Unit 9 - Physiology

System integration

Integrated activity of all the organ systems

Emergent properties

Describes properties which emerge in a complex system, which are not seen in the individual components making up the system

• permeable

• thin tissue layer

• moisture

• large SA:V

• concentration gradient

Properties of gas exchange surfaces (5)

• dense network of blood vessels

• continuous blood flow

• ventilation

• separation oxygenated/deoxygenated blood

Maintenance of concentration gradients in animals (4)

Pharynx

A

Epiglottis

B

Trachea

C

Capillary

D

Alveoli

E

Bronchioles

F

Bronchus

G

Larynx

H

• presence of surfactant

• branched bronchiole network

• extensive capillary beds

• high surface area

• thin membrane

Alveoli adaptations (5)

• flattening of cells

• microvilli

• invagination

Adaptations to increase SA:V ratio (3)

Relaxed

A

Contract to pull rib cage in and down

B

Contract to lift rib cage up and out

C

Relaxed

D

Expand

E

Move back in and down

F

Contracts and pulls down

G

Relax, arch back up

H

Relaxed

I

Used if forced breathing, relaxed otherwise

J

Increased

K

Decreased

L

Decreased

M

Increased

N

Inspiratory reserve volume

A

Tidal volume

B

Expiratory reserve volume

C

Residual volume

D

Vital capacity

E

Total lung capacity

F

Reduced diffusion distance

A

• secreting surfactant

• medium that gases can dissolve

• reduced surface tension

B, C, D

Alveolus

A

Type I pneumocytes

B

Type II pneumocytes

C

Capillary

D

• walls are 1 cell thick

• lumen is 1 blood cell wide

• fenestrations

Adaptations of capillaries (3)

• Thick tunica media to help artery recover when stretched and withstand high pressure

• Muscle within tunica media pushes blood

• Smaller lumen than veins to maintain blood pressure

Adaptations of arteries (3)

• thinner tunica media

• flexible wall

• large lumen

• valves

Adaptations of veins (4)

Atherosclerosis

hardening and narrowing of the arteries due to the deposition of cholesterol

Tissue fluid

Formed when blood plasma is pushed out of the capillary walls into the surrounding tissue aka interstitial fluid.

Lymph

colorless fluid containing excess tissue fluid/white blood cells/proteins. Functions to help transport immune cells + remove foreign particles/toxins

1. Atrial systole

2. ventricular systole

3. diastole

3 stages in cardiac cycle

Superior vena cava

A

Aortic valve

B

Pulmonary valve

C

Right atrium

D

Tricuspid valve

E

Inferior vena cava

F

Right ventricle

G

Left pulmonary artery

H

Left pulmonary veins

I

Left atrium

J

Bicuspid valve

K

Left ventricle

L

Septum

M

Myogenic

The ability of cardiac muscle to beat without external stimulation.

Sarcomeres

The basic contractile unit of a muscle, containing actin and myosin. Gives muscle striated appearance

Synovial joint

Joints that are enclosed in a joint capsule, where bones are separated by a fluid-filled cavity, allowing free movement between the bones.

Neuronal synapses

A small gap at the end of a neuron that allows a signal to pass from one neuron to the next.

Neuromuscular junction

A specialised synapse that connects a motor neuron to a muscle fibre

Neuroglandular junction

A small gap between a neuron and a gland.

Failed initiations

Not enough Na+ influx into post-synaptic neuron, cannot generate action potential

Threshold potential

The critical level to which a membrane potential must be depolarised to initiate an action potential

Saltatory conduction

The skipping motion of the action potential from one node of a myelinated axon to another.

Hyperpolarization

A change in the cell’s membrane potential that makes it more negative.

Summation

combined effect of the excitatory and inhibitory stimuli that are received from a number of presynaptic neurons and transmitted to the axon hillock (a specialized part of the cell body (soma) of a neuron that connects to the axon) of the postsynaptic neuron

All or nothing principle

This states that a stimulated nerve fibre either fires at full strength or does not fire at all

Epidermis

Outermost layer of skin. Protective barrier against external factors

Dermis

Contains blood vessels, hair follicles, sweat glands, sensory receptors

Thermoreceptors

Responsible for detecting change in temp

Meissner’s corpuscles

Detect light touch/low frequency vibrations

Nociceptors

Detect pain

Pacinian corpuscles

Detect deep pressure/high frequency vibrations

Ruffini endings

Detect skin stretch and continuous pressure

Free nerve endings

Detect pain/temp/itching

1. Cerebrum

   1. Largest part of brain

   2. Controls vision/hearing/touch/speech/thinking

   3. Initiates and coordinates movement

   4. Divided into 2 cerebral hemispheres

      1. Each divided into 4 lobes:

         1. Frontal lobe

         2. Parietal lobe

         3. Occipital lobe

         4. Temporal lobe

2. Cerebellum

   1. Back of head

   2. Voluntary muscular movements + balance + coordination

   3. 2 hemispheres

3. Brainstem

   1. Consists of midbrain + pons + medulla oblongata

1. _____

   1. Largest part of brain

   2. Controls vision/hearing/touch/speech/thinking

   3. Initiates and coordinates movement

   4. Divided into 2 cerebral hemispheres

      1. Each divided into 4 lobes:

         1. Frontal lobe

         2. Parietal lobe

         3. Occipital lobe

         4. Temporal lobe

2. ______

   1. Back of head

   2. Voluntary muscular movements + balance + coordination

   3. 2 hemispheres

3. _______

   1. Consists of midbrain + pons + medulla oblongata

Reflex arc

Pathway followed by reflex action.

3 roles of cerebellum:

1. Coordination of voluntary muscle movements

   • Timing + force of contraction of muscle groups

2. Maintenance of balance + posture

   • Uses inputs from proprioceptors + other receptors to bring in shifts inn body position

3. Motor learning

   • Ex. Playing cricket

3 roles of cerebellum:

1. Coordination of ______ _______ _________

   • Timing + force of contraction of muscle groups

2. Maintenance of _____ + ______

   • Uses inputs from proprioceptors + other receptors to bring in shifts inn body position

3. ____ learning

   • Ex. Playing cricket

peristalsis

movement of food down tract due to rhythmic contractions of muscles in waves

Quorum sensing

The regulation of gene expression in response to fluctuations in cell-population density.

Hormones, neurotransmitters, cytokines, calcium ions

4 types of signalling chemicals

Transmembrane receptors:

1. Binding of signalling chemical to outer side of transmembrane receptor → causes reversible changes to structure

2. Signal is amplified by triggering activation of protein kinases that phosphorylate many downstream proteins, causing chain reaction

3. Inner side (in contact with cytoplasm) becomes catalytically active + makes secondary messenger within cell (Ex. Cyclic AMP)

4. Protein kinases activated, that can phosphorylate proteins

5. Conveys signal to effectors within cell carrying responses

Transmembrane receptors:

1. Binding of signalling chemical to ____ side of transmembrane receptor → causes _____ changes to structure

2. Signal is _____ by triggering activation of ______ ______ that _________ many downstream proteins, causing chain reaction

3. Inner side (in contact with cytoplasm) becomes ______ active + makes ______ ________ within cell (Ex. Cyclic AMP)

4. Protein kinases activated, that can phosphorylate proteins

5. Conveys signal to _________ within cell carrying responses

Intracellular receptors:

1. Ligand passes through plasma membrane

2. Ligand binds to intracellular receptor

3. Active ligand-receptor complex

4. Complex can regulate gene expression 

Intracellular receptors:

1. Ligand passes through plasma membrane

2. Ligand binds to intracellular receptor

3. Active _____-____ _______

4. Complex can regulate gene expression 

Signal transduction cascade

Series of biochemical reactions that occur inside a cell in response to binding of a signalling molecule (like hormones/neurotransmitters) to its receptor on the cell surface

Insulin

Example of negative feedback mechanism

Blood clotting

Example of positive feedback mechanism

skin and mucous membranes

2 primary defence mechanisms against pathogens

Blood clotting process:

1. Activation + accumulation of platelets at site of injury

2. Platelets form a plug, sealing injury

3. Platelets + injured tissues release clotting factors (including Ca+)

4. When activated, clotting factors interact in cascade of chemical reactions

   1. Ex. Clotting factor "thromboplastin" + calcium ions convert prothrombin to its active state, thrombin

   2. Thrombin converts fibrinogen, a blood clotting factor normally dissolved in blood, to INSOLUBLE fibrin

5. Fibrin forms mesh over wound, trapping more platelets + red blood cells

6. Clot dries and shrinks over time, forming scab

Blood clotting process:

1. Activation + accumulation of _____ at site of injury

2. ____ form a ____, sealing injury

3. _____ + injured tissues release _____ ______ (including Ca+)

4. When activated, clotting factors interact in _____ of chemical reactions

   1. Ex. Clotting factor "_______" + _____ ions convert _______ to its active state, _______

   2. ______ converts ______, a blood clotting factor normally dissolved in blood, to INSOLUBLE _______

5. ______ forms ______ over wound, trapping more platelets + red blood cells

6. Clot dries and shrinks over time, forming scab

• Steps of phagocytosis:

  1. Recognition of pathogen by phagocytes: receptor molecules on plasma membrane of phagocytes recognize + bind to pathogen, triggering formation of pseudopodia

  2. Pseudopodia encircle target microorganism, then both protrusions seal --> resulting in formation of phagosome (vesicle)

  3. Phagosome undergoes maturation

  4. Phagosome fuses with lysosomes forming phagolysosomes that contain digestive enzymes originally present in lysosome

  5. Enzymes digest microbial components, then released from cell

Thus, Phagocytosis is the non-specific secondary line of defense

• Steps of phagocytosis:

  1. ______ of pathogen by phagocytes: receptor molecules on plasma membrane of phagocytes recognize + bind to pathogen, triggering formation of _______

  2. ________ encircle target microorganism, then both protrusions seal --> resulting in formation of _______ (vesicle)

  3. ______ undergoes maturation

  4. ______ fuses with _______ forming _________ that contain digestive enzymes originally present in lysosome

  5. Enzymes digest microbial components, then released from cell

Thus, Phagocytosis is the non-specific secondary line of defense

Overprescribing antibiotics

Unfinished treatment

Overuse in livestock

Causes of antibiotic resistance (3)

Zoonosis

An infection that can be transmitted from non-human animals to humans.

Spillover

when pathogens originally present in animal species (reservoirs) cross species barrier + enter humans

Examples of zoonosis:

1. Tuberculosis = Bacteria → Cattle → Humans

2. Rabies = Virus → Animal → Bite humans

3. Japanese encephalitis = Virus → Pigs/Waterbirds → Mosquito → Humans

4. COVID-19 = Bats → Pangolins → Humans

Examples of zoonosis:

1. Tuberculosis = Bacteria → ______ → Humans

2. Rabies = ____ → Animal → Bite humans

3. Japanese encephalitis = Virus → ____/Waterbirds → _____ → Humans

4. COVID-19 = Bats → Pangolins → Humans

DNA vaccine

Use plasmids to introduce gene encoding an antigen from a specific pathogen

Herd immunity

 Indirect immunity from an infectious disease which occurs when a large proportion of the population are immune to the infection either by vaccination or previous infection(s).