reproduction and the heart Flashcards
name 3 differences between asexual and sexual reproduction
- asexual has one parent but seuxal needs two
- asexual has no gametes but seuxla does
- asexual has offspring that are clones but sexual has genetic variation (both from parents and between offspring)
what process does asexual reproduction occur by? what process does sexual reproduction occur by?
- aseuxal = binary fission
- seuxal = meiosis (to make gametes), fertilisation and then mitosis
define gametes
males and female sex cells formed by meiosis
name the adaptations of the sperm cell
- acrosome
- haploid nucleus
- midpiece
- tail
adaptation of the sperm cell - acrosome
contains enzymes to digest jelly coating of the ovum
adaptation of the sperm cell - haploid nucleus
contains the genetic material of the father that makes up half of the zygote’s genetic material
adaptation of the sperm cell - midpiece
contains lots of mitochondria to release energy from respiration so that sperm can swim to egg
adaptation of the sperm cell - tail
allows sperm to swim to egg for fertilisation
names the adaptations of the ovum
- mitochondria
- cytoplasm
- ribosomes
adaptation of the ovum - mitochondria
respires to release energy for zygote to undergo mitosis
adaptation of the ovum - ribosomes
undergoes protein synthesis (makes proteins)
adaptation of the ovum - cytoplasm
contains nutrients such as mineral ions to provide for a growing embryo
define fertilisation
fusion of a male and female gamete to produce a zygote
explain process of fertilisation in humans
- penis is inserted into vagina and semen w/ sperm is ejaculated
- sperm travel through cervix into uterus and into one of the oviducts
- fertilisation occurs in the oviduct when sperm digests jelly coat and nuclei fuse
- a zygote is formed
function of the penis
- passes urine from bladder
- allows semen to pass into vagina during sex
- ejaculation and urination cannot occur at the same time
function of the sperm duct
passes sperm to the glands to be mixed with nutrient-rich fluid to produce semen
function of the urethra
tube inside penis that carries urine or semen, but there is a ring of muscle in this that prevents these from mixing
function of the testis
contained in the scrotum and makes the male gamete sperm and hormone testosterone
function of the scrotum
bag of skin supporting the testes that ensure sperm are kept outside body slightly lower than body temp for optimum sperm production
function of the prostate gland
produces a fluid called semen that provide the sperm cells with nutrients to travel to the egg
function of the foreskin
skin that protects the tip of the penis
function of the epididymis
where sperm cells mature so that they are fully functional
function of the oviduct
tube lined with cilia that connects ovaries to the uterus and is the site of fertilisation
function of the ovaries
contains female gamete ova that mature and develop when hormones are released
function of the uterus
muscular bag where the zygote implants itself to develop into a fetus
function of the cervix
a ring of muscle at end of uterus that closes it during pregnancy
function of vagina
muscular tube that leads to the inside of a woman’s body and is where semen is deposited during intercourse
what is the menstrual cycle?
a monthly cycle that prepares a woman’s uterus for a possible pregnancy
name the four main hormones that control the menstrual cycle
- oestrogen
- progesterone
- FSH
- LH
oestrogen
- produced in ovaries
- rebuilds uterus lining
- inhibits FSH production and stimulates LH production
progesterone
- produced in the ovaries
- thickens and maintains the uterus lining
- inhibits release of both FSH and LH
FSH
- produced in the pituitary gland (brain)
- stimulates ovaries to release oestrogen
- stimulates maturation of follicle containing ova
LH
- produced in the pituitary gland
- stimulates ovulation by causing a follicle to burst and release ova
describe the menstrual cycle
- pituitary gland secretes FSH which travels in blood to ovaries
- egg follicle is stimulated to mature by FSH
- oestrogen repairs uterine lining
- LH stimulates ovulation and an egg is released from an ovary
- empty follicle is called corpus luteum and releases progesterone
- progesterone maintains uterus lining and inhibits release of FSH and LH
- if egg not fertilised, corpus luteum breaks down and stops releasing progesterone
- LH and FSH are no longer inhibited and menstrual cycle restarts
why does puberty start?
pituitary gland releases hormones into blood that stimulate either testes or ovaries to release sex hormones (either testosterone or oestrogen)
what are secondary sexual characteristics?
changes that occur during puberty and are not the characteristics that we are born with
what hormones control puberty for each gender?
- females = oestrogen
- males = testosterone
secondary sexual characteristics of males
- voices deepen
- facial hair develops
- sperm production starts
- penis grows
- shoulders widen
secondary sexual characteristics of females
- periods start
- ovulation begins
- breasts develop
- hips widen
umbilical cord fucntion
connects the embryo’s blood supply to the placenta
placenta function
structure that forms at implantation site that exchanges substances between mother and fetal blood
amniotic sac function
produces and contains amniotic fluid
amniotic fluid function
surrounds the fetus and protects it from physical knocks and bumps, as well as some pathogens
cervix function
closes uterus during gestation but dilates to form part of the birth canal
what substances pass from mother to fetal blood (good and bad)?
- oxygen for respiration
- nutrients such as glucose, amino acids and mineral ions
- antibodies
- drugs
- alcohol
- substances from cigarette and vape smoke (e.g CO and nicotine)
what substances travel from fetus to mother?
waste products such as carbon dioxide and urea
why is placenta an efficient exchange surface?
- large surface area for diffusion between mother and fetal blood
- thin wall = short diffusion distance for substances
- both of these increase the rate of diffusion and so make the placenta an efficient exchange surface
Why don’t unicellular organisms need specialised exchange surfaces for the exchange of substances but multicellular organisms do?
- unicellular organisms have a large SA:V ratio
- they also have a very small distance to their center so diffusion at the cell surface is sufficient enough to meet their needs
- multicellular organisms have a small SA:V ratio
- they are composed of many layers of cells so distance to center is too large for diffusion alone
- this means that multicellular organisms need specialised exchange surfaces and transport systems whereas unicellular organisms don’t
factors increasing rate of diffusion
- short diffusion distance
- large SA:V ratio
- steep concentration gradient
- high temperature
- moistness (allows diffusion of gasses)
name the contents of the blood and their percentages
- plasma = 55%
- red blood cells = 44%
- white blood cells = less than 1%
- platelets = less than 1%
what substances does the plasma carry?
- all the other components of the blood are suspended in this
- digested food (e.g glucose and amino acids)
- urea
- heat energy
- hormones
- CO2
how does the plasma carry digested food?
- digestive system breaks down large insoluble molecules into smaller soluble ones
- these are diffused into bloodstream and are dissolved into plasma at the small intestine/ileum
- from here it is transported in the blood to wherever it is needed for various reactions
how does the plasma carry urea?
- urea is a toxic waste product made in the liver
- it enters the bloodstream in the liver and dissolves into the plasma
- it is filtered out the blood in the kidneys and is removed from body as urine
how does the plasma carry CO2?
- CO2 is a poisonous waste product of respiration
- it diffuses out of cells and into the bloodstream where it dissolves into the plasma
- blood is circulated to the lungs where CO2 diffuses into the alveoli and is eventually exhaled out of body
what other substances does the plasma carry?
- proteins such as hormones and antibodies are delivered to their target tissues
- heat energy from respiration to cooler parts of body (e.g skin - heat is easily lost)
what are the names of the types of white blood cells?
- lymphocytes
- phagocytes
name the adaptations of the red blood cell
- contain lots of haemoglobin
- biconcave shape
- diameter slightly wider than capillary diameter
- no nucleus
what is haemoglobin?
a protein found in RBCs that binds to oxygen to temporarily make the compound oxyhaemoglobin
adaptation of RBCs - haemoglobin
- RBCs contain lots of haemoglobin
- this means that lots of oxygen can be transported to respiring cells
adaptation of RBCs - biconcave shape
- creates large SA:V ratio for oxygen to diffuse into cell = more oxygen can travel = rate of diffusion of O2 into cell increases
- allows them to squeeze through small capillaries
adaptation of RBCs - diameter
- RBCs have a diameter slightly wider than that of the capillary
- forces them to slow down when passing through the blood vessel
- ensures that diffusion and gas exchange occurs as RBC surface is exposed to surface of capillary
adaptation of RBCs - no nucleus
- no nucleus means that more haemoglobin can be contained in the cell
- maximises the volume of oxygen that can be absorbed
what is the function of the plasma?
transport substances such as hormones, digested food, CO2 and heat energy around the body
what is the function of red blood cells?
transport oxygen around the body to respiring cells via the blood
what is the function of lymphocytes?
makes antibodies
what is the function of phagocytes?
phagocytosis = when a phagocyte engulfs a pathogen and releases enzymes to digest and kill it
what is the function of platelets?
make blood clots and scabs
how do platelets clot the blood and from scabs over wounds on skin?
- once skin is cut, exposure to air causes platelets and damaged tissue to release chemicals that convert soluble fibrinogen into insoluble fibrin
- fibrin forms a mesh around the wound and traps the RBCs
- this forms a blood clot
- the clot eventually dries to form a scab that protects the wound whilst new skin grows
what do blood clots and scabs prevent?
- excessive blood loss
- entry of microorganisms
define pathogen and give examples of kingdoms which could have pathogens in them
- pathogen = a microorganism that causes disease
- these are often fungi, bacteria and protoctista
define antigen
a chemical marker on the surface of a cell that marks it as ‘self’ of ‘foreign’
define antibody
a protein produced by lymphocytes that bind to specific antigens as part of an immune response
describe phagocytosis
- phagocyte’s sensitive cell membrane detects the pathogen’s antigens
- pathogen is engulfed and ingested by the phagocyte
- a membrane is formed around the pathogen within the phagocyte
- the bag of enzymes (phagosome) fuses with the membrane around the pathogen and enzymes are released
- enzymes digest and kill the pathogen
- waste products are removed from the phagocyte
what type of immune response is phagocytosis and why?
- it is a non-specific immune response
- phagocytes can target and destroy lots of different pathogens without needing to recognize a specific antigen
what do lymphocytes do?
release antibodies that are specific and complementary to the antigens of a pathogen
how do the antibodies made by lymphocytes aid removal of pathogens?
- aggregation = sticking microbes together so that they can be easily engulfed by phagocytes
- attaching antibodies to them that act as markers so they are more easily detected by phagocytes to be engulfed
- causes bacterial cells to burst open by cell lysis
- neutralising toxins produced by pathogens
what type of immune response is lymphocyte producing antibodies and why?
- specific immune response
- the antibodies are specific and complementary to the antigens
what is the primary immune response?
the production of antibodies following the first exposure to a foreign antigen
define memory cells
- memory cells are lymphocytes that were activated during an immune response and circulate in the blood for many years
- they ‘remember’ the antibodies required for the antigen and can release them again but much faster, earlier and in greater numbers if a second exposure of the same foreign antigen occurs
- memory cells are what drives the secondary immune response
describe the primary immune response
- pathogen enters the bloodstream and multiplies
- release of toxins and the infection of body cells causes symptoms in the patient
- phagocytes that encounter the pathogen recognise foreign antigens and engulf and digest them (non-specific response)
- pathogen encounters a lymphocyte which recognises its antigens
- lymphocyte starts to produce specific antibodies to antigens of pathogen
- lymphocyte clones itself to produce lots of lymphocytes (all producing the specific antibody required)
- antibodies destroy pathogens
- phagocytes engulf and digest the destroyed pathogens
describe secondary immune response
- pathogen re-enters bloodstream after long time
- memory cells created during the primary immune response quickly recognize the specific antigens of the pathogen
- memory cells rapidly clone themselves and produce a large amount of specific and complementary antibodies to the pathogen’s antigens
- antibodies target and neutralize the pathogen more quickly and effectively than during the primary response
- rapid removal of pathogens reduces numbers so that they cannot infect enough to produce symptoms in body
- phagocytes engulf and digest the neutralized pathogens
why is the secondary immune response better than the primary immune response? What does this make the individual?
- memory cells mean that the immune response produces antibodies EARLIER, FASTER and IN GREATER VOLUMES than a primary response
- rapid nature of response to pathogen makes it unable to cause disease so individual is now IMMUNE to the disease
how do vaccines work?
- vaccine is injected into bloodstream
- lymphocytes recognise antigens
- lymphocytes release antibodies specific and complementary to antigen encountered
- memory cells are formed from activated lymphocytes and circulate in blood for many years w/ antibodies until pathogen is re-encountered
- if pathogen is re-encountered, the memory cells quickly recognize it and release antibodies to neutralize the pathogen in greater numbers
why are vaccines good?
they provide long-term immunity by the manufacture of memory cells without having to be exposed to the disease for a primary response to develop the memory cells
what types of blood do each side of the heart receive and why?
- RHS = deoxygenated blood (sent to lungs via pulmonary artery to be oxygenated)
- LHS = oxygenated blood (comes from lungs from pulmonary vein to be sent to body’s respiring cells
what is pulmonary and systemic circulation?
- pulmonary circulation = transports deoxygenated blood from the heart to the lungs for oxygenation and returns oxygenated blood back to the heart
- systemic circulation= transports oxygenated blood from the heart to the body’s tissues and returns deoxygenated blood back to the heart.
name the adaptations of the heart
- thicker muscular wall on LHS of heart
- septum
- thin atria walls
- cardiac muscle
adaptations of the heart - thicker muscular wall on LHS of heart
- LHS of heart’s muscular wall is thicker than RHS
- it has oxygenated blood that must be circulated systemically
- so much higher pressure ana greater contraction of muscle is required
- this is more easily achieved if the muscle on LHS is thick
adaptations of the heart - septum
- septum separates the LHS and RHS of heart
- so oxygenated and deoxygenated blood are kept from mixing
- as a result, oxygenated blood is circulated by the systemic circulation to the body’s tissues, and deoxygenated blood is circulated by the pulmonary circulation to the lungs for oxygenation, instead of vice versa
adaptations of the heart - thin atria walls
- atria walls are thin
- they can stretch enough to receive blood into the heart and contract enough to send blood through the atrioventricular valves
- they are adapted to be thin as they only send blood to ventricles beneath them so a large contraction is not required
adaptations of the heart - cardiac muscle
- the heart is made out of cardiac muscle
- can contract and relax continuously without becoming fatigued
function of coronary arteries
- arteries found on the outside of the heart
- provide oxygenated blood and nutrients (e.g glucose) to cardiac cells
pathway of blood in heart
- atrioventricular valves are closed so blood can’t enter ventricles
- atrial walls contract + raise pressure in atria so atrioventricular valves are forced open and blood enters ventricles
- ventricles contract + increase pressure in ventricles so valves close to prevent backflow
- pressure continues to increase so semi-lunar valves are forced open
- deoxygenated blood is sent in pulmonary artery to be oxygenated in lungs + oxygenated blood is sent in aorta to be circulated systemically
- increased pressure in the aorta and pulmonary artery closes smei-lunar valves
- cycle restarts
what is heart rate and stroke volume?
- heart rate = number of beats per minute
- stroke volume = volume of blood pumped per beat
how is HR affected by exercise?
- HR increases during exercise
- oxygenated blood is circulated at a faster rate so that oxygen and glucose reaches rapidly respiring muscle cells so that more energy can be released
- more respiration = more respiratory waste so HR increases to quickly remove this from cells via diffusion
why does HR remain high after exercising?
- after exercise there will be an oxygen debt as some anaerobic respiration will have occured
- oxygenated blood must break down any lactic acid produced
- this means that HR must remain high so that this happens quickly
how is HR affected by adrenaline?
- adrenaline is secreted by the adrenal galnds near the kidneys
- adrenaline is secreted when we are stressed
- as a result HR increases
why do those who exercise more have a lower resting HR?
- increased exercise causes the heart muscle to become stronger
- this means it will pump a greater stoke volume
- this means that they will have a lower resting HR as thye can deliver the same amount of oxygen and glucose to cells in a given time period
