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BIO1OOS > Week 5 - The Integumentary System > Flashcards

Week 5 - The Integumentary System Flashcards

1
Q

What is the tissue type of the epidermis?

A

Stratified squamous epithelia

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2
Q

What is the tissue type of the dermis?

A

Dense irregular connective tissue

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3
Q

List the 4 different cell types found in the skin and their functions

A
  • Keratinocytes - Produce keratin which protects the cells from the external environment
  • Melanocytes - produce melanin which protects the skin agaisnt UV radiation
  • Langerhans cells - Are dendritic cells which phagocyte foreign substances.
  • Merkel cells - sensory receptors for fine touch
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4
Q

What layer of the epidermis are the 4 different cell types found in?

A
  • Keratinocytes - All layers
  • Melanocytes - stratum basale
  • Langerhan cells -All layers (mainly spinosum)
  • Merkel cells - stratum basale
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5
Q

What are the layers of the epidermis?

A
  • Stratum corneum
  • Stratum lucideum
  • Stratum granulosum
  • Stratum spinosum
  • Stratum basale
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6
Q

What are the two layers of the dermis and what type of connective tissue are they made from?

A
  • Papillary layer - areolar loose CT

* Reticular layer - dense irregular CT

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7
Q

Where are hair follicles found and not found?

A

Hair follicles are located all over the body except for the lips, palms of hands and soles of the feet.

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8
Q

How is hair structurally different from the epidermis?

A

The keratin in hair cells is tougher and more durable.

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9
Q

What are the functions of hair?

A
  • Increase sensation
  • Helps prevent heat loss
  • Protects the skin for UV radiation
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10
Q

How is hair colour determined?

A

By the amount and type of melanin produced in the outer layer of the hair shaft.

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11
Q

How are goosebumps formed?

A

Erector pili muscles contract causes the hair to stand up

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12
Q

Where are sweat glands found on the body?

A

All over the body except for the nipples and parts of the genitalia.

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13
Q

What makes up sweat?

A

Water, salts and wastes (urea)

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14
Q

What is the function of sweat?

A

Evaporation of sweat has a cooling effect on the body.

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15
Q

Where are sebaceous glands found?

A

All over the body except for the palms of the hand and soles of the feet.

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16
Q

What is sebum and what is its function.

A

Is an oily lubricant that waterproofs the skin and hair and helps protect against microbial growth.

17
Q

What stimulates sebaceous glands and when is their stimulation most active?

A

Hormones - puberty

18
Q

List and describe the three types of protection that the skin offer

A

• Physical barrier
• Keratanised layer of dead skin cells protects against
infection
• Chemical barrier
• Skin secretion - sebum creates a low pH
environment that inhibits bacterial growth
• Biological barrier
• Langerhan cells - phagocyose and destroy foreign particles

19
Q

How does the skin regulate body temperature when we get HOT?

A
  • Vasodilation of blood vessels close to the skins surface

* Sweat glands secrete sweat onto the skin which evaporates to help dissipate body heat

20
Q

How does the skin regulate body temperature when we get COLD?

A
  • Vasocontriction of blood vessels close to the skin surface to redirect blood flow to the bodies core.
  • arrector pilli contracts causing the hairs to stand on end and trap warm hair close to the skin
21
Q

What are the different sensory receptors found in the skin and briefly list their function

A
  • Meissners corpuscles - fine touch
  • Pacinian corpuscles - deep touch
  • Bare nerve endings - pain and temperature
22
Q

How is vitamin D produces and what is its function?

A

It is produced by modified cholesterol molecules located in the epidermal cells - involved in calcium metabolism

23
Q

What kind of wastes are eliminated by the body via sweat?

A

Nitrogenous wastes (ammonia, urea and uric acid) are eliminated from the body via sweat.

24
Q

What are the four key characteristics of skeletal muscle?

A
  • Excitable - ability to respond to stimuli
  • Extensible - ability to lengthen
  • Contractible - ability to shorten
  • Elastic - recoil back to a passive length
25
Q 
Identify the following structures of a skeletal muscle:
• I band
• H zone
• A band
• Z disk
• M line
A

[Google Images]

26
Q

What is the functional unit of a skeletal muscles? why?

A

Sarcomere - they are the smallest contractile unit

27
Q

Describe the organisation and basic function of myosin, actin, tropomyosin and tropinin.

A
  • Myosin makes up the thick filament - containing myosin heads that bind to actin to produce contraction
  • Actin - Makes up the thin filament and contains myosin binding sites.
  • Tropomyosin - located on the thin filaments and blocks mysosin binding sites
  • Troponin - bound to tropomyosin and free mysoin binding sites when it is bound to calcium
28
Q

Briefly describe the 4 steps involved in the cross bridge cycle

A

1) Cross bridge formation -calcium ions released from SR bind troponin which allows myosin head to bind actin to form a cross bridge.
2) Power stroke - ADP is released and the mysoin head pivots to slide the actin towards centre of sarcomere
3) Cross bridge detachment - Binding of ATP causes myosin head to detach from actin
4) Reactivation of myosin head - ATP is hydrolysed which activates the myosin head so the cycle can repeat
NOTE: Cycle ends when calcium is actively transported back into the SR

29
Q

Briefly describe the six steps involved in the transmission of ADH across the NMJ

A

1) Action potential arrives at the axon terminal of the motor neuron
2) Voltage gated Ca2+ channels open which cause influx of Ca2+
3) Ca2+ causes the exocytosis of acetylcholine (ACh)
4) ACh binds to receptors located on the sarcolemma
5) Binding of ACh to ion channels results in the influx of Na+ into the muscles fibres which depolarises the membrane
6) effect of ACh is terminated by diffusion, degradation and re-uptake

30
Q

Explain excitation - contraction coupling

A

1) Binding of ACh to ligand gated Na+ channels creates an action potential which is propagated along T-tubles to the Sarcoplasmic reticulum
2) SR releases calcium
3) calcium binds to troponin which removes the blocking effect of tropomyosin and uncovers the myosin head binding sites on the actin filament.

31
Q

What are the 3 stages involved in skeletal muscle contraction?

A

1) Membrane excitation
2) Excitation - contraction coupling
3) Sliding filament mechanism

32
Q

What is the function of intercalated in cardiac muscle?

A

They bond cardiac cells and help synchronize the contraction of the heart

33
Q

What junctions are present in intercalated discs?

A
  • Gap juctions - allow for the movement of ions to transmit current across the heart
  • Desmosomes - to keep cardiac cells from separating during contraction
34
Q

What does the term autorhythmicity mean?

A

Is the ability to spontaneously depolarise without external neural input.

35
Q

Instead of troponin, smooth muscles contain________?

A

Calmodulin

36
Q

List and describe the three phases of cardiac muscle contraction

A

1) Depolarisation - Voltage gated Na+ channels in the sarcolemma open allowing the influx of extracellular sodium
2) Plateau - Depolarisation is transmitted down the T-tubules to the sarcoplasmic reticulum (SR) which causes it to release Ca2+ - also opens Ca channels in the sarcolemma.
3) Repolarisation - Is due to Ca2+ channels closing and K+ channels opening which brings membrane potential back to resting.

37
Q

Why is the 2nd stage of cardiac contraction called the plateau phase?

A

Because the release of calcium from the sarcoplasmic reticulum prolongs depolarisation.

38
Q

What type of channel become inactivated in the repolarisation phase of cardiac muscle contraction? What type of channel opens?

A

Ca2+ inactivated

K+ open

BIO1OOS (12 decks)

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