Term 1 midterm

L1-15

Homeostasis, or the ability to…

Maintain a stable internal environment

Homeostasis is preserved when…

our physiological mechanisms use energy to keep body conditions steady in spite of disruption

Homeostatic regulation of a biological variable requires 3 components:

1. Sensor

2. Integrator

3. Effector

Allostasis refers to the body's ability to…

Adapt (change) our set points, or our behaviour - to meet different conditions.

Behavioural allostasis:

When we voluntarily perform behaviours that alter a regulated variable away from its current set point

Physiological allostasis:

Our internal integrators can shift their set points during specific states

Both forms of allostasis are feed-forward meaning they…

anticipate a future physiological need

Select the right answer. Why?

B - t’s a behavior that prepares the body for the expected energy demands of the race.

feedback loops occur when…

change detected by a sensor triggers an effector response that changes the environment

Negative feedback loops…

return the controlled variable toward its set point

Positive feedback loops…

Enhance or amplify changes - each cycle moves the regulated variable from its initial set point

Select the right answer and why

A - allostasis adjusting to set point, positive feedback moves away from set point

explain the difference in 1. size 2. organization 3.function of bones in hand and foot

key idea?

1. hand has thinner bones and Foot has thicker bone

2. + 3. hand has better mobility for grabbing and food is better for weight bearing for walking

key idea: structure determines function

The exact features of a structure may reflect _____-___ between _____ competeing functions

trade-offs, multiple

The cell cycle describes….

The balance in a typical cell between cell division and ‘simply’ performing normal physiological functions

interphase:

cells spend most of their time in this phase and are not dividing

mitosis

term for cell division period

if cell regulation is disrupted, what occurs (3 steps)

1. abnormal cell division can occur

2. leading to tumours

3. becomes cancers

Tumours are

an area with an abnormal cell division rate

Cancer is…

When tumours move out of tissue origin and spreads to other parts of the body

Which answer is correct

D

The plasma membrane…

Separates the cytoplasm (inside) from the extracellular fluid

what ions are common within the ECF

NA and Cl

What are ions common within the ICF (cytosol)

K+

what is the concentration of Cl- in the ECF and is it higher or lower than the ICF (cytosol)

Cl- : 120mM

higher

The plasma membrane is a…

selectively permeable lipid bilayer which also contains integral membrane proteins (channels) with a variety of functions (ways to open)

The plasma membrane is selectively permeable meaning…

different molecules have different abilities to cross it

free diffusion:

small non polar (ex. co2, o2) molecules can cross plasma membrane without any protein assistance based off of concentration

Facilitated diffusion/transport

Movement with the help of membrane proteins

Passive transport… (2)

does not require atp to move materials across plasma membrane

• allows substances to move according to their concentration (electrochemical) gradients

Active transport…

uses stored energy to move ions or molecules against a concentration gradient

Primary active transport:

‘ pump’ protein directly uses ATP to move ions or molecules

Secondary active transport:

uses a gradient of one molecule (created using ATP) to move another molecule

Vesicular transport:

a specialized form of active transport that can move large molecules or many molecules at a time.

1. where does secondary active transport occur

2. where does facilitated diffusion occur

1. A

2. C

which statements are true

only D

Differentiation

Cells become different types of specialized cells by expressing different combinations of proteins

Polarization

different regions within the same cell become specialized to preform different functions

Name all the types of tissue:

1. epithelial tissue

2. connective tissue

3. muscular tissue

4. nervous tissue

_____ and ____ tissue contain highly specialized cells adapted for very specific physiological roles

Muscle and nervous tissue

Muscle tissue is…

able to contract and produce mechanical force

Nervous tissue is…

specialized to send and receive information in the form of electrochemical signals

_____ and ____ tissues are more diverse in their functions, their specializations, and where they are found

Epithelial, connective

Epithelial tissues….

lines surfaces and spaces in the body

Connective tissue…

typically fills or stiffens (supports) spaces in your body

which type of tissue is @ A and which of the 4 is not within the image

A = epithelial tissue

missing tissue would be nervous

Epithelium:

A sheet of connect epithelial cells attached to a basement membrane

epithelial tissues covers surfaces in your body such as (4)

1. external surfaces

2. internal cavities

3. passageways

4. secreting structures (mucus, sweat glands)

4 functions of epithelial tissue

1. provide physical protection

2. control permeability

3. provide sensation

4. produce specialized secretions

what are some basic features of epithelial cells (3)

They have

1. polarization

2. apical surface (contact with lumen

3. basolateral surface (in contact with ISF)

Cells within an epithelium are ____ to each other by proteins. A common method of this is ____ ____ which has small gaps between cells

Bound, tight junctions

Leaky tight junctions:

Allows paracellular (in-between) transport of water and solutes between lumen & ISF

Tight Tight junctions:

Does not allow paracellular transport between lumen & ISF

Simple epithelia means…

Stratified epithelia means…

one layer

multiple layers

→ classified by apical surface layer

Squamous epithelia are…

flat, more wide than tall

Cuboidal epithelia are…

cube like

Columnar epithelia are…

taller than they are wide

Pseudo-stratified epithelia is…

one layer but looks like multiple

Select the correct answer

E

Connective tissue is defined by…(i.e. histological def)

Extracellular protein fibres and cells suspended within a ground substance (matrix), but can fulfill many functions

matrix = liquid

select the right answer

A

Connective tissue proper can be divided into (2) types

1. Loose

2. Dense

Loose ‘proper’ connective tissue:

Has low density of extracellular fibres

Has more diversity of cell types

ex. areolar tissue

Dense ‘proper’ connective tissue:

Has high density of extracellular fibres

has low diversity of cell types

ex. Tendon

What type of cells can be found in loose proper connective tissue? (3)

Fibroblasts

Fibrocytes

Mesenchymal cells

Fibroblasts:

Secret the proteins of extracellular matrix

fibrocytes:

maintain the proteins of the extracellular matrix

Mesenchymal cells:

Stem cells that can divide to replace damaged cells (fibroblast)

2 types of extracellular fibres in connective tissue proper

1. elastin fibres - elastic (stretch and recoil)

2. Collagen fibres - high tensile strength (create tension) (strong but not stretchy)

What is the strategy for repair for epithelium tissue

Rapid proliferation

• clot forms out of blood tissue

What is the strategy for repair for connective tissue

Increased rates of secretion

• scar forms when fibroblast secret collagen fibres at injury site

answer why you get bleeding gums

1. Fibroblasts aren’t able to produce collagen due to lack of vitamin C

2. Collagen gives connective tissue tensile strength

3. Gums struggle to hold teeth

4. Gums bleed

the integument consists of…

→ what is not apart of the integument

The cutaneous membrane:

• Epidermis

• Dermis

and Accessory structures

→ Hypodermis - subcutaneous

The integument has many functions including (3)

1. protection

2. detection

3. barrier

How does the integument protect?

barrier: immune and osmotic homeostasis

i.e. keeps things out and things in (water)

How does the integument detect?

Sensory organs - receptors

How does the integument regulate?

Thermal homeostasis

• detects change in temperature and regulates

What is the difference between thick and thin skin and where can they be found?

Thick skin: is hairless and can be found on palmar and plantar surfaces, has stratum lucidum

Thin skin: has hair and can be found everywhere else

is dark skin thicker than light skin?

No, its just darker

name all distinct strata (layers) of the epidermis from superficial to deep

• thick and thin skin are not the same

C - Stratum Corneum

L - Stratum Lucidum (only in thick skin)

G - Stratum Granulosum

S - Stratum Spinosum

B - Stratum Basale

what type of epithelium does the epidermis consist of ?

Stratified squamous epithelium

Epidermal cells are continuously generated in the _______ layers (strata), differentiated in the ____ layers and shed from the _____ layers

Deepest, middle, superficial

Explain how Epidermal cells are continuously generated

1. Basal stem cells in the stratum Basale proliferate (divide) producing new keratinocytes

2. Keratinocytes move upward through the stratum spinosum and continue differentiating.

3. Keratinization becomes more prominent in the stratum granulosum as keratinocytes flatten and accumulate keratin

4. by the stratum corneum, keratinocytes are dead, flattened, and filled with keratin

What does this mean “the epidermis is keratinized”?

cells of the epidermis become filled with keratin

• keratin is a tough, cross-linked, water-resistant protein, which limits insensible perspiration (water loss through cutaneous membrane itself)

what does Melanin do and why do we need it

Melanin can absorb UV photons and releases energy safely.

• Without it, UV light could damage cells - particularly DNA

Where and what do melanocytes do?

Melanocytes are located within the stratum Basale

• produces melanin pigments and transfers them to keratinocytes

_______ (packed with melanin) are transferred via vesicle transport

Melanosomes

answer for CV DNA damage and CV melanosome production

DNA damage - homeostasis - want to get rid of damage

Melanosome production - allostasis

The dermis contains…

Two layers of connective tissue:

1. stratum papillare - contains loose connective tissue proper (areolar)

2. Stratum reticulare - dense, irregular, elastic connective tissue

explain the process of skin repair. Be sure to list phases

1. Inflammatory Phase

• bleeding triggers clot formation

• Mast cells triggers inflammatory response

2. Migratory Phase

• A scab forms at the surface

• Macrophages remove pathogens and debris

• Rapid cell migration and division occur:

  • Epidermis: Basal cells proliferate and keratinocytes migrate to cover the wound

  • Dermis: Fibroblasts and other cells migrate and proliferate

• Granulation tissue forms: mixture of new blood vessels, mesenchymal cells, fibroblasts (dermis)

3. Proliferation Phase

• Deeper portions of the blood clot dissolve as new tissues replaces them

• Fibroblasts produce collagen fibers and ground substance

• New tissue fills the wound

4. Scarring Phase

• Scar tissue forms as a result of the Dermis’s enhanced collagen secretion

What is a callus?

A specific thickening of the stratum corneum, caused by keratinocytes being more strongly cross-linked

Key points of inflammation: (2)

1. increased blood flow

2. Attraction of immune phagocytic cells

why do cross links stay and what does more links between cells do?

stays because no nucleus and more links results in longer/more force for them to shed

Select the correct answer

E

Select the correct answer

D - think migratory phase where new blood vessels form

The dermis contains _____ _____ that support the epidermis or allow for secondary skin functions

Accessory structures

The dermis contains many ________ (touch) and ______ (pain) neurons

somatosensory, nociceptive

_____ in the integument are epithelial structures which contribute to _____ and or ______

glands, protection, homeostasis

name which glands are in the integument:

Sebaceous glands: secrete sebum

Sweat glands: secrete sweat

• Apocrine gland: Found in axillary and pubic regions - more active after puberty

• Eccrine gland: found almost everywhere

_______ in skin play a critical role as a sensor for thermal homeostasis

Thermoreceptors