Lec2 Flashcards
skeletal muscle
attached through structures to bone or skin, under voluntary control
cardiac muscle
only found in the heart- specialised to pump blood, involuntary control
smooth muscle
surround many tubes of the body, involuntary control
function of muscle cells
to generate mechanical force
neurons
cells of the central nervous system specialised to initiate and integrate and conduct electrical signals to other cells, sometimes over long distances
nervous tissue
a collection of neurons
a nerve
neurons packaged together with connective tissue
epithelial cells function
specialised for the selective secretion and absorption of ions and organic molecules and for protection
- cuboidal (cube like)
- columnar (elongated)
- squamous (flattened)
- ciliated (specialised function)
the 2 sides of the cell (apical and basolateral membranes) may have different functions. Epithelial cells can form barriers with tight junctions
connective tissue cells
connect, anchor and support the structures of the body
- loose connective
- dense connective
- bone and cartilage
- adipose
- blood
functions of the extracellular matrix
- provides scaffold for cellular attachment
- transmits info to cells to regulate activity eg migration
proteins of the extracellular matrix consist of…
collagen fibers and elastin fibers
organs are divided into…
functional units
organ systems are divided into…
organs
organs are composed of how many tissue types?
at least 2 (epithelial, connective, muscle, neuron)
extracellular fluid
fluid in the blood and surrounding cells
interstitial fluid
extracellular fluid around anf between cells
interstitium
the space containing interstitial fluid
exchange between body fluid compartments
the intracellular fluid is controlled by the interstitial fluid, which is conditioned by the plasma, which is conditioned by the organ systems it passes through
homeostasis
a state of reasonably stable balance
a state of dynamic constancy- physiological variables are maintained within a predictable range
pathophysiology
disordered/abnormal physiological processes associated with disease or injury
alterations to homeostasis outside the normal range
homeostatic control systems
the compensatory mechanisms that mediate responses to changes in the extracellular fluid, in order to correct the change
steady-state
a system in which a particular variable is not changing but in which energy must be added continuously to maintain a stable, homeostatic condition
negative feedback
an increase or decrease in the variable brings about responses that move the variable in the opposite direction of the original change
positive feedback
accelerates a process, leading to an explosive system. Not common in nature compared to negative feedback
set-point
the physiological variable around which the normal range fluctuates
why would we reset a set-point
sometimes adaptive- may increase body temp set point when fighting infection as increased temp inhibits proliferation of some pathogens
what is feed-forward control and why is it adaptive?
changes in regulated variables are anticipated and prepared for before they actually occur which improves the speed of the body’s homeostatic responses and minimises fluctuations in the level of the variable being regulated
reflex
specific, involuntary, unpremeditated, built-in response to a particular stimulus
reflex arc
pathway mediating a reflex
stimulus
detectable change in the internal or external environ
receptor
detects the environmental change, produces a signal that is relayed to an integrating centre
integrating center
receives signals from many receptors, its output reflects the net effect of the total afferent input
effector
receives output from integrating center and changes activity- constitutes the overall response of the system
afferent pathway
along which the signal from the receptor travels to the integrating center
efferent pathway
signal from the integrating center travels to the effector via this pathway
intercellular messengers
3 types- neurotransmitters, hormones and paracrine substances. Allow cells to communicate and respond to homeostatic challenges
hormones
chemical messenger, hormone-secreting cell communicates with other cells with the blood acting as the delivery system
neurotransmitters
released from the ends of neurons onto other neurons, muscle cells or gland cells, diffuse through the extracellular fluid between the neuron and target cell
paracrine substances
involved in local communication between cells, synthesised by cells and released into extracellular fluid where they diffuse to neighbouring cells. Generally inactivated by enzymes- do not enter the blood stream in large quantities
autocrine substances
secreted into the extracellular fluid and then acts on the same cell that secreted it. INTRACELLULAR messenger
adaptation
denotes a characteristic that favours survival in specific environments
acclimatisation
the improved functioning of an already existing homeostatic system - usually reversible
biological rhythms and how they effect homeostasis
add an anticipatory component to homeostatic control systems. They enable homeostatic mechanisms to be utilised immediately and automatically by activating them at times when a challenge is likely to occur but before it actually does
the pool
the body’s readily available quantity of substance, often identical to the amount present in the extracellular fluid
net gain
gain of substances to the body via. food, air or synthesis within the body
net loss
loss of substances to the body via metabolism or excretion
for any substance, 3 states of total body balance are possible
gain outweighs loss, positive balance
loss outweighs gain, negative balance
loss = gain, stable balance
adaptation
denotes a characteristic that favours survival in specific environments
acclimatisation
the improved functioning of an already existing homeostatic system - usually reversible
biological rhythms and how they effect homeostasis
add an anticipatory component to homeostatic control systems. They enable homeostatic mechanisms to be utilised immediately and automatically by activating them at times when a challenge is likely to occur but before it actually does
the pool
the body’s readily available quantity of substance, often identical to the amount present in the extracellular fluid
properties of molecules containing polar bonds
tend to be most soluble in water compared to non-polar molecules, readily dissolve in the blood, interstitial and intracellular fluid
hydrophilic
net loss
loss of substances to the body via metabolism or excretion
hydrogen bonding
very weak electrostatic attraction between 2 polar molecules in close contact
when are atoms most stable
when the outer shell is full and electrons are paired
the ionic forms of mineral elements are referred to as what?
electrolytes
polar covalent bonds
the shared pair of electrons resides closer to one atom of the pair
electronegativity
the ability of an atom to attract electrons
properties of molecules containing polar bonds
tend to be most soluble in water compared to non-polar molecules, readily dissolve in the blood, interstitial and intracellular fluid
where are non-polar molecules often found
in the lipid bilayers of the membranes of cells and intracellular organelles, because non-polar molecules are hydrophobic
hydrogen bonding
very weak electrostatic attraction between 2 polar molecules in close contact
amphipathic molecules
molecules that have a polar or ionised region at one end and a non-polar region at the opposite end- when mixed with water they form clusters
lipid subclasses
fatty acids
triglycerides
phospholipids
steroids
why are lipids important in physiology
some of them provide energy
some are a major component of all cellular membranes
some are important signalling molecules
structure of phospolipids
similar to trigylcerides (glycerol+ 3 fatty acids) but the third hydroxyl group of glycerol is linked to a phosphate group, In addition a small polar or ionised nitrogen-containing molecule is usually attached to this phosphate
properties of steriods
NOT water-soluble but can diffuse though membranes
examples
- cholesterol
- cortisol
- oestrogen
- testosterone
essential amino acids
must be obtained in the diet, cannot be synthesised
what are proteins composed of?
carbons, hydrogen, oxygen, nitrogen, and other elements such as sulfur
