Topic 11: Animal Physiology Flashcards
1
Q
Outline function of biceps.
A
Raise lower arm
2
Q
Outline function of cartilage.
A
Reduces friction, absorbs shock
3
Q
Outline function of distal convoluted tubule.
A
selective reabsorption of glucose/minerals/amino acids by active transport
4
Q
Explain the role of the medulla and the collecting duct of the kidney in the maintenance of the water balance in blood. [3]
A
- collecting duct has aquaporins
- high solute concentration of medulla
- reabsorption of water allows excretion of concentrated urine
- secretion of ADH increases permeability of collecting duct to water
5
Q
Outline how the skeletal muscle contracts. [6]
A
- calcium ions released from sarcoplasmic reticulum
- exposes myosin binding sites on actin
- cross-bridges form between actin and myosin
- ATP provides energy
- for actin filaments to slide over myosin filaments
- ATP provides energy to release myosin from binding sites
- action repeated further along the molecule
6
Q
Explain the role of the kidney in maintaining water balance in humans. [9]
A
- osmoregulation
- water passed into kidney tubules through ultrafiltration
- water reabsorbed in PCT
- water reabsorbed into blood from descending loop of Henle
- osmosis
- transport of salts into medulla of kidney
- changes salt conc, water is reabsorbed
- ADH releases into blood when water is required
- more reabsorption of water from the collecting duct
- causes concentrated urine
- urine conc. depends on the body’s needs for water
7
Q
Explain how the structure of the nephron and its associated blood vessels enable the kidney to carry out its functions. [8]
A
- osmoregulation
- ultrafiltration in the glomerulus
- basement membrane filters, prevents loss of proteins
- selective reabsorption of glucose in PCT
- water reabsorbed in descending loop of henle
- active transport of sodium ions out of ascending limb
- impermeable to water
- water reabsorbed in collecting duct
- collecting duct permeability depends on ADH
- osmoregulation by varying the amount of water reabsorbed
8
Q
Describe the role of ADH in human osmoregulation.
A
- secreted when blood plasma concentration is hypertonic/water content too low
- makes walls of collecting duct more permeable to water
- more aquaporins in membrane
- more water reabsorbed from filtrate
- small volume of concentrated urine excreted
9
Q
Explain the role of the nephron in maintaining the water balance of the blood in the human body. [8]
A
- ultrafiltration in the glomerulus produces large volumes of filtrate
- 80% of water absorbed in PCT
- water reabsorbed from filtrate in descending loop of henle
- pituitary gland secretes ADH if blood solute conc too high
- makes collecting duct more permeable to water
- moves aquaporins into membranes
- more water reabsorbed from filtrate
- small volume of urine with high conc excreted
- water reabsorption in collecting duct due to high solute conc of medulla
- active transport of Na+ ions from filtrate in ascending limb of loop of Henle
10
Q
Outline what is meant by homeostasis. [4]
A
- Maintaining a constant internal environment
- with narrow limits
- e.g. blood temp/pH
- levels monitored internally
- negative feedback mechanisms
- involves hormonal/nervous control
11
Q
Explain the processes occurring in the kidney that contribute to osmoregulation. [8]
A
- osmoregulation is the maintenance of water balance
- loop of henle creates hypertonic conditions in the medulla
- water reabsorbed as filtrate passes through collecting duct
- monitored by hypothalamus
- controls secretion of ADH
- ADH released when blood solute conc too high
- makes collecting duct more permeable to water
- due to more aquaporins
- more water reabsorbed
- small volume of concentrated urine produced
12
Q
Blood is a liquid tissue containing glucose, urea, plasma proteins and other components. List the other components of blood. [5]
A
- plasma
- dissolved gases
- red/white blood cells
- hormones
- lymphocytes/phagocytes
- platelets
- amino acids
13
Q
Explain the role of ATP in muscle contraction. [2]
A
- ATP binds to myosin heads
- ATP breaks cross-bridges
- energy released when ATP forms ADP and phosphate
- myosin heads reset
- actin slides over myosin
14
Q
Describe how skeletal muscle contracts. [3]
A
- action potential arrives at neuromuscular junction
- release of calcium ions from the sarcoplasmic reticulum
- calcium binds to troponin, exposes actin to form cross-bridges
- heads push actin filament towards sarcomere center
- use of ATP to break cross-bridges
15
Q
Explain how the kidney helps to retain useful substances in the blood and eliminate substances which the body does not need. [8]
A
- ultrafiltration in the glomerulus
- basement membrane acts as filter
- prevents large molecules (proteins) from passing
- filtered substances pass to bowman’s capsule
- to PCT
- selective reabsorption
- all glucose reabsorbed
- most water reabsorbed
- area of high solute conc surrounds loop of henle
- ions exchanged between filtrate and blood in DCT
- collecting duct has role in osmoregulation
- ADH regulates amount of water reabsorbed
- substances not reabsorbed are eliminated as urine
16
Q
Describe the production of semen. [5]
A
- sperm produced by meiosis
- in testis / seminiferous tubules
- sperm stored in the epididymis
- sperm can swim
- seminal vesicles add fluid
- seminal vesicles rich in fructose
- prostate glands add fluid
- fluid rich in proteolytic enzymes (protease)
- semen contains alkaline substances
- neutralizes the acidic environment of the vagina
17
Q
Explain the structure and function of the placenta. [8]
A
- disc-shaped
- connected to fetus by umbilical cord
- placenta is embryonic and maternal tissue
- placental villi increases SA
- fetal capillaries in placenta
- inter-villous spaces through which mother’s blood flows
- small distance between fetus and maternal blood
- transfer of nutrients/glucose from mother to fetus
- transfer of oxygen from mother to fetus
- transfer of antibodies from mother to fetus
- transfer of waste products/CO2 from fetus to mother
- placenta secretes progesterone and oestrogen
18
Q
Outline the hormonal control of birth. [4]
A
- at 38-40 weeks of pregnancy fetus produces oestrogen
- decreases progesterone production
- removes inhibition of oxytocin secretion
- oxytocin released by the pituitary gland
- oxytocin stimulates uterine contraction
- cervix dilates and widens
- increase in oxytocin increases the rate of contractions
- positive feedback loop
19
Q
Describe the process of fertilization in humans. [6]
A
- sperm breaks through follicle cells
- triggers acrosome reaction
- proteases released
- digests zona pellucida
- plasma membranes of egg and sperm fuse
- sperm nucleus enters egg
- cortical reaction
- hardens glycoproteins in zona pellucida
- prevents polyspermy
20
Q
Explain how the structure and function of the placenta help to maintain pregnancy. [8]
A
- disc-shape organ that attaches to uterus
- connected to the fetus by the umbilical cord;
- produces hormones/HCG that maintain pregnancy;
- estrogen and progesterone maintain uterine lining;
- nutrients/oxygen from mother’s blood transferred to fetal blood;
- antibodies from mother’s blood transferred to fetal blood (through umbilical vein);
- waste products transferred from fetal blood to maternal blood (through umbilical artery);
- embryonic tissue grows into the uterine wall;
- placental/chorionic villi increase the surface area’
- fetal capillaries in placenta
- inter-villous spaces through which mother’s blood flows;
- small distance between fetal and mother’s blood
21
Q
Outline the role of hormones in the menstrual cycle. [6]
A
- LH and FSH are pituitary hormones
- FSH promotes the development of follicles
- follicles produce oestrogen
- oestrogen repairs and grows uterine wall
- oestrogen causes negative feedback of FSH
- oestrogen stimulates LH production
- LH stimulates the development of the corpus luteum
- corpus luteum secretes progesterone
- progesterone maintains uterine wall
- progesterone inhibits FSH/LH
- lowered level of progesterone (due to degeneration of corpus luteum) leads to menstruation
22
Q
Draw a labelled diagram of a mature sperm cell. [4]
A
- head and midpiece/mid-section/body;
- tail/flagellum; (at least four times length of the head and containing fibres)
- acrosome; (shown as distinct structure near front of head)
- nucleus; (occupying more than half the width or length of head)
- mitochondria; (as repetitive structures inside membrane of mid piece)
- centriole; (between head and midpiece)
- (plasma) membrane; (shown as single line covering whole cell)
23
Q
Describe the functioning of immunoglobulins. [3]
A
- function as antibodies
- variety of binding sites
- specific to antigens on pathogens
- attracts phagocytes to engulf the pathogen
- agglutination
24
Q
Outline how antibiotics offer protection from certain forms of infectious disease. [4]
A
- inhibit the growth of bacteria
- bacteria processes blocked but not in eukaryotes
- block metabolic pathways (e.g. DNA replication/transcription/translation)
- do not protect against viruses (non-living)
- antibiotics fail to protect if bacteria are resistant
- used in animals/humans
25
Outline the role of hormones in the process of birth in humans. [4]
* level of progesterone falls before birth
* oxytocin secreted
* from pituitary
* stimulates uterine contractions
* contractions stimulate more release of oxytocin
* positive feedback loop
26
Outline the processes involved in oogenesis within the human ovary. [8]
* process where female gametes are produced
* begins in fetal development
* large number of cells formed by mitosis
* cells grow, become primary oocytes
* begin first mitotic division, stop in prophase I
* until puberty
* some follicles develop each month in response to FSH
* primary oocyte completes first meiotic division
* forms two cells of unequal sizes (unequal distribution of cytoplasm)
* creates polar body
* polar body degenerates
* secondary oocytes proceeds to meiosis II
* stops at prophase II
* meiosis II completed if cell is fertilized
* ovum and second polar body formed
27
Discuss the ethical issues surrounding IVF. [6]
pros
* chance for infertile couples to have children
* genetic screening of embryos reduces suffering from genetic diseases
* spare embryos safely stored for future pregnancies
cons
* IVF is expensive, not equally accessible
* cultural/religious objections
* lead to gender choice
* lead to unwanted pregnancies with associated risks
* inherited forms of infertility may be passed on to children
28
Discuss the cause, transmission and social implications of AIDS. [8]
causes
* AIDs caused by HIV
* penetrates T lymphocytes
* glycoprotein and cell receptors involved
* reverse transcriptase enables DNA to be produced from viral RNA
* number of lymphocytes reduced over the years
* results in lower immunity
* other illnesses develop
transmission
* HIV transmitted through sexual contact/breastfeeding
* minority of individuals have no cell receptors and do not develop AIDS
* condoms/latex barriers act as protection from transmission through sexual contact
social implications
* expensive treatment
* discrimination
* economic consequences
* traditions/beliefs/culture
29
Coughing to clear the airways is accomplished by muscle contractions. Explain muscle contraction. [8]
* myofibrils in muscle cells
* sarcomeres as the repeating units in myofibrils
* actin and myosin as overlapping protein filaments
* myosin (thick) actin (thin)
* nerve impulses stimulate contraction
* calcium ions released from sarcoplasmic reticulum and bind to troponin
* exposes actin binding sites
* myosin heads form cross-bridges with actin
* ATP breaks cross-bridges, causes movement of myosin heads
* myosin heads change angle
* myosin filaments pull actin towards centre
* sarcomeres shorten during contraction
30
All parts of the body change the composition of the blood. Explain how the nephron changes the composition of blood. [7]
* higher nitrogen/urea when blood enters bowman's capsule
* small soluble molecules/glucose/nutrients/ions removed from blood
* through ultrafiltration
* large molecules/proteins/blood cells remain in blood
* filtrate passes through nephron, water reabsorbed via osmosis
* selective reabsorption of glucose/nutrients in DCT via active transport
* sodium ions pumped into medulla in loop of Henle
* high sodium gradient enhances water reabsorption
* permeability of collecting duct dependent on ADH
31
Compare the processes of spermatogenesis and oogenesis. [8]
common
* produce haploid cells/mature sex gametes
* involve mitosis and meiosis
* cell growth before meiosis
* differentiation to produce specialized gametes
differences
* where: ovaries; testes
* when: development of embryo; puberty
* breaks: prophase I/prophase II/metaphase I; no breaks
* cytokinesis: split unequally, equal
* number of gametes per meiosis: one cell/egg, some polar bodies; four sperm
* number of gametes released: one per menstrual cycle; millions at a time
* timing of release: at ovulation; during intercourse
* if gametogenesis stops: menstrual pause; goes on until death
32
Describe the consequences of the potential overproduction of offspring. [5]
* more offspring than the environment can support
* increased mortality
* competition for resources
* better adapted more likely to survive
* better adapted pass on advantageous alleles
* natural selection leads to evolution
33
Draw a labelled diagram of a mature human egg. [5]
* haploid nucleus
* cytoplasm
* centrioles
* cortical granules
* plasma membrane
* zona pellucida
* follicle cells
* polar body (outside the egg cell)
* shown as 0.1mm
34
Draw a labelled diagram to show the structure of a sarcomere. [5]
* sarcomere labeled between Z lines
* Z lines at the ends
* actin as thin filaments attached to Z lines
* myosin as thick filaments
* myosin heads on both sides of myosin filaments
* light band (only actin) dark band (actin and myosin)
35
Explain the process of ultrafiltration. [3]
* blood in glomerulus under high pressure due to the difference in diameter of arterioles
* fluid plasma and small molecules forced into bowman's capsule
* prevents large molecules from passing through
36
Explain the principles of vaccination. [9]
* weakened/attenuated form of a pathogen
* introduced to patient
* pathogen stimulates specific immune response (primary)
* antigens stimulate T-cells
* stimulate cloning of B-cells
* develops memory cells
* that produce specific antibodies
* production of antibodies upon second exposure is much faster
* secondary response
* may need booster shots to maintain immunity
* example of artificial immunity
37
Describe the process of spermatogenesis in humans. [6]
* **spermatogonia** undergoes mitosis to keep a supply of germinal cells
* spermatogonia grow larger to become primary spermatocytes
* **primary spermatocytes** go through meiosis I
* forms secondary spermatocytes
* **secondary spermatocytes** go through meiosis II
* to produce spermatids
* **spermatids** differentiate (grow tail, reduce cytoplasm)
* associated with **Sertoli cells**
* sperm detaches from Sertoli cells, enter lumen of **seminiferous tubule**
* **testosterone** stimulates sperm production
38
ADH is a peptide hormone produced in the hypothalamus. Explain its action in the human body. [8]
* ADH plays a role in osmoregulation (regulating blood solute concentration)
* acts on the collecting duct
* acts in the DCT
* hypothalamus detects solute concentration
* if blood solution concentration is too high, pituitary releases ADH
* ADH stimulates insertion of aquaporins, increase permeability of collecting duct
* water moves by osmosis, reabsorbed into blood
* small volume of concentrated urine produced
* negative feedback
* if low blood solute concentration, no ADH released
* permeability of collecting duct decreases
* large volume of dilute urine produced
39
Describe the genetic and hormonal control of male sexual characteristics in a human. [3]
* male if (X and) Y chromosomes present
* gene on Y chromosome (SRY) promotes development of testes
* testes secrete testosterone
* testosterone stimulates sperm production/spermatogenesis
* testosterone stimulates development (in fetus) of male genitals/primary sexual
characteristics
* testosterone stimulates development of male secondary sexual characteristics
40
Explain the production of antibodies in humans. [7]
* antigens stimulate antibody production
* antibodies produced by lymphocytes
* macrophages engulf pathogens, display antigens
* T-cells activated by binding antigen
* activated T-cells activate B-cells
* mitosis of activated B-cells
* plasma cells formed from differentiating B-cells
* plasma cells secrete antibodies
* specific to one antigen
* some activated B-cells become memory cells
41
Explain two types of inheritance, using examples of parents heterozygous for two genes A and B. [7]
* unlinked genes on different chromosomes
* unlinked genes inherited independently
* equal chance for 4 options
* linked genes do not produce Mendelian ratios
* 1:1 chance of inheriting different options
* recombinants are formed
* crossing over in prophase I of meiosis
* causes changes in ratio/genetic variation
