Animal Physiology Flashcards
(115 cards)
1
Q
How are physiological processes moderated? How are homeostatic processes in general controlled?
A
Positive and negative feedback. Homeostatic processes are controlled by negative feedback specifically.
2
Q
What are the components of a feedback loop and what are their jobs?
A
- Receptor (monitor) –> monitors a controlled condition
- Control center (coordinating center) –> determines next action
- Effector (regulator)
–> receives directions from the control center
–> produces a response that changes the controlled condition
3
Q
What is homeostasis?
A
The property of a system that regulates its internal environment and tends to maintain a stable, constant condition. It keeps the system within a set range with the use of negative feedback loops.
4
Q
What are the two categories that organisms fit into when it comes to responding to changes?
A
- Osmoregulator
- Osmoconformer
5
Q
Explain an osmoregulator. Give an example of one.
A
–> Can regulate the solute concentration of their body fluids above or below that of their external environment
–> Can control the osmolarity of tissues within narrow limits
–> Changes in environment have no effect or cause minimal fluctuations in internal solute concentration
Possible answers below!
–> Humans
–> Birds
6
Q
Explain an osmoconformer. Give an example of one.
A
–> Actively or passively maintain an internal environment that is isosmotic to external environment
–> Solute concentration of body fluid is same as external medium in which organisms live
–> Cannot regulate the solutes of their body fluids at a concentration different to external medium
Possible answers below!
–> Sea stars
–> Molluscs
–> Marine crabs
–> Jellyfish
7
Q
What is the function of a negative feedback loop?
A
It’s employed to minimize the change in the internal environment and maintain a steady state.
8
Q
What is the function of a positive feedback loop?
A
It is employed to reinforce change and move away from a steady state. e.g. oxytocin levels during birth.
9
Q
What are aspects of internal regulation?
A
–> blood pH
–> carbon dioxide concentration
–> blood glucose concentration
–> body temperature
–> water balance (osmoregulation)
10
Q
What do the hypothalamus and pituitary act to coordinate?
A
The nervous system and the endocrine system.
11
Q
What is an example of positive feedback?
A
The pressure of a child on the uterus releases oxytocin, and this release stimulates contractions, which stimulates the release of more oxytocin until birth is completed.
12
Q
Outline how the stimulus of “increase in internal body temperature” impacts the body
A
Sensor: detected by skin receptors
Coordinator: hypothalamus
Effector (regulator): sweating + vasodilation
Response:
–> Sweating - secretion from sweat glands; excess body heat is converted to vapor
–> Vasodilation - widening vessels allows more heat to be lost
13
Q
Outline how the stimulus of “decrease in internal body temperature” impacts the body
A
Sensor: detected by skin receptors
Coordinator: hypothalamus
Effector (regulator): shivering + vasoconstriction + thyroxine + arrector pili muscles
Response:
–> Shivering - increases heat production
–> Vasoconstriction - narrowing vessels increases pressure of flow to skin
–> Thyroxine - released by thyroid to increase metabolic activity in cells
–> Arrector pili muscles - contraction raises skin hairs to trap heat
14
Q
Explain positive feedback with regard to oxytocin during childbirth.
A
- Pressure of child on uterus releases contractions.
- Oxytocin release stimulates contractions.
- Contractions stimulate the release of more oxytocin.
- Birth is completed and oxytocin release stops.
15
Q
Does the pancreas have exocrine or endocrine functions?
A
Both! As an exocrine gland (associated with the duct), it secretes enzymes that help with digestion. As an endocrine gland (ductless), it secretes hormones that regulate blood sugar levels.
16
Q
What are islets of Langerhans?
A
Pancreatic pits responsible for the secretion of insulin and glucagon
17
Q
Which cells release insulin and what does its release result in? When is it typically released?
A
–> Released from beta cells of the pancreas.
–> Cause a decrease in blood glucose concentration.
–> Released when blood glucose levels are high (e.g. after eating)
18
Q
Which cells release glucagon and what does its release result in? When is it typically released?
A
–> Released from the alpha cells of the pancreas
–> Causes an increase in blood glucose concentration
–> Released when blood glucose levels are low (e.g. after exercise)
19
Q
How does insulin decrease blood sugar concentration?
A
–> It stimulates glycogen synthesis in the liver (glycogenesis)
–> It promotes glucose uptake by the liver and adipose tissue
–> It increases the rate of glucose breakdown (increases cell respiration rates)
Cells become permeable to glucose.
20
Q
How does glucagon increase blood sugar concentration?
A
–> Stimulates glycogen breakdown in the liver (glycogenolysis)
–> Promotes glucose release by the liver and adipose tissue
–> Decreases the rate of glucose breakdown by reducing cell respiration rates
Glucose is released into the blood.
21
Q
Describe insulin function in normal physiology.
A
- (Bind) Insulin binds to insulin receptors.
- (Open) Triggers the opening of glucose transporters in fat and muscle cells.
- (Remove) Allows glucose removal from the bloodstream.
22
Q
Describe insulin failure in type I diabetes.
A
- Insulin is not produced by the beta cells in the pancreas.
- Glucose is not removed from the bloodstream, causing diabetes.
23
Q
Describe insulin failure in type II diabetes.
A
- Prolonged overproduction of insulin causes desensitization of insulin receptors.
- Glucose is not removed from the bloodstream, causing diabetes.
24
Q
List elements of type I diabetes mellitus. What is the treatment for it?
A
–> Juvenile onset
–> Unable to produce insulin
–> Often due to autoimmune disorders or viral infections that damage beta-pancreatic cells
–> Treatment involves:
- Insulin injection
- Pancreatic transplants
25
List elements of type 2 diabetes mellitus.
--> Adult onset (insulin resistance)
--> Insulin produced by body is unable to respond to it
--> Insulin receptors are ineffective at the cellular level (can't bind to its receptor on the cell membrane or leads to no response)
--> Treatments include
- Diet, exercise, lifestyle changes
- Prescription medications for glucose control and/or insulin injections
26
What is the function of endocrine glands?
They secrete hormones into the blood; the hormones travel through the blood and bind to the target tissue.
27
What does it mean for steroid hormones to be lipophilic? Give an example of a steroid hormone.
They can freely diffuse across the plasma membrane of a cell.
Examples:
- estrogen
- progesterone
- testosterone
28
What does it mean for peptide hormones to be hydophilic / lipophobic? Give an example of a peptide hormone.
They cannot freely cross the plasma membranes.
Examples:
- Insulin
- Glucagon
- Leptin
- ADH and oxytocin
29
What is leptin? What produces it? What is its function?
--> Leptin is a hormone that regulates fat stores within the body.
--> It is produced by adipose cells.
--> Leptin binds to receptors located within the hypothalamus to inhibit appetite and reduce food intake.
--> Circulating leptin levels provide a measure of the body's energy reserves.
30
What results in human obesity? What was discovered when attempts were made to use leptin supplements as a treatment for obesity?
--> Human obesity is a result of desensitized leptin receptors.
--> Leptin treatment had no positive effects on human obesity
--> Increased leptin levels caused skin irritations and other minor side effects
31
What are two elements that can cause leptin resistance?
--> Mutations - can cause failure in function of leptin receptors
--> Age - leptin resistance can develop with age
32
What is melatonin? What produces it? What is its function?
--> Melatonin is a hormone produced within the brain in response to changes in light.
--> It is produced by the pineal gland.
--> Its function is to control circadian rhythms, which are the body's physiological responses to the 24 hour day-night cycle.
--> It becomes entrained over time to anticipate the onset of night and day.
--> It promotes activity in nocturnal animals and sleep in diurnal animals.
33
What facilitates the secretion or lack thereof of melatonin?
Light exposure to the retina, which is relayed to the suprachiasmatic nucleus.
During light exposure, the SCN inhibits the pineal gland. During periods of darkness, there is no inhibition.
34
What are circadian rhythms driven by?
An internal (endogenous) circadian clock.
35
How is melatonin involved with jet lag?
--> Pineal gland continues to secrete melatonin according to the old time zone.
--> The sleep schedule is not synchronised with the new time zone.
--> Taking melatonin near the sleep time of the new time zone can help the body respond quicker to the new day-night schedule.
36
What is thyroxin? What produces it? What is its function?
--> Thyroxin is a hormone secreted in response to signals initially derived from the hypothalamus.
--> It's secreted by the thyroid gland.
--> It increases the basal metabolic rate by stimulating carbohydrate/lipid metabolism via the oxidation of glucose / fatty acids
--> It helps to control body temperature through its production of heat.
37
Name two effects of thyroxine.
Eight possible answers below!
--> Increased rate of utilization of foods for energy
--> Increased breathing rate to obtain oxygen / get rid of carbon dioxide
--> Increased rate of protein synthesis / catabolism
--> Increased number/size of mitochondria in body cells
--> Increased growth rate of children/adolescents
--> Growth/development of brain during fetal life / first years of post-natal life
--> Enhanced carbohydrate metabolism
--> Enhanced fat metabolism
38
Explain thyroxine deficiency. What are two symptoms of it?
Producing thyroxine requires four atoms of iodine. When iodine is not available in enough amounts to produce sufficient thyroxine, a goitre is developed (enlargement of the thyroid gland).
Five possible answers below!
--> Fatigue
--> Depression
--> Forgetfulness
--> Feeling cold
--> Constipation
--> Impaired brain development (in young children)
39
Explain negative feedback, and give an example of it.
--> A response that is the reverse of the change detected
--> a change is detected by a receptor and an effector is activated to induce an opposite effect, promoting equilibrium
Examples:
--> thermoregulation (if body temp changes, mechanisms to restore normal levels)
--> blood sugar regulation (insulin lowers high blood glucose, glucagon raises low blood glucose)
--> osmoregulation (ADH secreted to retain water when dehydrated, release inhibited when hydrated)
40
Explain positive feedback, and give an example of it.
--> A response that reinforces the change detected
--> A change is detected by a receptor and an effector is activated to induce the same effect, promoting further change
--> Change is amplified by feedback loop until the stimulus is removed
Examples:
--> Childbirth (stretching of uterine walls cause contractions that further stretch walls until birthing occurs)
--> Lactation (child feeding stimulates milk production which causes further feeding until baby stops feeding)
--> Ovulation (dominant follicle releases oestrogen which stimulates LH and FSH release to promote further follicular growth)
--> Blood clotting (platelets release clotting factors that cause more platelets to aggregate at the site of injury)
41
Name and describe the function of the eight different parts of the male reproductive system.
--> vas deferens (sperm duct) - carries sperm to penis during ejaculation
--> prostate gland - contributes alkaline fluid to the ejaculate, which helps to nourish the sperm.
--> urethra - delivers semen during ejaculation and urine during excretion
--> penis / erectile muscle - become erect to penetrate vagina during sexual intercourse, deliver sperm to top of vagina
--> seminal vesicle - produce fructose that provides sperm with a source of energy that helps with the sperm with a source of energy and helps with sperm motility
--> epididymis - functions in the transport and storage of the sperm cells that are produced in the testes
--> testis - produces millions of sperm every day, as well as testosterone
--> scrotum - protects and holds testes outside of the body to maintain an optimum temperature for sperm production
42
What does the male luteinizing hormone (LH) do? How is it secreted and released?
--> it promotes the production of testosterone by the interstitial cells
--> at puberty, the hypothalamus secretes the gonadotropin-releasing hormone (GnRH) which activates the pituitary gland to secrete/release FSH and LH
43
What are the two male sex hormones and where are they produced?
--> Androsterone and testosterone
--> They are produced in the interstitial cells (Leydig) of the testes
44
What does testosterone stimulate?
Spermatogenesis, the process by which spermatogonia divide and differentiate into mature sperm cells.
45
What is the effect of testosterone on the body during puberty?
- Pre-natal development of genitalia
- Development of male secondary sexual characteristics e.g.
--> Development of facial/body hair
--> Growth of larynx causes the lowering of voice
--> Strengthening of muscles
46
How does the Y chromosome factor into male development?
--> It includes a gene called the SRY gene
--> The SRY gene codes for a testis-determining factor (TDF) that causes embryonic gonads to form into testes
--> The testes secrete testosterone which causes the male genitalia to develop
47
What are the main female reproductive hormones, and where are they secreted from?
--> Estrogen and progesterone
--> They are secreted by the ovaries
48
What are the main effects of estrogen and progesterone on the body during puberty?
- Pre-natal development of female reproductive organs
- Development of secondary sex characteristics
--> Body hair
--> Breast development
- Involved in a monthly preparation of egg release following puberty (via the menstrual cycle)
49
How does the absence of the Y chromosome factor into female development?
In the absence of TDF protein, the embryonic gonads develop into ovaries due to the presence of maternal estrogen and progesterone. As a result, female reproductive organs develop.
50
Which chromosome is bigger, and carries more genes (between X and Y)?
The X chromosome --> carries many genes in the non-homologous region not present on Y.
51
Define TDF.
A DNA binding protein that acts as a transcription factor promoting the expression of genes involved in the differentiation of the gonads into the testis.
52
Is there any difference between the gonads in embryos?
Nope -- they could become either ovaries or testes.
53
Okay, label the eight major parts of the male reproductive system! You can check them in the slides on the back!
https://docs.google.com/presentation/d/16xdikS-RT0GQTDw2eic3NB1ToWCICDesGb5ACMRvaC4/edit#slide=id.g125598e6b9d_0_6
54
Where does spermatogenesis occur? Where are spermatogonia located? Explain the four steps of spermatogenesis (More Guys Die Deaths)
--> In the seminiferous tubules of the testes
--> At the periphery of each tubule
1. (Mitosis) Germline epithelium of tubules divides by mitosis.
2. (Growth) Spermatogonia undergo a period of cell growth, becoming diploid spermatocytes.
3. (Division) Spermatocytes undergo two meiotic divisions to form four haploid daughter cells (spermatids).
4. (Differentiation) Spermatids differentiate to become functional sperm cells (spermatozoa).
55
How are negative feedback systems utilized in the male reproductive system?
They ensure that adequate numbers of sperm cells and constant levels of testosterone are maintained.
56
What is the function of the pituitary gland in the male reproductive system?
It produces and stores the gonadotropic hormones, which regulate the function of the testes.
57
What does FSH stand for, and what does it do in the male reproductive system?
"Follicle-stimulating hormone"
--> It initiates spermatogenesis by triggering the first meiotic division of spermatocytes
--> It activates Sertoli cells, which nourish cells undergoing spermatogenesis
58
Take a look at the diagram on the back and make sure you can identify each part of the cross-section of the testes!
https://docs.google.com/presentation/d/1opVBgM-8AkOrcKb3XxAH883-IgcbamJtIM2FyKbXEdU/edit#slide=id.p8
59
Describe the progression of male hormones starting with secretion from the hypothalamus.
1. Hypothalamus secretes GnRH
2. GnRH activates anterior pituitary
3. Anterior pituitary secretes/releases:
FSH
--> activates Sertoli cells, which influence sperm production
LH
--> promotes production of testosterone by interstitial cells
60
Describe the nature and functions of the six major parts of the female reproductive system.
Uterus
--> Site for gestation of embryo and fetus
--> provides protection, nutrients, and waste removal for developing fetus
--> Muscular walls contract to aid birthing process
Fallopian tubes
--> Connects ovary to the uterus, transports oocyte to uterus
--> Where fertilization of the egg occurs
Ovary
--> Location of meiosis - eggs stored, develop, and mature
--> Produces estrogen and progesterone
Endometrium
--> Mucous membrane lining of uterus
--> Develops each month to prepare for implantation of fertilized egg
--> Site of implantation becomes placenta
Cervix
--> Muscular opening/entrance to uterus
--> Closes to protect developing fetus, opens to form birth canal
Vagina
--> Forms birth canal, receptacle for penis during heterosexual intercourse
61
Try to label the female reproductive system without looking!
https://docs.google.com/presentation/d/1yWDeNXDIJF6jJZkGiyPa5EB9GRgCerakxKwrKP0MMTI/edit#slide=id.g1253290f0fa_0_79
62
How is GnRH involved with the menstrual cycle?
1. Hypothalamus secretes GnRH
2. GnRH activates anterior pituitary
3. Anterior pituitary gland secretes/releases FSH and LH
63
Where does oogenesis occur? Explain the process of oogenesis.
Oogenesis takes place in the ovaries.
--> (FSH production) At puberty, FSH begins to be produced, causing some follicles to develop each month.
--> (First meiotic division) This allows the oocyte to complete the first meiotic division.
--> (Secondary oocyte) The first meiotic division forms two cells -- a polar body which eventually degenerates, and a secondary oocyte which enters meiosis II.
--> (Halting) Meiosis II is halted at metaphase II if fertilization does not occur.
--> (Continuation) If fertilization occurs, then meiosis II continues and a second polar body and ovum are produced.
64
Name two similarities of spermatogenesis and oogenesis.
Four possible answers below!
--> Involve mitosis
--> Involve cell growth
--> Involve two divisions of meiosis and differentiation
--> Result in haploid gametes
65
What is the difference between sperm cells and egg cells in terms of cytoplasm? Why do sperm cells have less cytoplasm?
Sperm cells have almost no cytoplasm, while egg cells have increased cytoplasm. Sperm cytoplasm becomes reduced with every division.
66
How do sperm cells and egg cells differ in terms of number of gametes?
In oogenesis, the polar body in meiotic division continually degenerates, meaning that only one egg is produced per oogonium. In humans, only one egg cell matures and is released during every menstrual cycle.
In spermatogenesis, mature spermatozoa have undergone a complete meiotic division, yielding four sperm cells per spermatogonium. In humans, millions of sperm are produced daily.
67
Wild carrrrrd! Can you annotate the process of spermatogenesis?
For reference:
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/11.4.2.1-Spermatogenesis.91b4f16daf05466acda9.png
68
Wild carrrrrd! Can you annotate the process of oogenesis?
For reference:
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/11.4.2.2.51c87c75ae4d813f662c.png
69
Wild carrrrrd! Can you annotate a sperm cell?
https://old-ib.bioninja.com.au/higher-level/topic-11-animal-physiology/114-sexual-reproduction/egg-and-sperm.html
70
Wild carrrrrd! Can you annotate an ovum?
https://old-ib.bioninja.com.au/higher-level/topic-11-animal-physiology/114-sexual-reproduction/egg-and-sperm.html
71
What is fertilization and where does it occur? What type of cell is the resulting zygote? (haploid vs diploid)
It is the fusing of two gametes (egg cell and sperm cell) and it takes place in the fallopian tube of the female body. The resulting zygote is diploid.
72
Outline the steps of human fertilization.
1. (Capacitation) Chemicals released by the uterus dissolve the sperm's cholesterol coat, improving sperm motility and destabilizing the acrosome cap of the sperm.
2. (Acrosomal reaction) A sperm cell penetrates follicle cells and binds to the receptors of the zona pellucida. Hydrolytic enzymes released from the acrosome digest the egg's jelly coat, so the sperm nucleus can enter the egg cell.
3. (Fusion) The first sperm to make it through the zona pellucida fertilizes the egg. The proteins on its head bind to the receptors on the egg membrane --> the membranes fuse, and the sperm nucleus enters the egg cell.
4. (Cortical reaction) The cortical granules of the egg release enzymes via exocytosis into the zona pellucida -- this destroys sperm binding sites and thickens/hardens the glycoprotein matrix of the jelly coat, preventing polyspermy.
73
Define/describe external and internal fertilization and state which animals they occur in.
External fertilization involves two haploid gametes (a sperm and egg cell) fusing together outside of the parents' body.
--> Vast quantities of eggs and sperm are produced
--> Can be predated upon by other animals
--> Lower chances of fertilization (low proximity)
--> It occurs in fish and amphibians.
Internal fertilization involves the transfer of sperm into the female's body for fertilization to occur.
--> Fewer eggs and sperm
--> Higher chances of fertilization (close proximity)
--> It occurs in mammals (sperm need fluid to swim to egg)
74
Name and explain the four phases of the menstrual cycle.
1. Follicular phase
--> FSH causes several follicles in the ovary to develop -- one matures
--> The follicle secretes estrogen as it develops
--> This stimulates the endometrium to thicken with mucus and a rich supply of blood vessels
--> These changes last for approx 10 days
2. Ovulation
--> A high level of estrogen in the blood causes the pituitary gland to reduce FSH secretion (negative feedback) and begin LH secretion (positive feedback
--> The decrease of FSH decreases the production of estrogen in turn
--> When the concentration of LH in the blood reaches a certain level, mature follicle ruptures and releases a mature egg
--> Occurs in the middle of the menstrual cycle
3. Luteal stage
--> After ovulation, LH causes the ruptured follicle to fill with cells, forming the corpus luteum
--> The corpus luteum begins to secrete progesterone, which maintains endometrium growth
--> Corpus luteum produces estrogen
--> When concentration of estrogen and progesterone rise to a certain level, they inhibit FSH and LH secretion (negative feedback)
4. Menstruation:
--> If fertilization does not occur, the corpus luteum breaks down
--> Progesterone and estrogen levels decrease in response
--> The thickened endometrium breaks down without progesterone.
--> The extra endometrium, unfertilized egg, and a small amount of blood exit the body
--> Lasts for 3-5 days
--> The amount of estrogen in the blood falls, reducing inhibition of FSH secretion
--> The pituitary gland increases FSH output, and the cycle continues
75
What are the roles/levels of progesterone, estrogen, FSH, and LH throughout the menstrual cycle?
Progresterone: highest at the start of the luteal phase, thickens/maintains endometrium
Estrogen: Peaks at end of follicular phase, stimulates endometrium repair and increase in FSH receptors
FSH: Rises towards end of cycle, stimulates follicle development and estrogen production
LH: Peaks at end of follicular phase, stimulates meiosis completion of oocyte, and thinning of follicular wall for ovulation. After ovulation, stimulates development of corpus luteum
76
What is IVF? Detail its eight steps. (Don't Steal My Candy, Steal My Green Ink)
1. (Drugs) Woman given drugs to suppress natural cycle, administers her hormones herself
2. (Superovulation) FSH and LH injected at higher than normal doses for 12 days to stimulate production of multiple ova
3. (Mature!) 34-38 hours before collection, hormone injection -- usually hCG -- to help eggs mature
4. (Collection) Eggs collected from ovaries with ultrasound guidance while person is sedated
5. (Sperm collection) Sperm sample is collected and checked for viability
6. (Mix!) Eggs and sperm are mixed, eggs cultured in labs for 16-20 hours after where they are checked for fertilization
7. (Growth) New embryos are grown in lab incubator for up to 6 days, best embryo chosen for transfer
8. (Implantation) 1-3 embryos implanted in uterus depending on age
77
What are the scientific arguments against IVF?
--> Often results in multiple births, putting babies/mother at risk
--> Hormonal injections can cause harm to women
78
What was Aristotle's theory of fertilization? How did William Harvey debunk it?
The man produces a seed which develops into an egg, which further develops into an embryo with the help of menstrual blood.
--> Harvey observed and dissected female deer in mating season to see if small embryos could be found after fertilization.
--> He could not find any in the uterus and theorized that the "seed and soil" theory was wrong.
79
Define gametogenesis.
The process by which the cells of the germinal epithelium undergo cell division/differentiation to form haploid gametes.
80
What happens over the next seven days following fertilization?
--> Ovum divides by mitosis
--> After approx 48 hours, four-cell embryo developed
--> Embryo slowly divides further while migrating from fallopian tubes to uterus
81
Explain a blastocyst and its composition.
A blastocyst is what a fertilized egg has become once it has migrated to the uterus--it usually consists of approx 125 cells.
It is made up of:
--> Zona pellucida
--> Thin-walled hollow structure containing an outer layer of cells (trophoblast) -- develops into placenta and other supporting tissues for fetal development
--> Fluid-filled blastocyst cavity (blastocoel)
--> Cluster of cells (embryoblast) -- develops into embryo
82
Explain the implantation stage of pregnancy.
-->Zona pellucida breaks down, allows blastocyte to implant into uterine wall
--> Finger-like projections grow into endometrium and develop into placenta, allowing embryo to access nutrients
83
How is the endometrium maintained throughout pregnancy? How can failure to maintain it cause miscarriages?
--> Early in pregnancy, trophoblast of embryo begins producing hCG
--> hCG stimulates corpus luteum to continue production of progesterone and estrogen, which maintain endometrium
--> hCG also ensures that corpus luteum remains until placenta can take over progesterone and estrogen secretion.
Loss of corpus luteum before placenta is fully established is responsible for miscarriages.
84
State and detail the function of the chorionic villi of the placenta.
They provide maximum surface area for contact with maternal blood.
--> Fetal blood circulates in capillaries close to the surface of the villus
--> The villi project into the intervillous space of the placenta, where maternal blood collects
--> The resulting proximity of the fetal and maternal blood facilitates diffusion.
85
What are the two important functions of the placenta throughout pregnancy?
--> Exchange of material to keep the fetus alive during pregnancy
--> Production of progesterone and estrogen
86
What materials pass from the mother to the fetus across the placenta, and vice versa?
Mother:
--> Oxygen
--> Glucose, amino acids, vitamins, minerals via facilitated diffusion
--> Water
--> Hormones via endocytosis
--> Drugs, alcohol, other harmful substances
--> Some viruses (rubella, HIV) via receptors
Fetus:
--> Carbon dioxide
--> Urea via facilitated diffusion
--> Water
--> Hormones (e.g. hCG) via exocytosis
87
How do arteries/veins help bring oxygen to the fetus?
The two fetal arteries bring deoxygenated blood from the fetus to the placenta. The fetal vein brings oxygenated blood back from the placenta to the fetus.
88
How does gestation period of mammals change based on animal mass?
The higher the average mass of an animal, the longer the gestation period.
Smaller mammals often have helpless offspring that need a lot of protection. Larger mammals have more developed young.
89
Explain the eight steps of the birth process (Pick On Rich People, Labor Doesn't Want Empathy)
1. (Progesterone stops) Fetus signals to placenta to stop producing progesterone.
2. (Oxytocin) Triggers secretion of oxytocin by posterior pituitary gland / fetus
3. (Receptors) Estrogen levels continue to rise, developing oxytocin receptors on the endometrium
4. (Prostaglandins) Endometrium secretes prostaglandins that start uterine contractions
5. (Labor) Oxytocin stimulates the myometrium to contract, contractions growing progressively stronger through positive feedback
6. (Dilation) Strength of contractions increases, baby's head is pushed down the cervix, helping it to open
7. (Water breaks) Amniotic sac breaks
8. (Expulsion) Eventually, the baby, umbilical cord, and placenta are pushed through the cervix and out of the vagina
90
What causes lactation after birth?
After the baby is born, prolactin (hormone produced by anterior pituitary gland) stimulates milk production. Prolactin production is stimulated when the baby suckles.
91
Explain overhydration. Name two of its effects.
The normal balance of electrolytes in the body exceed safe limits; the body cells swell, which leads to intercranial pressure in the brain.
Possible answers below!
--> Dysfunction in central nervous system
--> Seizures
--> Nausea
--> Vomiting
--> Changes in mental state
--> Muscle weakness
--> Cramps
--> Unconsciousness
--> Coma
--> Death
92
Explain dehydration. Name two possible causes of it, and two of its effects.
Use/loss of fluid is greater than intake, and the body does not have enough water or fluids to carry out normal functions.
Possible answers below!
--> Vigorous exercise
--> Intense diarrhea
--> Vomiting
--> Fever
--> Excessive sweating
Possible answers below!
--> Urine becomes darker
--> Skin becomes less elastic
--> Heart and breathing rate increases
--> Blood pressure decreases
93
How do the kidneys facilitate osmoregulation and excretion?
They filter your body to rid your body of nitrogenous waste, regulate osmolarity, and produce urine, which leaves the kidney via the ureter.
94
Name three compounds that are removed from the blood through kidney filtration. What remains in the blood?
Possible answers below:
--> Drugs
--> Toxins
--> Nitrogenous waste
--> Excess water
--> Salt
Large proteins remain in the blood.
95
Wild carrrrrd! Can you label and draw the kidney?
https://kognity-prod.imgix.net/media/edusys_2/content_uploads/11.3.2.1-Human-kidney.5aa915a919ea0c079bb6.jpe?w=900&auto=compress
96
What are the three important differences between the composition of blood entering and leaving the kidney?
Glucose - lower concentration in the renal vein, some glucose reabsorbed for metabolic processes
Oxygen - lower concentration in the renal vein, some oxygen used in metabolic processes
Carbon dioxide - higher concentration in the renal vein, production of carbon dioxide during cell respiration
97
Wild carrrrrd! Label the nephron.
https://old-ib.bioninja.com.au/_Media/nephron1_med.jpeg
98
State the nine parts of the nephron, and detail their functions.
--> Bowman's capsule: highly porous wall which collects the filtrate
--> Glomerulus: knot-like capillary bed where high-pressure filtration takes place
--> Proximal convoluted tubule: twisted section of the nephron, reabsorption site of water/salt/nutrients, contains many mitochondria and microvilli
--> Loop of Henle: hairpin shaped tube with a descending and ascending limb, where water/salt are reabsorbed
--> Distal convoluted tube: twisted section of the nephron, reabsorption site of water/salt/nutrients, contains many mitochondria and microvilli
--> Collecting duct: tube that carries filtrate to the renal pelvis
--> Afferent arteriole: brings blood from renal artery
--> Efferent arteriole: narrow blood vessel that restricts blood flow, helping to generate pressure needed for filtration
--> Vasa recta: unbranched capillary shaped like the loop of Henle -- descending limb brings blood deep into medulla
99
What does the glomerulus consist of? How do podocytes regulate the filtration process?
A knot of intertwined capillaries enveloped by podocytes, the cells of the Bowman's capsule's inner wall.
--> Podocytes have cellular extensions (pedicels) that fold around the blood capillary
--> They form a network of filtration slits that hold back the blood cells during ultrafiltration
100
Where does the basement membrane lie?
Between the glomerulus and the Bowman's capsule.
101
Explain ultrafiltration.
--> (Pressure) Driven by the high pressure in the capillaries
--> (Flow) The fenestrations -- small openings -- of the capillary wall allow blood to flow out
--> (Sieve) Basement membrane -- glycoprotein matrix -- acts as a sieve and stops blood cells / large proteins
--> (Exit) Small proteins, salts, and nutrients pass out
102
What is the high capillary pressure in the glomerulus caused by?
--> Wide afferent arterioles convey blood at high arterial pressure directly to the glomerular capillaries.
--> The smaller diameter of the efferent arterioles restrict outflow of blood
--> Extensive narrow branches increase surface area available for filtration
--> Net pressure gradient within glomerulus forces blood to move into capsule space
103
What are the three aspects of the reabsorption process in the proximal convoluted tubule?
1. (Active transport) Pumps use ATP for active transport to shuttle Na+ out of tubule and K+ into tubule.
2. (Secondary active transport) Glucose and amino acids absorbed with Na+ by specific carrier proteins down concentration gradient -- powered by active transport.
3. (Concentration increase) Glucose and amino acid concentration within PCT increases -- higher concentration than blood plasma, so they are reabsorbed by diffusion.
104
How do microvilli in the tubule wall cells enhance the diffusion process?
They greatly increase the surface area.
105
What percentage of the water, glucose, and mineral ions are reabsorbed by the end of the proximal convoluted tubule?
80%.
106
What is the vasa recta?
Blood capillaries that run parallel to the loop of Henle.
107
How does the loop of Henle work?
--> In the descending limb, water moves out into the medullary interstitial fluid by osmosis, before being reabsorbed into the vasa recta
--> Descending loop is impermeable to Na+; osmolarity of filtrate increases as water is lost.
--> Ascending limb is impermeable to water but permeable to Na+
--> Na+ moves out of filtrate into interstitial fluid of medulla
--> Salt remains temporarily near loop of Henle, helps to maintain concentration gradient in medulla
--> Absorption of Na+ from the interstitial fluid into vasa recta by active transport
--> Fluid leaving loop of Henle is less concentrated than surrounding tissue fluid
--> As Na+ is pumped out of ascending loop, interstitial fluid in medulla becomes hypertonic
--> Reabsorption of water in descending limb
TL;DR - the loop of Henle maintains hypertonic conditions in the medulla
108
How do desert animals manage to better reabsorb water?
They have longer loops of Henle, and sometimes as a result a thicker medulla to accommodate.
109
What triggers ADH secretion?
--> Osmoreceptors in hypothalamus monitor solute concentration of blood.
--> When solute concentration is too high, pituitary gland secretes ADH
--> ADH travels through bloodstream to the collecting ducts and the distal convoluted tubule.
110
Detail the function of ADH.
--> ADH increases permeability of ducts and DCT to water, so more water can be reabsorbed and solute concentration decreases
--> Urine becomes more concentrated and darker in color
--> Once situation returns to normal, ADH secretion stops
111
How does ADH increase permeability to water? Explain with reference to aquaporin.
--> ADH acts on receptors in the cell membranes of collecting tubule cells.
--> Binding of ADH to receptors initiates a series of events that causes aquaporin to move to surface membrane
--> Aquaporin allows water molecules to pass through
--> When osmolarity returns to normal, ADH secretion stops
--> Water molecules are removed from membrane and reform as vesicles
--> Collecting duct becomes impermeable to water, filtrate is lost as urine
(Note: Aquaporins are membrane proteins that cause vesicles with aquaporins to fuse with the surface membrane. The aquaporin allows water molecules to pass through)
112
Name one possible cause of kidney failure, and the two medical solutions for it.
Possible answers below!
--> Diabetes
--> Hypertension
--> Untreated UTIs
Two medical solutions:
--> Hemodialysis
--> Kidney transplant
113
Explain the process of hemodialysis and its elements.
An artificial membrane -- dialysis tubing -- is used to remove wastes, balance electrolytes in the blood, and eliminate extra fluid.
Elements
--> Dialyser: made up of two parts -- one for blood, and one for dialysate (washing fluid)
--> Dialysis tube: thin membrane that separates the two parts
During hemodialysis
--> Blood cells, protein, and other important molecules remain in the blood because they are too big to pass through the membrane.
--> Smaller waster products in the blood pass through the membrane and are washed away in dialysate.
114
What does the presence of glucose, blood/leucocytes, and protein respectively in a urine kit test indicate?
--> Too much glucose suggests diabetes
--> Blood or leucocytes indicates an infection or a kidney tumor
--> Protein indicates that ultrafiltration is failing, possibility of advanced/prolonged hypertension
115
Explain the details of how insects excrete nitrogenous waste.
--> Internal organs are bathed in hemolyph, a fluid combining characteristics of blood and interstitial fluid
--> Insects rely on branching tubules that extends from the alimentary canal -- Malpighian tubule system
--> Tubules absorb solutes, water, and waste from surrounding hemolymph
--> Hind gut reabsorbs most of the water and mineral salts
--> Insects convert ammonia into uric acid, which is insoluble in water, and excreted as semisolid
