30 Short Answer questions

Question 1

1) positive FB mechanism and example

Answer 1

Positive FB mechanisms are stimulatory systems
Enhance changes in variables, by generating effector response that amplifies initial change
effectors cause change in variable to move further away from set point and this continues until stimuli is ultimately removed.

For example, positive feedback mechanisms used in childbirth
uterine contractions push baby onto cervix.
Stretch receptors of cervix detect pressure and send nerve impulse to hypothalamus which responds by releasing oxytocin.
Oxytocin increases strength of contractions.
positive feedback cycle continues until baby is born, and pressure on stretch receptors is removed

Question 2

2) body chemistry / homeostasis / water - role it plays in our body in general

Answer 2

1) Good solvent
water is polar (ends of the molecule have slight positive / negative charge)
polarity of water makes it a good solvent - evenly distributes broken ionic compounds,

2) thermoregulation-
water is abundant compound in our body
unique properties of water enable it to withstand changes in temp without changing internal body temp
- high heat capacity - water absorbs / releases a lot of heat energy, before its own temp changes . heat can also be transferred around the body by water in blood
-high heat of vapourisation - a lot of heat energy is required to convert liquid to gas (condensation), thus sweating is a very effective way to cool hte body

Question 3

describe physical processes happening in our body - diffusion, osmosis, exocytosis- what is difference btween diffusion + osmosis, which is active + passive

Answer 3

Passive (no ATP used)
- movement of substance from [h] to [l] conc. down membrane gradient. Phospholipid tails prevent free movement of substances, but passive diffusion can occur if substances are lipid soluble (hydrophobic), small enough to pass through membrane channel, assisted by carrier protein

• Simple Diffusion - Passive transport of substance from [h] to [l] concentration down membrane gradient.
  substances that are non-polar / lipid soluble - e.g. alcohol, Oxygen
• Osmosis- passive transport of water from [h] to [l] conc down osmotic gradient. ‘pockets’ in the bilayer enable water to move through, despite the hydrophobic tails
• Facilitated Diffusion - passive transport of substances from [h] to [l] concentration across plasma membrane, facilitated by carrier or channel proteins
• Filtration- passive transport of water + solutes through cell membrane from [h] to [l] pressure.

Active
use ATP to move substances across cell membrane against conc. graditients
- Protein pumps -
- primary - ATP used to change shape of protein, so the protein can ‘pump’ solute across membrane
-secondary - tranport of molecule against conc. gradient, using other forms of energy than ATP (e.g. Conc. gradient of another molecule being tranported in other direction)

e.g. Sodium / Potassium pump uses ATP to keep Na unnaturally high in ECM and K unnaturally high in ICM (at resting state)

vesicular transport - transport of fluids with macromolecules across Cell membrane
vesicles surround the fluid to be transported
-exocytosis- vesicle binds to cell membrane and releases contents outside cell
endocytosis- susbtance outside cell is ‘wrapped’ in a bit of membrane, and brought into cell

Question 4

4) structure of cell - organelles - not mitochondria - think about RER + SER, what is difference between these .

Answer 4

Endoplasmic Reticulum-

• Organelle in eukaryotic cell
• forms series of membranes

RER-
- membrane structure that has ribosomes attached externally
Function- site of Protein synthesis, transport to Golgi Apparatus via transport vesicles
Found in muscle cells that need lots of protein

SER
- membrane structure that has smooth appearance (no ribosomes attached)
Function - synthesize lipids, cholesterol, phospholipids, metabolise drugs and toxins
transport to Golgi apparatus via transport vesicles
Found in testes to produce testosterone

Question 5

compare meiosis and mitosis

Answer 5

meiosis

• occurs in gamete cells only (ovum and spermatozoa)
• purpose- sexual reproduction - to increase genetic variability
• 2 cell divisions
• outcome-
• 4 haploid cells, each genetically different to each other, containing half # of chromosomes as original nucleus
• • • mitosis
• occurs in all body cells except gametes
• purpose- cell growth, repair, regeneration
• 1 cell division
• outcome-
• 2 diploid cells- both genetically identical to the original nucleus

Question 6

phases of uterine cycle

Answer 6

menstrual phase day 1-5
- shedding of functional endometrial layer

Proliferative Phase day 6-14

• proliferation of endometrial cells (size + number of cells) to rebuild endometrial wall
• enlargement and growth of endometrial glands
• increase blood supply to glands

Secretory Phase day 15-28

• cont proliferation of endometrial cells
• cont. enlargement of endometrial glands and increased blood supply
• endometrial glands secrete glycogen into uterine cavity (glycogen will nourish early embryo)

Question 7

label a picture of female reproductive system (frontal view, not sagittal view- internal)- i.e. fallopian tubes. structure + function- 4 main parts

Answer 7

1) ovaries
- site of oogenesis (egg production))
- produce + secrete oestrogen + progesterone - help maintain early pregnancy
- release secondary oocyte at ovulation
- regulated by hormones from hypothalamus / APG

2) Fallopian tube
transport fertilised ovum (Sometimes secondary oocyte ) to uterus
made up of fimbriae (hang over ovaries), infundibulum (opening into FT), ampulla (Widest bit where fertilisation normally occurs) and isthmus (narrow exit)

3) Uterus
- receive, retain, nourish fertilised ovum
- 3 parts (fundus / body / cervix)

4) Vagina
- forms birth canal
- receives penis and ejaculate

Question 8

Tissue repair- 3 stages of tissue repair

Answer 8

1) Inflammation
injured cells release inflammatory chemicals:
- dilate capillary / increase blood flow
-increase capillary permeability to allow White blood cells + clotting substances can seep into injured tissue
- WBC’s clean up debris / fight + prevent infection at site
- blood clotting substances stop blood loss, and hold edges of wound together to isolate site
- pain receptors triggered

2) organisation
macrophage digests original blood clot
Blood clot replaced by granulation tissue which
- contains capillaries that lay down new capillary bed
- produce growth factors and new collagen fibres

3) regeneration and / or fibrosis
regeneration - uninjured cells near injury site undergo mitosis to regenerate new cells
cells migrate to injury site and replace destroyed cells

fibrosis- if there are insufficient uninjured cells for full regneration, or cells are limited in their ability to regenerate, then injured tissue is replaced with fibrous tissue (forming scar tissue)

Question 9

describe 4 types of tissues, and their functions

Answer 9

1) muscular tissue
description- composed of muscle cells capable of excitability, contractilty, extensibility, elasticity
3 types - skeletal, cardiac, smooth.
functions-
stabilise joints
heat production
produce movement (move skeletal bones / substances through hollow organs)
maintain posture + balance

2) Epithelial tissue
description - covers body surfaces, lines body cavities, forms glands. densely packed cells - classified by shape / arrangement of cells
Avascular - supported by connective Tissues. high capacity for regeneration
Function- protection, surface for secretion + absorption, excretion

3) Connective Tissue
description- most abundant and diverse tissue.
made up of cell + matrix (ground substance (unstructured material found btwn cells and contains the fibres) + fibres to give support and strength)
includes blood, bone, cartilage, tendons + ligaments, adipose
function- binding + support, protection, insulation, transport

4) Neural Tissue
main tissue of nervous system
made up of neurons (Send and receive impulses )+ neuroglia (support neurons )
Function-
- rapid communication btwen cells
- control body functions
-coordinate many homeostatic functions

Question 10

integumentary system- what are main functions

Answer 10

1) protection (mechanical - thick waterproof layer / chemical- acidic secretions inhibit bacteria / biological - cells within skin attack and destroy foreign microbes )
2) metabolic function (produce melanin and vit D)
3) blood reservoir - 5% blood vol circulates under skin and can be moved to other organs as req
4) Body temp regulation (dermal arterioles can vasodilate / constrict to bring blood to surface, sweat can reduce heat)
5) excretion of waste
6) site of cutaneous sensory nerve receptors (Touch, pressure, temperature, pain)

Question 11

microflora of body - which areas are normal for microflora, which are not.

Answer 11

Normal (skin, upper resp tract, mouth + gastrointestinal system (large intestine), external eye, urethra, and ear, reproductive system (mainy vagina)
abnormal ( blood, CSF, urine, semen, internal organs, brain, sinal cord, bone marrow, glands, organs, few in the lower resp tract, few in the stomach, internal eye, kidney, ureter, bladder, middle + inner ear, ovaries and testes)

Question 12

What are 3 benefits of microflora?

Answer 12

1) Crowd out pathogenic bacteria -
2) stimulate immune response improving defence against pathogens
3) help rpocess waste in gut

Question 13

13) viruses- why do we all them intracellular parasites - think about how they reproduce

Answer 13

Viruses are acellular and lack genetic info and enzymes to reproduce / grow by themselves
they thus enter a host cell and use it’s resources to produce viral components

Question 14

14) NS- what are different types of neuroglia in our body

Answer 14

Neuroglia (‘supporting cells’ of the NS)

Neuroglia in CNS

• Astrocytes - allow nutrient exchange between neurons / blood vessels, form part of the BBB (blood-brain barrier)
• Microglia- monitor health of neurons / remove dead + injured neurons
• Epyndymal cells- line cavity in brain + spinal cord, circulate CSF
• Oligodendrocytes- produce myelin which insulates neurons in CNS / increaess conduction speed

Neuroglia in PNS

• Satellite cells- surround and support neuron cell bodies
• Schwann cells - produces myelin which insulates neurons in PNS / increases conduction sped)

Question 15

15) label the neuron - 6 things

Answer 15

1) dendrites
2) cell body + nucleus
3) axon hillock
4) axon
5) axon terminal
6) myelin sheath (surrounded by oligodendrocyte or schwann cell)

Question 16

17) Fill in the sentence on Neurotransmitters

Neurotransmitters are packaged in ……..within ……. …..of the axon terminal membrane leads to opening of …..channels in the axon terminal membrane and …..ions flow in across the axon terminal membrane. This stimulates the vesicles containing neurotransmitters to move to the ……membrane and release the neurotransmitters by ……..into the synaptic cleft. Neurotransmitters diffuse across the synaptic cleft to attach to ……on the post-synaptic membrane. This triggers ………across that membrane.

Answer 16

Neurotransmitters are packaged in vesicles within axon terminals. Depolarisation of the axon terminal membrane leads to opening of calcium channels in the axon terminal membrane and calcium ions flow in across the axon terminal membrane. This stimulates the vesicles containing neurotransmitters to move to the pre-synaptic membrane and release the neurotransmitters by exocytosis into the synaptic cleft. Neurotransmitters diffuse across the synaptic cleft to attach to receptors on the post-synaptic membrane. This triggers local graded potentials across that membrane.

Question 17

18) Structure of NS- ANS / Somatic. describe divsions of SNS/ PNS

Answer 17

Motor division is made up of

• Somatic system under voluntary control
• ANS under involuntary

Effector for somatic nervous system is Skeletal system
Effector for ANS is smooth + cardiac muscle and endocrine glands

ANS subdivided further

• Sympathetic NS- ‘fight / flight’
• Parasympathetic NS- rest / digest

Question 18

19- Fill in map of brain - 6 things

Answer 18

cerebrum (4 lobes)

• frontal
• parietal
• temporal
• occipital

Cerebellum

Brainstem

Diencephalon

Question 19

explain where certain things are in particular lobes. e.g. movement, smell, vision

Answer 19

Cerebrum-

• Frontal - motor cortex / integrative functioning
• Parietal- Somatosensory + association cortex
• Occipital- Visual cortex
• Temporal- Olfactory, Gustatory, Visceral, Auditory, vstibular

cerebellum
- balance / smooth planned motor movement

Brain stem- reptilian brain / basic life functioning

Question 20

20) CNS- Meninge layers- list the meninge layers

Answer 20

dura mata - outer most thickest layer, directly under skull and vertebral column.

arachnoid mater (middle layer)- thin layer- spiderweb like appearance from CT projections. has subarachnoid space that contains CSF to help cushion brain

Pia mater- adheres directly to brain + spinal cord. Carries blood into CNS and helps contain CSF

Question 21

21) Hormones- 3 hormones, state target tissue, effect, mode of regulation

Answer 21

See https://www.brainscape.com/p/409BC-LH-C1O37

Question 22

22) descibe hormones from APG that are releaesd and have influence on Ovarian cycle.

Answer 22

2 Gonadotrophin Hormones -
-Releaesed from APG
regulated by Gonadotrophin Releasing Hormone (from hypothalamus)
- Hormonal stimuli (negative feedback from oestrogen / progesterone levels)
Target ovary and regulate ovarian cycle

1) Follicle Stimulating Hormone
- Stimulate Follicular Phase
1) development of follicle into secondary and then mature follicle
2) stimulate oocyte to become secondary oocyte via miosis I, start and then halt meiosis II

Luteinising Hormone

• Triggers ovulation
• Stimulates erupted follicle to transform into corpus luteum and secrete progesterone and some oestrogen

Question 23

23) describe hormones involved in blood levels- insulin and glucagon

Answer 23

Insulin - reduces Blood glucose levels
*targets most body cells (esp liver, fat and skeletal muscle_
*Effect
-stimulate glucose uptake into cells (esp. fat and skeletal muscle)
- stimulating conversion of glucose to glycogen (glycogenesis) in muscle + liver
-stimulating conversion of glucose to fat (to be stored in fat cells)
- inhibit glycogenolysis and gluconeogenesis
* regulated by humoral stumuli (glucose levels in blood )

Glucagon - increases blood glucose levels
Targets liver
effect
-converting glycogen to glucose (glycogenolysis)
-gluconeogenesis (create glucose from Amino acid and glycerol)
-stimulate release of glucose from liber
regulated by humoral stimuli (Blood glucose levels too low),

Question 24

24) list main functions of skeletal system

Answer 24

1) Allow movement - skeletal muscles pull on bone which act as levers allowing movement
2) Protection- some bones overlie soft tissue /viscera - e.g. cranial bones
2) Haematopoiesis (produce blood cells in bone marrow)
3) mineral an fat storage (Ca + ph stored in bones, fat stored in bone marrow)

Question 25

25) intramembranous / endochondral ossification -what are processes and differences there

Answer 25

1) intramembranous ossification- 
bone development (ossification) that occurs directly within fibrous CT membrane 
occurs in flat bones (e.g. skull/ clavicle)

osteoblasts invade fibrous tissue and begin screting osteoid, eventually forming flat bone structure.

2) endochondral ossification
occurs within cartilage intermediate
majority of bones (long, irregular,

bone is formed using a hyaline cartilage intermediate that forms a ‘preform’ in utero, that is roughly shape of completed bone.

cartilage continues to grow outward, whilst osteoblasts continue to replace cartilage with bone- until adult shape and size is obtained

Question 26

26) what is bone remodelling

what are 2 main factors that cause bone remodelling

Answer 26

bone remodelling is:

• lifelong process
• continuing process of bone destruction / synthesis, so mature bone tissue is removed from the skeleton and new bone tissue is formed

2 factors

1) Hormones-
Calcitonin helps reduce bone breakdown (inhibits osteoclasts/ stimulates osteoblasts to build bone), parathyroid stimulates bone breakdown (stimulates osteoclasts)
2)Mechanical stress -
bones remodel in response to demand from pull of muscles / force of gravity. Bone is thickest in areas of most stress (thicker attachment site the more it’s used).

Question 27

Describe 3 synovial movements and give an example

Answer 27

1) Flexion - angular movement that decreases angle at joint, bringing bones closer together (e.g. bending knee)
2) Extension- angular movement that increases angle at joint-( e.g. straighten a flexed neck)
3) Abduction - movement away from midline of body, along frontal plane (e.g raise arm laterally)

Question 28

Complete sentence on muscle contraction

A neurotransmitter binds to ………in the ………fibres. This generates an …..within the muscle and causes the receptors of the muscle fibre to release …..ions. The calcium ions binds to …..and this causes ………to slide along the actin, exposing the ……….binding sites on actin. The myosin heads bind to actin when their binding sites are exposed, forming a …….The myosin heads flex, pulling the thin filaments towards the centre of the ……..and this shortens the …….., causing the entire muscle fibre to shorten.

Answer 28

A neurotransmitter binds to receptors in the skeletal muscle fibres. This generates an action potential within the muscle and causes the sarcoplasmic reticulum of the muscle fibre to release calcium ions. The calcium ions binds to troponin and this causes tropomyosin to slide along the actin, exposing the myosin binding sites on actin. The myosin heads bind to actin when their binding sites are exposed, forming a cross bridge The myosin heads flex, pulling the thin filaments towards the centre of the sacrcomere and this shortens the sarcomeres, causing the entire muscle fibre to shorten.

Question 29

list 2 ways that smooth muscle contraction differs from skeletal muscle contraction

Answer 29

Diffuse junction (Rather than NMJ)
Smooth muscle innervated with autonomic sensory neurons that have varicosities at their Presynaptic junction 
varicosities expel contents of vesicles into wide synapitc cleft so that NT are spread across wider area of smooth muscle

Smooth muscles lack myobrils (rod like structures that run length of skeletal muscle), and has thin / thick myofilaments that criss cross each other and arranged diagonally (hence doesn’t appear striated).
tihs causes ‘corkscrew’ twisting the muscle cell when it contracts, enabling smooth muscle to have slower more economic contractions

Question 30

list 2 characteristics of muscle tissue

Answer 30

1) Contractility- ability to shorten, with adequate stimulation.
2) Extensibility- ability to extend / stretch ( when not contracting)