Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physiology of Organisms > 3-5 > Flashcards

3-5 Flashcards

1
Q

Define Homeostasis

A

The maintenance of relatively constant conditions in the body by physiological processes that act to counter any departure from the normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Who first used the term homeostasis

A

Walter Bradford Cannon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which variables are controlled in mammals

A

1) core body temperature
2) Osmotic Pressure
3) Arterial blood pressure 4) extracellular fluid volume
5) Blood gas concentrations
6) Concentrations of extracellular solutes like Na+, K+, and protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is a conformer

A

An organism who do not complete active homeostasis as they have the same components as surroundings
- Hag fish

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Regulators?

A

GRAPH

Homeostatic organims

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Poikilothermy

A

An organism that does not regulate it’s own internal temperature—> Naked Mole rat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is homeostasis usually maintained

A

Negative feedback loops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Positive feedback examples

x 3

A

Urination
Parturition
Metamorphosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does negative feedback work

A
  • Disturbance affects controlled system
  • Sensor picks up difference
  • Inverting amplifier
  • Response which affects the controlled system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the main sensors for negative feedback loops in mammals
x 5

A
  1. Thermoreceptors (skin and hypothalamus)
  2. Osmoreceptors (hypothalamus)
  3. High pressure baroreceptors (carotid sinus, aortic arch and afferent arteriole of kidney)
  4. Low pressure baroreceptors (atria, great veins and pulmonary vasculature)
  5. Chemoreceptors (medulla oblongata and carotid and aortic bodies)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are neurocrine transmitters

A

Substances released by neurones in the immediate vicinity of target cells or into the blood—>neurotransmitters are a subset of this group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Endocrine transmitters

A

Hormones

1) Synthesised by a specific tissue
2) Secreted into the bloodstream
3) Change the activity of that target tissue or organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Paracrine transmitters

A

‘local hormones’
Diffuse through extracellular fluid to reach and affect target cells of a different cell type to itself
Histamine and Nitric oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Autocrine transmitters

A

Like paracrine but act on same cell type as those that secrete them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cytokines

A

Transmitters released by immune cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pheromones

A

Released by animal into environment to affect physiology or behaviour of another animal of the same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Water-soluble hormones

explain and 3 types

A

Stored in vesicles and released by exocytosis—>travel loose in blood and bind to membrane-based receptors

TYPES

1) Peptide/ protein hormones
2) Glycoproteins
3) Catecholamines (derived from tyrosine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Lipid-soluble hormones

what and 4 types

A

Diffuse out of cells once made and transported in blood bound to special carrier proteins. Usually intracellular receptors

1) Steroid hormones
2) Thyroid hormones
3) fatty acid derivatives
4) Indolamines (melatonin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

G-protein coupled receptor

A

GRAPH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How to deactivate g-protein coupled receptor

A

Upon hydrolysis of GTP to GHDP on α-subunit will cause it to rebind to βγ-subunit and become inactive
- in cell a phosphodiesterase hydrolyses cAMP and terminates cell response

21
Q

Lipid-soluble hormone receptors

A

Usually in cells and act directly as transcription factors

22
Q

Getting rid of chemical messengers and half-lives

A

Most hormones metabolised by liver or kidneys

Half-lives of hormones in plasma can vary from 1-3 minutes for adrenaline to 7 days for thyroxine (T4)

23
Q

Blood-brain barrier

A

Prevents circulating substances which also act as neurotransmitters from acting on the brain

  • its formed of endothelial cells being connected by particularly tight junctions
  • held there by glial cells foot processes
24
Q

Where is the blood-brain barrier ‘leaky’

x4

A
  1. Posterior pituitary gland
  2. Median eminence
  3. Pineal gland
  4. Circumventricular organs
  • fenestrated BBB so release hormones into blood or detect their presence
25
Q

Where is the hypothalamus

A

Small region of the forebrain above the pituitary gland

26
Q

What does the hypothalamus do?

A

Received input from many sources relating to both internal and external environment
—integrates information and controls physiological response—>homeostatic control centre

27
Q

The hypothalamus contains multiple intercommunicating nuclei

A

These are collections of nerve bodies

28
Q

Leptin example

intro

A

Protein hormone secreted by white fat cells and detected in arcuate nucleus of hypothalamus.

Use levels to establish body’s nutritional state

29
Q

What if leptin levels are high?—so well fed

A

1) Feeding behaviour suppressed
2) Release for TRH
3) activates hypothalamic-pituitary-thyroid axis—>increase metabolic rate
4) other function regulated reproductive axis in women

30
Q

Posterior pituitary

A

Downgrowth of the brain made of bundles of axons of nerve cells whose bodies are in the hypothalamus

31
Q

Anterior pituitary

A

Originates from Rathke’s pouch and lies outside of the BBB—>produces hormones

32
Q

ADH

A

Released from PP

  • release at high osmotic pressure and in lower concentrations when there is low blood volume
    1) Acts on kidney collecting ducts to increase water permeability
    2) at higher concentrations causes vasoconstriction and compensates for loss of blood volume
33
Q

Oxytocin

A

released by PP

mainly in reproductive functions like the fergusson reflex
(where stretch of cervix then causes more contractions to push baby out, expanding cervix more)

34
Q

What is a portal vein

A

A vein that travels between two capillary beds

35
Q

Anterior pituitary hormones

A

Involved mostly in control of endocrine glands elsewhere in the body

1) Glycoproteins
2) Somatomammotropins
3) Pro-opiomelanocortin

36
Q

Hypothalamic-pituitary-thyroid axis

A

Hypothalamus send hormones to AP which cause release of another hormone which causes an endocrine gland (like thyroid) to release another hormone

—one of the jobs of this hormone is to inhibit the releasing hormone from hypothalamus=LONG-LOOP FEEDBACK
Short is from AP hormone inhibit hypothalamus and ultrashort is hypo prevents hypo

37
Q

TPT example

A

GRAPH

38
Q

Pulsatility

A

The releasing of hormones in bursts to prevent receptor down-regulation

39
Q

Feed-forward control

A

A mechanim by which to prevent ‘overshooting’ the set point and requiring negative feedback to go the other way
- like in drinking

Prevents oscillating levels

40
Q

What is dynamic equilibrium

A

Where there is no net force acting across a membrane as the concentration gradient is equal to the electrical gradient.
Represented by E (subscript of the ion)

41
Q

Why do we say that concentration stays roughly constant

A

very few ions move across membrane before dynamic equilibrium

42
Q

What is the Nernst equation?

at 20 degrees

A

E (ion) in mV = (58/z) log10(conc ion out/conc ion in)

43
Q

what does it mean if the membrane potential does not equal the equilibrium potential of one ion

A

Then the membrane is permeable to more than one ion

44
Q

Line predicted by the GHK equation fits the resting membrane potential of frog muscle cells than the line predicted by nernst K

What is the GHK equation

A

Picture

45
Q

What does P represent in the GHK equation?

goldman-Hodgkin-katz

A

The relative permeability of the ion

46
Q

What is ouabain

A
  • toxin
  • binds to sodium pump
  • stops from working
  • small loss of -5mV at first
  • then slow to zero
47
Q

What is the actual name of the sodium pump

- what does it do

A

Sodium-potassium ATPase

  • pumps out 3Na+ with 2K+ into the cell
  • requires ATP
48
Q

role of sodium pump

A

Maintain the concentration gradients of sodium and potassium over long term and the slow leaking increases the concentration of sodium in the cell

49
Q

How to change membrane permeabilities to ions

A

Open more channels specific to that ion

Physiology of Organisms (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions