human physiology Flashcards
kelly 21-23
give the definition of homeostasis
Maintaining a
relatively constant internal environment
(steady state) in the face of dynamic change
what do animals rely on
negative feedback
what is negative feedback?
when a variable i.e. heat produces a counteracting response in the body. to bring back to homeostasis.
what is positive feedback
Amplifies a stimulus and
only contributes to homeostasis in animals in
a small number of functions (childbirth,
blood clotting, electrical impulses in nerves).
can you give an example of positive feedback in birth.
when a baby is boing born, the stretching cervix causes the influx or hormones that amplifies contractions and cervix contractions
what is feedfarward
anticipatory responses to
expected change (eg increased heart rate in
anticipation of exercise; increased secretion
of insulin before food is digested to yield
glucose; stimulation of gastric secretions due
to thought/smell of food)
what is the internal environment of the body?
Composition of body
fluids
Temperature
Metabolites
Blood pressure
O2 and CO2 in tissues
Etc.
What are the fluid compartments of the body?
total body water, intracellular fluid, extracellular fluid,plasma, and interstitial fluid
what is interstitial fluid?
Interstitial fluid is found in the spaces between cells in tissues, also known as the interstitial spaces. It surrounds and bathes the cells, providing nutrients and removing waste.
The Total Body Water (TBW) percentage is typically lower in females (around 50%) why?
The fat percentage is different typically higher then men.
how does interstitial fluid maintain the environment
interstitial fluid is maintained by homeostasis, which ensures a stable environment for cells. Several physiological mechanisms regulate its composition, volume, and pressure, cells sit in this matrix
what was the important note she said about endocrine vs nervous system?
If you want a fast-acting response use the neurons if you want a slow response use endocrine.
The nervous system and the endocrine system can work together- give one example.
Innervate means to supply nerves to a tissue or organ, allowing it to receive signals from the nervous system.-
Some nerves innervate endocrine glands eg. adrenal glands
what parts of the brain regulate endocrine function
Hypothalamus and pituitary are brain regions that regulate endocrine function
what parts of the brain regulates endocrine function?
hypothalamus and pituitary gland
blood is an example of the togetherness of the blood and the nerves how ?
- Blood pressure is regulated by nerves acting on the heart and blood vessels
- hormones acting
on the kidneys to regulate blood volume
what do Glial cells do
nervous system play an important role in nervous function- galial cells are typically called supporting cells- They do not conduct electrical impulses- but work for homeostatis
how to build percepts
Sensory reception Transduction Transmission Perception Response
what are effector organs?
They are activated by the nervous system to produce a response to a stimulus.
name some effector cells -
Muscles (Skeletal, Smooth, and Cardiac)
the central nervous sysem is made up of?
Brain
Spinal
cord
the peripheral nervous system?
Cranial nerves
Ganglia outside CNS Spinal nerves
Enteric
nervous
system
The Gut
Sympathetic
division
is responsible for the “fight-or-flight”, It is part of the autonomic nervous system (ANS) and works involuntarily.
parasympathetic division
is responsible for the “rest and digest”
Efferent neurons
are part of what and stem to where?
PERIPHERAL NERVOUS
SYSTEM
and stem to Autonomic
nervous system and Motor
system
the forebrain is…
Cerebrum
Thalamus
Hypothalamus
what is the Diencephalon and its components?
Thalamus
Pineal gland
Hypothalamus
Pituitary gland, for hormone regulation
Gross anatomy of the brain ie the types of matters
Grey matter (cell bodies)( on the outside)
White
Matter (axons)
Ventricles
cerebral fluid is constantly secreted by what
ependymal cells
where does cerebral fluid collect in?
Cerebrospinal fluid surrounds the brain and spinal cord and fills the ventricles. It is
modified blood plasma
enables the right and left cerebral cortices to communicate
A thick band of axons called the corpus callosum
ie Callum makes everyone communicate
Pons and medulla
to transfer information between the PNS and the midbrain and forebrain
The midbrain
receives and integrates sensory information and sends it to specific regions of the brain
controls several basic functions such as breathing, heart and blood vessel activity, swallowing,
vomiting, and digestion
Medulla
coordinates movement and balance and helps in learning and remembering motor skills
Cerebellum
Cerebrum
controls skeletal muscle contraction and is the centre for learning, emotion, memory, and
perception
what do the cerebral cortex do?
and is vital for perception, voluntary
movement, and learning
Frontal lobe
for decision making
Parietal lobe
integration of
sensory information
Occipital lobe
processing
visual stimuli and pattern
Temporal lobe
Auditory cortex (hearing)
what would I typically have a shit one of?
Wernicke’s area
how many cranial nerves are there?
12
The olfactory nerves (Cranial Nerve I)
are responsible for smell.
The optic chiasm
is the crossing point where the optic nerves (Cranial Nerve II) from each eye meet and partially cross over
Spinal cord functions
Neuronal link between brain and PNS
Integrating center for spinal reflexes
how many spinal nerves- l nerves emerge from spinal cord through spaces
formed between vertebrae
31 pairs
Visceral Afferents
Incoming pathway for information from internal viscera
(organs in body cavities)
Sensory Afferents
Somatic (body sense) sensation: arises from body surface
and proprioception (touch, pain, orientation of body and
limbs)
Special senses: vision, hearing, taste, smell
The PNS has two efferent components
the motor system and the autonomic
nervous system
the motor system does what?
carries signals to skeletal muscles and is mainly voluntary
autonomic nervous system
regulates smooth and cardiac muscles and is
generally involuntary
what do enteric nervous system do?
exerts direct control over the digestive tract, pancreas,
and gallbladder
Autonomic nerve pathway consists of a two neuron chain, what is this chain.
Preganglionic fibre (synapses with cell body of second neuron)
Postganglionic fibre (innervates effector organ
what is a ganglion and what is it equivalent to?
A ganglion is a collection of cell bodies in the peripheral nervous system
The equivalent in the CNS is a nucleus
Most (but not all) visceral
organs are innervated by both
sympathetic and
parasympathetic fibres what is the exception to this rule?
eg
sweat glands only receive
sympathetic innervation
Dual innervation of organs by
both branches of autonomic nervous system allows
allows
precise control over organ’s
activity
if we had to compare the eye shape to the parsymetictic and the systematic
Parasympathetic division
Constricts pupil of eye
Sympathetic division
Dilates pupil of eye
what about the lungs?
Parasympathetic division- constricts bronchiole in lungs
Sympathetic division relaxes bronchiole in lungs
what is noted about the frequency of the action potentials?
information is coded by FREQUENCY of AP firing
relate frequency to strength
Increase frequency: more neurotransmitter released: bigger effect on target cell
Response depends on number and type of receptors on plasma membrane of target cell
where are motor neurons found?
areas include spinal cord, motor regions of cortex,
basal nuclei, cerebellum, and brain stem
what is the final common pathway of motor neurons, what does this mean?
through which the central nervous system (CNS) exerts control over skeletal muscle activity
what ends the endplate potential?
Acetylcholinesterase
Black widow spider venom
causes explosive release of ACh
prolonged depolarization: respiratory failure
Botulinim toxin
blocks release of ACh: causes flaccid
paralysis
what is Curare and what does it do?
blocks action of ACh at receptor sites (antagonist,
competitive with ACh). Used as an arrow poison by indigenous
peoples of S. America
Organophosphates (eg Sarin)
prevent inactivation of acetylcholinesterase inhibitors too much ach not being broke down – lung
muscle paralysis – death by suffocation. Used as chemical weapons
Adrenal medulla is a modified part of sympathetic
nervous system what does this mean?
Modified sympathetic ganglion that does not give rise
to postganglionic fibres ( no postganglionic fibres)
Stimulation of preganglionic fibres prompts secretion of
hormones into blood
what is the percentages realised by the adrenal medulla ?
About 20% of hormone release is noradrenaline
About 80% of hormone released is adrenaline
Sympathetic what is released and where?
ACh
secreted from preganglionic neurodrenaline secreted from postganglionic
Also causes release of Ad(adrenaline)
from adrenal gland
in the perisymthetic what is released?
Parasympathetic: ACh
released from both preganglionic and postganglionic neurons
ACh receptors:
cholinergic (different types)
NAd receptors:
adrenergic (different types)
Cholinergic receptors
Nicotinic receptors – found on postganglionic cell bodies of all autonomic
ganglia
Muscarinic receptors – found on effector cell membranes
Andrenergic receptors – bind noradrenaline and adrenaline, but what types?
Alpha (α) receptors
Beta (β) receptor
Receptor agonists
Bind to same receptor as neurotransmitter
Elicit an effect that mimics that of neurotransmitter
Receptor antagonists
Bind to receptor
Block neurotransmitter’s response
Hypothalamus plays important role in what?
integrating autonomic, somatic, and endocrine
responses that automatically accompany
various emotional and behavioral states
Medulla within brain stem is region directly
responsible for
autonomic output
what is automimic response?
pissing, hard peepee and poops
parysmthetics is sometimes called what?
general housekeeper
Bronchodilator give the example and what it does
salbutamol (β2-adrenergic agonist)
β2-adrenergic receptors are
predominant receptors on bronchial
smooth muscle
Bronchodilators
bronchodilators mimic a response similar to that which occurs during exercise. (acts as nerodremiline)
anti-hypertensive
Metoprolol
what does Metoprolol do?
blocks β1 adrenergic receptors in heart
muscle cells
‘β-blocker’ class of drugs: β-blockers block the effects of
sympathetic nerve
neurotransmitters relating to disease: GABA
huntingsons disease
seritonin
depression
glutamate
schizophrenia, epilepsy
norpethidine
anxiety
dopamine
Parkinson’s disease
acetal choline
Alzheimer’s
the blood brain barrier includes what?
specific arrangement of glial cells
in blood vessels what does serotonin do?
5-HT2 for vasoconstriction also acts as a vasorelaxant for 5-HT28
what does the 5-HT 4 receptor do?
gut relaxation
fluroxene
antidepressant blocks serotonin reuptake
what are the dopamine receptors?
D1-Like increase camp
D2 like resptors do what
decrese camp
D2 agonists
inhibit prolactin and Parkinson’s disease
D2 antagonists
skitsophrenia treatment.
Muscle cells consist
of filaments of the
proteins actin and myosin
Muscle tissue in the vertebrate body is
divided into three types:
Skeletal muscle, or striated muscle,
is responsible for voluntary
movement
Smooth muscle is responsible for
involuntary body activities
Cardiac muscle is responsible for
contraction of the heart
Muscle contraction generates what?
heat
The paired muscles work
how ?
antagonistically
cooperatively
what is Locomotion
movement through space
Skeletal muscle is characterised how?
characterized by a hierarchy of smaller
and smaller units
A skeletal muscle consists of
A bundle of long
fibres, each a single cell, running along the
length of the muscle, Each muscle fibre is itself a bundle of smaller
myofibrils arranged longitudinally
Skeletal muscle is also called striated (striped)
muscle because of why?
the regular arrangement of
myofilaments creates a pattern of light and
dark bands
The Sliding-Filament Model of Muscle Contraction
According to the sliding-filament model, thin and thick filaments ratchet past each other
longitudinally, powered by the myosin molecules – the muscle shortens
outline the process of a power stroke?
The head of a myosin molecule binds to an actin filament, forming a cross-bridge and pulling the thin
filament toward the centre of the sarcomere
what is cross-bridge cycling
Muscle contraction requires repeated cycles of this binding and release
muscle contraction is dependent on what?
ATP
What is the regulatory protein complex?
tropomyosin and the troponin complex
what does the regulatory protein complex do?
Bind to actin strands
on thin filaments when a
muscle Fibre is at rest
This prevents actin and myosin
from interacting
how does calcium aid in muscle contraction
For a muscle fibre to contract,
myosin-binding sites must be
exposed
This occurs when calcium ions
(Ca2+) bind to the troponin
complex and expose the
myosin-binding sites
acetal choline does what to the muscle?
ACh depolarizes the muscle (endplate potential), causing it to produce
an action potential
how does the action potential move across the interir of the muscle fibre
It travels along the tubules
What does the travelling along the tubule cause
causing
the sarcoplasmic reticulum (SR) to release Ca2+
How do we stop the cell then from contraction/ how do you relax the muscle?
When motor neuron input stops, the muscle cell relaxes - transport proteins in the SR pump
Ca2+ out of the cytosol - regulatory proteins bound to thin filaments shift back to their starting
positions
what does it mean when the muscle cell has graded contraction
The extent
and strength of its contraction can be
voluntarily altered
how are graded contractions produced?(2)
Varying the number of fibres that contract
Varying the rate at which fibres are stimulated
what is one single motor unit?
A motor unit consists of a single motor neuron and
all the muscle fibres it controls
Tetanus
physiological term-muscles fail to relax after contraction, as if continuously carrying a heavy weight
Amyotrophic lateral sclerosis/Motor Neurone
Disease
neurons gradually break down and die. nerves (motor neurons) that control muscles. These nerves stop working properly, causing muscles to weaken over time
Myasthenia gravis
An autoimmune disease that attacks ACh
receptors on muscle fibres: muscle weakness
Multiple sclerosis
It happens when the body’s immune system mistakenly attacks the protective covering (myelin) of nerve fibers, causing communication problems between the brain and the rest of the body
Duchenne Muscular Dystrophy
Lack of dystrophin (muscle protein)
Muscles weaken and degenerate over time (x-linked)
what is special about heart muscle?
Cardiac muscle can generate action potentials without neural input (because of the pacemaker), it also does NOT fatigue
why does heart muscle never fatigue?
lots of mitochondria,
what is Tetanic contraction
muscle is stimulated so rapidly that it does not relax between contractions, leading to a sustained, powerful contraction
where is smooth muscle found?
found mainly in walls of hollow organs such as those of the circulatory, digestive, and
reproductive systems;Smooth muscle lacks striations because the actin and myosin are not regularly arrayed
growth of muscle
hypertrophy
shrinkage of muscle
atrophy
muscles tend to be use it or lose it. How do you lose it molecularly?
if a muscle is inactive, the mTOR pathway) is turned down, reducing the production of muscle proteins like myosin and actin. AND UDIQUINIONE ligases causes breakdown too
long term effects of Long-term excess of glucocorticoids
can lead to muscle breakdown as it inhibits AKT
during endurance training what happens to the heart?
: heart chambers increase in volume –
can pump more blood with each beat
resistance training
Resistance training: heart chamber wall increases in mass: generates
more force to pump against resistance
Maternal adaptation to pregnancy
This means 1.5–2 liters more blood than before pregnancy
how much muscle do you lose in space?
Up to 20% loss of muscle mass on spaceflights lasting five to 11 day- Heart becomes more spherical in shape and loses muscle
mas- Hearts become 9.4% more spherical
