term test 2 Flashcards
1
Q
kidney location
A
- located at dorsal lumbar area outside of the abdomen , between peritoneum and dorsal abdominal muscles outside the peritoneal cavity
- right kidney more cranial than the left in most domestic animals
2
Q
gross anatomy of kidney
A
- bean-shaped structure
- in cattle , it is lobulated
- hilus
- renal pelvis
- renal cortex
- renal medulla
- calyx
3
Q
hilus - kidney
A
- indented area in medial side
- where ureters , nerves , blood and lymph vessels enter and leave the kidney
4
Q
renal pelvis - kidney
A
- funnel-shaped area
- beginning of ureter
- collects urine produced by renal cortex before it travels through the ureter into the bladder
5
Q
renal cortex and renal medulla - kidney
A
renal cortex ;
- outer portion of kidney
renal medulla ;
- inner portion around renal pelvis
6
Q
calyx / calyces - kidney
A
- cup-like structure
- formed when renal pelvis extends into the medulla pyramid
- directs and collects fluids into renal pelvis
7
Q
microscopic anatomy of kidney
A
- basic functional unit : nephron
each nephron consists ;
- renal corpuscle
- proximal convoluted tubule (PCT)
- loop of henle (LOH)
- distal convoluted tubule (DCT)
renal corpuscle -> PCT -> LOH -> DCT -> urine
- some parts of a nephron eg renal corpuscle are only in the cortex while others eg loop of henle is only in the medulla
8
Q
renal corpuscle
A
- located in renal cortex
- glomerulus / glomerular tuft ; cluster of capillaries
- bowman’s capsule ; surrounds the glomerulus to hold the capillaries
- capsular space / bowman’s space ; between capsule and glomerulus , there is a space
- filters blood in the first stage of urine formation
- fluid that is filtered OUT of blood through capillaries and into capsular space = glomerular filtrate
9
Q
blood supply into glomerulus
A
- renal artery enters kidneys at the hilus , dividing into smaller arteries and even smaller arterioles
- afferent glomerular arterioles carries blood into glomerular capillaries of renal corpuscle
- glomerular capillaries filters some plasma out of the blood into the bowman’s space and it becomes glomerular filtrate
- efferent glomerular arterioles receives blood from glomerular capillaries
- A goes in , E goes out
10
Q
proximal convoluted tubule (PCT)
A
- continuation of capsular space
- twisting path through the cortex
- when glomerular filtrate enters the PCT from the capsular space , it becomes tubular filtrate
- where 65% of reabsorption takes place
11
Q
loop of henle (LOH)
A
- long , u-shaped portion of the tubule
- descends from PCT into medulla (descending LOH)
- turns and heads upwards back into the cortex (ascending LOH)
12
Q
distal convoluted tubule (DCT)
A
- DCT is the continuation of the ascending LOH
- DCT of all nephrons will drain urine into collecting ducts
- collecting ducts carries tubular filtrate (which is now waste products only / urine) through the medulla and empties into renal pelvis
- primary site of action of ADH (antidiuretic hormone)
13
Q
reabsorption in the tubules is possible because …
A
- efferent glomerular arterioles divide to form peritubular capillaries (small capillaries that surround the tubules)
- allows oxygen supply to the tubules , tubular reabsorption , tubular secretion
- peritubular capillaries will converge at the end to form a larger vein (renal vein)
- renal vein leaves the kidney at the hilus to join the caudal vena cava
14
Q
3 steps of urine formation
A
- kidney filters unwanted substances to excrete them
1. glomerular filtration
2. tubular reabsorption
3. tubular secretion
15
Q
glomerular filtration
A
- glomerular capillaries are permeable (not enough to allow blood cells and large proteins to pass through)
- plasma proteins and substances such as calcium that are bound to them are unable to pass
- fluids leave bloodstream into capsular space
- in glomerular capillaries , blood pressure is very high and forces some plasma out into capsular space
- glomerular filtrate = primitive urine (first stage)
16
Q
glomerular filtrate
A
- fluid that passes through glomerular capillaries into capsule space
- any product that is smaller than plasma protein or freely dissolved in plasma appears in glomerular filtrate
- eg sugars , amino acids , toxins
- glomerular filtrate in the capsule space will move on to the next section of the renal tubule (proximal convoluted tubule PCT)
17
Q
reabsorption
A
- ensures the body gets back small useful molecules from the filtrate
- eg amino acids , peptides , glucose , water , Na+ , Cl-
- substances to be reabsorbed pass through the tubular lumen , tubular wall and capillary wall back into the bloodstream
- 65% of reabsorption takes place in the PCT , and remaining in the DCT / LOH
- 80% of water , sodium chloride & bicarbonate are reabsorbed
- 100% of glucose & amino acids are reabsorbed [if they are detected in the urine , it could suggest problems]
18
Q
sodium / glucose & amino acid / potassium & calcium / chloride / water reabsorption
A
sodium ;
- PCT , LOH , DCT
glucose & amino acid ;
- PCT
potassium & calcium ;
- PCT
chloride ;
- diffuses through in response to an imbalance created by sodium reabsorption
- moves with sodium
water ;
- follows ions through osmosis
- once sodium , glucose , amino acids & chloride have left tubular filtrate , water molecules follow
19
Q
antidiuretic hormone (ADH) - urinary
A
- ADH from pituitary gland
- acts on DCT to promote water reabsorption
- tells DCT to reabsorb more water
- concentrates urine
- released when an animal is dehydrated or hypotensive to increase water content in the blood
20
Q
alosterone
A
- from adrenal cortex
- acts on DCT to increase reabsorption of sodium
- tells DCT to reabsorb more sodium
- more sodium reabsorbed = osmotic imbalance = water molecules follow
- concentrates urine
- Na+ reabsorbed = K+ secrete
- if sodium is taken in, must be replaced by potassium to maintain salt balance
21
Q
tubular secretion
A
- substances from blood capillaries move into tubules / urine
- substances not filtered in the glomerulus eg urea , ammonia OR due to reabsorption of sodium eg potassium , hydrogen for salt and acid-base balance
- occurs in PCT , LOH and DCT
22
Q
renin - osmoregulation
A
- hormone secreted in glomerulus in response to low arterial pressure
- if pressure is low , glomerulus cannot filter blood to form glomerular filtrate
- converts angiotensinogen into angiotensin
23
Q
angiotensin - osmoregulation
A
- vasoconstriction to raise blood pressure
- the constriction stimulates the release of aldosterone from adrenal cortex , causing water to be reabsorbed into the bloodstream
- more water = higher pressure = glomerulus able to filter blood to form glomerular filtrate
24
Q
ureters
A
- leavers kidney at the hilus
- has 3 layers :
1. outer fibrous
2. middle smooth muscle (propels urine by peristaltic contractions)
3. inner layer lined with transitional epithelium (allows ureters to stretch as urine passes through) - enters urinary bladder at oblique angle , forming a valve to prevent back flow
- when bladder is full , urine presses on the entrance to close the valve
25
Q
urinary bladder
A
- lined with transitional epithelium , can stretch as it is filled
- wall of the urinary bladder has smooth muscle
- around the neck of the urinary bladder , there are sphincter muscles
26
Q
sphincter muscles
A
- internal sphincter : smooth muscles under involuntary control
- external sphincter : skeletal muscle under voluntary control , allows control of urination
- when the bladder is full , it sends a signal to the spinal cord which tells the smooth muscle / internal sphincter to tract
- the contraction of the smooth muscle when the bladder is full , we get the urge to pee
27
Q
urethra
A
- continuation of the neck of urinary bladder
- carries urine from bladder to the external environment
- lined with transitional epithelium that allows it to stretch
- female ; shorter , straighter , only urinary function
- male ; longer , curved , runs down centre of the penis and also carries semen
28
Q
control of urination process
A
- urination = excretion of urine from urinary bladder to urethra to external environment
- build-up of pressure in the bladder activates stretch receptors (senses pressure) in the bladder wall
- stretch receptors activate spinal reflex that cause smooth muscles of the bladder to contract
- contraction gives the sensation of needing to urinate
- voluntary control of the external sphincter (skeletal muscle) around the neck of the bladder allows temporary control of the urination
- house-trained animals exercise some form of voluntary control and temporarily hold urine (eg grass trained dogs)
- however , beyond a certain pressure limit , the sphincter must relax to release the urine
29
Q
formation of urine
A
filtration -> reabsorption -> secretion -> concentration -> excretion
30
Q
mitosis
A
- cell division that results in 2 daughter cells each having the same number and kind of chromosomes as the parent cell
- aka diploids
- daughter cells are identical to each other and parent cell
- typical form for tissue growth , but NOT for sperm and ovum .
31
Q
meiosis
A
- cell division that results in daughter cells each with half the number of chromosomes as the parent cell
- aka haploids
- daughter cells are not identical to the parent cell
- sex cells eg sperm and ovum are produced this way
- this ensures the fertilised egg from the union of sperm and ovum has the same number of chromosomes as a parent cell (half + half = one)
32
Q
components of male reproductive system
A
- testes
- dust system (epididymis , vas deferens , urethra)
- external genetalia (penis , scrotum)
- accessory glands (prostate gland , bulbourethral gland that dogs do not have , vesicle glands in rats only)
33
Q
testes
A
- produces sperm cells and testosterone
- “held” inside the scrotum , outside the abdomen as normal internal body temperature is too high for sperm development
- concentration of testosterone influences the development of sperm and other male secondary sexual characteristics (eg bigger body, having penis and testes)
34
Q
testes microscopic
A
- seminiferous tubules ; coiled mass of tubules , produces sperm
- seminiferous tubules eventually combine / join to form epididymis (a long convoluted tubule)
- interstitial cells ; between the tubules , secretes testosterone
35
Q
scrotum
A
- skin pouch that houses testes
- regulates temperature of testes
- maintains testes at 3 degrees celsius lower than normal body temperature to protect sperm’s viability
- 2 muscles attached to the scrotum : cremaster and dartos , pull scrotum close to the body when it is cold and relax when it is warm
36
Q
epididymis
A
- highly convoluted duct , caudal to testes
- tail of epididymis continues as vas deferens (epididymis eventually converge to form vas deferens . sperm goes from epididymis to vas deferens to prostate , urethra and out)
- sperm that is formed in the seminiferous tubules will mature as they pass into the epididymis
- sperm is stored in the epididymis before they are propelled along vas deferens during ejaculation
37
Q
vas deferens
A
- aka ductus deferens
- carries sperm quickly from epididymis to urethra during ejaculation
38
Q
penis
A
- urethra surrounded by layers of erectile tissue , muscle and connective tissue
- erectile tissues have many holes where blood can enter to erect the penis , enabling entry to the vagina
- penis has rich blood supply with many nerve endings
- delivers semen (sperm + fluids) from the testes into the female reproductive tract during mating
- also expels urine from the bladder to the outside via urethra
39
Q
os penis
A
- embedded in erectile tissue close to the tip is the os penis
- os penis allows the entry of the penis into the vagina before erection is fully complete
40
Q
accessory glands
A
- semen = sperm + fluid
- fluid = secretions from various accessory glands
- alkaline fluid (includes electrolytes, etc) to protect the sperm by counteracting the acidity of the female reproductive tract
- vagina = acidic , good for female’s health but hard for sperm to survive . alkaline fluid counteracts that
- different species have different combinations of accessory glands
41
Q
prostate gland
A
- present in all domestic animals
- particularly large in dogs
42
Q
bulbourethral glands
A
- only in cats and a few other animals
43
Q
seminal vesicle glands
A
- not present in dogs and cats
- rats have
44
Q
components of female reproductive system
A
- ovary
- uterine tube
- uterus (uterine horns , uterine body)
- cervix
- vagina
- vulva
45
Q
ovaries
A
- lies on each side of the dorsal part of the abdominal cavity (very close to kidneys)
- produces ova/eggs
- produces oestrogen during follicle development stage and preparing for mating
- products progesterone to prepare for and maintain pregnancy by creating a comfortable environment in uterine lining
- contains primary follicles which develop into mature follicles
- number of follicles in a female is fixed from birth
46
Q
primary follicles
A
- within ovarian connective tissue
- contains an immature ovum surrounded by a single layer of follicular cells
- each follicle has only one egg cell
- can develop into a mature follicle
47
Q
mature follicle
A
- contains small amount of fluid and an ovum
- each follicle has only one egg cell
48
Q
oviduct
A
- aka uterine tube / fallopian tube
- small tubes that extend from the tips of uterine horns
- finger-like projections at the tip known as fimbriae which capture the ovum released from ovaries
- also a site for fertilisation (sperm -> vagina -> cervix -> uterus -> oviduct -> meets ovum)
- cilia inside the oviduct move the fertilised ova slowly through uterine horns towards the uterus
- fertilised = embeds in uterus = pregnant
- not fertilised = still pushed eventually
- collects ova as they are released from ovaries
- conveys ova from ovaries to the uterine horns
- provide correct environment for the survival of both ova and sperm to aid fertilisation
49
Q
uterus
A
- Y-shaped (horns and body)
3 walls ;
1. endometrium
2. myometrium
3. perimetrium
- provides a new site where embryos can develop into a baby
- provides means for developing embryos to receive nutrients from the mother via placenta / umbilical cord
50
Q
endometrium - uterus
A
- inner mucosal layer
- a lot of blood supply
- secretes mucous and other substances
- allows implantation of a fertilised egg
- this layer thickens during pregnancy to provide nutrition to the embryo and support the development of the placenta
- nutrients from mother’s blood vessels -> placenta -> embryo
51
Q
myometrium - uterus
A
- middle layer , smooth muscle
- strong contractions during parturition
- assists in pushing the baby out
52
Q
perimetrium - uterus
A
- outer visceral layer of peritoneum
- suspends uterus from the dorsal body wall
- fixes uterus in its position
53
Q
cervix
A
- short , thick-walled muscular sphincter
- connects uterine body with vagina
- lumen / inside space = cervical canal
- it is normally tightly closed to prevent uterine infections , only dilating to allow sperm or foetus to pass
- during pregnancy , cervical canal is blocked by a mucous plug which ensures bacteria and foreign particles cannot go in , protecting the embryo from infections
54
Q
vagina
A
- a tube that leads to the external opening
- receives the penis at breeding
- serves as birth canal at birth
55
Q
vulva
A
- external part of the female reproductive system
- guarded by a pair of vertical labia
- lying between the labia is a knob of erectile tissue aka clitoris
56
Q
uniparous species
A
- one mature ovum produced per cycle only
- rare to have more
- humans , horses , cows
57
Q
multiparous species
A
- multiple ova produced per cycle
- big litters
- cats , dogs , sow
58
Q
ovarian cycle
A
- starts with primary follicle with an immature ovum in the centre
- follicle stimulating hormone (FSH from pituitary gland) stimulates selected follicles to mature
- as follicle grows , fluid holes form and continue to “merge” and get larger (more fluid)
- when the follicle and ovum have reached the maximum size , it is considered fully mature .
- oestrogen will be produced by follicular cells to assist in stimulating the release of the ovum
- luteinising hormone from pituitary gland is released and ovulation occurs as a result
- the surface of a mature follicle will weaken and rupture , releasing the ovum along with fluid into the oviduct
- empty follicle fills with blood after the ovum is released
- after an ovum has left the follicle , the empty follicle develops into corpus luteum
- if there is pregnancy , the corpus luteum is maintained through an endocrine signal
- if no pregnancy , the corpus luteum regresses
- cycle ends when corpus luteum has regressed.
59
Q
corpus luteum
A
- after an ovum has left the follicle , the empty follicle develops into corpus luteum
- the process is influenced by the stimulation of luteinising hormone
- produces progesterone
- if there is pregnancy , the corpus luteum is maintained through an endocrine signal
- if no pregnancy , the corpus luteum regresses
60
Q
progesterone
A
- necessary to maintain pregnancy
- thickens uterine lining and prepares for the implantation of fertilised egg
- allows fertilised egg to grow comfortably
- lack of progesterone may cause an unfavourable condition for the egg and may result in miscarriage
61
Q
4 stages of estrous cycle - bitches
A
- proestrus (approx 9 days)
- estrus (approx 9 days)
- metestrus / diestrus (if not pregnant , 90 days. if pregnant , 50-60 days , delivery at approx 63 days after ovulation)
- anestrus (5 months)
62
Q
proestrus - bitches
A
- initial phase, approximately 9 days
- body prepares for potential mating and pregnancy
- females release pheromones to attract males , but mating does not take place yet
- increased oestrogen in the blood (relate to maturation of follicles and ovarian cycle)
- oestrogen helps the body to prepare
- swelling of vulva
- bloody vulval discharge
63
Q
estrus - bitches
A
- when follicle is mature enough to release the ovum
- approximately 9 days
- females become receptive to mating
- may actively seek out males and exhibit behavioural changes eg restlessness , changes in appetite , and increased frequency of urination
- oestrogen declines and luteinising hormone reaches its peak level
- triggers ovulation (releasing ovum)
- if a female mates with a male , fertilisation can take place
- corpus luteum forms in place of the empty follicle
- regress if not pregnant
- maintain and secrete progesterone if pregnant
64
Q
metestrus / diestrus - bitches
A
- approximately 60-90 days
- if fertilisation has occurred , corpus luteum maintains and produces progesterone
- if no fertilisation has occurred , corpus luteum regresses and the female will enter a non-pregnant diestrus phase where uterus returns to the normal state
65
Q
anestrus - btiches
A
- several months
- lack of ovarian activity , reproductive system rests before the next cycle begins
- if not pregnant , progesterone level gradually declines
- when a new cycle is about to start , some primary follicles will begin to develop
66
Q
fertilisation
A
- ovum + sperm = fertilisation = zygote
- sperm is propelled up the ductus deferens into the urethra , through the penis and into the female reproductive tract
- sperm “swim” from the vagina through the cervix into the uterus
- once a sperm penetrates the ovum , further sperms are prevented from entering due to a rapid chemical change that thickens the ovum’s surface
- zygote = diploid = ready for mitosis
67
Q
pregnancy
A
- after fertilisation , zygote undergoes mitosis
- as it is dividing , it also moves along the oviduct
- once it reaches the uterine horn , it has many cells and a fluid cavity ; it is now known as a blastocyst
- blastocyst implants in the uterine horn and continues to divide
- endometrium and myometrium are thickened by progesterone = new blood vessels grow and mucous secretes = more nutrients and comfortable for blastocyst to maintain pregnancy
- increased progesterone
- physical changes eg weight gain , enlargement of abdomen and development of mammary glands
68
Q
stage 1 of parturition
A
- can last up to 24 hours
- restless , nesting behaviour
- decreased body temperature
- uterine contractions
- cervix gradually dilates to allow the passage of puppies
69
Q
stage 2 of parturition
A
- can last up to a few hours to a full day
- active delivery
- uterine contractions intensify and female dog must push to deliver each puppy
- puppies are enclosed in individual amniotic sacs which may rupture during delivery
- mother typically breaks the sac , cleans the puppies and stimulates their breathing
- interval between each puppy can vary , but it usually ranges between 10 minutes to an hour
70
Q
stage 3 of parturition
A
- involves the delivery of the placenta
- placenta nourished and protected puppies during gestation
- female dogs may eat the placenta which is natural as it can provide nutrients and clean the whelping area
71
Q
major endocrine glands in cats
A
- pituitary gland
- thyroid gland
- parathyroid gland
- pancreas
- ovaries
- testes
- adrenal glands
72
Q
mechanisms controlling hormone secretion
A
- nerve impulses (eg adrenaline from adrenal gland in response to nerve impulses from sympathetic nervous system)
- stimulating or releasing hormone (eg secretion of thyroid hormone is controlled by thyroid stimulating hormone from pituitary gland)
- levels of certain chemicals in the blood (eg glucose high , pancreas releases insulin)
- negative feedback system (eg oestrogen secreted after the follicle has matured prevents further secretion of FSH from pituitary gland)
73
Q
pituitary gland
A
- small , ventral to the hypothalamus
2 portions with different functions and structure :
- anterior pituitary (cranial portion) ; produces hormone
- posterior pituitary (caudal portion) ; stores and releases hormones produced in the hypothalamus , does not produce any hormone
74
Q
hormones released by pituitary gland (anterior pituitary)
A
- growth hormone
- prolactin
- thyroid-stimulating hormone (TSH)
- adrenocorticotropic hormone (ACTH)
- follicle-stimulating hormone (FSH)
- luteinising hormone (LH)
- interstitial cell stimulating hormone
75
Q
growth hormone (GH)
A
- aka somatotropin hormone
- promotes body growth in young animals
- helps to regulate metabolism of proteins , carbohydrates and lipids
76
Q
prolactin
A
- triggers and maintains lactation (secretion of milk from mammary glands)
- if nipple is stimulated by nursing , prolactin will continue to be released
77
Q
thyroid-stimulating hormone (TSH)
A
- stimulates the development of the thyroid gland
- stimulates the thyroid gland to produce thyroid hormone
78
Q
adrenocorticotropic hormone (ACTH)
A
- stimulates the growth and development of the adrenal gland
- stimulates the release of hormones from the adrenal gland (eg cortisol)
- in sudden stress , hypothalamus is stimulated and ACTH is released very quickly (cortisol -> signs of nervousness eg heart beating fast)
79
Q
follicle stimulating hormone (FSH)
A
- female : growth and development of ovarian follicles (source of ovum)
- also stimulates follicular cells to secrete oestrogen (more oestrogen = negative feedback = less FSH)
- male : acts on tubules of the testis to aid sperm production
80
Q
luteinising hormone (LH)
A
- stimulated by the presence of oestrogen in the blood
- stimulates mature follicles to rupture and release their ovum
- signals the empty follicle to form yellow body / corpus luteum
81
Q
interstitial cell stimulating hormone (ICSH)
A
- stimulates the interstitial cells in the testes to secrete testosterone when concentration is low in the body
82
Q
hormones stored and released by the pituitary gland (posterior pituitary)
A
- does not produce hormones
- only stores and releases hormones produced by the hypothalamus
- antidiuretic hormone (ADH)
- oxytocin
83
Q
antidiuretic hormone (ADH) - endocrine
A
- acts on kidney
- reabsorbs more water from the urine and returns it to the bloodstream (more concentrated urine)
- released when the receptor in the hypothalamus detects a change of osmotic pressure in the blood due to dehydration
84
Q
oxytocin - endocrine
A
- acts on mammary glands during late pregnancy
- causes milk to be released in response to a neonates suckling
- at the end of gestation , oxytocin causes the contraction of the smooth muscle of the uterus which results in parturition of the foetuses
85
Q
thyroid gland
A
- ventral to first few rings of the trachea
- triiodothyronine (T3)
- thyroxine (T4)
- they regulate metabolic rate of body cells and are essential for normal growth
- allows animal to generate heat , maintain a constant internal body temperature and maintain blood glucose
- if metabolic rate is too high , nutrients are used too fast , body produces a lot of heat
** if metabolic rate is too low , nutrients are used too slow and body weight will increase with just a bit of eating . body doesn’t produce enough heat - calcitonin
86
Q
calcitonin
A
- regulates calcium level in the blood (together with parathyroid hormone)
- lowers calcium levels by inhibiting the rate of decalcification of bone and stimulating bone growth
- tells bone not to release calcium into the blood and absorb more calcium from the blood
87
Q
hypothyroidism
A
- undersecretion of thyroid hormones (especially T3 and T4)
- stunted growth
- hair loss
- slow heart rate
- fat
- sluggish
88
Q
hyperthyroidism
A
- oversecretion of thyroid hormones (especially T3 and T4)
- hyperactive
- aggressive
- increased appetite
- fast heart rate
89
Q
parathyroid gland
A
- small nodules in , on or near the thyroid glands
- parathyroid hormone (PTH / parathormone)
90
Q
parathyroid hormone (PTH)
A
- maintain blood calcium levels
- along with calcitonin
- calcitonin deposits calcium from the blood into the bone when blood calcium levels are too high
- parathyroid hormone reabsorbs calcium from the bone into the blood when blood calcium levels are too low
91
Q
pancreas
A
- located in the curve of the duodenum
- small islets inside the endocrine component have cells that secrete 3 hormones
- beta cells : insulin
- alpha cells : glucagon
- delta cells : somatostatin
92
Q
insulin
A
- produced by beta cells of the pancreas
- response to high blood glucose
- decreases blood glucose by increasing the uptake of glucose into the blood cells and storing excess glucose as glycogen in the liver
- lack of insulin = diabetes mellitus , unable to lower blood glucose
93
Q
glucagon
A
- produced by alpha cells of the pancreas
- response to low blood glucose
- signals liver to break down glycogen to release glucose
94
Q
somatostatin
A
- produced by delta cells of the pancreas
- inhibits the secretion of insulin and glucagon
- if insulin / glucagon has finished their jobs and blood glucose has returned to regular levels , somatostatin inhibits their secretion
95
Q
adrenal gland
A
- in a pair , at cranial ends of the kidneys
- adrenal cortex (outer) and adrenal medulla (inner)
96
Q
adrenal cortex (outer)
A
produces :
- aldosterone
- glucocorticoids
- sex hormones
97
Q
aldosterone - endocrine
A
- acts on the kidney at the distal convoluted tubule (DCT)
- increases reabsorption of sodium ions (water molecules follow to maintain balance)
- more concentrated urine
- regulates acid-base balance
98
Q
glucocorticoids
A
- cortisone
- corticosterone
- low levels that increase in response to stress
- increases blood glucose levels (that’s why there may be hyperglycaemia during stress)
- when present in large quantity , it depresses inflammation reactions
99
Q
sex hormones
A
- androgens (male)
- oestrogen (female)
- both are present in all animals , but the opposite sex hormones will be in small quantities with minimal effect
- concentration is important : low testosterone will cause tiredness
100
Q
adrenal medulla (inner)
A
produces :
- epinephrine
- norepinephrine
- prepares the body for emergency action / fight or flight
- secretion is controlled by the autonomic / sympathetic nervous system (involuntary)
101
Q
functions of epinephrine and norepinerphrine
A
- raise blood glucose levels by breaking down glycogen in the liver (increases energy levels)
- increase heart rate and respiration (meet high demand of oxygen in times of stress)
- dilate blood vessels (increase supply of glucose and oxygen)
- decrease the activity of the GI tract and bladder (as they are less important in stress)
102
Q
ovaries - endocrine
A
- oestrogen
- progesterone
- relaxin
103
Q
oestrogen
A
- prepares animal for mating
- prepares body to produce follicles and release ovum
- causes behaviour associated with estrus cycle
- prepares reproductive tract and external genetalia for mating
104
Q
relaxin
A
- produced by ovaries in later stages of pregnancy
- softens and relaxes ligaments around the birth canal
- prepares for parturition and foetus delivery
105
Q
testes
A
- testosterone
106
Q
testosterone
A
- produced in response to ICSH (interstitial cell stimulating hormone) from anterior pituitary gland
- leads to the development of male characteristics
- muscle development
- male behavioural patterns
- development of sperm
107
Q
nervous system
A
- brain , spinal cord , sensory organs and all of the nerves that connect these organs with the rest of the body
- allows an animal to respond in coordinated manner to both the demands of the external environment and internal changes within the body
108
Q
3 functions of the nervous system
A
- receive information / stimuli from external and internal environments via sensory nerves
- analyse and integrate these stimuli from the sensory pathway to the central nervous system (CNS)
- after a response has been decided , motor nerves send a signal to initiate response of effector
109
Q
movement of nerve impulses
A
sensory nerves receive stimulus -> CNS analyse stimulus -> makes decision what to do -> motor nerves initiate response according to CNS decision
110
Q
peripheral nerves
A
- cranial nerves
- spinal nerves (sensory and motor)
- autonomic nervous system (sympathetic and parasympathetic)
111
Q
central nervous system
A
- brain
- spinal cord
112
Q
sensory nerves
A
- carries information into the central nervous system
- has 2 types
- somatic : receives stimuli from external environment ; skin , muscle , joints , eyes , voluntary control (eg seeing a snake)
- visceral : receives stimuli from internal environment ; internal organs , glands , blood vessels , involuntary control (eg stomach sends message to CNS that more gastric juice is needed when food is consumed , prompting gallbladder to prepare to release bile and liver to prepare for digestion)
113
Q
motor nerves
A
- carries information from the central nervous system
- somatic nervous system : voluntary , skeletal muscles (eg hand movements)
- autonomic nervous system : involuntary , cardiac muscles , smooth muscles , glands (eg make heart beat faster)
- autonomic nervous system has 2 divisions ; sympathetic and parasympathetic
114
Q
sympathetic nervous system
A
- controls body in times of stress (eg seeing a snake = stimulates adrenal glands to secrete adrenaline)
- opposite effect on organs compared to parasympathetic nervous system
- dilate pupils
- inhibit saliva
- increase heartbeat
- relax airways
- inhibit stomach activity
- stimulate release of glucose
- inhibit gallbladder
- inhibit intestinal activity
- relax bladder
- promote ejaculation and vaginal contraction
115
Q
parasympathetic nervous system
A
- controls body in times of rest (eg during sleep)
- opposite effect on organs compared to sympathetic nervous system
- constrict pupils
- stimulate saliva
- slow heartbeat
- constrict airways
- stimulate stomach activity
- inhibit release of glucose
- stimulate gallbladder
- stimulate intestinal activity
- contract bladder
- promote erection of genitals
116
Q
cells of the nervous system
A
- neurons / nerve cells
- gila / glial cells are support and protect neurons
117
Q
structure of neurons
A
- dendrite branch out from dendron to receive stimuli
- cell body : soma ; has nucleus , cell membrane
- long structure / tail : axon
- bundle of axons is called a nerve fibre
- schwann cells protect the axon by secreting myelin
- forms a myelin sheath
118
Q
glial cells
A
- many types
- schwann cells (PNS)
- oligodendrocytes (CNS)
- both are responsible to myelin sheath that facilitates impulse transmission in an axon
- multiple glial cells cover the length of an axon
- there are small gaps between each glial cell (nodes of ranvier)
- myelin is insulating and thus nerve impulses jump from node to node and are conducted through the axon at a much faster speed
119
Q
grey and white matter - nervous system
A
- myelin wrapped axons appear white
- unmyelinated axons , dendrites and cell body will appear grey
120
Q
action potential
A
- electrical signal that allows nerve impulses to spread along the axon of a neuron
- generation process involves several membrane mechanisms :
- resting membrane potential
- depolarisation
- resting phase
- repolarisation
- hyperpolarisation
121
Q
resting membrane potential
A
- resting status , no need for action potential
- charge inside of the neuron is negative relative to the outside (mainly due to the distribution of different ions on each side)
- the difference between the charges on the inside and outside = resting membrane potential
- typically around -70 mV
- outside of cell : positive , a lot of positively charged sodium ions
- inside of cell : negative ; some positive ions (eg potassium) but much less than outside , negatively charged proteins
- ion channels ; voltage-gated (important in nervous system context) , Ligand-gated , mechanically gated
122
Q
depolarisation
A
- polar = outside positive , inside negative
- depolarisation = remove polar situation / difference in charge between the 2 sides
- positive must enter and negative must leave
- when a neuron receive a strong enough signal or signal from a neighbouring neuron , sodium ion channels open temporarily and allow sodium ions to rush into the neuron
- influx of positive charge in the neuron (less negative inside , depolarising)
- charge inside the neuron will reach a peak (30 - 40 mV) and sodium will stop coming in.
- depolarisation leads to activation of the neuron
- as ion channels along the axon receive stimulus , they open
- thus , the signal can pass to the end of the axon (depolarisation excites node of ranvier 1 , action potential , excites node of ranvier 2 , etc)
123
Q
rising phase , generating action potential
A
- rapid influx of positively charged sodium ions leads to a sharp rise in membrane potential
- reverse polarity
- inside becomes more positively charged than the outside
- creates action potential (AP)
- depolarised neurons have AP which generates electrical impulse that travels along the axon
124
Q
repolarisation
A
- after the charge inside the neuron reaches its peak of 30 - 40 mV
- potassium ion channel opens
- potassium ions inside the cell go out
- positive charge ions go out and the inside becomes more negative
- sodium ions inside the cell may also be used by the cell after some time
- cell goes back to its negative resting potential
125
Q
hyperpolarisation
A
- in some neurons , the escape of potassium ions can briefly cause membrane potential to be more negative than resting membrane potential
- usually short lived
126
Q
conduction of action potential between the neurons
A
- happens at synapse : end of an axon / start of another neuron (gap between 2 neurons)
- when action potential reaches the end of the axon (terminal) , translated to chemical signals / neurotransmitters
- receptors on the dendrite of the next neuron are stimulated by neurotransmitters
- the next neuron is activated , and a new AP would be generated in the next neuron
127
Q
types of neurotransmitters
A
- excitatory neurotransmitters
- inhibitory neurotransmitters
128
Q
excitatory neurotransmitters
A
- causes influx of sodium so that neurons will be depolarised
- acetylcholine
- norepinephrine
- epinephrine
- dopamine
- serotonin
- glutamate
129
Q
inhibitory neurotransmitters
A
- causes entry of chloride ions which lead to hyperpolarisation (when hyperpolarised, cell will not pass a signal)
- gamma-aminobutyric acid (GABA)
- glycine
130
Q
brain - central nervous system
A
- cerebrum (typically left and right cerebrum , cerebral cortex)
- diencephalon (thalamus , hypothalamus)
- brain stem (very important for life , midbrain , pons , medulla oblongata)
- cerebellum (caudal to cerebrum)
131
Q
cerebrum - brain
A
- controls conscious activities , intelligence , memory , language and muscles
132
Q
cortex - brain
A
- organised into different functional regions
- highly developed (especially in humans)
- in higher species (eg humans) , the cortex has a bigger surface area due to folds
- functional regions : sensory , motor areas , auditory areas , visual areas , higher functional areas (eg prefrontal cortex in humans)
133
Q
functional regions in the cortex - brain
A
- sensory : receive somatic sensory information from different parts of the body
- motor : initiate / coordinate motor activity in the muscles
- auditory : receive hearing information from the ears
- visual : receive visual information from the eyes
- higher functional areas (eg prefrontal cortex in humans) : solving complex tasks
134
Q
cerebellum - brain
A
- responsible for coordination of movement , balance and posture
- if damaged , may not be able to move in a straight line and movements become jerky
135
Q
brain sterm
A
- medulla oblongata , pons , midbrain
- responsible for vital life functions
- breathing , heartbeat , blood pressure
- many cranial nerve pairs originate from the brain stem
136
Q
diencephalon
A
- below the cerebrum
- relay station between brainstem and cerebrum
- thalamus : relay station for sensory inputs to the cerebrum
- hypothalamus : interface between nervous system and endocrine system
137
Q
protection of the CNS
A
- CNS protected by cranium , vertebral column and meninges
138
Q
cranium
A
- bones of the skull
- hard outer covering to the brain
139
Q
meninges
A
- coverings of the brain and spinal cord
- 3 layers of membrane (surface , middle , deep)
- dura mater : double-layered , periosteal and meningeal , external covering blow the bone of skull
- arachnoid layer : middle , web-like layer
- pia mater : internal layer
140
Q
brain ventricles and fluid
A
- network of cavities within the brain
- filled with fluid (CSF - cerebrospinal fluid)
- CSF is in both the brain and spinal cord
141
Q
cerebrospinal fluid (CSF)
A
- cushions the brain within the skull
- shock absorber
- circulates nutrients and chemicals
- removes waste products from CNS
- similar function to blood except it doesn’t contain blood cells
- composition is similar to blood plasma but without blood cells
- circulated in brain ventricles and spinal cavity in the arachnoid space (space below the arachnoid layer of meninges)
142
Q
cranial nerves
A
- 12 nerve pairs that originate from the brain stem
- each nerve may contain axons of motor neurons , sensory neurons or a combination of both
I - olfactory
II - optic
III - oculomotor
IV - trochlear
V - trigeminal
VI - abducens
VII - facial
VIII - vestibulocochlear
IX - glossopharyngeal
X - vagus
XI - accessory
XII - hypoglossal
143
Q
cranial nerve I
A
- olfactory
- smell
144
Q
cranial nerve II
A
- optic
- sight
145
Q
cranial nerve III
A
- oculomotor
- moves eye and pupil
146
Q
cranial nerve IV
A
- trochlear
- moves eye
147
Q
cranial nerve V
A
- trigeminal
- face sensation
148
Q
cranial nerve VI
A
- abducens
- moves eye
149
Q
cranial nerve VII
A
- facial
- moves face
- salivation
150
Q
cranial nerve VIII
A
- vestibulocochlear
- hearing
- balance
151
Q
cranial nerve IX
A
- glossopharyngeal
- taste
- swallow
152
Q
cranial nerve X
A
- vagus
- heart rate
- digestion
153
Q
cranial nerve XI
A
- accessory
- moves head
154
Q
cranial nerve XII
A
- hypoglossal
- moves tongue
155
Q
spinal cord
A
- consists of well-organised nerve fibres running in tracts
- uniform structure throughout entire length
- myelinated outer white matter surrounding central unmyelinated grey matter
- enveloped by meninges and surrounded by cerebrospinal fluid (CSF)
- CSF also flows within the central canal
156
Q
cross-section of the spinal cord
A
- grey matter displays a distinctive “butterfly” shape
- dorsal horns / nerve roots ; houses cell bodies of the sensory neurons (smaller than motor)
- ventral horns / nerve roots stand out ; houses cell bodies of the large motor neurons
- central canal : continuation of brain ventricle , filled with CSF (cushioning , shock absorber , etc)
157
Q
reflexes
A
- involuntary and nearly instantaneous movement in response to a stimulus
- eg pulling your finger back from a hot object
- reflex arcs which are organised at spinal cord level without involvement of the brain
- response is very fast and doesn’t go through the brain , protecting the body from potential harm due to the short neuronal circuit
158
Q
neuronal circuit in reflexes
A
- when your hand touches something very hard ,
- sensory neurons forward sensory information to the spinal cord via dorsal nerve root
- motor neurons in spinal cord forward information to the muscle via ventral nerve root
- muscle are effectors that quickly remove the hand from the hot object.
159
Q
reflex arc
A
- receptor , nerve endings in the skin that receive the sensation
- sensory neuron passes information to the spinal cord via dorsal nerve root
- spinal cord quickly decides what action to take
- motor neuron passes information to the muscles via ventral nerve root
- muscles are effectors that perform the action
160
Q
taste buds
A
- organs responsible for taste
- chemical receptors on dorsal side of the tongue receive chemical signals from food
- chemical signals stimulate taste cells to produce a signal
- connected to nerve endings / sensory nerves , which send the signal to CNS
- 2 types : taste cell , surrounded by supporting cell
161
Q
which nerves carry taste information to the brain?
A
- cranial nerves IX (9 - glossopharyngeal) and VII (7 - facial)
- facial nerve carries taste information from the FRONT of the tongue to the brain
- glossopharyngeal nerve carries taste information from the BACK of the tongue to the brain
162
Q
sense of smell
A
- made possible by olfactory epithelium covering the naval cavities
- odour molecules move in the air
- when the molecules contact their specific receptors , it can be translated into a signal
- odorant -> receptors that match its shape -> chemical reaction within the receptor cell
- activated receptor cell sends nerve impulse
- impulse travels through olfactory nerve (I) to the olfactory bulb
163
Q
structure of the eyes
A
- outer fibrous layer (sclera - consists of sclera and cornea)
- middle layer (uvea - consists of iris , ciliary body , choroid)
- inner nervous layer (retina - consists of retina)
164
Q
sclera
A
- white layer surrounding the eyes
- connects with cornea to form outer sclera layer
165
Q
cornea
A
- dome-shaped structure covering the pupils / iris area
- connects with sclera to form outer sclera layer
166
Q
iris
A
- controls amount of light entering the eye
- contraction of radial and circular smooth muscles to control the size of pupil (circular contract = smaller , radial contract = dilated)
- coloured part of the eye
167
Q
ciliary body
A
- contains ciliary muscles muscles that attach the suspensory ligaments of the lens
- pulls the suspensory ligament attached to the lens to control thickness and shape
- contract = lens thinner , relax = lens thicker
168
Q
suspensory ligaments
A
- continuation of ciliary body
- suspends the lens
169
Q
choroid
A
- pigmented vascular layer
- layer right beneath the sclera
- presents light from escaping the retina by bouncing it back to the retina
- ensures retina receives most of the light
170
Q
retina
A
- receives light / image signal
- contains photoreceptor cells (rods and cones)
171
Q
rod cells (in retina)
A
- functions well under dim light
- not sensitive to colour
- responsible for light of different intensity (black and white , night vision)
172
Q
cone cells (in retina)
A
- functions well under bright light
- responsible for colour vision
173
Q
image formation
A
- light rays pass through the cornea , iris , lens and vitreous body
- lens helps to focus the light rays onto the retina by adjusting the thickness of the lens (inverted image)
- photoreceptor cells on the retina generate nerve impulses
- image signal is sent to the optic nerve (cranial nerve II)
- optic nerve sends it to the brain’s visual cortex where the image is interpreted
174
Q
vitreous body
A
- very clear , jelly-like structure in the middle of the eye that gives the eye its shape
- works with aqueous humour to provide nutrients to the structures in the eye and maintain the shape of the eye
175
Q
conjunctiva
A
- a very thin , transparent layer surrounding the outer surface / sclera
- squamous epithelium
- also the inner layer of the eyelid
176
Q
limbus
A
- connection point between the cornea and sclera
177
Q
anterior / posterior chambers
A
- iris divides the space between the lens and cornea into anterior and posterior chambers
- posterior = very small (between iris and lens)
- anterior = bigger (between iris and cornea)
- chambers are filled with aqueous humour
178
Q
aqueous humour
A
- fluid secreted by the ciliary body
- works with vitreous body to provide nutrients to the structures in the eye and maintain the shape of the eye
179
Q
circulation of aqueous humour
A
- watery fluid produced by ciliary body and secreted into posterior chamber
- flows over the surface of the lens
- circulates through the pupil
- drains into canal of Schlemm in the anterior chamber
- important to maintain the pressure of the eye and provide nutrients for the lens and cornea that have no blood vessels
180
Q
myopia
A
- short-sightedness
- image falls in front of the retina
- cannot see objects that are far away clearly
- due to abnormality in the lens that could be caused by any factors e.g. age or injury
181
Q
hyperopia
A
- long-sightedness
- image falls behind the retina
- cannot see objects that are nearby clearly (far away objects appear more clear)
- due to abnormality in the lens that could be caused by any factors e.g. age or injury
182
Q
eyelids
A
- protects the eye
- external surface covered by a thin , folded skin
- internal surface covered by a smooth conjunctiva (a very thin membrane)
183
Q
meibomian glands / tarsal glands
A
- opening is directly on the edge of the eyelid
- produces oily tears (not watery tears)
- these tears float on the surface of watery tears , preventing evaporation and making sure eyes do not dry out
184
Q
tear apparatus and pathway of tears
A
- tears are produced in the tear (lacrimal) gland
- disperses across corneal surfaces
- enters the tear duct (lacrimal canaliculi) at punctum
- enters nasal cavity via nasolacrimal duct
185
Q
external / outer ear
A
- pinna
- external auditory canal
186
Q
pinna
A
- outer portion of the ear
- the part we can see
- mainly elastic cartilage and skin
187
Q
external auditory canal
A
- carries sound waves to tympanic membrane / eardrum
188
Q
middle ear
A
- air filled cavity
- ear drum
- 3 small ossicles in the cavity behind the ear drum (malleus , incus , stapes)
189
Q
ear drum
A
- paper-thin membrane
- vibrates when a sound wave strikes it
190
Q
3 small ossicles
A
- malleus , incus and stapes
- amplify and transmit sound vibrations from external to inner ear
- when the sound from the external ear reaches the middle ear , the ear drum starts vibrating and this vibration is passed to the ossicles
191
Q
inner ear
A
- eustachian tube
in a small , fluid filled cavity deep within the skull :
- cochlea
- vestibular system
192
Q
eustachian tube
A
- connects middle ear cavity with the pharynx
- balances air pressure on the 2 sides of the ear drum
193
Q
cochlea
A
- coiled , snail-shell-shaped structure
- lined with sensory cells called hair cells
- hair cells convert sound vibrations into electrical signals
- sensitive to different sound frequencies
- information is transmitted via auditory nerve (cranial nerve VIII / vestibulocochlear)
194
Q
sound perception
A
- sound vibrations travel through the external auditory canal to the ear drum
- ear drum vibrates
- vibration transfers to 3 ossicles which amplify vibrations to oval window on inner ear
- when a vibration enters the cochlea from the middle ear , fluid in the cochlea vibrates
- vibration of fluid causes hair cells to bend
- bending of hair cells sends a signal to the cochlear nerve (cranial nerve XII / vestibulocochlear)
- vestibulocochlear nerve sends the signal to the brain’s auditory cortex where it gets translated to a sound
195
Q
vestibular system
A
- responsible for balance and equilibrium
- 3 semicircular canals (tiny fluid filled tubes) and otolith organs (utricle and saccule)
- they contain fluid and sensory hair cells
- fluid shifts when head shifts
- movement of fluid bend hair cells
- hair cells predict loss of balance and position of the head
- sends signal to the cranial nerve XII vestibulocochlear nerve
- the brain sends signal and the body adjusts movement
- helps to stay balanced and oriented
196
Q
integumentary system
A
- outer covering of the body
- skin
- hair
- claws
- footpads
197
Q
skin
A
- largest organ of the body
- barrier against external environment
- perforated (where skin blends with mucous membrane) by mouth , anus , urinary orifice and vulva
- 3 layers : epidermis , dermis and hypodermis
198
Q
epidermis
A
- outermost layer
- stratified epithelial cells
- new cells are produced on the basal layer and reach the outermost layer as they get older , thus cells on the epidermis are usually already dead and contains a lot of keratin
- no blood vessels
- no nerves
- 4 layers of cells : stratum basale , stratium spinosum , stratum granulosum , stratum corneum
199
Q
stratum basal
A
- lowest / basal layer
- newest cells
200
Q
stratum spinosum
A
- 2nd lowest layer
- spinous layer
201
Q
stratum granulosum
A
- 2nd highest layer
- granulated = older
- granular cell layer
202
Q
stratum corneum
A
- highest. layer
- contains keratin , slightly hard
- most cells are already dead
203
Q
dermis
A
- dense connective tissue , collagen and elastin fibres
- rich in blood vessels and nerve endings
- includes hair follicles (a channel that hair grows from) , sebaceous glands and sweat glands
204
Q
functions of the skin
A
- sensory (nerve endings to detect temperature , pressure , touch and pain)
- protection (barrier between external environment and internal structures ; prevents entry of microorganisms and injury of organs , protects against damage from UV light and water loss , prevents absorption of harmful substances)
- production (glands to produce secretion)
- storage (fat ; important as it provides energy and keeps warm . mainly stored in the hypodermis layer)
- thermoregulation (heat loss ; dilation of surface blood vessel = more blood flow = heat escapes quickly / sweating = loss of water = evaporation = cools skin surface . heat gain ; constriction of surface blood vessel = not much blood passes = heat cannot escape quickly = conserve heat . insulation ; fat under the skin prevents heat loss and hair traps warm hair)
- communication ; skin produces pheromones for intraspecific communication , colour also provides communication eg when attracting a mate
205
Q
sensory - skin function
A
nerve endings to detect temperature , pressure , touch and pain
206
Q
protection - skin function
A
- barrier between external environment and internal structures
- prevents entry of microorganisms and injury of organs
- protects against damage from UV light and water loss
- prevents absorption of harmful substances
207
Q
production - skin function
A
- glands to produce secretion
208
Q
storage - skin function
A
- fat ; important as it provides energy and keeps warm
- mainly stored in the hypodermis layer)
209
Q
thermoregulation - skin function
A
- heat loss ; dilation of surface blood vessel = more blood flow = heat escapes quickly
- sweating = loss of water = evaporation = cools skin surface
- heat gain ; constriction of surface blood vessel = not much blood passes = heat cannot escape quickly = conserve heat
- insulation ; fat under the skin prevents heat loss
- hair traps warm air
210
Q
communication - skin function
A
- skin produces pheromones for intraspecific communication
- colour also provides communication eg when attracting a mate
211
Q
sebaceous glands
A
- surrounds the hair follicles and secretes sebum
- forms a thin , oily , water-repellent layer over the skin surface
- gives coat hair a shiny appearance
- prevents bacterial growth on skin surface (has an aseptic function and can kill some microorganisms)
212
Q
sweat glands (2 types)
A
- 1 type opens into hair follicle
- other type opens onto skin surface
- sweat evaporates to cool the body
- sweat removes some waste from the body
213
Q
tail glands
A
- dorsal surface at the base of the tail
- rich with sweat and sebaceous glands
- release of sweat and sebum give off a unique scent that allows for recognition and identification of individual animals
214
Q
anal glands
A
- pair of glands on either side of the anus
- has a small duct that opens into the anus
- powerful smelling secretions
- secretions coat faeces to cover it with a unique smell for territory marking and attracting a mate
215
Q
structure of hair
A
- everything outside that can be seen = hair shaft
- everything inside that cannot be seen = hair root
- surrounding the hair root = hair follicle
- deepest part of hair follicle = hair bulb
- 2 layers holding the hair root = inner and outer root sheath
- bottom of hair follicle where there is a cluster of dermal cells and blood vessels , provides nutrients to hair = hair papilla
- pulls hair so it can erect = arrector pili muscle
- nerve endings
216
Q
arrector pili muscle
A
- small , smooth muscle
- attached to each hair follicle
- controlled by sympathetic nervous system (involuntary)
- muscle contraction pushes the hair to an erect position (can be due to temperature , fear , aggression , etc)
217
Q
growth cycles of hair (4 phases)
A
- anagen (growing)
- catagen (transitional)
- telogen (resting)
- return to anagen
218
Q
anagen phase
A
- growth phase
- young hair cells divide to build hair
- shaft lengthens
- papilla attached to blood vessels provides nutrients
219
Q
catagen phase
A
- transitional phase
- hair is grown
- hair follicle shrinks
- hair follicle begins to detach from the blood vessels
220
Q
telogen phase
A
- resting phase
- hair stops growing
- fully detaches from blood vessels
221
Q
return to anagen
A
- new hair grows
- papilla attaches to blood vessels
- new hair shaft pushes out old hair shaft
- sheds old hair
222
Q
types of hair
A
- guard hairs
- wool hairs
- sinus hairs
223
Q
guard hairs
A
- longer and coarser
- prevent water from soaking into the coat
- protect against mechanical damage
224
Q
wool hairs
A
- softer and wavy
- close to body surface
- insulating layer to regulate body temperature
225
Q
sinus hairs
A
- long , coarse hairs that extend beyond the body outside
- e.g. whiskers
- whiskers have nerve endings and are sensitive
- they are connected to blood-filled sinuses with rich nerve supply
- when they move , they stimulate nerve fibres and send a nerve impulse to the brain
226
Q
claws
A
- beak shaped
- 2 layers of epidermis
- keratinised epidermis forms a hard outer covering of each claw
- protects distal phalanges during walking and weight bearing
- provides grip
227
Q
claws of dog
A
- thick and strong
228
Q
claws of cat
A
- fine
- much sharper than a dog’s
- can be retracted into pockets of skin by an elastic ligament
- used as a defensive weapon
229
Q
forelimb footpads
A
- dog forelimb = 6 pads (4 digits , carpal pad , metacarpal pad)
- cat forelimb = 7 pads (5 digits , carpal pad , metacarpal pad)
230
Q
hindlimb footpads
A
- dog hindlimb = 5 pads (4 digits , metatarsal pad)
- cat hindlimb = 5 pads (4 digits , metatarsal pad)
231
Q
footpads
A
- contains thick layers of fat and connective tissue
- outer surface has the toughest and thickest skin in the body
- protects underlying joints
- acts as shock absorbers
