Nervous system, endocrine system, Homeostatis

Question 1

Systems contributing to coordination

Answer 1

nervous system and the endocrine system.

Question 2

Fore brain consists of

Answer 2

Cerebrum, thalamus, hypothalamus and pineal body

Question 3

Hind brain consists of

Answer 3

Cerebellum, pons varolli and medulla oblongata

Question 4

Cerebro-ventricles

Answer 4

Central canal of the brain forms 4 irregular shaped cavities called ventricles. Three ventricles are present in the forebrain and 1 in the hind brain.
Central canal and ventricles are filled with cerebro-spinal fluid.

Question 5

Functions of cerebrospinal-spinal fluid

Answer 5

Maintains uniform pressure within the CNS.
Acts as a shock absorber between brain and the skull
Circulates nutrients, hormones as well as to remove waste matter.

Question 6

Protection of CNS

Answer 6

Brain is enclosed by a skull while the spinal cord is surrounded by the vertebral column.
Further protection is given by 3 meninges known as dura matter (outermost), Pia matter (innermost) and in between the arachnoid matter.

Question 7

Thalamus

Answer 7

Located in the cerebral hemisphere just below the corpus callosum.

Acts as the main input centre for sensory information from special sense organs and sensory receptors in the skin and integral organs. These sensory information are sent to specific locations in the cerebral cortex for further processing.
It mainly relays and redistribute nerve impulses from most parts of the brain to the cerebral cortex.

Question 8

Hypothalamus

Answer 8

Located below and infront of the thalamus immediately above the pituitary gland.
Connected to the posterior lobe of the pituitary gland by nerve fibres and to the anterior lobe of the pituitary gland by a complex system of blood vessels.

Regulates body temperature 
Regulates thirst and water balance
Regulates appetite 
Regulates sleep and wake cycles 
Control of autonomic nervous system
Initiates fight or flight response 
Plays a role in sexual behaviour 
Source for posterior pituitary hormones and releasing hormones that acts on anterior pituitary

Question 9

Mid brain

Answer 9

Mid brain is the upper part of the brain stem. Situated between the cerebrum above and pons varolli below surrounding the crebro-spinal fluid filled connections of the 3rd and the 4th ventricles.

Acts as a relay station for ascending and descending nerve fibres
Receives and integrates sensory information (auditory and visual) and sends it to particular regions of the forebrain
Coordinates auditory and visual reflexes

Question 10

Pons varoli

Answer 10

Situated infront of the cerebellum below the midbrain and above the medulla oblongata

Transfer information between the PNS and the forebrain and midbrain
Coordinates large scale body movements climbing and running
Together with the medulla oblongata helps regulate respiration

Question 11

Medulla Oblongata

Answer 11

Lowest part of the brain stem situated below the pons varolli and is continuous with the spinal cord. Consists of respiratory center, cardiovascular center and reflex centres.

Transfer information between the PNS and the forebrain and midbrain.
Coordinates large scale body movements such as running and climbing.
Controls several autonomic, homeostatic functions including breathing, heart and blood vessel activities.
Controls involuntary reflexes such as vomiting, swallowing, coughing, sneezing through reflex centres.

Question 12

Cerebellum

Answer 12

Located behind the pons varoli and below the posterior part of the cerebrum

Coordinates voluntary muscle movements
Maintains posture and balance
Helps in learning and remembering motor skills

Question 13

Spinal cord

Answer 13

I the spinal cord outer region is composed of white matter while the inner region is composed of grey matter

Links the CNS to sensory neurones and motor neurones and facilitates nerve impulse propagation towards the brain and away from the brain.
Coordinates and produces reflexes

Question 14

Antagonistic

Answer 14

Opposite

Question 15

2 divisions of autonomic nervous system

Answer 15

Sympathetic stimulations prepare the body to deal with exciting/stressful and energy generating situations (fight of flight)
Parasympathetic division causes opposite responses that promote calming or return to self-maintenance functions (rest and digest)

Parasympathetic nerves exit the CNS at the base of the brain and spinal cord as cranial nerves or spinal nerves respectively. On the other hand sympathetic nerves exit only from the spinal cord.

Question 16

Constricts pupil of the eye

Answer 16

Parasympathetic

Question 17

Inhibits salivary gland secretion

Answer 17

Sympathetic

Question 18

Constricts bronchi in lungs

Answer 18

Parasympathetic

Question 19

Accelerates heart

Answer 19

Sympathetic

Question 20

Stimulates activity of the stomach and intestine

Answer 20

Parasympathetic

Question 21

Inhibits activity of the pancreas

Answer 21

Sympathetic

Question 22

Stimulates gall bladder

Answer 22

Parasympathetic

Question 23

Stimulates adrenal medulla

Answer 23

Sympathetic

Question 24

Promotes emptying of bladder

Answer 24

Parasympathetic

Question 25

Promotes ejaculation and vaginal contractions

Answer 25

Sympathetic

Question 26

Resting potential

Answer 26

When a neurone is at rest (not sending a signal/non conducting) the membrane potential is called the resting membrane potential. -60 mV to -80mV Maintained by the distribution ion concentrations inside and outside of the cell Concentration of K+ is higher inside the cell while the concentration of Na+ is higher outside the cell. In addition Cl- and large proteins anions are present inside the cell. Due to this there is a relative negative charge inside the cell and a positive charge outside the cell. Selective permeability of the membrane to K+ and Na+ ions There are more potassium channels open than sodium channels. As a result there is a net negative charge inside the cell. Sodium-pottasium pump This pump transports 3 Na+ out of the cell for every 2 K+ that is transports in. This pump uses ATP to actively transport these ions.

Question 27

Action potential

Answer 27

An action potential occurs due to the change in the membrane potential above a threshold level due to a stimulus. Consists of depolarization, repolarization and hyperpolarization.

Question 28

Depolarization

Answer 28

A change in the membrane potential such that inside of the cell is made less negative relative to the outside. Depolarization results due to Na+ inflow in response to a stimulus.

Question 29

Repolarization

Answer 29

Sodium channels close blocking the inflow of Na+. However most potassium channels open permitting K+ outflow making inside of the cell negative.

Question 30

Hyperpolarization

Answer 30

Sodium channels are closed but potassium channels are opened. As a result inside of the cell becomes more negative.

Question 31

Refractory period

Answer 31

Short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of sodium channels. This prevents reverse conduction of an impulse in an axon.

Question 32

Conduction of a nerve impulse

Answer 32

A series of action potentials that move along an axon is known as a nerve impulse Axon potential spreads to the neighbouring location while the initial location repolarizes

Question 33

The speed of conduction depends on

Answer 33

Conduction speed increases with the diameter of the axon | Precense of myelinated axon

Question 34

Synapses

Answer 34

A synapse is a junction where a neurone (presynaptic cell) communicates with a postsynaptic cell across a narrow gap (synaptic cleft).

Question 35

Neurotransmitter

Answer 35

Neurotransmitters are molecules secreted at synaptic terminals of presynaptic neuron, diffused across synaptic cleft, bind to receptors at the postsynaptic membrane, triggering a response.

Question 36

Common neurotransmitters

Answer 36

``` Acetylcholine Some amino acids Biogenic amines Neuropeptides Some gases ```

Question 37

Schizophrenia

Answer 37

This is a severe mental disturbance characterized by psychotic episodes in which patients have distorted perception of reality. Evidence suggests that this affects neural pathways that use dopamine as a neurotransmitter.

Question 38

Alzheimer's disease

Answer 38

This is a severe mental deterioration (dementia) characterized by confusion and memory loss. Cause of this is due to the progressive and irreversible degeneration of neurones in the brain especially in the cerebral cortex.

Question 39

Parkinson's disease

Answer 39

This is a progressive motor disorder that leads to lack of control and coordination of muscle movements. Associated with the gradual degeneration of dopamine neurotransmitter releasing neurones in the brain.

Question 40

Infoldings present in the cerebral cortex increasing surface area

Answer 40

Gyri and Sulci

Question 41

Diffused and localised

Answer 41

E.g: While localized TGCT is a clearly defined tumor, diffuse TGCT is spread out so that “you can't draw a circle around it,” says Bernthal. “With the localized type, you can see where it begins and where it ends, whereas with the diffuse type, it looks like the roots of a tree

Question 42

Portal blood vessels

Answer 42

They starts and terminates with blood capillary beds

Question 43

Tropic hormones

Answer 43

Hormones of which the target site is another endocrine gland

Question 44

Only part in the nephron where water reabsorption does not occur

Answer 44

Ascending limb of the loop of henle

Question 45

Gluconeogenesis

Answer 45

Gluconeogenesis is a process that transforms non-carbohydrate substrates (such as lactate, amino acids, and glycerol) into glucose

Question 46

What is the gland and the hormone that it secretes which increases immunity

Answer 46

Thymosin secreted by the thymus

Question 47

Structure secreting cerbro spinal fluid

Answer 47

Lining epithelium of cerebro ventricles

Question 48

Structural differences of sympathetic and parasympathetic nerves

Answer 48

Parasympathetic nerves contains both cranial nerves and spinal nerves originated from the brain and the spinal cord respectively while sympathetic nerves contains only spinal nerves. Sympathetic pre-ganglionic neurones are shorter and post-ganglionic neurones are longer. Parasympathetic pre-ganglionic neurones are longer and post-ganglionic neurones are shorter

Question 49

Hormones released from the hypothalamus

Answer 49

7 hormones are acting on the anterior pituitary (5 releasing hormones and 2 release inhibiting hormones) Other 2 hormones oxytocin and antidiuretic hormones are produced by the hypothalamus and stored in the posterior pituitary.

Question 50

GHRH

Answer 50

Growth hormone releasing hormone Stimulates the secretion of growth hormone (GH) from anterior pituitary

Question 51

TRH

Answer 51

Thyrotropin releasing hormone Stimulates the secretion of thyroid stimulating hormone (TSH) from anterior pituitary

Question 52

CRH

Answer 52

Corticotropin releasing hormone (CRH) Stimulates the secretion of adrenocorticotropic hormone (ACTH) from anterior pituitary

Question 53

GnRH

Answer 53

Gonadotropin releasing hormone Stimulates the secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from anterior pituitary

Question 54

PRH

Answer 54

Prolactin releasing hormone Stimulates the secretion of prolactin hormone from anterior pituitary

Question 55

PIH

Answer 55

Prolactin inhibiting hormone Inhibits the secretion of prolactin hormone from anterior pituitary

Question 56

GHRIH

Answer 56

Growth hormone release inhibiting hormone Inhibits the secretion of GH and TSH from the anterior pituitary

Question 57

Growth hormone shows

Answer 57

Both tropic and non-tropic properties

Question 58

Most abundant hormone secreted by the anterior pituitary

Answer 58

GH

Question 59

GH

Answer 59

All body cells Promotes tissue growth (especially bones and muscles) by stimulating protein synthesis; Regulates metabolism

Question 60

TSH

Answer 60

Thyroid gland Stimulates secretion of thyroid hormones (triiodothyronine and thyroxin); Stimulates growth of thyroid gland,

Question 61

ACTH

Answer 61

Adrenal cortex Stimulates secretion of adrenal cortex hormones (Glucocorticoid hormones)

Question 62

FSH

Answer 62

Ovary - Stimulates growth and development of ovarian follicle Testis - Stimulate spermatogenesis

Question 63

LH

Answer 63

Ovary- Ovulation; promote formation of corpus luteum in the ovary (structure formed after ovulation) and stimulates progesterone hormone secretion by the corpus luteum. Testes - Stimulates secretion of testosterone hormone

Question 64

Prolactin

Answer 64

Mammary gland Stimulates milk production; Together with other hormones (oxytocin) promotes milk secretion by the mammary glands.

Question 65

Difference between anterior and posterior pituitary glands

Answer 65

Posterior pituitary gland does not synthesises hormones

Question 66

ADH

Answer 66

Vasopressin, also called antidiuretic hormone Distal convoluted tubules of the nephrons and collecting ducts in the kidney Stimulates resorption of water by increasing permeability to water

Question 67

Oxytocin

Answer 67

Mammary gland-Stimulates milk ejection by stimulating contraction of smooth muscles Uterine muscles-Promotes parturition by contraction of smooth muscles

Question 68

Thyroid gland

Answer 68

Located in the neck in-front of the trachea. Releases triiodothyronine (T3) and thyroxin (T4). Increases the basal metabolic rate. Calcitonin helps to lower blood calcium ion level if it raised above the normal limit. Promotes storage of Ca2+ ions within bones and inhibits reabsorption of Ca2+ in kidney tubules.

Question 69

Parathyroid glands

Answer 69

Set of 4 small glands embedded in the posterior surface of the thyroid gland. Secretes parathyroid hormone (PTH). Main function of PTH is to promote high Ca levels by stimulating Ca2+ reabsorption, absorption through the small intestine and promotes release of Ca from bones by acting on bone destroying cells.

Question 70

Thymus gland

Answer 70

Thymus gland is located in the upper part of the chest, directly behind the sternum and between the lungs. Thymus gland secretes the hormone thymosin. Thymosin acts on the lymphocytes and regulates development and maturation of T lymphocytes.

Question 71

Pineal glands

Answer 71

Melatonin secreted by the pineal gland is involved in the regulation of biological rhythms related to reproduction and daily activity levels. Associated with coordination of circadian and diurnal rhythms of many tissues and inhibition of growth and development of sex organs before puberty.

Question 72

Adrenal glands

Answer 72

two parts: adrenal cortex (outer) and adrenal medulla (inner). Hormones secreted can mediate stress responses.

Question 73

Hormones mainly produced by the adrenal cortex and their functions

Answer 73

Glucocorticoids and mineralocorticoids. Glucocorticoids have a main effect on glucose metabolism and promote glucose synthesis from non-carbohydrate sources such as protein and fat. Main mineralocorticoid produced by the adrenal gland is aldosterone which is involved in maintaining water and electrolyte balance Adrenal cortex hormones are steroids

Question 74

Main glucocorticoid produced by the adrenal gland

Answer 74

Cortisol

Question 75

Main mineralocorticoid produced by the adrenal gland

Answer 75

Aldesterone

Question 76

Hormones mainly produced by the adrenal medulla and their functions

Answer 76

Adrenaline (epinephrine) and noradrenaline (norepinephrine) which could mediate ‘short term stress responses which can potentiate the “fight or flight response” by increasing the heart rate and blood pressure, diverting blood to essential organs (i.e heart, brain, skeletal muscles) and increasing metabolic rate etc

Question 77

Islets of Langerhans in the pancreas

Answer 77

The endocrine part of the pancreas is the islets of Langerhans. Liver and skeletal muscles are the main target sites of these hormones

Question 78

Gonads

Answer 78

Paired female gonads (ovaries) are located in the pelvic cavity. Paired male gonads (testes) lie in the scrotum. Ovarian follicle produces the hormone estrogen. In addition ovaries and testes secrete inhibin that inhibits secretion of FSH from anterior pituitary.

Question 79

Regulatory systems operating with positive feedback mechanisms

Answer 79

Positive feedback mechanisms involving oxytocin hormone operate in childbirth and breast milk ejection.

Question 80

Type 2 diabetes mellitus

Answer 80

Known as non-insulin dependant diabetes mellitus. | Even though insulin is produced and secreted into the blood, target cells fail to take up glucose from the blood.

Question 81

Hyperthyroidism

Answer 81

occurs due to exposure of body tissues to excessive levels of T3 and T4. Common effects include increased basal metabolic rate, weight loss, warm, sweaty skin and diarrhea. Some conditions lead to bulging of eyes Treatment may include surgical removal of part or all of the thyroid gland and using medicine to block thyroid hormone synthesis.

Question 82

Hypothyroidism

Answer 82

Insufficient secretion of thyroid hormones (T3 and T4) can be due to lack of TSH production by anterior pituitary or iodine deficiency in diet. Common effects include low basal metabolic rate, weight gain, lethargy, dry, cold skin and constipation.

Question 83

Normal body temperature of man is typically

Answer 83

37'C (36.50'C – 37.50'C)

Question 84

Heat loss mechanisms

Answer 84

- dilation of blood vessels in the skin which causes filling of blood capillaries with warm blood and radiating heat from the skin surface - increase sweat secretion from the sweat glands which promotes heat dissipation through evaporative cooling

Question 85

Heat gain mechanisms

Answer 85

- constriction of blood vessels in the skin which divert the blood from the skin to deeper tissues thereby reducing heat loss through the skin surface - shivering: rapid repetitive contractions of skeletal muscles to generate heat - contracting hair erector muscles to generate heat to some extent - stimulating secretions of more thyroid hormones (e.g. thyroxin) and adrenalin into the blood which increase the metabolic rate and cellular metabolism (especially oxidation of fat in the liver) to produce more heat

Question 86

Normal bood glucose level

Answer 86

70 – 110 mg/100 mL (while fasting)

Question 87

Homeostatic blood osmolarity level

Answer 87

300 mOsmol/l

Question 88

Role of liver in homeostasis

Answer 88

Carbohydrates, protein and fat metabolism Breakdown of erythrocytes and defence against microbial infections Detoxification of drugs and toxicants Production of heat Storage of nutrients Inactivation of hormones Secretion of bile

Question 89

3 neurones in the reflex arc

Answer 89

Afferent (sensory) Efferent (motor) Inter

Question 90

Blance receptors are found in the

Answer 90

Ampullae of semi-circular canals and in the vestibules (utricle and saccule)

Question 91

Shunt vessels

Answer 91

A blood vessel that links an artery directly to a vein