction, associated with nerve endings, function as sensory receptors
What are the appendages of the skin?
Appendages of the Skin
• Nails
• Glands (oil and sweat)
• Hair (and hair follicles)
Describe the accessory structure nails, of the integumentary system?
Nails
- What:
modifications of the epidermis, densely packed epithelial cells containing fibres of hard keratin (kera = horn)
- Where:
located distally on the posterior surface of the
fingertips and distally on the superior surface of the toes
- Why:
protection of the underlying nerves
aids in picking things up, scratching, digging, grooming, manipulating small objects, etc
Describe the accessory structure glands, of the integumentary system?
Glands - What:
clusters of specialised epithelial cells that secrete a substance. eg, oil, sweat, wax, milk, etc
- Where:
sweat glands: whole body except nipples and parts of external genitalia
sebaceous glands: whole body except palms and soles
- Why:
sweat glands: regulate body temp, remove wastes
sebaceous glands: softens skin and hair, ↓bacterial growth, ↓ water loss
Describe the location and function of hair as an accessory structure of the integumentary system?
Hair - What:
shaft: slender filament of keratinised cells
root: below the surface, embedded within skin
follicle: group of cells that surround the root, holds hair in place
- Where:
whole body except palms, soles, lips, nipples and parts
of the external genitalia
- Why:
warmth, protection against physical trauma, heat loss,
sunlight, detect insects on skin, keep out foreign particles, etc
Describe protection as a major function of the integumentary system? Explain how the integument achieves this function using examples:
Functions of the Skin
• Protection
The skin is the most vulnerable organ of the body. It is constantly exposed to bacteria, abrasions, temperature extremes, chemicals, etc
Acts as 3 types of barriers:
- Chemical barrier: Skin secretions and melanin
- Physical barrier: Continuity of skin, waterproof
- Biological barrier: Langerhan’s cells, macrophages
Other than protection describe the major functions of the integumentary system? Explain how the integument achieves this function using examples:
• Body temperature regulation
Sweating - 500ml/day at rest (unnoticeable)
- up to 12L/day during vigorous exercise
• Cutaneous sensation
Sensory receptors on the skin allow us to feel light touch,
pressure, vibration, tickling (mechanoreceptors), temperature (thermoreceptors), pain (nociceptors), etc
Hair follicle receptors – insects, wind, etc
• Metabolic function
Produces vitamin D (when exposed to UV) for calcium and phosphorous absorption (bone development)
• Blood reservoir
The dermis is highly vascularised
Blood can be temporarily shunted from the skin and relocated to another part of the body that requires it
• Excretion and Absorption
Removal of nitrogenous wastes such as urea,
ammonia, uric acid, and salts, etc in sweat. Absorbs vitamins A, D, E and K and oxygen
Explain the concept of homeostasis and its importance in the human body?
Homeostasis refers to the body’s ability to maintain a stable internal environment within a narrow preset range, relative to a variable external environment
each bodily structure contributes to keeping internal environment within normal limits, for example the lungs allow just the right amount of oxygen into the body
Imbalance and disruption to optimum range for normal body functions
• Must be corrected
• If not corrected, will result in:
- disease (eg, diabetes mellitus, rickets, anaemia, etc) - death
What are the two regulating systems the body has to reach homeostasis?
The body has regulating systems:
- nervous system (brain, spinal cord and nerves)
- endocrine system (glands and hormones)
These nerve impulses and/or chemical messengers transmit information needed to maintain homeostasis through Feedback Systems
List the components in homeostatic/ regulatory mechanism? Use examples to demonstrate the role of each component:
Feedback System Components
Receptor:
- receives the “information/stimulus” from the surrounding
Control centre-brain
- sets the range of values
- evaluates the incoming info (thinks about it)
- determines next action (decides what to do next)
- conveys output to the effector (gives the order)
Effector:
- receives the order from the control centre
- carries out the work = response (ie, brings about the effect)
Describe negative feedback with an example:
The response OPPOSES the initial stimuli to REVERSE the change, if one goes down the other goes up.
An example of negative feedback is the control of blood sugar (glucose) by insulin. When blood sugar rises, receptors in the body sense a change. In turn, the control centre (pancreas) secretes insulin into the blood to lower blood sugar levels. Once blood sugar levels have reach homeostasis, the pancreas stops releasing insulin.
Describe positive feedback with an example:
Positive feedback is a body response that STRENGTHENS or ENHANCES the stimuli to produce an EVEN GREATER (amplified) change.
Positive feedback loops are used when you want to produce a large or rapid change.
Some examples include:
-release of oxytocin (hormone) during childbirth
-release of oxytocin during breastfeeding
-formation of the platelet plug during blood clotting
-activation of immune cells.
Childbirth example explained:
During labor, a hormone called oxytocin
What triggers the secretion of oxytocin in childbirth?
Oxytocin is produced in the hypothalamus and released by the posterior pituitary
It is initiated by physical stimulation such as suckling of the nip
In childbirth
Increased uterine contractions —> message is sent to the hypothalamus —> hypothalamus produces oxytocin —> oxytocin is then released from the posterior pituitary —> oxytocin secreting neurons travel down to cervix and increase uterine contractions, this positive feedback loop repeats itself with uterine contractions increasing in pressure until the baby is born.
Discuss the role of homeostasis with a particular emphasis on temperature regulation:
Thermostat in hypothalamus activates cooling mechanisms
I I
sends message to skin blood vessels to dilate Sends messages to the eccrine gland
I I
capillaries fill with warm blood Eccrine glands secrete water to skin by evaporation -cooling
I
heat then radiates from skin surface
Eccrine sweat glands extend from out layer of skin to the dermis layer, they are distributed all over the surface layer of the skin, the sweat glands are controlled by sympathetic cholinergic nerves which are controlled by the hypothalamus, the hypothalamus senses core temperature directly, and also has input from temperature receptors in the skin and modified the sweat output.
Shivering:
When the cor body temperature drops, the shivering reflex is triggered to maintain homeostasis. Skeletal muscles begin to shake in small movements, creating warmth by expending energy.
What is the name of the process that allows your body to maintain its core internal temperature approx. 37 degrees Celsius:
Thermoregulation.
All thermoregulation mechanisms are designed to return your body to homeostasis. This is a state of equilibrium.
Describe the location and function of the erector muscles?
A tiny muscle that attaches to the base of a hair follicle at one end and to the dermal tissue on the other end.
In order to generate heat when the body is cold the erector muscles contract all at once, causing the hair to stand up straight on the skin.
Define the process of diffusion with an example, and explain its role in the physiological system?
Simple diffusion: is the net movement of a (solute) molecule, either in a gas or liquid, from an area of high concentration to an area of low concentration.
The rate in which they diffuse is affected by:
-mass of molecule
-distance
-temperature
- steepness of gradient
Diffusion of chemicals and gases in and out of a cell is an essential activity in human organs. Diffusion of oxygen and carbon dioxide gas occurs in the lungs. Diffusion of water, salts, and waste products occurs in the kidney. Diffusion of calcium from food into cells occurs in the intestines.
Define the process of osmosis with an example, and explain its role in the physiological system?
A special type of diffusion, referring to the diffusion of water, as opposed to solutes (molecules) along its own concentration gradient.
The net movement of water across a selectively permeable mb from a dilute solution to a more concentrated solution as water molecules try to reach equilibrium (balancing of opposing forces)
What is facilitated diffusion and what is an example?
Facilitated diffusion uses protein carries to transport molecules down a concentration gradient. It is helped along by a protein channel. However, once reached saturation or transport maximum no more molecules will be able to diffuse as you can only transport as many molecules and you can carries.
Example:
What is active transport and what is an example?
Active transport requires energy as solutes are pushed against the concentration gradient.
It also requires the use of carrier proteins working against the concentration gradient.
And example of this are na+/ k- pumps (explain)
Differentiate between active and passive transport processes?
Passive transport doesn’t require ATP active transport does.
Passive transport moves molecules WITH the concentration gradient (high to low)
Active transport moves molecules AGAINST the concentration gradient (low to high)
Define semipermeable membrane:
Allowing certain substances to pass through it but not others. Especially allowing the passage of a solvent but not of certain solutes
E.g A semipermeable membrane
Solute vs Solvent
Solute - substance (salt)
Solvent- liquid (water)
Lipid soluble vs water soluble
Lipid soluble=
Name the categories of microbes that may affect the human body?
- bacteria (can be good or bad)
- fungi/yeast
- helminths (can be seen with the naked eye)
- viruses (are not considered living)
- Protozoa
Identify key characteristic of a virus:
- very small
- not considered living so can not reproduce
- must use host machinery to reproduce
- can not be cultured (requires a living host)
- no cellular structure
- no cell wall
- protein capsules containing nucleic acid (rna or dna)
Explain fungi/ yeast
- eukaryotic cell
- more organised than bacteria
- can be uni cellular or multi cellular
- cell wall present
- capable of reproducing spores
Explain Protozoa:
- eukaryotic cell
- unicellular
- usually motile (can move around)
Explain helminth worms:
- eukaryotic cells
- mostly unicellular
- they have cell walls
- capable of independent survival (do not need a host)
- can be motile and visible to the naked eye
What are the two most common shapes of bacteria?
Bacillus (rod-like)
coccus (spherica)
What’s the difference between prokaryote and a eukaryote?
Prokaryotes are much older than eukaryotes.
A prokaryote has no nucleus or membrane bound organelles where as eukaryotes do.
A cell wall is not present in a prokaryote and they are mostly unicellular, the cell wall is present in eukaryotes and they are mostly multicellular.
A prokaryote are a mass of different things mashed up where as a eukaryote is more complex and developed. Examples of a prokaryote is bacteria, an example of eukaryotes are plants, fungi, animals, yeast, moulds, Protozoa etc.
In order for bacteria to grow what is required?
Only need to know oxygen, Ph and temp
Temperature:
10-39 degrees
PH:
6-8
Water:
Bacteria needs water to reproduce, but can stay dormant in dry conditions
Oxygen:
aerobic-requires oxygen to survive
facultative anaerobic- with or without oxygen
Obligate anaerobic-must not have oxygen
Nutrients:
needed in order to reproduce, chemical requirements: carbon, nitrogen etc. organic growth requirements: vitamins, minerals, amino acids etc
Time: needs time to divide/ in ideal conditions (37 deg) can divide every 20 mins.
Competition: must be at bay
Explain the relevance of gram-negative and gram-positive bacteria in health and disease?
A gram stain test is very useful in quickly eliminating a big portion of what the bacteria could be.
If the bacteria stains blue/ positive it means a thicker cell was is present as it retains the dye
If the bacteria stains a pinky red/negative it means it has a thinner cell wall as it has not retained the dye
Bacillus will stain blue, coccus will stain red.
Describe the role of normal flora in your body defences:
Bacteria that normally live in/on the host
It lives any where there is surface contact with the outside environment i.e the skin, mouth, GI tract, ears. The skin is mostly G+ cocci, the gut is mostly, G- rods.
Normal bacteria lives on our skin and in our gut. It acts as a protective agent for our immune system as different bacteria are constantly fighting for the same space and nutrients, one will usually win and the other will usually die out.
Natural flora is already living on us and not causing any harm, however they are there to protect us if more harmful bacteria lands on us.
Explain natural floras ability to become opportunistic pathogens?
An opportunistic Pathogen is a pathogen that strikes when your immune system is weak, but not necessarily strong enough to when your immune system is strong. I.e if you’re old you’re more susceptible
Describe the 3 modes of transmission of microorganisms?
- contact transmission
- common vehicle transmission
- transmission via vectors
Describe contact transmission:
-direct
(touching source of infection, human to human, kissing, sexual contact, touching open wound)
-Indirect
(Not human to human, through formites (inanimate objects)
-droplet transmission (breathing, sneezing, coughing)
Describe common vehicle transmission:
Refers to a source lots of people catch the disease form- it can affect many people at once.
Airborne: pathogens carried on air currents for long distances
Water-borne: contaminated water carry pathogens which can be transmitted to host bia drinking breathing etc
Food-born: food spoilage causing food poisoning.
Describe transmission via vectors:
Vectors are living agents, usually insects that carry the infectious agent from one host to another. Eg mosquitoes, fleas, lice, ticks, bugs. Flies.
Mechanical transmission:
passive transport of the pathogen on the outside vectors body. Eg fly lands on open wound after landing on faeces matter.
Biological transmission:
- vector bites a host containing the pathogen
- pathogen multiplies in vector
- vector bites another host, pathogen is transferred to new host. I.e malaria.
Explain the relevance of portals of entry and exit for microorganisms:
There are two types:
Endogenous infection: cause by microbes already in/on the body. E.g thrush
Exogenous infection: cause by microbes derived from outside the body
Can get in through skin -wounds, cuts, cracks etc.
across mucous membranes i.e nose mouth and eyes
Portals of exit:
Can be the same way they came i.e sneezing, exit the GI tract via the bowel—> can be lead to contaminated water supply.
Skin e.g scabs pus, exudates boils, lesions etc.
What are the 5 simultaneous requirements for disease:
- pathogens must be present
- pathogens must have sufficient virulence
- dose acquired must be large enough
- portals of entry must be available
- host must be susceptible (animals can carry bacteria without being sick)
Explain how presence of a pathogenic property enables a microorganism to more easily cause disease in the body:
Adherence: are they good at sticking onto things?
Invasiveness (into tissue): maybe it can produce enzymes which can digest or eat into the protective layer and it can burrow its way into the epithelial cell.
Evasion: avoid detection/ attack by immune system. Can it mutate?
Toxins: does the microbe produce poison?
-endotoxins: part of cell wall and released when cell dies
-exotoxins: secreted (released) into host tissues by the bacterium. The bacteria doesn’t have to die for then exotoxin to be released.
List examples of first line defences of the body:
- skin (physical barrier, no holes, designed to keep things outside)
- gastric juices (highly acidic to kill off bacteria)
- mucous membranes (sticky, thick, pathogens, viruses dust etc get stuck or swept up and spat out)
- urinary flow (the flush motion pushes the bacteria back out)
- hair and cilia (traps bacteria or large particles so that they don’t go further into your body)
- vaginal secretion (Ph 3.8, 4)
- tears, sweat, saliva (contain lycozmes, enzymes that degrade cellular products)
- cerumen (ear wax)
In the second line defence what is the role of a phagocyte:
A type of cell within the body capable of engulfing and absorbing bacteria and other small cells and particles.
They are non-specific, Any invader is attacked the same way.
Phago-eat cytosis-cells
Discuss the importance of pH and the role of buffers in the body fluid:
The lower the pH the more *acidicthe solution,
the higher the pH the more alkaine/basic the solution,
Pure water has a pH of 7 and is neutral
What is the pH of:
- skin
- blood
- vagina
- stomach
- small intestine
- saliva
Skin around 5 Blood- 7.35 Vagina- less than 4.5 Stomach- 1-2 Small intestine 6-6.5 Saliva 6-6.5
Explain the role of natural killer cells in the second line of defence:
Natural killer cells are a type of lymphocyte (white blood cell) part of the innate immune system.
Made in the bone marrow, once it has matured it comes out and circulates looking for abnormalities and kills it.
Kill them off before they turn into a cancer
Explain action of compliment in the second line defence system:
Is a set of plasma proteins that complement all aspects of the immune response
-they promote phagocytosis, inflammation and cell lysis
Bunch of plasma proteins/ chemicals that enhance the second line defence
Explain interferon in the second line defence:
A type of cytokine (chemical) that interferes with viral replication and activates immune cells such as NK, macrophages
What is inflammation in the second line defence of the immune system:
It is a localised response to the area of damage.
The damaged cells will send chemical messages,
the body responds with inflammation
This process is supported by phagocytosis
Brief overview of the process of inflammation:
Stage 1: vasodilation
- Dead or dying cells release chemical mediators. (Increased vessel diameter, blood flow and permeability of capillaries)
- cells and chemicals leave the capillaries and enter the tissues
- removal of toxic products and dead cells/debris
- explains swelling, redness and heat
Stage 2: phagocyte migration
- neutrophils are first on site (attracted by chemotaxis, fight hard die young)
- then monocytes come (once in the tissue they mature into macrophages or big eaters)
- dead phagocytes, damaged tissue, pathogens, debris= pus
Stage 3: repair
Repair cannot occur until the source of injury (injurious agent) is removed
-by mitosis and scar formation
-inflammation is essential for healing
What is the purpose of inflammation:
To destroy and remove antigens
It limits effects of injurious agents
It cleans up dead tissue and debris
It promotes healing
Explain the role of fever in the body:
Its a non-localised or systemic response where the temperature in the hypothalamus resets to attain temp over 37.2
When your body temp rises wbc become more active. Increased metabolism for healing Harder for pathogens to survive Suppress bacterial activity A fever for too long can be detrimental
Explain the role of the third line defence:
The third line defence is an acquired or specific body defence
Aims to kill/destroy pathogen by making antibodies and developing ‘memory’
Its specific
The host has to be exposed to the pathogen first
The pathogens has surface antigens
Describe the action of antigens as “triggers” for b and T cell activation:
Finish answer
Where is Calcitonin produced and what is its function?
Calcitonin slows down the activity of the osteoclasts found in the bone
What is glucagon and where is it produced?
Produced in the pancreas and it causes the liver to convert stored glycogen into glucose which is released into the blood stream
Where is growth hormone (GH) produced and what is its function:
Produced in the anterior pituitary it stimulates the growth of essentially all tissues of the body including bone
Distinguish between exocrine and endocrine glands:
Exocrine glands:
Secrete products into ducts which empty into body cavities or body surfaces
E.g sweat, oil, mucous, digestive, salivary, mammary
Endocrine glands:
-secrete products (hormones) directly into bloodstream i.e no ducts
E.g hypothalamus, pituitary, thymus, pancreas, thyroid, parathyroid, adrenal, pineal etc
How do hormones synthesised in the hypothalamus reach the anterior and posterior pituitary?
Anterior pituitary communicate via hormones (hypothalamus produces hormones which travel through the blood and
Posterior pituitary communicate via neurons
What is the difference between trophic and inhibitory hormones released from the hypothalamus
Trophic hormones : are the hormones that work on other glands that tell the gland to release their hormones
Inhibitory hormones: tell the gland to stop release that hormone
Which hormones come from the hypothalamus?
Growth hormone releasing hormone (GHRH) -trophic
Thyroid releasing hormone (TRH) -trophic
Thyrotropin-releasing hormone (TRH) -trophic
Prolactin releasing hormone (PRH) -trophic
Prolactin inhibiting hormone (PIH) -inhibitory
Somatostatin/ growth hormone inhibiting hormone (GHIH) -inhibitory
It also produces oxytocin and antidiuretic hormone but does not release it, it is stored and released by the posterior pituitary gland
What is the anterior pituitary gland and what hormones does it secrete?
The anterior pituitary gland is under the control of the hypothalamus
It produces and secretes:
- human growth hormone (hGH) in response to GHRH or GHIH from the hypothalamus
- thyroid stimulating hormone (TSH) in response to thyrotropin-releasing hormone (TRH) from hypothalamus
- follicle stimulating hormone (FHS)-in response to gonadotrophin from hypothalamus
- luteinising hormone (LH) -in response to gonadotrophin from hypothalamus
- prolactin (PRL) in response to the PRLRH from hypothalamus
- adenocorticotrophic hormone (ACTH) in response to corticotrophin releasing hormone from hypothalamus
FHS
Stimulates follicles, affects ovaries and testes, in ovaries causes growth of follicles and estrogen in women and sperm production in men
LH
Regulated by GnRH and feedback systems
Affects ovaries and testes: cause ovulation in women, testosterone secretion in men
Prolactin PRL
Regulated by prolactin releasing/ inhibiting hormone
Produce milk
Affects mammary glands and testes: synthesis of milk in breast feeding women
ACTH
Regulated by CHR and feedback systems
Works on the adrenal glands (on top of your kidneys)
Tells your adrenal glands to release its hormones
Hormone regulation by feedback systems using TRH as an example
- Hypothalamus releases TRH which acts on the ant pit gland
- Ant pit gland responds by releasing TSH which acts on the thyroid gland
- Thyroid gland responds by releasing TH into the blood stream
- The TH acts on target tissues
- Abundance of TH in the blood feeds back to ant pit gland to stop releasing TSH feeds back to hypothalamus to stop releasing TRH
Posterior pituitary gland:
Does not synthesise hormones, but stores and secretes then when prompted to do so
Hormones:
-oxytocin (OT)
Affects uterus, mammary glands, stimulates smooth muscle contractions eg labour and milk secretion, promotes affection/ bonding
-antidiuretic hormone ADH
Affects kidneys —> promotes water retention
The thyroid gland
Located in the throat, anterior to the trachea
Responds to TSH (anterior pituitary) to release TH
Increases metabolism, oxygen consumption, heat, heart rate
Overactive thyroid skinny, gittery, hot
Cold all the time, fatigue, fat, etc
Important for metabolism
Thyroid gland also releases calcitonin: promotes the re-uptake of calcium from the blood to be deposited as bone when blood calcium levels are too high.
Calcitonin helps increase calcium absorption in gut, parathyroid hormone does the opposite so that are antagonist
The adrenal gland
Sits on top of the kidney
Responds to ACTH
Two parts: cortex and medulla
Cortex: (steroids/ the corticoids)
- mineralcorticoids
- glucocorticoids
- androgens
Medulla:
- epinephrine (adrenaline)
- norepinephrine (noradrenaline)
The adrenal cortex hormones
Mineralcorticoids:
One of them is aldosterone which causes the reabsorption of sodium, and therefor h2o because it tries to follow the solute
Conserves water
Glucocorticoids:
Cortisol, corticosterone, cortisone
—> protein and lipid breakdown, formation of glucose and resistance to stress, anti inflammatory effects
Androgens:
Stimulates the growth of pubic and axillery hair
May contribute to sexdrive
Converted to testosterone in males, estrogen in females
The adrenal medulla hormones
Epinephrine
Sympathetic NS
Norepinephrine
Increase in alertness, anxiety, fear, prepares the body for physical activity.
The pancreas
Is both and endocrine and an exocrine gland
As an endocrine gland it release glucagon and insulin
As an exocrine gland it releases digestive enzymes that help digest your food
Glucagon
Promotes release of glucose breaks down fats to increase blood glucose, when glucose levels go down glucagon is release to make glucose levels go back up it restore some stored glucose to make levels go back up
Insulin :
released after you have eaten
Absorb glucose and stimulates muscles cells to store glycogen and fat and decrease blood glucose levels
These two hormones work together to regulate blood glucose levels making sure its not too high and not too low
The gonads
-ovaries
Estrogen, progesterone, relaxin and inhibin
Regulates reproductive cycle maintain pregnancy and prepare mammary glands for lactation
Testes
Testosterone and inhibin
Masculinising hormones, regulating spermatogenesis and development of male secondary sex characteristics
What’s the difference between the nervous system and the hormonal system in terms of speed?
The nervous system is fast, there are dedicated neural pathways, which induce a fast electrochemical response
The hormonal system has no dedicated pathways, chemicals are released into the blood stream, effects are widespread and sustained, response is relatively slow
