HUMAN PHYSIOLOGY EXAM QUESTIONS Flashcards
EXPLAIN THE RELATIONSHIP BETWEEN STRUCTURE AND FUNCTION OF ARTERIES
thick walls to withstand high pressure
collagen fibres give wall
strength/flexibility to stretch and recoil
muscle layer to maintain P
narrow lumen maintains high pressure
EXPLAIN THE RELATIONSHIP BETWEEN STRUCTURE AND FUNCTION OF CAPILLARIES
wall has one layer of cell allowing fast diffusion of substances
pores to increase permeability
extensive branching increase S.A for exchange of materials
smaller diameter allows them to fit between cells
EXPLAIN THE RELATIONSHIP BETWEEN STRUCTURE AND FUNCTION OF VEINS
thin walls allow muscles to exert pressure on veins
thin outer layer of collagen/ muscle/ elastic fibres provide structural support
wide lumen allows for great volume of blood to pass
valves prevent backflow
OUTLINE HOW LEUCOCYTES DEFEND THE BODY AGAINST PATHOGENS
leucocytes/ phagocytes can recognize pathogens
phagocytes engulf pathogens by endocytosis/phagocytosis
each pathogen has specific antigens
leucocytes/ lymphocytes produce antibodies be reacting to specific antigen
antibody joins to antigen destroying them
lymphocyte makes clone/copies of itself
thus increasing numbers of antibodies
EXPLAIN THE MECHANISM OF VENTILATION IN THE LUNGS IN ORDER TO PROMOTE GAS EXCHANGE FOR CELL RESPIRATION
inhalation brings air into lungs
external intercostal muscles contract
and move rib cage upwards and outwards
diaphragm flattens/ contracts
increasing thoracic volume
pressure decreases from atmospheric pressure so air rushes into lungs
exhalation forces air out
internal intercostal muscles relax/ external intercostal muscles and diaphragm relax
abdominal muscles contract and push diaphragm up
decreasing thoracic volume
increase lung pressure so air is forced out
a concentration gradient between air sacs and blood needs to be maintained
EXPLAIN THE CONTROL OF BODY TEMPERATURE IN HUMANS
normal body core temperature constant (37)
regulate by negative feedback
hypothalamus is the centre of thermoregulation
hypothalamus sends impulses to the body to increase/ decrease temperatures
release of sweat if the skin temp rises
evaporation of water cools the body
heat is transferred by blood
vasodilation if temp rises
vasoconstriction if temp decreases
shivering increases heat production
STATE THE SOURCE, SUBSTRATE AND OPTIMAL PH CONDITION FOR LIPASE IN THE HUMAN DIGESTIVE SYSTEM
source: pancrease
substrate: triglycerides/ lipids/fats/oil
product: glycerol and three fatty acid
optimal ph: 8
DESCRIBE THE DIGESTION OF FOOD IN THE HUMAN DIGESTIVE SYSTEM
chewing food makes smaller particles
starch digestion begins in the mouth by salivary amylase
digestion of proteins in the stomach
acid condition in stomach provides optimum pH for enzymes
stomach muscle contraction causes mechanical digestion
enzymes in small intestine complete digestion
alkaline conditions in S.I provide optimum pH for enzymes
bile salts help to emulsify fats
example: amylase/protease/lipase with source substrate and products
OUTLINE THE CONTROL OF THE HEARTBEAT BY THE NERVOUS AND ENDOCRINE SYSTEM
myogenic muscle contraction
contracts without stimulation
pacemaker/SAN in wall of right atrium
initiates contraction
nerves from brain transmit messages to pacemaker
to alter the rate of the pacemaker
medulla of the brain controls the heart rate
adrenaline is hormone produced by adrenal gland
adrenaline accelerates the heart rate
EXPLAIN THE PRINCIPLES OF SYNAPTIC TRANSMISSION
Ca ions enter presynaptic neuron
release of neurotransmitter
from pre-synaptic neuron
diffusion across cleft/gap
to post synaptic neuron
binding to the neurotransmitter to receptors
change in membrane permeability
Na ions flow into post synaptic neuron
depolarization of post synaptic membrane
initiation of action potential
removal of the neurotransmitter
by enzyme
inactivated neurotransmitter returns to pre synaptic neuron
OUTLINE THE ROLE OF HORMONES IN THE MENSTRUAL CYCLE
FSH stimulates follicle growth
egg cells mature
cell of growing follicle produce estrogen
estrogen signals lining of uterus to thicken
causes final maturation of follicle
high levels of estrogen stimulate secretion of LH
LH spikes stimulates ovulation
LH stimulates follicle to dev into corpus luteum
LH stimulates corpus luteum to secrete progesterone and estrogen
progesterone/estrogen stimulate continued dev/maintenance of lining of uterus
if no pregnancy occurs then corpus luteum dis-integrates
drop in progesterone/ estrogen hormone levels cause breakdown in uterine lining= menstruation
progesterone/ estrogen inhibit FSH/LH release
DIABETES TYPE I AND TYPE II
type I caused by destruction of insulin secreting cells (beta)/ genetic disorder
early onset
treat with insulin
type II caused by decrease response of body cells to insulin
adult onset
treat with diet/lifestyle
DISCUSS THE ETHICAL ISSUES ASSOCIATED WITH IVF
:)
infertile couples can conceive
allows children who are genetically related to them
decision to have children is clearly a conscious one
screening of embryos decreases chances of disease
increases reproductive age
cancer patients can harvest ova/sperm before chemo
production of extra embryos may be used for research
:(
potential risk from drug treatment
IVF unnatural procedure/ against some religions
infertility may be heritable and passed on to offspring
spare embryos are destroyed = murder?
production of extra embryos raises economic/legal ?
higher risk of multiple births/birth defects
expensive = exclusive
EXPLAIN THE PROCESS OF TRANSLATION LEADING TO POLYPEPTIDE FORMATION
genetic code consists of codon of base triplets
mRNA is complementary to DNA strand
mRNA carries information (transcribed) from the DNA gene
translation occurs in a ribosome
mRNA attaches to the small subunit of the ribosome
has specific codons
each codon codes for one amino acid
tRNA matches its anticodons with the codons of the mRNA
by hydrogen bonds between complementary bases
each tRNA carries specific amino acid
the amino acids area attached to each other by condensation reactions/ peptide bonds
process is repeated
forming polypeptides
OUTLINE HOW NERVE IMPULSES ARE TRANSMITTED ALONG A NERVE FIBRE
Na channels open and Na+ diffuses into the neuron down a concentration gradient
inside of the neurone become positive compared to the outside of the neuron: potential is reversed/ depolarization
wave of depolarisation moves down the membrane
K channels open and K+ diffuses out down concentration gradient
inside of neuron becomes negative compared with the outside/ potential across membrane restored/ repolarisation
active transport of K+ into neuron and Na+ out of neuron restores resting potential
FUNCTION OF MOTOR NEURONS
carry electrical impulses from CNS to muscle glands
RESTING POTENTIAL
neuron is not conducting an impulse
DESCRIBE THE ACTION OF THE HEART PUMPING BLOOD
both atria collect blood from veins
SA node sends impulses to muscle initiating contraction
blood is pushed to ventricles by contraction of atria/ atrial systole
AV valves are open as atria contract
semilunar valves are closed so that ventricles fill with blood
ventricles contract/ ventricular systole
AV valves close (prevent backflow)
blood is pushed out through the semilunar valves/ into pulmonary artery and aorta
when ventricles relax/diastole, semilunar valves close preventing back flow of blood
simultaneous contraction
NERVES CONNECTING THE BRAIN AND HEART CONTAIN NEURONS THAT CONTROL HEART RATE. EXPLAIN HOW A NERVE MESSAGE PASSES FROM ONE NEURON TO ANOTHER NEURON.
nerve impulses reaches the end of the presynaptic
depo causes Ca channels in membrane to open
Ca diffuses into the presynaptic neuron
vesicle of neurostransmitter move to and fuse with presynpatic membrane
neurotransmitter released by exocytosis into synaptic cleft/ space
neuroT diffuses across the space/ synapse
neuroT attaches to receptors on post synaptic neuron
receptors cause ion channels to open and Na diffuse into the postsynaptic neuron
post synaptic neuron is depolarized
depo causes a new action potential
neuroT on post synaptic membrane is broken down
neuroT is reabsorbed into the presynaptic neuron.
(a) Outline the exchange of materials between capillaries and tissues.
a. molecules move by diffusion / move down a concentration gradient
b. nutrients move into tissues
c. gas exchange / Oxygen and carbon dioxide exchange between tissues and
blood/capillaries
d. (nitrogenous) wastes/excess water move from cells/tissues into blood/capillaries
e. hormones leave capillaries in target tissues/to attach to receptors on cells / (endocrine) organs/gland tissues release hormones into the bloodstream
(b) Explain the structures and functions of arteries and veins.
a. arteries and veins have three layers in their walls
OR
walls of arteries and veins have tunica externa, media and intima
b. pressure is high in arteries/pressure is low in veins
c. arteries receive blood from ventricles/heart / carry blood away from heart
d. lumen of artery is small to keep pressure high
e. arteries have thick (muscular) walls (with elastic fibres) to withstand pressure
f. elastic fibres recoil in response to ventricle/heart contraction
g. muscle / elastic fibres help maintain pressure between heartbeats
OR
muscle / elastic fibres help propel blood toward capillary beds
h. veins receive blood from capillaries/capillary beds / carry blood to heart
i. large lumen of veins so there is less resistance to blood flow
j. valves in veins keep blood flowing toward heart/prevent backflow
(c) Describe what happens in alveoli
gas exchange
b. oxygen diffuses from air to blood and carbon dioxide diffuses from blood to air
c. oxygen binds to hemoglobin in red blood cells
d. pressure inside/volume of alveoli increases/decreases / air enters/exits alveoli during inspiration/ expiration/ventilation
e. blood flow through capillaries / concentration gradients of
gases/oxygen/CO2 maintained
f. type II pneumocytes secrete fluid/surfactant / secretion of surfactant to
prevent sides of alveolus adhering
