asas psikologi asas biologi dalam tingkah laku

Asas Biologi Dalam Tingkah Laku

MINGGU 2

BIOPSYCHOLOGY

• Kajian saintifik tentang hubuungkait biologi dan tingkah laku

• Contoh persoalan:– Kenapa rasa lapar?– Apabila rasa sangat lapar, apa yang anda rasa?

• Isu penting dalam biopsychology:– Struktur dan fungsi neuron– Struktur dan fungsi sistem saraf– Sistem endokrin

NEURON

(Cell Body)

STRUKTUR ASAS NEURON

• Bagaimanakah maklumat yang diterima melalui deria boleh menghasilkan tindak balas tubuh badan, sensation (perasaan), dan tingkah laku overt?

• Ini semua disebabkan oleh NEURON.• Neuron terbahagi kepada 3 bahagian:

1. Cell Body (Soma)2. Axon3. Dendrite


• Dendrite membawa maklumat ke cell body, axon pula membawa maklumat dari cell body ke axon terminal.

• Komunikasi neuron adalah satu hala.• Axon diliputi oleh myelin sheath.• Antara myelin sheath ada ruang (gap).• Myelin sheath dan ruang ini memainkan

peranan penting dalam menentukan sejauh mana maklumat dapat dipindahkan.


• Dalam myelin sheath juga mengandungi set neuron yang disebut sebagai glial cells.

• Hujung axon terbahagi kepada cabang yang disebut sebagai axon terminals yang rapat kedudukannya tetapi tidak menyentuh neuron yang lain.

• Ruang antara hujung axon terminal dengan neuron yang lain disebut sebagai synapse.

FUNGSI ASAS NEURON

KOMUNIKASI DALAM NEURON

• Apabila neuron dalam keadaan rehat, terdapat sejumlah kecil cas elektrik (-70 millivolts) dalam cell membrane .

• Cas elektrik ini disebabkan banyak ion positif dan negatif wujud di luar dan di dalam sel. Keadaan ini menghasilkan cas negatif dalam membrane cell, manakala di luarnya adalah cas positif.

• Neuron terus berkerja bagai memastikan keadaan resting potential dan action potential sentiasa berterusan iaitu dengan mengepam ion positif balik ke luar setelah memasuki cell, dan mengepam masuk semula ion negatif yang telah keluar dari cell secara terus menerus.

• Komunikasi dalam neuron bergerak dari axon ke axon melalui ruang antara axon yang disebut sebagai nodes of ranvier.

• Kelajuan komunikasi ini menjangkau 270 batu per jam.

KOMUNIKASI ANTARA NEURON

• Proses action potential berlaku sepanjang axon hingga ke axon terminal.

• Di antara axon terminal terdapat banyak struktur synaptic vesicles yang mengandungi neurotransmitter yang membawa maklumat neuron ke hujung axon terminal.

• Neurotransmitter ini dilepaskan ke synapse (ruang antara axon terminal dengan dendrite neuron lain).

• Action potential terus berlaku dalam perjalanan neurotransmitter melalui synapse ini.

• Neurotransmitter ini kemudiannya sampai ke bahagian penerima (receptor) yang terletak di hujung dendrite neuron lain, dan terus bergabung.

• Bahagian penerima ini adalah sejenis molekul protein yang kompleks, yang hanya menerima unsur-unsur kimia yang sepadan dengannya.

• Oleh itu neurotransmitter tidak semestinya melepaskan maklumat melalui synapse terus kepada neuron terdekat tetapi boleh juga melepaskannya melalui body fluids ke sel-sel yang lain.

• Selepas neurotransmitter dilepaskan ke synapse mungkin akan berlaku 2 keadaan:– Sama ada ia di ambil balik masuk ke dalam axon

terminal asal (reuptake), atau– Ia di nyahktifkan oleh enzim-enzim yang terdapat

di ruangan synapse.

• Jika neurotransmitter mengandungi unsur yang bersifat excitatory, maka proses depolarization, iaitu penghantaran maklumat dalam cell membrane neuron kedua adalah menjadi lebih aktif.

• Tetapi jika neurotransmitter mengandungi unsur yang bersifat inhibitory, akan menyebabkan hyperpolarize, iaitu penghantaran maklumat dalam cell membrane neuron kedua menjadi lemah.

• Synapses dan DadahSesetngah jenis dadah menghasilkan kesan psikologi dengan meningkatkan atau mengurangkan kuantiti neurotransmitter di ruang synapse. Terdapat jenis dadah yang berkerja di bahagian penerima (receptor), berperanan untuk menghalang atau mengganggu penyerapan neurotransmitter. Contohnya, dadah (dopamine) yang menghalang bahagian penerima sebagai dapat mengurangkan simptom skizofrenia.

NEUROTRANSMITTER: KUNCI BAHAN KIMIA KE OTAK

• Sekurang-kurangnya terdapat 9 unsur bahan, manakala 40 atau lebih peptides (kombinasi asid amino) yang berfungsi sebagai neurotransmitter.

• Setiap jenis neurotransmitter itu mengandungi fungsi tertentu dan berada dilokasi tertentu.

NEUROTRANSMITTER KESAN DAN LOKASI

Acetylcholine (ACh) Involved in a wide variety of behaviors and emotions, including pleasure. Implicated in schizophrenia and Parkinson’s disease. Distributed widely throughout the central nervous system, where it is involved in arousal, attention, memory, motivation, and movement.

Dopamine Involved in muscle action through presence at neuromuscular junctions (specialized type of synapse where neuronsconnect to muscle cells). Degeneration of neurons that produce ACh have been linked to Alzheimer’s disease.Too much can lead to spasms and tremors; too little, to paralysis or torpor.


Serotonin Involved in the regulation of sleep, dreaming, mood, eating, pain, and aggressive behavior. Implicated in depression.

Norepinephrine Affects arousal, wakefulness, learning, memory, and mood.

Endorphins Involved in the inhibition of pain. Released during strenuous exercise. May be responsible for “runner’s high.”

Glutamate Involved in long-term memory and the perception of pain.


GABA(Gamma amino butyric acid)

A largely inhibitory neurotransmitter distributed widely throughout the central nervous system. Implicated in sleep and eating disorders. Low levels of GABA have also been linked to extreme anxiety.

Glycene Principally responsible for inhibition in the spinal cord and lower brain canters

SISTEM SARAF (THE NERVOUS SYSTEM)

THE CENTRAL NERVOUS SYSTEM (SISTEM SARAF PUSAT)

THE PERIPHERAL NERVOUS SYSTEM(SISTEM SARAF PERIFERAL)

BAHAGIAN SISTEM SARAF

SISTEM SARAF PUSAT

• Sistem saraf pusat mengawal kebanyakan fungsi tubuh dan minda.

• Mengandungi 2 bahagian iaitu otak dan tulang belakang.

• Otak – pusat pemikiran, pentafsir persekitaran, asas kawalan tubuh badan.

• Tulang belakang (spinal cord) – jalan penghubung antara tubuh badan dan otak. Membawa maklumat daripada receptor ke otak melalui pelbagai jenis saraf dan membawa maklumat dari otak ke otot dan kelenjar melalui saraf juga. Kunci utama tindak balas refleks.

SISTEM SARAF PERIFERAL

• Mengandungi saraf, serta sejumlah axon daripada neuron, yang menghubungkan sistem saraf pusat dengan organ deria dan dengan otot dan kelenjar di seluruh tubuh badan.

• Terbahagi kepada 2 bahagian:– Sistem Saraf Somatic – Sistem Saraf Autonomic

• Sistem Saraf Somatic– Menghubungkan sistem saraf pusat dengan otot

voluntary di seluruh tubuh badan.

• Sistem Saraf Autonomic– Menghubungkan sistem saraf pusat dengan

kelenjar dan organ dalaman.– Mengandungi 2 bahagian:

• Sistem Saraf Simpetatik• Sistem Saraf Parasimpetatik

• Sistem Saraf Simpetatik:– Menyediakan tubuh badan untuk menggunakan

tenaga, seperti dalam aktiviti fizikal.– Rangsangan sistem ini mengakibatkan peningkatan

kadar nadi, dan peningkatan tekanan darah.• Sistem Saraf Parasimpatetik

– Merangsang proses untuk menyimpan tenaga.– Mengakibatkan kadar nadi perlahan, tekanan darah

menurun, dan peralihan darah keluar dari otot rangka (seperti otot lengan dan kaki) ke sistem perkumuhan.

OTAK (THE BRAIN)

STRUKTUR OTAK

• Terdapat 4 stuktur utama otak iaitu:– Cerebrum– Cerebellum– Brain stem– Limbic System

CerebrumBahagian Fungsi

Frontal Lobe Behavior, Abstract thought processes, Problem solving, Attention, Creative thought, Some emotion, Intellect, Reflection, Judgment, Initiative, Inhibition, Coordination of movements, Generalized and mass movements, Some eye movements, Sense of smell, Muscle movements, Skilled movements, Some motor skills, Physical reaction, Libido (sexual urges)

Occipital Lobe Vision, Reading

Parietal Lobe Sense of touch (tactile senstation), Appreciation of form through touch (stereognosis), Response to internal stimuli (proprioception), Sensory combination and comprehension, Some language and reading functions, Some visual functions

Bahagian Fungsi

Temporal Lobe Auditory memories, Some hearing, Visual memories, Some vision pathways, Other memory, Music, Fear, Some language, Some speech, Some behavior amd emotions, Sense of identity

Right Hemisphere (the representational hemisphere)

The right hemisphere controls the left side of the body, Temporal and spatial relationships, Analyzing nonverbal information, Communicating emotion

Left Hemisphere (the categorical hemisphere)

The left hemisphere controls the right side of the body, Produce and understand language

Corpus Callosum

Communication between the left and right side of the brain

Cerebellum

• Balance • Posture • Cardiac, respiratory, and vasomotor centers

The Brain Stem

• Underneath the limbic system is the brain stem. This structure is responsible for basic vital life functions such as breathing, heartbeat, and blood pressure. Scientists say that this is the "simplest" part of human brains because animals' entire brains, such as reptiles (who appear early on the evolutionary scale) resemble our brain stem.

Bahagian Fungsi

Midbrain The rostral part of the brain stem, which includes the tectum and tegmentum. It is involved in functions such as vision, hearing, eye movement, and body movement. The anterior part has the cerebral peduncle, which is a huge bundle of axons traveling from the cerebral cortex through the brain stem and these fibers (along with other structures) are important for voluntary motor function

Pons part of the metencephalon in the hindbrain. It is involved in motor control and sensory analysis... for example, information from the ear first enters the brain in the pons. It has parts that are important for the level of consciousness and for sleep. Some structures within the pons are linked to the cerebellum, thus are involved in movement and posture.

Medulla Oblongata

this structure is the caudal-most part of the brain stem, between the pons and spinal cord. It is responsible for maintaining vital body functions, such as breathing and heartrate

The Limbic System

• The limbic system, often referred to as the "emotional brain", is found buried within the cerebrum. Like the cerebellum, evolutionarily the structure is rather old.

• This system contains the thalamus, hypothalamus, amygdala, and hippocampus. Here is a visual representation of this system, from a midsagittal view of the human brain:

Bahagian Fungsi

Thalamus a large mass of gray matter deeply situated in the forebrain at the topmost portion of the diencephalon. The structure has sensory and motor functions. Almost all sensory information enters this structure where neurons send that information to the overlying cortex. Axons from every sensory system (except olfaction) synapse here as the last relay site before the information reaches the cerebral cortex.

Hypothalamus part of the diencephalon, ventral to the thalamus. The structure is involved in functions including homeostasis, emotion, thirst, hunger, circadian rhythms, and control of the autonomic nervous system. In addition, it controls the pituitary.

Bahagian Fungsi

Amygdala- part of the telencephalon, located in the temporal lobe; involved in memory, emotion, and fear. The amygdala is both large and just beneath the surface of the front, medial part of the temporal lobe where it causes the bulge on the surface called the uncus. This is a component of the limbic system.

Hippocampus the portion of the cerebral hemispheres in basal medial part of the temporal lobe. This part of the brain is important for learning and memory . . . for converting short term memory to more permanent memory, and for recalling spatial relationships in the world about us

SISTEM ENDOKRIN

• Hypothalamus memainkan peranan penting dalam sistem endokrin.

• Kelenjar endokrin merembeskan hormon.• Hormon yang berhubung dan memberi kesan

pada sistem saraf disebut – Neurohormones.• Neurohormones sama seperti

neurotransmitter mempengaruhi aktiviti neuro.

• Hypothalamus merangsang proses rembesan hormon melalui kelenjar pituitari (pituitary gland).

• Pituitary gland:– terletak di bawah hypothalamus – mengawal dan

menyelia semua aktiviti kelenjar.– Terdapat 2 bahagian:

• Posterior pituitary • Anterior pituitary

• Posterior pituitary – Merembeskan hormon yang mengawal selia

proses penyerapan semula air oleh buah pinggang– Bagi wanita pula, penghasilan susu

• Anterior pituitary– Merembeskan hormon yang mengawal selia lain-

lain aktiviti kelenjar seperti:• ACTH merangsang adrenal cortex menyebabkan

penghasilan cortisone, cortisone pula memberi kesan kepada tubuh badan

Endocrine Glands

Hormone Produced Function

Pituitary Gland

Antidiuretic hormone (vasopressin) Its primary function is to help the kidneys to retain water in the body.

Corticotropin (ACTH)

These hormones are there for regulating the hormones of the adrenal glands.

Human growth hormone

As the name suggests, it is associated with the growth and development of the body. It is also known to encourage the production of protein.

Oxytocin Helps contraction of the uterus muscles and mammary ducts in the breast.

Prolactin The process of milk production in the mammary glands is carried out by this hormone.

Thyroid-stimulating hormone

Again, as the name suggests, this hormone is responsible for the functions of the hormones of the thyroid gland.

Endocrine Glands


Thyroid gland

Thyroid hormone The body's metabolic rate is controlled by this hormone.

Calcitonin It regulates calcium balance in species other than humans. Studies are still in progress to find its function in the human species.Read more at

Pancreas Glucagon The blood sugar level raises with its help.

Insulin It helps in lowering the blood sugar level. Apart from this, metabolism of sugar, protein, and fat are also carried out with its help.

Endocrine Glands


Adrenal glands

Aldosterone Responsible for maintaining the salt and water balance in the body.

Cortisol The functions which regulate the blood sugar level, blood pressure, and muscle strength in the body is controlled by the cortisol.

Dehydroepiandrosterone (DHEA)

It is related to the immune system, bones growth and also to the mood of an individual.

Epinephrine and norepinephrine

The nervous system is associated with it.

Endocrine Glands


Hypothalamus

Hormone-releasing hormone (GHRH)

It is known as the growth hormone.

Somatostatin It works by regulating the endocrine system.

Dopamine It inhibits the release of prolactin from the anterior lobe of the pituitary gland.

Endocrine Glands


Parathyroid glands

Parathyroid hormone Calcium and phosphorus are eliminated from the body with the help of this hormone, which is also responsible for bone formation.

Pineal gland

Melatonin Maintains the body's circadian rhythm, apart from what has been mentioned in the earlier segment.

Ovaries Ovaries Estrogen The female sexual characteristics and the function of the reproductive system are influenced by the secretion of this hormone.

Progesterone It plays vital roles in pregnancy. For instance, it helps in preparing the lining of the uterus for the fertilized egg to get implanted.

Testes Testosterone Men's sexual characteristics and the nature of the reproductive system, involve the secretion of this hormone.

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